@article {pmid34525167,
year = {2021},
author = {Rivas, DP and Hedgecock, ND and Stebe, KJ and Leheny, RL},
title = {Dynamic and mechanical evolution of an oil-water interface during bacterial biofilm formation.},
journal = {Soft matter},
volume = {17},
number = {35},
pages = {8195-8210},
doi = {10.1039/d1sm00795e},
pmid = {34525167},
issn = {1744-6848},
abstract = {We present an experimental study combining particle tracking, active microrheology, and differential dynamic microscopy (DDM) to investigate the dynamics and rheology of an oil-water interface during biofilm formation by the bacteria Pseudomonas Aeruginosa PA14. The interface transitions from an active fluid dominated by the swimming motion of adsorbed bacteria at early age to an active viscoelastic system at late ages when the biofilm is established. The microrheology measurements using microscale magnetic rods indicate that the biofilm behaves as a viscoelastic solid at late age. The bacteria motility at the interface during the biofilm formation, which is characterized in the DDM measurements, evolves from diffusive motion at early age to constrained, quasi-localized motion at later age. Similarly, the mobility of passively moving colloidal spheres at the interface decreases significantly with increasing interface age and shows a dependence on sphere size after biofilm formation that is orders-of-magnitude larger than that expected in a homogeneous system in equilibrium. We attribute this anomalous size dependence to either length-scale-dependent rheology of the biofilm or widely differing effects of the bacteria activity on the motion of spheres of different sizes.},
}

@article {pmid34524972,
year = {2021},
author = {Gajdács, M and Kárpáti, K and Nagy, ÁL and Gugolya, M and Stájer, A and Burián, K},
title = {Association between biofilm-production and antibiotic resistance in Escherichia coli isolates: A laboratory-based case study and a literature review.},
journal = {Acta microbiologica et immunologica Hungarica},
volume = {},
number = {},
pages = {},
doi = {10.1556/030.2021.01487},
pmid = {34524972},
issn = {1588-2640},
abstract = {Bacteria can enhance their survival by attaching to inanimate surfaces or tissues, and presenting as multicellular communities encased in a protective extracellular matrix called biofilm. There has been pronounced interest in assessing the relationship between the antibiotic resistant phenotype and biofilm-production in clinically-relevant pathogens. The aim of the present paper was to provide additional experimental results on the topic, testing the biofilm-forming capacity of Escherichia coli isolates using in vitro methods in the context of their antibiotic resistance in the form of a laboratory case study, in addition to provide a comprehensive review of the subject. In our case study, a total of two hundred and fifty (n = 250) E. coli isolates, originating from either clean-catch urine samples (n = 125) or invasive samples (n = 125) were included. The colony morphology of isolates were recorded after 24h, while antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method. Biofilm-formation of the isolates was assessed with the crystal violet tube-adherence method. Altogether 57 isolates (22.8%) isolates were multidrug resistant (MDR), 89 isolates (35.6%) produced large colonies (>3 mm), mucoid variant colonies were produced in 131 cases (52.4%), and 108 (43.2%) were positive for biofilm formation. Biofilm-producers were less common among isolates resistant to third-generation cephalosporins and trimethoprim-sulfamethoxazole (P = 0.043 and P = 0.023, respectively). Biofilms facilitate a protective growth strategy in bacteria, ensuring safety against environmental stressors, components of the immune system and noxious chemical agents. Being an integral part of bacterial physiology, biofilm-formation is interdependent with the expression of other virulence factors (especially adhesins) and quorum sensing signal molecules. More research is required to allow for the full understanding of the interplay between the MDR phenotype and biofilm-production, which will facilitate the development of novel therapeutic strategies.},
}

@article {pmid34524634,
year = {2021},
author = {Liu, Z and Zhao, Z and Zeng, K and Xia, Y and Xu, W and Wang, R and Guo, J and Xie, H},
title = {Functional Immobilization of a Biofilm-Releasing Glycoside Hydrolase Dispersin B on Magnetic Nanoparticles.},
journal = {Applied biochemistry and biotechnology},
volume = {},
number = {},
pages = {},
pmid = {34524634},
issn = {1559-0291},
support = {31771032//National Natural Science Foundation of China/ ; 51911530153//National Natural Science Foundation of China/ ; },
abstract = {Dispersin B (DspB) is a member of glycoside hydrolase family 20 (GH20) and catalyzes degradation of biofilms forming by pathogenic bacteria such as Staphylococcus aureus. Magnetoreceptor (MagR) is a magnetic protein that can be used as a fusion partner for functionally immobilizing proteins on magnetic surfaces. In the present study, a recombinant protein DspB-MagR was constructed by fusing MagR to the C-terminus of DspB and expressed in Escherichia coli. Magnetic immobilization of purified DspB-MagR on magnetic core-shell structured Fe3O4@SiO2 nanoparticles was achieved and characterized by means of various techniques including SDS-PAGE, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential measurement, and scanning electron microscopy. It was evaluated the influence of temperature, pH, and storage time on the performance of immobilized DspB-MagR on Fe3O4@SiO2 nanoparticles. Removal of biofilms forming by Staphylococcus aureus and other medical sourced bacterial species was achieved by using Fe3O4@SiO2 nanoparticles loading with DspB-MagR. This work promoted potential applications of DspB and similar enzymes for medical purposes.},
}

@article {pmid34523997,
year = {2021},
author = {Staats, A and Burback, PW and Eltobgy, M and Parker, DM and Amer, AO and Wozniak, DJ and Wang, SH and Stevenson, KB and Urish, KL and Stoodley, P},
title = {Synovial Fluid-Induced Aggregation Occurs across Staphylococcus aureus Clinical Isolates and is Mechanistically Independent of Attached Biofilm Formation.},
journal = {Microbiology spectrum},
volume = {},
number = {},
pages = {e0026721},
doi = {10.1128/Spectrum.00267-21},
pmid = {34523997},
issn = {2165-0497},
abstract = {Rapid synovial fluid-induced aggregation of Staphylococcus aureus is currently being investigated as an important factor in the establishment of periprosthetic joint infections (PJIs). Pathogenic advantages of aggregate formation have been well documented in vitro, including recalcitrance to antibiotics and protection from host immune defenses. The objective of the present work was to determine the strain dependency of synovial fluid-induced aggregation by measuring the degree of aggregation of 21 clinical S. aureus isolates cultured from either PJI or bloodstream infections using imaging and flow cytometry. Furthermore, by measuring attached bacterial biomass using a conventional crystal violet assay, we assessed whether there is a correlation between the aggregative phenotype and surface-associated biofilm formation. While all of the isolates were stimulated to aggregate upon exposure to bovine synovial fluid (BSF) and human serum (HS), the extent of aggregation was highly variable between individual strains. Interestingly, the PJI isolates aggregated significantly more upon BSF exposure than those isolated from bloodstream infections. While we were able to stimulate biofilm formation with all of the isolates in growth medium, supplementation with either synovial fluid or human serum inhibited bacterial surface attachment over a 24 h incubation. Surprisingly, there was no correlation between the degree of synovial fluid-induced aggregation and quantity of surface-associated biofilm as measured by a conventional biofilm assay without host fluid supplementation. Taken together, our findings suggest that synovial fluid-induced aggregation appears to be widespread among S. aureus strains and mechanistically independent of biofilm formation. IMPORTANCE Bacterial infections of hip and knee implants are rare but devastating complications of orthopedic surgery. Despite a widespread appreciation of the considerable financial, physical, and emotional burden associated with the development of a prosthetic joint infection, the establishment of bacteria in the synovial joint remains poorly understood. It has been shown that immediately upon exposure to synovial fluid, the viscous fluid in the joint, Staphylococcus aureus rapidly forms aggregates which are resistant to antibiotics and host immune cell clearance. The bacterial virulence associated with aggregate formation is likely a step in the establishment of prosthetic joint infection, and as such, it has the potential to be a potent target of prevention. We hope that this work contributes to the future development of therapeutics targeting synovial fluid-induced aggregation to better prevent and treat these infections.},
}

@article {pmid34523579,
year = {2021},
author = {Fung, AHY and Rao, S and Ngan, WY and Sekoai, PT and Touyon, L and Ho, TM and Wong, KP and Habimana, O},
title = {Exploring the optimization of aerobic food waste digestion efficiency through the engineering of functional biofilm Bio-carriers.},
journal = {Bioresource technology},
volume = {341},
number = {},
pages = {125869},
doi = {10.1016/j.biortech.2021.125869},
pmid = {34523579},
issn = {1873-2976},
abstract = {The possibility of breaking down cellulose-rich food waste through biofilm engineering was investigated. Six previously isolated strains from naturally degrading fruits and vegetables, screened for biofilm-forming ability and cellulolytic activity, were selected to enrich a biocarrier seeding microbial consortium. The food waste model used in this study was cabbage which was aerobically digested under repeated water rinsing and regular effluent drainage. The engineered biocarrier biofilm's functionality was evaluated by tracing microbial succession following metagenomic sequencing, quantitative PCR, scanning electron microscopy, and cellulolytic activity before and after the digestion processes. The engineered microbial consortium demonstrated superior biofilm-forming ability on biocarriers than the original microbial consortium and generally displayed a higher cellulolytic activity. The presented study provides one of the few studies of food waste aerobic digestion using engineered biofilms. Insights presented in this study could help further optimize aerobic food waste digestion.},
}

@article {pmid34523551,
year = {2021},
author = {Song, Z and Su, X and Li, P and Sun, F and Dong, W and Zhao, Z and Wen, Z and Liao, R},
title = {Facial fabricated biocompatible homogeneous biocarriers involving biochar to enhance denitrification performance in an anoxic moving bed biofilm reactor.},
journal = {Bioresource technology},
volume = {341},
number = {},
pages = {125866},
doi = {10.1016/j.biortech.2021.125866},
pmid = {34523551},
issn = {1873-2976},
abstract = {Biochar prepared from pineapple peel was facially combined with polyurethane sponges for the first time to form homogeneous biocompatible biocarriers, which can enhance denitrification performance in an anoxic MBBR. The experiments showed that a higher NO3--N removal efficiency (96.24 ± 1.3%) and kinetic constant (0.26 h-1) were obtained in the MBBR employing these new biocarriers (B-MBBR), compared with a control MBBR with polyurethane sponges (C-MBBR). The attached and suspended biomass of the B-MBBR was increased by 47% and 26%, respectively. Biochar significantly enhanced the abundance of functional bacteria in terms of promoting biofilm (i.e., Leptonema), denitrifying bacteria (i.e., Thauera, Enterobacter and Pseudomonas) and electroactive bacteria (i.e., Geobacter) in the B-MBBR. Meanwhile, based on the content of coenzyme I (NADH) and denitrifying enzymes, biochar would also enhance electron transport activity for denitrification. Consequently, these facial prepared biocarriers are effective to enhance denitrification performance in MBBR with application significance.},
}

@article {pmid34523549,
year = {2021},
author = {Huang, T and Zhao, J and Hu, B and Zhao, J and Yuan, C},
title = {Effective restoration of partial nitritation and anammox biofilm process by short-term hydroxylamine dosing: Mechanism and microbial interaction.},
journal = {Bioresource technology},
volume = {341},
number = {},
pages = {125910},
doi = {10.1016/j.biortech.2021.125910},
pmid = {34523549},
issn = {1873-2976},
abstract = {The one-stage partial nitritation and anammox (PN-A) process frequently experiences deterioration from ammonium accumulation and nitrate build-up. In this study, hydroxylamine was dosed to restore the process from deterioration in a continuously aerated PN-A sequencing biofilm batch reactor, and the impact of hydroxylamine on the metabolism of PN-A process was studied. PN-A process was totally restored in 5 days via 10 mg N·L-1 hydroxylamine dosing, reducing nitrate-produced/ammonium-removed ratio from 28.5% to less than 11.0%. hydroxylamine dosing promoted biological production of nitric oxide and nitrous oxide and reduced the production of nitrate in the PN-A process. This study advanced the understanding of the metabolism versatility of hydroxylamine and nitric oxide as well as their function in interaction between aerobic ammonium oxidation bacteria and anaerobic ammonium oxidation bacteria, and proposed the potential application of hydroxylamine dosing in ammonium-contained wastewater treatment.},
}

@article {pmid34522977,
year = {2021},
author = {Sun, X and Xiang, J},
title = {Mechanism Underlying the Role of LuxR Family Transcriptional Regulator abaR in Biofilm Formation by Acinetobacter baumannii.},
journal = {Current microbiology},
volume = {},
number = {},
pages = {},
pmid = {34522977},
issn = {1432-0991},
support = {16ZR1420800//Natural Science Foundation of Shanghai Municipal Science and Technology Commission/ ; },
abstract = {Our study attempted to explore the mechanism underlying the role of LuxR family transcriptional regulator abaR in biofilm formation by Acinetobacter baumannii. The abaR gene was knocked out in ATCC 17978 strain using homologous recombination method. The growth curve and biofilm formation were measured in the wild type and abaR gene knockdown strains. Transcriptome sequencing was performed in the wild type and abaR gene knockdown strains following 8 h of culture. The growth curve in the abaR gene knockdown strain was similar to that of the wild-type strain. Biofilm formation significantly declined in the abaR gene knockdown strain at 8 and 48 h after culture. A total of 137 differentially expressed genes (DEGs) were obtained including 20 downregulated DEGs and 117 upregulated DEGs. Genes with differential expression were closely related to viral procapsid maturation (GO:0046797), acetoin catabolism (GO:0045150), carbon metabolism (ko01200), and the glycolysis/gluconeogenesis (ko00010)-related pathways. The results of the eight verified expression DEGs were consistent with the results predicted by bioinformatics. AbaR gene knockdown significantly affected biofilm formation by A. baumannii ATCC 17978 strain. The glycolysis/gluconeogenesis pathways were significantly dysregulated and induced by abaR gene knockdown in A. baumannii.},
}

@article {pmid34522106,
year = {2021},
author = {Yang, F and Liu, C and Ji, J and Cao, W and Ding, B and Xu, X},
title = {Molecular Characteristics, Antimicrobial Resistance, and Biofilm Formation of Pseudomonas aeruginosa Isolated from Patients with Aural Infections in Shanghai, China.},
journal = {Infection and drug resistance},
volume = {14},
number = {},
pages = {3637-3645},
doi = {10.2147/IDR.S328781},
pmid = {34522106},
issn = {1178-6973},
abstract = {Purpose: To investigate molecular characteristics, antimicrobial resistance, and biofilm formation ability of Pseudomonas aeruginosa strains isolated from patients with aural infections.

Methods: Isolates (n = 199) were collected from ear discharges of patients with aural infections from January 2019 to December 2020. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute guidelines. All isolates were subjected to multilocus sequence typing (MLST) with amplification and sequencing of seven housekeeping genes. Biofilm formation and eradication were quantitatively assessed in microtiter plates. Genes associated with biofilm formation and the quinolone-resistance-determining region (QRDR) of genes gyrA and parC were investigated using polymerase chain reaction amplification and sequencing.

Results: Of the 199 P. aeruginosa strains isolated, 109 (54.77%) were from females and 90 (45.23%) were from males. The isolates exhibited very low rates of resistance to most antibiotics tested, including piperacillin (1.51%), ceftazidime (0.50%), and imipenem (3.52%); however, the quinolones ciprofloxacin (80.40%) and levofloxacin (82.91%) were notable exceptions. The QRDR sequence results of the quinolone-resistant P. aeruginosa isolates showed Thr83Ile (n = 155) was the most common amino acid mutation in gyrA (n = 165), while Ser87Leu (n = 157) was widely detected in parC (n = 165). MLST analysis identified 34 sequence types (STs) with most isolates belonging to ST316 (73.87%). Almost all of the P. aeruginosa isolates (96.98%) produced biofilms and biofilm-forming genes algD (98.49%), pslD (96.98%), and pelF (96.48%) were highly prevalent.

Conclusion: The P. aeruginosa strains isolated from aural discharges in this study exhibited very low rates of resistance to most antibiotics tested, except for the resistance rates to quinolones, which were relatively high. The isolates also exhibited a strong biofilm formation ability and low susceptibility to eradication, indicating that more effective drugs and treatment methods are needed to combat these infections.},
}

@article {pmid34521475,
year = {2021},
author = {Du, C and Huo, X and Gu, H and Wu, D and Hu, Y},
title = {Acid resistance system CadBA is implicated in acid tolerance and biofilm formation and is identified as a new virulence factor of Edwardsiella tarda.},
journal = {Veterinary research},
volume = {52},
number = {1},
pages = {117},
pmid = {34521475},
issn = {1297-9716},
support = {2019CXTD413//Natural Science Foundation of Hunan Province/ ; },
abstract = {Edwardsiella tarda is a facultative intracellular pathogen in humans and animals. The Gram-negative bacterium is widely considered a potentially important bacterial pathogen. Adaptation to acid stress is important for the transmission of intestinal microbes, so the acid-resistance (AR) system is essential. However, the AR systems of E. tarda are totally unknown. In this study, a lysine-dependent acid resistance (LDAR) system in E. tarda, CadBA, was characterized and identified. CadB is a membrane protein and shares high homology with the lysine/cadaverine antiporter. CadA contains a PLP-binding core domain and a pyridoxal phosphate-binding motif. It shares high homology with lysine decarboxylase. cadB and cadA are co-transcribed under one operon. To study the function of the cadBA operon, isogenic cadA, cadB and cadBA deletion mutant strains TX01ΔcadA, TX01ΔcadB and TX01ΔcadBA were constructed. When cultured under normal conditions, the wild type strain and three mutants exhibited the same growth performance. However, when cultured under acid conditions, the growth of three mutants, especially TX01ΔcadA, were obviously retarded, compared to the wild strain TX01, which indicates the important involvement of the cadBA operon in acid resistance. The deletion of cadB or cadA, especially cadBA, significantly attenuated bacterial activity of lysine decarboxylase, suggesting the vital participation of cadBA operon in lysine metabolism, which is closely related to acid resistance. The mutations of cadBA operon enhanced bacterial biofilm formation, especially under acid conditions. The deletions of the cadBA operon reduced bacterial adhesion and invasion to Hela cells. Consistently, the deficiency of cadBA operon abated bacterial survival and replication in macrophages, and decreased bacterial dissemination in fish tissues. Our results also show that the expression of cadBA operon and regulator cadC were up-regulated upon acid stress, and CadC rigorously regulated the expression of cadBA operon, especially under acid conditions. These findings demonstrate that the AR CadBA system was a requisite for the resistance of E. tarda against acid stress, and played a critical role in bacterial infection of host cells and in host tissues. This is the first study about the acid resistance system of E. tarda and provides new insights into the acid-resistance mechanism and pathogenesis of E. tarda.},
}

@article {pmid34519903,
year = {2021},
author = {Kijkla, P and Wang, D and Mohamed, ME and Saleh, MA and Kumseranee, S and Punpruk, S and Gu, T},
title = {Efficacy of glutaraldehyde enhancement by D-limonene in the mitigation of biocorrosion of carbon steel by an oilfield biofilm consortium.},
journal = {World journal of microbiology & biotechnology},
volume = {37},
number = {10},
pages = {174},
pmid = {34519903},
issn = {1573-0972},
abstract = {Microbiologically influenced corrosion (MIC) is one of the major corrosion threats in the oil and gas industry. It is caused by environmental biofilms. Glutaraldehyde is a popular green biocide for mitigating biofilms and MIC. This work investigated the efficacy of glutaraldehyde enhancement by food-grade green chemical D-limonene in the biofilm prevention and MIC mitigation using a mixed-culture oilfield biofilm consortium. After 7 days of incubation at 37 °C in enriched artificial seawater in 125 mL anaerobic vials, the 100 ppm (w/w) glutaraldehyde + 200 ppm D-limonene combination treatment reduced the sessile cell counts on C1018 carbon steel coupons by 2.1-log, 1.7-log, and 2.3-log for sulfate reducing bacteria, acid producing bacteria, and general heterotrophic bacteria, respectively in comparison with the untreated control. The treatment achieved 68% weight loss reduction and 78% pit depth reduction. The 100 ppm glutaraldehyde + 200 ppm D-limonene combination treatment was found more effective in biofilm prevention and MIC mitigation than glutaraldehyde and D-limonene used individually. Electrochemical tests corroborated weight loss and pit depth data trends.},
}

@article {pmid34519743,
year = {2021},
author = {Fan, Q and Wang, C and Guo, R and Jiang, X and Li, W and Chen, X and Li, K and Hong, W},
title = {Step-by-step dual stimuli-responsive nanoparticles for efficient bacterial biofilm eradication.},
journal = {Biomaterials science},
volume = {},
number = {},
pages = {},
doi = {10.1039/d1bm01038g},
pmid = {34519743},
issn = {2047-4849},
abstract = {Biofilm-related bacterial infections are extremely resistant to antibiotics, mainly due to the impermeability of the intensive matrices, which allow the bacteria to survive antibiotic treatment. Herein, step-by-step dual stimuli-responsive azithromycin-loaded nanoparticles (CM/AZM@Tyr) was constructed for efficient biofilm eradication. CM/AZM@Tyr was prepared by the self-assembly of poly(ε-caprolactone)-polyethylene glycol-polyethylenimine (PCL-PEG-PEI) into cationic micelles and simultaneously encapsulated AZM into the hydrophobic core, which is further bound with cis-aconityl-D-tyrosine (CA-Tyr) through electrostatic interaction. Upon initial penetration, CM/AZM@Tyr could show step-by-step dual-response to the microenvironment of biofilms. Firstly, the CA-Tyr shell rapidly responded to the acidic microenvironment and released D-Tyr to disassemble the biofilm mass. Then, the exposed cationic CM/AZM micelles could bind firmly to the negatively-charged bacteria cell membrane. With the enzymolysis of the PCL core, the rapidly releasing AZM could kill the bacteria over the depth of biofilms. Massive accumulation was observed in the infected lungs of biofilms-associated lung infection mice after the i.v. injection of CM/Cy5.5@Tyr under the 3D mode of the in vivo Imaging System. Reduced bacterial burden and alleviated fibrosis in the infected lungs were also obtained after treatment with CM/AZM@Tyr mainly due to its intensive penetration in the biofilm and the orderly release of the biofilm dispersant and antimicrobial agents. In summary, this research developed an effective strategy for the treatment of blood-accessible biofilm-induced infections.},
}

@article {pmid34519474,
year = {2021},
author = {Zou, Y and Lu, K and Lin, Y and Wu, Y and Wang, Y and Li, L and Huang, C and Zhang, Y and Brash, JL and Chen, H and Yu, Q},
title = {Dual-Functional Surfaces Based on an Antifouling Polymer and a Natural Antibiofilm Molecule: Prevention of Biofilm Formation without Using Biocides.},
journal = {ACS applied materials & interfaces},
volume = {},
number = {},
pages = {},
doi = {10.1021/acsami.1c10747},
pmid = {34519474},
issn = {1944-8252},
abstract = {Pathogenic biofilms formed on the surfaces of implantable medical devices and materials pose an urgent global healthcare problem. Although conventional antibacterial surfaces based on bacteria-repelling or bacteria-killing strategies can delay biofilm formation to some extent, they usually fail in long-term applications, and it remains challenging to eradicate recalcitrant biofilms once they are established and mature. From the viewpoint of microbiology, a promising strategy may be to target the middle stage of biofilm formation including the main biological processes involved in biofilm development. In this work, a dual-functional antibiofilm surface is developed based on copolymer brushes of 2-hydroxyethyl methacrylate (HEMA) and 3-(acrylamido)phenylboronic acid (APBA), with quercetin (Qe, a natural antibiofilm molecule) incorporated via acid-responsive boronate ester bonds. Due to the antifouling properties of the hydrophilic poly(HEMA) component, the resulting surface is able to suppress bacterial adhesion and aggregation in the early stages of contact. A few bacteria are eventually able to break through the protection of the anti-adhesion layer leading to bacterial colonization. In response to the resulting decrease in the pH of the microenvironment, the surface could then release Qe to interfere with the microbiological processes related to biofilm formation. Compared to bactericidal and anti-adhesive surfaces, this dual-functional surface showed significantly improved antibiofilm performance to prevent biofilm formation involving both Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus for up to 3 days. In addition, both the copolymer and Qe are negligibly cytotoxic, thereby avoiding possible harmful effects on adjacent normal cells and the risk of bacterial resistance. This dual-functional design approach addresses the different stages of biofilm formation, and (in accordance with the growth process of the biofilm) allows sequential activation of the functions without compromising the viability of adjacent normal cells. A simple and reliable solution may thus be provided to the problems associated with biofilms on surfaces in various biomedical applications.},
}

@article {pmid34517785,
year = {2021},
author = {Fu, R and Li, Z and Zhou, R and Li, C and Shao, S and Li, J},
title = {The mechanism of intestinal flora dysregulation mediated by intestinal bacterial biofilm to induce constipation.},
journal = {Bioengineered},
volume = {12},
number = {1},
pages = {6484-6498},
doi = {10.1080/21655979.2021.1973356},
pmid = {34517785},
issn = {2165-5987},
abstract = {To explore mechanism of intestinal flora dysregulation promoting constipation, 60 specific pathogen-free (SPF) mice were used as research objects and were treated with constipation population fecal fluid gavage and distilled water gavage. Then, relationship between intestinal dysregulation and constipation in mice with biofilm-mediated intestinal flora was investigated in vitro. The results showed that recombinant serotonin transporter (SERT) messenger ribonucleic acid (mRNA) level of the constipation population fecal fluid gavage group and the relative expression level of SERT mRNA were 1.61 ± 0.08 and 1.49 ± 0.06, which were higher markedly than those of distilled water group (P < 0.05). The level of 5-hydroxytryptamine (5-HT) in colonic tissue of the constipation population fecal fluid gavage group was 145.36 ± 14.12 ng/mL, and the expression level of 5-HT on the surface of epithelial cells of biofilm-positive colonic tissue was 20.11 ± 2.03, which were significantly lower than those of the distilled water group, with statistical significance (P < 0.05). Besides, the microbial sequencing of fecal flora indicated that The Akk and bacteroidetes ofconstipation population fecal fluid gavage group were higher hugely than those of distilled water group (P < 0.05).In conclusion, after the occurrence of constipation, the diversity of intestinal microflora decreased, and the probiotics reduced. Iintestinal microflora dysregulation would lead to increase of SERT expression level in defecation function and intestinal motility in mice, and the decrease of 5-HT, thereby changing the intestinal movement resulting in mucosal protective barrier damage,thereby causing changes in intestinal movement and the destruction of the intestinal mucosal protective barrier, which eventually resulted in constipation. The occurrence of constipation could be improved by regulating balance of intestinal flora, increasing the diversity of flora, and reducing the genus of opportunistic pathogens.},
}

@article {pmid34517574,
year = {2021},
author = {T, AV and Paramanantham, P and Sb, SL and Sharan, A and Alsaedi, MH and Dawoud, TMS and Syed, A and Siddhardha, B},
title = {Corrigendum to "Antimicrobial photodynamic activity of rose bengal conjugated multi walled carbon nanotubes against planktonic cells and biofilm of Escherichia coli" [Photodiagn. Photodyn. Ther. 24 (2021) 300-310].},
journal = {Photodiagnosis and photodynamic therapy},
volume = {35},
number = {},
pages = {102363},
doi = {10.1016/j.pdpdt.2021.102363},
pmid = {34517574},
issn = {1873-1597},
}

@article {pmid34517572,
year = {2021},
author = {Gao, Y and Mai, B and Wang, A and Li, M and Wang, X and Zhang, K and Liu, Q and Wei, S and Wang, P},
title = {Corrigendum to "Antimicrobial properties of a new type of photosensitizer derived from phthalocyanine against planktonic and biofilm forms of Staphylococcus aureus" [Photodiagn. Photodyn. Ther. 21 (2018) 316-326].},
journal = {Photodiagnosis and photodynamic therapy},
volume = {35},
number = {},
pages = {102337},
doi = {10.1016/j.pdpdt.2021.102337},
pmid = {34517572},
issn = {1873-1597},
}

@article {pmid34516283,
year = {2021},
author = {Kassety, S and Katharios-Lanwermeyer, S and O'Toole, GA and Nadell, CD},
title = {Differential surface competition and biofilm invasion strategies of Pseudomonas aeruginosa PA14 and PAO1.},
journal = {Journal of bacteriology},
volume = {},
number = {},
pages = {JB0026521},
doi = {10.1128/JB.00265-21},
pmid = {34516283},
issn = {1098-5530},
abstract = {Pseudomonas aeruginosa strains PA14 and PAO1 are among the two best characterized model organisms used to study the mechanisms of biofilm formation, while also representing two distinct lineages of P. aeruginosa. Previous work has shown that PA14 and PAO1 use different strategies for surface colonization; they also have different extracellular matrix composition and different propensities to disperse from biofilms back into the planktonic phase surrounding them. We expand on this work here by exploring the consequences of these different biofilm production strategies during direct competition. Using differentially labeled strains and microfluidic culture methods, we show that PAO1 can outcompete PA14 in direct competition during early colonization and subsequent biofilm growth, that they can do so in constant and perturbed environments, and that this advantage is specific to biofilm growth and requires production of the Psl polysaccharide. In contrast, the P. aeruginosa PA14 is better able to invade pre-formed biofilms and is more inclined to remain surface-associated under starvation conditions. These data together suggest that while P. aeruginosa PAO1 and PA14 are both able to effectively colonize surfaces, they do so in different ways that are advantageous under different environmental settings. Importance Recent studies indicate that P. aeruginosa PAO1 and PA14 use distinct strategies to initiate biofilm formation. We investigated whether their respective colonization and matrix secretion strategies impact their ability to compete under different biofilm-forming regimes. Our work shows that these different strategies do indeed impact how these strains fair in direct competition: PAO1 dominates during colonization of a naïve surface, while PA14 is more effective in colonizing a pre-formed biofilm. These data suggest that even for very similar microbes there can be distinct strategies to successfully colonize and persist on surfaces during the biofilm life cycle.},
}

@article {pmid34516241,
year = {2021},
author = {Singulani, JL and Oliveira, LT and Ramos, MD and Fregonezi, NF and Gomes, PC and Galeane, MC and Palma, MS and Fusco Almeida, AM and Mendes Giannini, MJS},
title = {The antimicrobial peptide MK58911-NH2 acts on planktonic, biofilm and intramacrophage cells of Cryptococcus neoformans.},
journal = {Antimicrobial agents and chemotherapy},
volume = {},
number = {},
pages = {AAC0090421},
doi = {10.1128/AAC.00904-21},
pmid = {34516241},
issn = {1098-6596},
abstract = {Cryptococcosis is associated with high rates of morbidity and mortality, especially in AIDS patients. Its treatment is carried out by combining amphotericin B and azoles or flucytosine, which cause unavoidable toxicity issues to the host. Thus, the urgency in obtaining new antifungals drives the search for antimicrobial peptides (AMPs). This study aimed to extend the understanding of the mechanism of action of an AMP analog from wasps peptide toxins, MK58911-NH2, on Cryptococcus neoformans. It was also evaluated if MK58911-NH2 can act on cryptococcal cells in macrophages, biofilms, and an immersion zebrafish model of infection. Finally, we investigated the structure-antifungal action and the toxicity relation of MK58911-NH2 fragments and a derivative of this peptide (MH58911-NH2). The results demonstrated that MK58911-NH2 did not alter the fluorescence intensity of cell wall - binding dye calcofluor or capsule- binding dye 18b7 antibody-FITC of C. neoformans, but rather reduced the number and size of fungal cells. This activity reduced the fungal burden of C. neoformans both in macrophages and in zebrafish embryos as well as within biofilms. Three fragments of the MK58911-NH2 peptide showed no activity against Cryptococcus or toxicity in lung cells. The derivative peptide MH58911-NH2, in which the lysine residues of MK58911-NH2 were replaced by histidine, reduced the activity against extracellular and intracellular C. neoformans. On the other hand, it was active against biofilm, and reducing toxicity. In summary, the results showed that peptide MK58911-NH2 could be a promising agent against cryptococcosis. The work also opens a perspective for the verification of the antifungal activity of other derivatives.},
}

@article {pmid34512560,
year = {2021},
author = {Thieme, L and Hartung, A and Tramm, K and Graf, J and Spott, R and Makarewicz, O and Pletz, MW},
title = {Adaptation of the Start-Growth-Time Method for High-Throughput Biofilm Quantification.},
journal = {Frontiers in microbiology},
volume = {12},
number = {},
pages = {631248},
doi = {10.3389/fmicb.2021.631248},
pmid = {34512560},
issn = {1664-302X},
abstract = {Colony forming unit (CFU) determination by agar plating is still regarded as the gold standard for biofilm quantification despite being time- and resource-consuming. Here, we propose an adaption of the high-throughput Start-Growth-Time (SGT) method from planktonic to biofilm analysis, which indirectly quantifies CFU/mL numbers by evaluating regrowth curves of detached biofilms. For validation, the effect of dalbavancin, rifampicin and gentamicin against mature biofilms of Staphylococcus aureus and Enterococcus faecium was measured by accessing different features of the viability status of the cell, i.e., the cultivability (conventional agar plating), growth behavior (SGT) and metabolic activity (resazurin assay). SGT correlated well with the resazurin assay for all tested antibiotics, but only for gentamicin and rifampicin with conventional agar plating. Dalbavancin treatment-derived growth curves showed a compared to untreated controls significantly slower increase with reduced cell doubling times and reduced metabolic rate, but no change in CFU numbers was observed by conventional agar plating. Here, unspecific binding of dalbavancin to the biofilm interfered with the SGT methodology since the renewed release of dalbavancin during detachment of the biofilms led to an unintended antimicrobial effect. The application of the SGT method for anti-biofilm testing is therefore not suited for antibiotics which stick to the biofilm and/or to the bacterial cell wall. Importantly, the same applies for the well-established resazurin method for anti-biofilm testing. However, for antibiotics which do not bind to the biofilm as seen for gentamicin and rifampicin, the SGT method presents a much less labor-intensive method suited for high-throughput screening of anti-biofilm compounds.},
}

@article {pmid34511397,
year = {2021},
author = {Segundo Zaragoza, C and López Ortiz, I and Contreras Caro Del Castillo, DA and Domínguez Hernández, YM and Rodríguez García, JA},
title = {Characterization, enzymatic activity and biofilm formation of Candida species isolated from goat milk.},
journal = {Revista iberoamericana de micologia},
volume = {},
number = {},
pages = {},
doi = {10.1016/j.riam.2021.06.001},
pmid = {34511397},
issn = {2173-9188},
abstract = {BACKGROUND: Data regarding yeast microbiota in goat milk is scarce.

AIMS: To isolate and identify species of the genus Candida in milk samples from clinically healthy goats, and evaluate their enzymatic activity and biofilm formation.

METHODS: 1092 milk samples from clinically healthy goats were collected and processed. The yeast isolates were identified by phenotypic, methods and their enzymatic activity (phospholipase, hemolysin and protease) and biofilm formation evaluated.

RESULTS: We obtained 221 Candida isolates belonging to six species: Candida kefyr (35.7%), Candida guilliermondii (33%), Candida famata (23.5%), Candida glabrata (5.9%), Candida albicans (1.35%) and Candida parapsilosissensu lato (0.45%). Protease activity was detected in all Candida species while hemolysin activity was only present in C. kefyr, C. guilliermondii, C. famata and C. albicans. Only C. albicans showed phospholipase activity. With the exception of C. parapsilosis sensu lato, all Candida species formed biofilm, with 60.19% of the isolates being poor producers, 9.93% moderate producers, and 1.35% strong producers.

CONCLUSIONS: The milk of clinically healthy goats contains several species of the genus Candida that could play a role as opportunistic pathogens in mastitis.},
}

@article {pmid34511035,
year = {2021},
author = {Zhang, W and Li, H and Zhao, N and Luo, X and Liu, S and Bao, A and Chen, Y and Wang, H and Wang, J and Wang, J},
title = {Lactobacillus johnsonii BS15 combined with abdominal massage on intestinal permeability in rats with nonalcoholic fatty liver and cell biofilm repair.},
journal = {Bioengineered},
volume = {12},
number = {1},
pages = {6354-6363},
doi = {10.1080/21655979.2021.1954134},
pmid = {34511035},
issn = {2165-5987},
abstract = {This study aimed to analyze the effect of lactobacillus johnsonii BS15 (isolation of homemade yogurt from Ahu Hongyuan Grassland) combined with abdominal massage on intestinal permeability in rats with nonalcoholic fatty liver disease (NAFLD) and cell biofilm repair. Forty-five rats were divided randomly into five groups, four of which were fed with high-fat diet to establish NAFLD models. According to the treatment methods, they were grouped into group A (lactic acid bacteria feeding), group B (abdominal massage), group A + B (a combination of the two methods), model group (distilled water feeding), and normal group (distilled water feeding). Then, the pathological indexes of liver and intestinal permeability were observed. FITC-Dextran content of the model group elevated markedly compared with normal group (P < 0.01), indicating that the intestinal permeability of NAFLD rats fed with high-fat diet increased. The intestinal permeability of groups A, B, and A + B was lower sharply than that of model group (P < 0.01), and the effect of group A + B was the most obvious. HE staining of liver tissues showed that combined treatment could improve structural changes in liver cells caused by modeling and restore the normal structure of intestinal cells. Lactobacillus combined with abdominal massage was better than two treatments alone, further promoting the permeability of intestinal mucosa in NAFLD rats and repair biofilm of hepatocytes. The results initially verified the intervention effect of abdominal massage on intestinal mucosal permeability, and further revealed the mechanism of abdominal massage in treatment of NAFLD by improving intestinal mucosal barrier permeability.},
}

@article {pmid34510307,
year = {2021},
author = {Gomaa, OM and Abd El Kareem, H and Selim, N},
title = {Nitrate modulation of Bacillus sp. biofilm components: a proposed model for sustainable bioremediation.},
journal = {Biotechnology letters},
volume = {},
number = {},
pages = {},
pmid = {34510307},
issn = {1573-6776},
abstract = {The presence of different pollutants in wastewater hinder microbial growth, compromise enzymatic activity or compete for electrons required for bioremediation pathway. Therefore, there is a need to use a single microorganism that is capable of tolerating different toxic compounds and can perform simultaneous bioremediation. In the present study, nitrate reducing bacteria capable of decolorizing azo dye was identified as Bacillus subtillis sp. DN using protein profiling, morphological and biochemical tests X-ray diffraction pattern, Raman spectroscopy and cyclic voltammetry confirm that the bacterium under study possesses membrane-bound nitrate reductase and that is capable of direct electron transfer. The addition of nitrate concentrations (0-50 mM) resulted in increased biofilm formation with variable exopolysaccharides, protein, and eDNA. Fourier Transform Infrared spectrum revealed the presence of a biopolymer at high nitrate concentrations. Effective capacitance and conductivity of the cells grown in different nitrate concentrations suggest changes in the relative position of polar groups, their relative orientation and permeability of cell membrane as detected by dielectric spectroscopy. The increase in biofilm shifted the removal of the azo dye from biodegradation to bioadsorption. Our results indicate that nitrate modulates biofilm components. Bacillus sp. DN granular biofilm can be used for simultaneous nitrate and azo dye removal from wastewater.},
}

@article {pmid34509685,
year = {2021},
author = {Garcia, BA and Panariello, BHD and Pontes, KMF and Duarte, S},
title = {Candida biofilm matrix as a resistance mechanism against photodynamic therapy.},
journal = {Photodiagnosis and photodynamic therapy},
volume = {},
number = {},
pages = {102525},
doi = {10.1016/j.pdpdt.2021.102525},
pmid = {34509685},
issn = {1873-1597},
abstract = {BACKGROUND: The antimicrobial photodynamic therapy (aPDT) efficiency on Candida albicans is recognized in free-floating cultures. Though, the lack of aPDT effectiveness against C. albicans organized in biofilms is still unclear. This study aimed to explore the role of the extracellular matrix (ECM) in the protection against aPDT in C. albicans biofilms.

METHODS: C. albicans SN 425 wild-type and two mutant strains CNJ 2302; Δ/Δefg1 and CJN 2330; Δ/Δtec1 (ECM deficient) were used. Biofilms were grown on 24-well plates and exposed twice-daily to aPDT with 44 μM toluidine blue-O (TBO) for 5 min followed by red light (635 nm) for 1 min (87.6 J/cm²) or 2 min (175.2 J/cm2). Application of just TBO, light, 0.12% chlorhexidine, and ultrapure water were used as controls. After 48 h, biofilms were assessed for dry-weight (DW), colony forming units (CFU), extracellular DNA (eDNA), soluble and insoluble protein (SP/IP), water-insoluble (alkali-soluble) polysaccharide (ASP), water-soluble polysaccharides (WSP), and confocal scanning laser microscopy.

RESULTS: The strains with ECM deficient were affected by aPDT. For the mutant strain Δ/Δefg1, aPDT significantly reduced CFU, ASP, DW, eDNA, WSP and IP when compared to NC (p<0.001) and for the Δ/Δtec1, aPDT significantly reduced CFU, eDNA, IP and SP. Whereas CFU, DW, ASP of the wild-type strain biofilms were not reduced (p>0.05).

CONCLUSIONS: C. albicans strains with reduced ECM compounds were more sensitive to aPDT suggesting that the ECM may have a significant protection role from aPDT in C. albicans biofilms.},
}

@article {pmid34507762,
year = {2021},
author = {Fernández-Gómez, P and Figueredo, A and López, M and González-Raurich, M and Prieto, M and Alvarez-Ordóñez, A},
title = {Heterogeneity in biofilm formation and identification of biomarkers of strong biofilm formation among field isolates of Pseudomonas spp.},
journal = {Food research international (Ottawa, Ont.)},
volume = {148},
number = {},
pages = {110618},
doi = {10.1016/j.foodres.2021.110618},
pmid = {34507762},
issn = {1873-7145},
abstract = {The biofilm formation ability of a collection of thirty-three Pseudomonas spp. isolates from food processing facilities was investigated in order to find biomarkers of strong biofilm production, a characteristic that can determine persistence in food processing environments. The strains were classified according to the colony pigmentation on solid media as green, brown or not pigmented. The biofilm production on stainless steel and polystyrene was assessed by spectrometric determination of the fixed crystal violet, and the biofilm formed on glass, through confocal laser scanning microscopy. Besides, pyoverdine production, catalase activity, RpoS status and cellular hydrophobicity were also monitored. A significantly higher biofilm production level on stainless steel and polystyrene was observed for green-pigmented strains as compared to brown or not pigmented strains. The influence of iron availability on biofilm formation on stainless steel was studied through the addition of the iron scavenger 2,2-bipyridine resulting in a decrease of 40 % in biofilm formation for the not pigmented strains. For most of the potential biomarkers studied (i.e., pyoverdine production, catalase activity, cellular hydrophobicity), the phenotypic heterogeneity observed among strains was mainly dependent on the Pseudomonas species and no strong associations with the biofilm formation capacity were detected. However, the green colony pigmentation on solid media showed good potential as a biomarker of strong biofilm formation on stainless steel and polystyrene both in P. aeruginosa and Pseudomonas spp.},
}

@article {pmid34507740,
year = {2021},
author = {Hossain, MI and Mizan, MFR and Roy, PK and Nahar, S and Toushik, SH and Ashrafudoulla, M and Jahid, IK and Lee, J and Ha, SD},
title = {Listeria monocytogenes biofilm inhibition on food contact surfaces by application of postbiotics from Lactobacillus curvatus B.67 and Lactobacillus plantarum M.2.},
journal = {Food research international (Ottawa, Ont.)},
volume = {148},
number = {},
pages = {110595},
doi = {10.1016/j.foodres.2021.110595},
pmid = {34507740},
issn = {1873-7145},
abstract = {Owing to their preservative and antimicrobial effects, postbiotics (metabolic byproducts of probiotics) are promising natural components for the food industry. Therefore, the present study aimed to investigate the efficacy of postbiotics collected from isolated Lactobacillus curvatus B.67 and Lactobacillus plantarum M.2 against Listeria monocytogenes pathogens in planktonic cells, motility, and biofilm states. The analysis of the metabolite composition of the postbiotics revealed various organic acids, along with a few well-known bacteriocin-encoding genes with potential antimicrobial effects. Postbiotics maintained their residual antimicrobial activity over the pH range 1-6 but lost all activity at neutral pH (pH 7). Full antimicrobial activity (100%) was observed during heat treatment, even under the autoclaving condition.Minimum inhibitory concentration (MICs) of L. curvatus B.67 and L. plantarum M.2 against L. monocytogenes were 80 and 70 mg/mL, respectively. However, four sub-MICs of the postbiotics (1/2, 1/4, 1/8, and 1/16 MIC) were tested for inhibition efficacy against L. monocytogenes during different experiment in this study. Swimming motility, biofilm formation, and expression levels of target genes related to biofilm formation, virulence, and quorum-sensing were significantly inhibited with increasing postbiotics concentration. Postbiotics from L. plantarum M.2 exhibited a higher inhibitory effect than the postbiotics from L. curvatus B.67. Nonetheless, both these postbiotics from Lactobacillus spp. could be used as effective bio-interventions for controlling L. monocytogenes biofilm in the food industry.},
}

@article {pmid34506798,
year = {2021},
author = {Oh, JH and Park, J and Park, Y},
title = {Anti-biofilm and anti-inflammatory effects of Lycosin-II isolated from spiders against multi-drug resistant bacteria.},
journal = {Biochimica et biophysica acta. Biomembranes},
volume = {},
number = {},
pages = {183769},
doi = {10.1016/j.bbamem.2021.183769},
pmid = {34506798},
issn = {1879-2642},
abstract = {Currently, multidrug-resistant bacteria are rapidly increasing worldwide because of the misuse or overuse of antibiotics. In particular, few options exist for treating infections caused by long-persisting oxacillin-resistant strains and recently proliferating carbapenem-resistant strains. Therefore, alternative treatments are urgently needed. The antimicrobial peptide (AMP) Lycosin-II is a peptide consisting of 21 amino acids isolated from the venom of the spider Lycosa singoriensis. Lycosin-II showed strong antibacterial activity and biofilm inhibition effects against gram-positive and gram-negative bacteria including oxacillin-resistant Staphylococcus aureus (S. aureus) and meropenem-resistant Pseudomonas aeruginosa (P. aeruginosa) isolated from patients. In addition, Lycosin-II was not cytotoxic against human foreskin fibroblast Hs27 or hemolytic against sheep red blood cells at the concentration of which exerted antibacterial activity. The mechanism of action of Lycosin-II involves binding to lipoteichoic acid and lipopolysaccharide of gram-positive and gram-negative bacterial membranes, respectively, to destroy the bacterial membrane. Moreover, Lycosin-II showed anti-inflammatory effects by inhibiting the expression of pro-inflammatory cytokines that are increased during bacterial infection in Hs27 cells. These results suggest that Lycosin-II can serve as a therapeutic agent against infections with multidrug-resistant strains.},
}

@article {pmid34505216,
year = {2021},
author = {Gross, M and Ashqar, F and Sionov, RV and Friedman, M and Eliashar, R and Zaks, B and Gati, I and Duanis-Assaf, D and Feldman, M and Steinberg, D},
title = {Sustained release varnish containing chlorhexidine for prevention of Streptococcus mutans biofilm formation on voice prosthesis surface: an in vitro study.},
journal = {International microbiology : the official journal of the Spanish Society for Microbiology},
volume = {},
number = {},
pages = {},
pmid = {34505216},
issn = {1618-1905},
support = {20180025//The Israeli Cancer Association/ ; },
abstract = {OBJECTIVES: In this study, we aimed to develop a novel, sustained release varnish (SRV) for voice prostheses (VP) releasing chlorhexidine (CHX), for the prevention of biofilm formation caused by the common oral bacteria Streptococcus mutans on VP surfaces.

METHODS: This study was performed in an in vitro model as a step towards future in vivo trials. VPs were coated with a SRV containing CHX (SRV-CHX) or SRV alone (placebo-SRV) that were daily exposed to S. mutans. The polymeric materials of SRV were composed of ethylcellulose and PEG-400. Biofilm formation was assessed by DNA quantification (qPCR), crystal violet staining, confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and kinetics experiments.

RESULTS: The amount of DNA in the biofilms formed by S. mutans on VP surfaces coated once with SRV-CHX (1.024 ± 0.218 ng DNA/piece) was 58.5 ± 8.8% lower than that of placebo-SRV-coated VPs (2.465 ± 0.198 ng DNA/piece) after a 48-h exposure to S. mutans (p = 0.038). Reduced biofilm mass on SRV-CHX-coated VPs was visually confirmed by CLSM and SEM. CV staining of SRV-CHX single-coated VPs that have been exposed to S. mutans nine times showed a 98.1 ± 0.2% reduction in biofilm mass compared to placebo-SRV-coated VPs (p = 0.003). Kinetic experiments revealed that SRV-CHX triple-coated VPs could delay bacterial growth for 23 days.

CONCLUSIONS: Coating VPs with SRV-CHX has an inhibitory effect on biofilm formation and prevents bacterial growth in their vicinities. This study is a proof-of-principle that paves the way for developing new clinical means for reducing both VPs' bacterial biofilm formation and device failure.},
}

@article {pmid34504987,
year = {2021},
author = {Arias, SL and Brito, IL},
title = {Biophysical determinants of biofilm formation in the gut.},
journal = {Current opinion in biomedical engineering},
volume = {18},
number = {},
pages = {},
doi = {10.1016/j.cobme.2021.100275},
pmid = {34504987},
issn = {2468-4511},
abstract = {The gastrointestinal (GI) tract harbors the most complex microbial ecosystem in the human body. The mucosal layer that covers the GI tract serves as a polymer-based defensive barrier that prevents the microbiome from reaching the epithelium and disseminating inside the body. Colonization of the mucus may result in the formation of structured polymicrobial communities or biofilms, a hallmark in pathologies such as colorectal cancer, inflammatory bowel disease, and chronic gut wounds. However, the mechanisms by which multispecies biofilms establish on the gut mucosa is unknown. Whether mucus-associated biofilms exist as part of a healthy mucosal barrier is still debated. Here, we discuss the impact that diet and microbial-derived polymers has on mucus structure and microcolony formation and highlight relevant biophysical forces that further shape nascent biofilms.},
}

@article {pmid34504737,
year = {2021},
author = {Janssen, K and Low, SL and Wang, Y and Mu, QY and Bierbaum, G and Gee, CT},
title = {Elucidating biofilm diversity on water lily leaves through 16S rRNA amplicon analysis: Comparison of four DNA extraction kits.},
journal = {Applications in plant sciences},
volume = {9},
number = {8},
pages = {e11444},
doi = {10.1002/aps3.11444},
pmid = {34504737},
issn = {2168-0450},
abstract = {Premise: Within a broader study on leaf fossilization in freshwater environments, a long-term study on the development and microbiome composition of biofilms on the foliage of aquatic plants has been initiated to understand how microbes and biofilms contribute to leaf decay and preservation. Here, water lily leaves are employed as a study model to investigate the relationship between bacterial microbiomes, biodegradation, and fossilization. We compare four DNA extraction kits to reduce biases in interpretation and to identify the most suitable kit for the extraction of DNA from bacteria associated with biofilms on decaying water lily leaves for 16S rRNA amplicon analysis.

Methods: We extracted surface-associated DNA from Nymphaea leaves in early stages of decay at two water depth levels using four commercially available kits to identify the most suitable protocol for bacterial extraction, applying a mock microbial community standard to enable a reliable comparison of the kits.

Results: Kit 4, the FastDNA Spin Kit for Soil, resulted in high DNA concentrations with better quality and yielded the most accurate depiction of the mock community. Comparison of the leaves at two water depths showed no significant differences in community composition.

Discussion: The success of Kit 4 may be attributed to its use of bead beating with a homogenizer, which was more efficient in the lysis of Gram-positive bacteria than the manual vortexing protocols used by the other kits. Our results show that microbial composition on leaves during early decay remains comparable and may change only in later stages of decomposition.},
}

@article {pmid34503352,
year = {2021},
author = {Sharma, A and Vashistt, J and Shrivastava, R},
title = {Response surface modeling integrated microtiter plate assay for Mycobacterium fortuitum biofilm quantification.},
journal = {Biofouling},
volume = {},
number = {},
pages = {1-14},
doi = {10.1080/08927014.2021.1974846},
pmid = {34503352},
issn = {1029-2454},
abstract = {In this study, the effects of agitation, temperature, and pH on biofilm formation by Mycobacterium fortuitum were studied and quantified through response surface modeling. The microtiter plate assay was optimized to achieve conditions favoring maximum mycobacterial biofilm quantification. Optical density (OD) measurement using a crystal violet assay was performed to estimate the amount of biofilm formed. Response surface methodology (RSM) results revealed an R2 value of 96.18%, exhibiting a maximum OD of 2.119 (λ570 nm) at a temperature of 37 °C and pH 7.0, under a static environment. The conditions were experimentally validated. Statistically significant results showed that the maximum biofilm was produced 96 h after mycobacterial inoculation. Thus, the results provide a basis for using RSM as an efficient optimization method for M. fortuitum biofilm assays. This approach can also be incorporated into strategies for screening anti-biofilm compounds, synthetic chemicals, drugs, or inhibitors against pathogenic mycobacteria.},
}

@article {pmid34499698,
year = {2021},
author = {Taggart, MG and Snelling, WJ and Naughton, PJ and La Ragione, RM and Dooley, JSG and Ternan, NG},
title = {Biofilm regulation in Clostridioides difficile: Novel systems linked to hypervirulence.},
journal = {PLoS pathogens},
volume = {17},
number = {9},
pages = {e1009817},
doi = {10.1371/journal.ppat.1009817},
pmid = {34499698},
issn = {1553-7374},
abstract = {Clostridiodes difficile (C. difficile) was ranked an "urgent threat" by the Centers for Disease Control and Prevention (CDC) in 2019. C. difficile infection (CDI) is the most common healthcare-associated infection (HAI) in the United States of America as well as the leading cause of antibiotic-associated gastrointestinal disease. C. difficile is a gram-positive, rod-shaped, spore-forming, anaerobic bacterium that causes infection of the epithelial lining of the gut. CDI occurs most commonly after disruption of the human gut microflora following the prolonged use of broad-spectrum antibiotics. However, the recurrent nature of this disease has led to the hypothesis that biofilm formation may play a role in its pathogenesis. Biofilms are sessile communities of bacteria protected from extracellular stresses by a matrix of self-produced proteins, polysaccharides, and extracellular DNA. Biofilm regulation in C. difficile is still incompletely understood, and its role in disease recurrence has yet to be fully elucidated. However, many factors have been found to influence biofilm formation in C. difficile, including motility, adhesion, and hydrophobicity of the bacterial cells. Small changes in one of these systems can greatly influence biofilm formation. Therefore, the biofilm regulatory system would need to coordinate all these systems to create optimal biofilm-forming physiology under appropriate environmental conditions. The coordination of these systems is complex and multifactorial, and any analysis must take into consideration the influences of the stress response, quorum sensing (QS), and gene regulation by second messenger molecule cyclic diguanosine monophosphate (c-di-GMP). However, the differences in biofilm-forming ability between C. difficile strains such as 630 and the "hypervirulent" strain, R20291, make it difficult to assign a "one size fits all" mechanism to biofilm regulation in C. difficile. This review seeks to consolidate published data regarding the regulation of C. difficile biofilms in order to identify gaps in knowledge and propose directions for future study.},
}

@article {pmid34497894,
year = {2021},
author = {Fasiku, VO and Omolo, CA and Devnarain, N and Ibrahim, UH and Rambharose, S and Faya, M and Mocktar, C and Singh, SD and Govender, T},
title = {Chitosan-Based Hydrogel for the Dual Delivery of Antimicrobial Agents Against Bacterial Methicillin-Resistant Staphylococcus aureus Biofilm-Infected Wounds.},
journal = {ACS omega},
volume = {6},
number = {34},
pages = {21994-22010},
doi = {10.1021/acsomega.1c02547},
pmid = {34497894},
issn = {2470-1343},
abstract = {Chronic wound infections caused by antibiotic-resistant bacteria have become a global health concern. This is attributed to the biofilm-forming ability of bacteria on wound surfaces, thus enabling their persistent growth. In most cases, it leads to morbidity and in severe cases mortality. Current conventional approaches used in the treatment of biofilm wounds are proving to be ineffective due to limitations such as the inability to penetrate the biofilm matrix; hence, biofilm-related wounds remain a challenge. Therefore, there is a need for more efficient alternate therapeutic interventions. Hydrogen peroxide (HP) is a known antibacterial/antibiofilm agent; however, prolonged delivery has been challenging due to its short half-life. In this study, we developed a hydrogel for the codelivery of HP and antimicrobial peptides (Ps) against bacteria, biofilms, and wound infection associated with biofilms. The hydrogel was prepared via the Michael addition technique, and the physiochemical properties were characterized. The safety, in vitro, and in vivo antibacterial/antibiofilm activity of the hydrogel was also investigated. Results showed that the hydrogel is biosafe. A greater antibacterial effect was observed with HP-loaded hydrogels (CS-HP; hydrogel loaded with HP and CS-HP-P; hydrogel loaded with HP and peptide) when compared to HP as seen in an approximately twofold and threefold decrease in minimum inhibitory concentration values against methicillin-resistant Staphylococcus aureus (MRSA) bacteria, respectively. Similarly, both the HP-releasing hydrogels showed enhanced antibiofilm activity in the in vivo study in mice models as seen in greater wound closure and enhanced wound healing in histomorphological analysis. Interestingly, the results revealed a synergistic antibacterial/antibiofilm effect between HP and P in both in vitro and in vivo studies. The successfully prepared HP-releasing hydrogels showed the potential to combat bacterial biofilm-related infections and enhance wound healing in mice models. These results suggest that the HP-releasing hydrogels may be a superior platform for eliminating bacterial biofilms without using antibiotics in the treatment of chronic MRSA wound infections, thus improving the quality of human health.},
}

@article {pmid34496717,
year = {2021},
author = {Martins Antunes de Melo, WC and Celiešiūtė-Germanienė, R and Šimonis, P and Stirkė, A},
title = {Antimicrobial photodynamic therapy (aPDT) for biofilm treatments. Possible synergy between aPDT and pulsed electric fields.},
journal = {Virulence},
volume = {12},
number = {1},
pages = {2247-2272},
doi = {10.1080/21505594.2021.1960105},
pmid = {34496717},
issn = {2150-5608},
abstract = {Currently, microbial biofilms have been the cause of a wide variety of infections in the human body, reaching 80% of all bacterial and fungal infections. The biofilms present specific properties that increase the resistance to antimicrobial treatments. Thus, the development of new approaches is urgent, and antimicrobial photodynamic therapy (aPDT) has been shown as a promising candidate. aPDT involves a synergic association of a photosensitizer (PS), molecular oxygen and visible light, producing highly reactive oxygen species (ROS) that cause the oxidation of several cellular components. This therapy attacks many components of the biofilm, including proteins, lipids, and nucleic acids present within the biofilm matrix; causing inhibition even in the cells that are inside the extracellular polymeric substance (EPS). Recent advances in designing new PSs to increase the production of ROS and the combination of aPDT with other therapies, especially pulsed electric fields (PEF), have contributed to enhanced biofilm inhibition. The PEF has proven to have antimicrobial effect once it is known that extensive chemical reactions occur when electric fields are applied. This type of treatment kills microorganisms not only due to membrane rupture but also due to the formation of reactive compounds including free oxygen, hydrogen, hydroxyl and hydroperoxyl radicals. So, this review aims to show the progress of aPDT and PEF against the biofilms, suggesting that the association of both methods can potentiate their effects and overcome biofilm infections.},
}

@article {pmid34495971,
year = {2021},
author = {Santos, AAN and Ribeiro, PDS and da França, GV and Souza, FN and Ramos, EAG and Figueira, CP and Reis, MG and Costa, F and Ristow, P},
title = {Leptospira interrogans biofilm formation in Rattus norvegicus (Norway rats) natural reservoirs.},
journal = {PLoS neglected tropical diseases},
volume = {15},
number = {9},
pages = {e0009736},
doi = {10.1371/journal.pntd.0009736},
pmid = {34495971},
issn = {1935-2735},
abstract = {Rattus norvegicus (Norway rat) is the main reservoir host of pathogenic Leptospira, the causative agent of leptospirosis, in urban environments. Pathogenic Leptospira forms biofilms in the environment, possibly contributing for bacterial survival and maintenance. Nonetheless, biofilms have not yet been studied in natural animal reservoirs presenting leptospiral renal carriage. Here, we described biofilm formation by pathogenic Leptospira inside the renal tubules of R. norvegicus naturally infected and captured in an urban slum endemic for leptospirosis. From the 65 rats carrying Leptospira in their kidneys, 24 (37%) presented biofilms inside the renal tubules. The intensity of leptospiral colonization in the renal tubules (OR: 1.00; 95% CI 1.05-1.1) and the type of occlusion pattern of the colonized renal tubules (OR: 3.46; 95% CI 1.20-9.98) were independently associated with the presence of Leptospira biofilm. Our data showed that Leptospira interrogans produce biofilms during renal chronic colonization in rat reservoirs, suggesting a possible role for leptospiral biofilms in the pathogenesis of leptospirosis and bacterial carriage in host reservoirs.},
}

@article {pmid34495103,
year = {2021},
author = {Viana, CS and Maske, TT and Signori, C and VAN DE Sande, FH and Oliveira, EF and Cenci, MS},
title = {Influence of caries activity and number of saliva donors: mineral and microbiological responses in a microcosm biofilm model.},
journal = {Journal of applied oral science : revista FOB},
volume = {29},
number = {},
pages = {e20200778},
doi = {10.1590/1678-7757-2020-0778},
pmid = {34495103},
issn = {1678-7765},
abstract = {OBJECTIVE: this study evaluated the mineral and microbiological response of biofilms originating from different types of saliva inoculum with distinct levels of caries activity.

METHODOLOGY: the biofilms grown over enamel specimens originated from saliva collected from a single donor or five donors with two distinct levels of caries activity (caries-active and caries-free) or from pooling saliva from ten donors (five caries-active and five caries-free). The percentage surface hardness change (%SHC) and microbiological counts served as outcome variables.

RESULTS: the caries activity of donors did not affect the %SHC values. Inoculum from five donors compared to a single donor showed higher %SHC values (p=0.019). Higher lactobacilli counts were observed when saliva from caries-active donors was used as the inoculum (p=0.017). Pooled saliva from both caries activity levels showed higher mutans streptococci counts (p<0.017).

CONCLUSION: Overall, pooled saliva increased the mineral response of the derived biofilms, but all the inoculum conditions formed cariogenic biofilms and caries lesions independently of caries activity.},
}

@article {pmid34494311,
year = {2021},
author = {Togo, Y},
title = {Editorial Comment to Intraluminal diamond-like carbon coating with anti-adhesion and anti-biofilm effects for uropathogens: A novel technology applicable to urinary catheters.},
journal = {International journal of urology : official journal of the Japanese Urological Association},
volume = {},
number = {},
pages = {},
doi = {10.1111/iju.14691},
pmid = {34494311},
issn = {1442-2042},
}

@article {pmid34494127,
year = {2021},
author = {Liu, Y and Luan, J},
title = {Letter to the Editor: Proper Skin Management in Breast Augmentation with a Periareolar Incision Prevents Implant Contamination and Biofilm-Related Capsular Contracture.},
journal = {Aesthetic plastic surgery},
volume = {},
number = {},
pages = {},
pmid = {34494127},
issn = {1432-5241},
}

@article {pmid34492866,
year = {2021},
author = {Zhou, B and Hou, P and Xiao, Y and Song, P and Xie, E and Li, Y},
title = {Visualizing, quantifying, and controlling local hydrodynamic effects on biofilm accumulation in complex flow paths.},
journal = {Journal of hazardous materials},
volume = {416},
number = {},
pages = {125937},
doi = {10.1016/j.jhazmat.2021.125937},
pmid = {34492866},
issn = {1873-3336},
abstract = {Complex flow paths (CFPs) are commonly applied in precision equipment to accurately supply controllable fluids with designed structures. However, the presence of biofilms in CFPs causes quite a few unwanted issues, such as bio-erosion, clogging, or even health risks. To date, visualizing and quantifying the interaction between biofilm distribution and local hydrodynamics remains difficult, and the mechanism during the process is unclear. In this paper, the remodeling simulation method (3D industrial computed tomography scanning-inverse modeling-numerical simulation) and 16S rRNA high-throughput sequencing were integrated. The results indicated that local hydrodynamic characteristics significantly affected biofilm thicknesses on CFP surfaces (relative differences of 41.3-71.2%), which inversely influenced the local turbulence intensity. The average biofilm thicknesses exhibited a significant quadratic correlation with the near-wall hydraulic shear forces (r > 0.72, p < 0.05), and the biofilm reached a maximum thickness at 0.36-0.45 Pa. On the other hand, the near-wall hydraulic shear forces not only affected microbial community characteristics of biofilms, but they also influenced the number of microorganisms involved, which determined the biofilm accumulation thereafter. The PHYLUM Firmicutes and Proteobacteria were the dominant bacteria during the process. The results obtained in this paper could provide practical conceptions for the targeted control of biofilms and put forward more efficient controlling methods in commonly applied CFP systems.},
}

@article {pmid34492791,
year = {2021},
author = {Yang, T and Jiang, L and Cheng, L and Zheng, X and Bi, X and Wang, X and Zhou, X},
title = {Characteristics of size-segregated aerosols emitted from an aerobic moving bed biofilm reactor at a full-scale wastewater treatment plant.},
journal = {Journal of hazardous materials},
volume = {416},
number = {},
pages = {125833},
doi = {10.1016/j.jhazmat.2021.125833},
pmid = {34492791},
issn = {1873-3336},
abstract = {Aerosol emissions from wastewater treatment plants (WWTPs) have been associated with health reverberation but studies about characteristics of size-segregated aerosol particulate matter (PM) are scarce. In this study, the measurement of particulate number size distribution in the range of < 10 µm, and the collection of PM10-2.5, PM2.5-1.0 and PM1.0, were conducted from an aerobic moving bed biofilm reactor (MBBR) at a full-scale WWTP. MBBR aerosols showed a unimodal number size distribution, with the majority of particles (>94%) in the ultrafine size range (<100 nm). For toxic metal(loid)s or potential pathogens, significant differences were found within MBBR aerosols (PM10-2.5, PM2.5-1.0, and PM1.0), and also between MBBR aerosols and wastewater. Both wastewater and ambient air had important source contributions for MBBR aerosols. The compositions of toxic metal(loid)s in PM1.0, and the populations of potential bacterial or fungal pathogens in PM10-2.5 and PM2.5-1.0, were dominated by that from wastewater. Compared to PM10-2.5 and PM2.5-1.0, PM1.0 had the highest aerosolization potential for the toxic metal(loid)s of As, Cd, Co, Cr, Li, Mn, Ni, U, and Zn, and the genera of Acinetobacter, Pseudomonas and Fusarium. Due to the size-segregated specialty, targeted measures should be employed to reduce the health risks. CAPSULE: The compositions of toxic metal(loid)s in PM1.0, and the populations of potential pathogens in PM10-2.5 and PM2.5-1.0, were dominated by that from wastewater.},
}

@article {pmid34489569,
year = {2021},
author = {Deng, X and Zhang, C and Chen, J and Shi, Y and Ma, X and Wang, Y and Wang, Z and Yu, Z and Zheng, J and Chen, Z},
title = {Antibacterial and anti-biofilm activities of histidine kinase YycG inhibitors against Streptococcus agalactiae.},
journal = {The Journal of antibiotics},
volume = {},
number = {},
pages = {},
pmid = {34489569},
issn = {1881-1469},
support = {JCYJ20180302144345028//Shenzhen Science and Technology Innovation Commission/ ; JCYJ20180508162403996JCYJ20190809151817062;//Shenzhen Science and Technology Innovation Commission/ ; 2020A1515111146//Natural Science Foundation of Guangdong Province (Guangdong Natural Science Foundation)/ ; },
abstract = {This study aims to investigate the antibacterial and anti-biofilm activities of YycG inhibitors H2-60 and H2-81 against Streptococcus agalactiae. A total of 118 nonduplicate S. agalactiae clinical isolates were collected, and the minimal inhibitory concentrations (MICs) of H2-60 and H2-81 were determined. H2-60 and H2-81 inhibit biofilm formation of S. agalactiae were detected by crystal violet staining, and against established biofilms of S. agalactiae were observed by confocal laser scanning microscope. Inhibitory effect of H2-60 and H2-81 on the phosphorylation activity of the HisKA domain of YycG' protein was measured. The MIC50/MIC90 was 3.13/6.25 μM for H2-60 and 6.25/12.5 μM for H2-81 against S. agalactiae, respectively. S. agalactiae planktonic cells can be decreased by H2-60 or H2-81 for more than 3 × log10 CFU ml-1 after 24 h treatment. Biofilm formation of 8 S. agalactiae strains (strong biofilm producers) was significantly reduced after treated with 1/4 × MIC of H2-60 or H2-81 for 24 h. H2-60 and H2-81 could reduce 45.79% and 29.56% of the adherent cells in the established biofilm of S. agalactiae after 72 h treatment, respectively. H2-60 combined with daptomycin reduced 83.63% of the adherent cells in the established biofilm of S. agalactiae, which was significantly better than that of H2-60 (45.79%) or daptomycin (55.07%) alone. The half maximal inhibitory concentrations (IC50) were 35.6 μM for H2-60 and 46.3 μM for H2-81 against the HisKA domain of YycG' protein. In conclusion, YycG inhibitors H2-60 and H2-81 exhibit excellent antibacterial and anti-biofilm activities against S. agalactiae.},
}

@article {pmid34489479,
year = {2021},
author = {Duraj-Thatte, AM and Praveschotinunt, P and Nash, TR and Ward, FR and Nguyen, PQ and Joshi, NS},
title = {Author Correction: Modulating bacterial and gut mucosal interactions with engineered biofilm matrix proteins.},
journal = {Scientific reports},
volume = {11},
number = {1},
pages = {18033},
doi = {10.1038/s41598-021-96036-w},
pmid = {34489479},
issn = {2045-2322},
}

@article {pmid34488149,
year = {2021},
author = {Dong, X and Zhu, L and Jiang, P and Wang, X and Liu, K and Li, C and Li, D},
title = {Seasonal biofilm formation on floating microplastics in coastal waters of intensified marinculture area.},
journal = {Marine pollution bulletin},
volume = {171},
number = {},
pages = {112914},
doi = {10.1016/j.marpolbul.2021.112914},
pmid = {34488149},
issn = {1879-3363},
abstract = {The environmental pollution caused by microplastics has received increasing attention recently. In this paper, we present the results of research into the bacterium attached to microplastics in four coastal mariculture zones in southeast China during winter and summer. Polyethene and polypropylene are the main microplastics in the surface water of mariculture area. The differences between the bacteria species composition found on the surface of microplastics in winter and summer were less than that found in the planktonic bacteria, indicating that biofilms protect the bacterium that live inside. Potentially pathogenic Vibrio and Pseudomonas spp. were more abundant in samples from ShanTou and QuanZhou during the summer. Bacteria related to the degradation of microplastics were found extensively on the surface of microplastics at all of the sampling sites. More attention should be paid to the risks resulting from the accumulation of harmful bacteria on microplastic surfaces during the summer.},
}

@article {pmid34486975,
year = {2021},
author = {Kalamara, M and Abbott, JC and MacPhee, CE and Stanley-Wall, NR},
title = {Biofilm hydrophobicity in environmental isolates of Bacillus subtilis.},
journal = {Microbiology (Reading, England)},
volume = {167},
number = {9},
pages = {},
doi = {10.1099/mic.0.001082},
pmid = {34486975},
issn = {1465-2080},
abstract = {Biofilms are communities of bacteria that are attached to a surface and surrounded by an extracellular matrix. The extracellular matrix protects the community from stressors in the environment, making biofilms robust. The Gram-positive soil bacterium Bacillus subtilis, particularly the isolate NCIB 3610, is widely used as a model for studying biofilm formation. B. subtilis NCIB 3610 forms colony biofilms that are architecturally complex and highly hydrophobic. The hydrophobicity is linked, in part, to the localisation of the protein BslA at the surface of the biofilm, which provides the community with increased resistance to biocides. As most of our knowledge about B. subtilis biofilm formation comes from one isolate, it is unclear if biofilm hydrophobicity is a widely distributed feature of the species. To address this knowledge gap, we collated a library of B. subtilis soil isolates and acquired their whole genome sequences. We used our novel isolates to examine biofilm hydrophobicity and found that, although BslA is encoded and produced by all isolates in our collection, hydrophobicity is not a universal feature of B. subtilis colony biofilms. To test whether the matrix exopolymer poly γ-glutamic acid could be masking hydrophobicity in our hydrophilic isolates, we constructed deletion mutants and found, contrary to our hypothesis, that the presence of poly γ-glutamic acid was not the reason for the observed hydrophilicity. This study highlights the natural variation in the properties of biofilms formed by different isolates and the importance of using a more diverse range of isolates as representatives of a species.},
}

@article {pmid34485498,
year = {2021},
author = {Boswell, MT and Cockeran, R},
title = {Effect of antimicrobial peptides on planktonic growth, biofilm formation and biofilm-derived bacterial viability of Streptococcus pneumoniae.},
journal = {Southern African journal of infectious diseases},
volume = {36},
number = {1},
pages = {226},
doi = {10.4102/sajid.v36i1.226},
pmid = {34485498},
issn = {2313-1810},
abstract = {Streptococcus pneumoniae is a leading cause of pneumonia mortality globally. Pneumococcal disease is often associated with prolonged colonisation of hosts and this process is facilitated by biofilm formation that is largely resistant to conventional antibiotics. We investigated the effects of antimicrobial peptides (AMPs) lysozyme, lactoferrin, LL37 and a combination of all three on planktonic growth, biofilm formation and biofilm-derived bacterial viability by S. pneumoniae, serotype 23F. Planktonic growth and biofilm-derived bacterial viability were determined using standard colony-forming techniques, while biofilm formation was measured using a crystal violet based spectrophotometric method. Relative to controls, lysozyme significantly reduced biofilm formation (0.08 OD vs. 0.10 OD at 570 nm, p = 0.01), while LL37 and the AMP combination increased biofilm formation (0.14 OD vs. 0.10 OD at 570 nm, p = 0.01). The combination of AMPs significantly decreased planktonic growth (1.10 × 108 colony-forming units per millilitres [CFU/mL] vs. 2.13 × 108 CFU/mL, p = 0.02). Biofilm-derived bacterial viability was greatly reduced by exposure to a combination of AMPs (1.05 × 105 CFU/mL vs. 1.12 × 106 CFU/mL, p = 3.60 × 10-8). Streptococcus pneumoniae displays marked resistance to the individual AMPs. A combination of lysozyme, lactoferrin and LL37 effectively inhibited planktonic growth and biofilm-derived bacterial viability; however, persister cell growth was still evident after exposure.},
}

@article {pmid34485167,
year = {2021},
author = {Ramírez-Granillo, A and Bautista-Hernández, LA and Bautista-De Lucío, VM and Magaña-Guerrero, FS and Domínguez-López, A and Córdova-Alcántara, IM and Pérez, NO and Martínez-Rivera, MLA and Rodríguez-Tovar, AV},
title = {Microbial Warfare on Three Fronts: Mixed Biofilm of Aspergillus fumigatus and Staphylococcus aureus on Primary Cultures of Human Limbo-Corneal Fibroblasts.},
journal = {Frontiers in cellular and infection microbiology},
volume = {11},
number = {},
pages = {646054},
doi = {10.3389/fcimb.2021.646054},
pmid = {34485167},
issn = {2235-2988},
abstract = {Background: Coinfections with fungi and bacteria in ocular pathologies are increasing at an alarming rate. Two of the main etiologic agents of infections on the corneal surface, such as Aspergillus fumigatus and Staphylococcus aureus, can form a biofilm. However, mixed fungal-bacterial biofilms are rarely reported in ocular infections. The implementation of cell cultures as a study model related to biofilm microbial keratitis will allow understanding the pathogenesis in the cornea. The cornea maintains a pathogen-free ocular surface in which human limbo-corneal fibroblast cells are part of its cell regeneration process. There are no reports of biofilm formation assays on limbo-corneal fibroblasts, as well as their behavior with a polymicrobial infection.

Objective: To determine the capacity of biofilm formation during this fungal-bacterial interaction on primary limbo-corneal fibroblast monolayers.

Results: The biofilm on the limbo-corneal fibroblast culture was analyzed by assessing biomass production and determining metabolic activity. Furthermore, the mixed biofilm effect on this cell culture was observed with several microscopy techniques. The single and mixed biofilm was higher on the limbo-corneal fibroblast monolayer than on abiotic surfaces. The A. fumigatus biofilm on the human limbo-corneal fibroblast culture showed a considerable decrease compared to the S. aureus biofilm on the limbo-corneal fibroblast monolayer. Moreover, the mixed biofilm had a lower density than that of the single biofilm. Antibiosis between A. fumigatus and S. aureus persisted during the challenge to limbo-corneal fibroblasts, but it seems that the fungus was more effectively inhibited.

Conclusion: This is the first report of mixed fungal-bacterial biofilm production and morphological characterization on the limbo-corneal fibroblast monolayer. Three antibiosis behaviors were observed between fungi, bacteria, and limbo-corneal fibroblasts. The mycophagy effect over A. fumigatus by S. aureus was exacerbated on the limbo-corneal fibroblast monolayer. During fungal-bacterial interactions, it appears that limbo-corneal fibroblasts showed some phagocytic activity, demonstrating tripartite relationships during coinfection.},
}

@article {pmid34485075,
year = {2021},
author = {Svensson Malchau, K and Tillander, J and Zaborowska, M and Hoffman, M and Lasa, I and Thomsen, P and Malchau, H and Rolfson, O and Trobos, M},
title = {Biofilm properties in relation to treatment outcome in patients with first-time periprosthetic hip or knee joint infection.},
journal = {Journal of orthopaedic translation},
volume = {30},
number = {},
pages = {31-40},
doi = {10.1016/j.jot.2021.05.008},
pmid = {34485075},
issn = {2214-031X},
abstract = {Background: Periprosthetic joint infections (PJI) are challenging complications following arthroplasty. Staphylococci are a frequent cause of PJI and known biofilm producers. Biofilm formation decreases antimicrobial susceptibility, thereby challenging favourable treatment outcomes. The aims of this study were to characterize the biofilm abilities and antimicrobial susceptibilities of staphylococci causing first-time PJI and correlate them to clinical outcome (infection resolution and recurrence).

Methods: Reoperations for PJI of the hip or knee between 1st January 2012 to 30th June 2015 performed at the Sahlgrenska University Hospital were identified in a local database. Medical records were reviewed and clinical parameters recorded for patients whose intraoperative bacterial isolates had been stored at the clinical laboratory. Staphylococcal strains isolated from reoperations due to first-time PJI were characterised by their ability to form biofilms using the microtiter plate test. Antimicrobial susceptibility of the strains was determined by minimum inhibitory concentration (MIC) when grown planktonically, and by minimum biofilm eradication concentration (MBEC) when grown as biofilms. MBEC determination was conducted using the Calgary biofilm device (CBD) and a custom-made antimicrobial susceptibility plate containing eight clinically relevant antimicrobial agents.

Results: The study group included 49 patients (70 bacterial strains) from first-time PJI, whereof 24 (49%) patients had recurrent infection. Strong biofilm production was significantly associated with recurrent infection. Patients infected with strong biofilm producers had a five-fold increased risk for recurrent infection. Strains grown as biofilms were over 8000 times more resistant to antimicrobial agents compared to planktonic cultures. Biofilms were more susceptible to rifampicin compared to other antimicrobials in the assay. Increased biofilm susceptibility (MBEC ​> ​MIC) was observed for the majority of the bacterial strains and antimicrobial agents.

Conclusions: Strong biofilm production was significantly associated with increased antimicrobial resistance and PJI recurrence. This underscores the importance of determining biofilm production and susceptibility as part of routine diagnostics in PJI. Strong staphylococcal biofilm production may have implications on therapeutic choices and suggest more extensive surgery. Furthermore, despite the increased biofilm resistance to rifampicin, results from this study support its use in staphylococcal PJI.

Like for many biomaterial-associated infections, staphylococci are a common cause of PJI. Their ability to adhere to surfaces and produce biofilms on medical devices is proposed to play a role. However, clinical studies where biofilm properties are directly linked to patient outcome are scarce. This study demonstrates that the majority of staphylococci isolated from first-time PJI were biofilm producers with increased antimicrobial resistance. Patients suffering an infection caused by a staphylococcal strain with strong biofilm production ability had a five-fold greater risk of recurrent infection. This novel finding suggests the importance of evaluating biofilm production as a diagnostic procedure for the guidance of treatment decisions in PJI.},
}

@article {pmid34484613,
year = {2021},
author = {Liao, MH and Wang, XR and Hsu, WL and Tzen, JTC},
title = {Pu'er tea rich in strictinin and catechins prevents biofilm formation of two cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus.},
journal = {Journal of dental sciences},
volume = {16},
number = {4},
pages = {1331-1334},
doi = {10.1016/j.jds.2021.05.011},
pmid = {34484613},
issn = {2213-8862},
abstract = {Cariogenic bacteria, such as Streptococcus mutans and Streptococcus sobrinus, are main pathogens responsible for human dental caries. Pu'er tea is empirically observed to prevent tooth decay. Besides caffeine and catechins commonly found in oolong tea, strictinin is also found as an abundant phenolic compound in Pu'er tea. Infusion of Pu'er tea as well as single compound, strictinin, caffeine or (-)-epigallocatechin gallate (EGCG) was examined for its inhibitory effects on S. mutans and S. sobrinus. Relatively weak inhibition of bacterial growth was observed for these Pu'er tea constituents. However, biofilm formation of S. mutans or S. sobrinus was strongly prevented by the infusion of Pu'er tea as well as by strictinin or EGCG, but not caffeine. Relatively, strictinin showed a higher potency than EGCG to prevent biofilm formation. Anti-caries effect of Pu'er tea seems to be resulted from the prevention of biofilm formation of cariogenic bacteria mainly by strictinin and catechins.},
}

@article {pmid34482605,
year = {2021},
author = {Huang, Z and Dai, H and Zhang, X and Wang, Q and Sun, J and Deng, Y and Shi, P},
title = {BSC2 induces multidrug resistance via contributing to the formation of biofilm in Saccharomyces cerevisiae.},
journal = {Cellular microbiology},
volume = {},
number = {},
pages = {e13391},
doi = {10.1111/cmi.13391},
pmid = {34482605},
issn = {1462-5822},
abstract = {Biofilm plays an imoprtant role in fungal multidrug resistance (MDR). Our previous studies showed that BSC2 is involved in resistance to amphotericin B (AMB) through anti-oxidation in Saccharomyces cerevisiae. In the present study, overexpression of BSC2 and IRC23 induced strong MDR in S. cerevisiae. BSC2-overexpression affected cellular flocculation, cell surface hydrophobicity, biofilm formation, and invasive growth. However, it failed to induce caspofungin (CAS) resistance and affect the invasive growth in FLO mutant strains (FLO11Δ, FLO1Δ, FLO8Δ, and TUP1Δ). Furthermore, overexpression of BSC2 compensated for chitin synthesis defects to maintain the cell wall integrity, and significantly reduced the cell morphology abnormality induced by CAS. However, it could not repair the cell wall damage caused by CAS in the FLO mutant strains. Although BSC2-overexpression increased the level of mannose in the cell wall, DPM1-overexpression in both BY4741 and bsc2∆ could confer resistance to CAS and AMB. Additionally, BSC2-overexpression significantly increased the mRNA expression of FLO11, FLO1, FLO8, and TUP1. BSC2 may function as a regulator of FLO genes and be involved in cell wall integrity in yeast. Taken together, our data demonstrate that BSC2 induces MDR in a FLO pathway-dependent manner via contributing to the formation of biofilm in S. cerevisiae. This article is protected by copyright. All rights reserved.},
}

@article {pmid34482564,
year = {2021},
author = {Watari, S and Wada, K and Araki, M and Sadahira, T and Ousaka, D and Oozawa, S and Nakatani, T and Imai, Y and Kato, J and Kariyama, R and Watanabe, T and Nasu, Y},
title = {Intraluminal diamond-like carbon coating with anti-adhesion and anti-biofilm effects for uropathogens: A novel technology applicable to urinary catheters.},
journal = {International journal of urology : official journal of the Japanese Urological Association},
volume = {},
number = {},
pages = {},
doi = {10.1111/iju.14675},
pmid = {34482564},
issn = {1442-2042},
support = {19K18585//Grant-in-Aid for Early Career Scientists/ ; //Ministry of Education, Culture, Sports, Science and Technology, Japan/ ; },
abstract = {OBJECTIVES: To examine anti-adhesion and anti-biofilm effects of a diamond-like carbon coating deposited via a novel technique on the inner surface of a thin silicon tube.

METHODS: Diamond-like carbon coatings were deposited into the lumen of a silicon tube with inner diameters of 2 mm. The surface of the diamond-like carbon was evaluated using physicochemical methods. We used three clinical isolates including green fluorescent protein-expressing Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. We employed a continuous flow system for evaluation of both bacterial adhesion and biofilm formation. Bacterial adhesion assays consisted of counting the number of colony-forming units and visualization of adhered bacterial cells by scanning electron microscope to evaluate the diamond-like carbon-coated/uncoated samples. The biofilm structure was analyzed by confocal laser scanning microscopy on days 3, 5, 7 and 14 for green fluorescent protein-expressing Pseudomonas aeruginosa.

RESULTS: The smooth and carbon-rich structure of the intraluminal diamond-like carbon film remained unchanged after the experiments. The numbers of colony-forming units suggested lower adherence of green fluorescent protein-expressing Pseudomonas aeruginosa and Escherichia coli in the diamond-like carbon-coated samples compared with the uncoated samples. The scanning electron microscope images showed adhered green fluorescent protein-expressing Pseudomonas aeruginosa cells without formation of microcolonies on the diamond-like carbon-coated samples. Finally, biofilm formation on the diamond-like carbon-coated samples was lower until at least day 14 compared with the uncoated samples.

CONCLUSIONS: Intraluminal diamond-like carbon coating on a silicone tube has anti-adhesion and anti-biofilm effects. This technology can be applied to urinary catheters made from various materials.},
}

@article {pmid34481121,
year = {2021},
author = {Eze, EC and El Zowalaty, ME and Pillay, M},
title = {Antibiotic resistance and biofilm formation of Acinetobacter baumannii isolated from high risk effluent water in tertiary hospitals in South Africa.},
journal = {Journal of global antimicrobial resistance},
volume = {},
number = {},
pages = {},
doi = {10.1016/j.jgar.2021.08.004},
pmid = {34481121},
issn = {2213-7173},
abstract = {INTRODUCTION: The discharge of drug-resistant, biofilm-forming pathogens from hospital effluent water into municipal wastewater treatment plants poses a public health concern. The present study examined the relationship between antibiotic resistance levels and biofilm formation of Acinetobacter baumannii strains isolated from hospital effluents.

METHODS: Antibiotic susceptibility of 71 A. baumannii isolates was evaluated using the Kirby Bauer disc diffusion method. The minimum inhibitory concentration was performed by the agar dilution method, while the minimum biofilm eradication concentration was performed by the broth dilution method. Genotyping was performed with plasmid DNA. Biofilm formation was evaluated by the microtitre plate method and quantified using crystal violet. P-values < 0.05 were regarded as statistically significant in all the tests conducted.

RESULTS: The extended spectrum resistant (XDR) strains made up 58% of the isolates while MDR and pan drug resistance (PDR) were observed in 50% of the isolates from the final effluent. The MBEC of ciprofloxacin increased by 255-fold while that of ceftazidime was as high as 63-1310-fold compared to their respective MICs. Isolates were classified into four plasmid pattern groups and no significance difference exists between biofilm formation and plasmid type (P = 0.0921). The degree of biofilm formation was independent of the level of antibiotic resistance, although MDRs, XDRs and PDRs produced significant biofilm biomass (P = 0.2580).

CONCLUSION: The results suggest that hospital effluent is a potential risk for multidrug-resistant biofilm-forming A. baumannii strains. Appropriate treatment and disposal for effluents are essential to prevent presence of drug resistance pathogens in waste water.},
}

@article {pmid34480246,
year = {2021},
author = {Joshi, K and Navalgund, L and Rathod, K and Shet, VB and Srinikethan, G and Shet, T and Rachitha, U and Anand, A},
title = {Biofilm characterization in removal of total chemical oxygen demand and nitrate from wastewater using draft tube spouted bed reactor.},
journal = {Biotechnology letters},
volume = {},
number = {},
pages = {},
pmid = {34480246},
issn = {1573-6776},
abstract = {The present paper investigates the effect of dilution rate on the removal of total chemical oxygen demand and nitrate in the draft tube spouted bed reactor and morphological characteristics of biofilms formed by microorganisms of mixed culture on granular activated carbon (GAC). The nitrate and total chemical oxygen demand (COD) decreased from 97 to 81% and 95% to 87% respectively with increase in dilution rate from 0.6/h to 1.5/h showing that residence time in the reactor governs the nitrate and total COD reduction efficiency. Lower dilution rates favor higher production of biomass and extracellular polymeric substances (EPS). It was observed that the nitrate and total COD reduction rate increased with time along with simultaneous increase in EPS production. Thus, the performance of a reactor in terms of dynamic and steady-state biofilm characteristics associated with nitrate and organic reduction is a strong function of dilution rate. Hence these findings indicate that a draft tube spouted bed reactor is capable of simultaneously reducing total organics and nitrogen in industrial/municipal wastewater, as this reactor possesses two distinct regions aerobic and anoxic conditions which can prevail in different parts of a reactor.},
}

@article {pmid34479647,
year = {2021},
author = {Toledo-Silva, B and de Souza, FN and Mertens, K and Piepers, S and Haesebrouck, F and De Vliegher, S},
title = {Bovine-associated non-aureus staphylococci suppress Staphylococcus aureus biofilm dispersal in vitro yet not through agr regulation.},
journal = {Veterinary research},
volume = {52},
number = {1},
pages = {114},
pmid = {34479647},
issn = {1297-9716},
support = {G0H2516N (AUGE/15/05)//fonds wetenschappelijk onderzoek/ ; },
abstract = {Biofilm formation is a significant virulence factor in Staphylococcus (S.) aureus strains causing subclinical mastitis in dairy cows. A role of environmental signals and communication systems in biofilm development, such as the agr system in S. aureus, is suggested. In the context of multispecies biofilm communities, the presence of non-aureus staphylococci (NAS) might influence S. aureus colonization of the bovine mammary gland, yet, such interspecies interactions have been poorly studied. We determined whether 34 S. chromogenes, 11 S. epidermidis, and 14 S. simulans isolates originating from bovine milk samples and teat apices (TA) were able to affect biofilm formation and dispersion of S. aureus, and if so, how isolate traits such as the capacity to regulate the S. aureus agr quorum sensing system are determinants in this process. The capacity of an agr-positive S. aureus strain to form biofilm was increased more in the presence of S. chromogenes than in the presence of S. simulans and S. epidermidis isolates and in the presence of NAS isolates that do not harbor biofilm related genes. On the other hand, biofilm dispersion of this particular S. aureus strain was suppressed by NAS as a group, an effect that was more pronounced by isolates from TA. Furthermore, the observed effects on biofilm formation and dispersion of the agr-positive S. aureus strain as well as of an agr-negative S. aureus strain did not depend on the capacity of NAS to repress the agr system.},
}

@article {pmid34478899,
year = {2021},
author = {Ghazi, M and Pourhajibagher, M and Bahador, A and Chiniforush, N and Dadpour, S and Dadpour, Y},
title = {Evaluation of adding Nanosized natural Zeolite to photodynamic therapy against P. gingivalis biofilm on titanium disks.},
journal = {Photodiagnosis and photodynamic therapy},
volume = {},
number = {},
pages = {102519},
doi = {10.1016/j.pdpdt.2021.102519},
pmid = {34478899},
issn = {1873-1597},
abstract = {BACKGROUND: Antibacterial photodynamic therapy (aPDT) can be used as an adjunctive therapy for eliminating bacterial biofilm. The application of nanotechnology in aPDT, which is on a growing trend, has improved the delivery of photosensitizers (PSs) into microorganisms. Encapsulation of molecules and ions is considered as an outstanding potential feature of zeolites. This study sought to enhance the effect of aPDT using a diode laser (810 nm) with a potential PS, indocyanine green (ICG), combined with nanosized natural zeolite (NZ), against biofilm of P. gingivalis on sandblasted, large-grit, and acid-etched (SLA) implant titanium disks surface.

METHODS: A bacterial suspension of standard P. gingivalis (™ATCC® 33277) strains was prepared. To prepare bacterial biofilm, the titanium disks were added to 48 microtubes containing bacterial suspension, and divided into eight groups, i.e., the control groups (positive and negative), and 6 test groups (ICG; NZ; Diod laser; NZ+ICG; aPDT; NZ+aPDT). After the treatments, the total number of colony-forming units per disk was calculated. Finally, the data was analyzed, and the eight groups were compared together.

RESULTS: The highest reduction in the number of P. gingivalis was seen in group 8 (NZ+aPDT) with 3.55 log10 CFU/ml and the antibacterial effect of 45.7% compared with the negative control group. Conversley, group 5 (Diode Laser solely) represented the highest mean of colony count with the lowest antibacterial effects per disk (6.42 log10 CFU/ml, 1.8%).

CONCLUSIONS: The antibacterial effect of NZ+aPDT against P. gingivalis biofilm was noticeable. Thus, adding NZ to ICG improved the result of aPDT in this study.},
}

@article {pmid34475672,
year = {2021},
author = {Garg, A and Mala, K and Kamath, PM},
title = {Biofilm models in endodontics-A narrative review.},
journal = {Journal of conservative dentistry : JCD},
volume = {24},
number = {1},
pages = {2-9},
doi = {10.4103/JCD.JCD_621_20},
pmid = {34475672},
issn = {0972-0707},
abstract = {The knowledge of biofilm and its eradication from the root canal system are of utmost importance in the clinical practice of an endodontist. Various treatment strategies and protocols have been demonstrated and discussed by numerous clinicians and researchers, on these models, that play an important role in the treatment outcome . Once a biofilm model is developed by considering various factors, several methods can be used to assess the biofilms formed on these models. This review discusses the importance of biofilm models in endodontics, types of biofilm models and factors associated with developing and the methods to evaluate these models.},
}

@article {pmid34474869,
year = {2021},
author = {Song, X and Liu, P and Liu, X and Wang, Y and Wei, H and Zhang, J and Yu, L and Yan, X and He, Z},
title = {Dealing with MDR bacteria and biofilm in the post-antibiotic era: Application of antimicrobial peptides-based nano-formulation.},
journal = {Materials science & engineering. C, Materials for biological applications},
volume = {128},
number = {},
pages = {112318},
doi = {10.1016/j.msec.2021.112318},
pmid = {34474869},
issn = {1873-0191},
abstract = {The rapid development of multidrug-resistant (MDR) bacteria due to the improper and overuse of antibiotics and the ineffective performance of antibiotics against the difficult-to-treat biofilm-related infections (BRIs) have urgently called for alternative antimicrobial agents and strategies in combating bacterial infections. Antimicrobial peptides (AMPs), owing to their compelling antimicrobial activity against MDR bacteria and BRIs without causing bacteria resistance, have attracted extensive attention in the research field. With the development of nanomaterial-based drug delivery strategies, AMPs-based nano-formulations have significantly improved the therapeutic effects of AMPs by ameliorating their hydrolytic stability, half-life in vivo, and solubility as well as reducing the cytotoxicity and hemolysis, etc. This review has comprehensively summarized the application AMPs-based nano-formulation in various bacterial infections models, including bloodstream infections (specifically sepsis), pulmonary infections, chronic wound infections, gastrointestinal infections, among others. The design of the nanomaterial-based drug delivery systems and the therapeutic effects of the AMPs-based nano-formulations in literature have been categorized and in details discussed. Overall, this review provides insights into the advantages and disadvantages of the current developed AMPs-based nano-formulations in literature for the treatment of bacterial infections, bringing inspirations and suggestions for their future design in the way towards clinical translation.},
}

@article {pmid34474857,
year = {2021},
author = {Qiu, G and Wu, H and Huang, M and Ma, T and Schneider, A and Oates, TW and Weir, MD and Xu, HHK and Zhao, L},
title = {Novel calcium phosphate cement with biofilm-inhibition and platelet lysate delivery to enhance osteogenesis of encapsulated human periodontal ligament stem cells.},
journal = {Materials science & engineering. C, Materials for biological applications},
volume = {128},
number = {},
pages = {112306},
doi = {10.1016/j.msec.2021.112306},
pmid = {34474857},
issn = {1873-0191},
abstract = {Osteomyelitis is caused by Staphylococcus aureus (S. aureus), with associated progressive bone loss. This study developed for the first time a calcium phosphate cement (CPC) for delivery of doxycycline (DOX) and human platelet lysate (hPL) to fight against S. aureus infection and enhance the osteogenesis of human periodontal ligament stem cells (hPDLSCs). Chitosan-containing CPC scaffolds were fabricated in the absence (CPCC) or presence of DOX (CPCC+DOX). In addition, hPL was encapsulated in alginate microbeads and incorporated into CPCC+DOX (CPCC+DOX+ hPL). Flexural strength of CPCC+DOX + hPL was (5.56 ± 0.55) MPa, lower than (8.26 ± 1.6) MPa of CPCC+DOX (p < 0.05), but exceeding the reported strength of cancellous bone. CPCC+DOX and CPCC+DOX + hPL exhibited strong antibacterial activity against S. aureus, reducing biofilm CFU by 4 orders of magnitude. The hPDLSCs encapsulated in microbeads were co-cultured with the CPCs. The hPDLSCs were able to be released from the microbeads and showed a high proliferation rate, increasing by about 8 folds at 14 days for all groups. The hPL was released from the scaffold and promoted the osteogenic differentiation of hPDLSCs. ALP activity was 28.07 ± 5.15 mU/mg for CPCC+DOX + hPL, higher than 17.36 ± 2.37 mU/mg and 1.34 ± 0.37 mU/mg of CPCC+DOX and CPCC, respectively (p < 0.05). At 7 days, osteogenic genes (ALP, RUNX2, COL-1, and OPN) in CPCC+DOX + hPL were 3-10 folds those of control. The amount of hPDLSC-synthesized bone mineral with CPCC+DOX + hPL was 3.8 folds that of CPCC (p < 0.05). In summary, the novel CPC + DOX + hPL-hPDLSCs scaffold exhibited strong antibacterial activity, excellent cytocompatibility and hPDLSC osteogenic differentiation, showing a promising approach for treatment and prevention of bone infection and enhancement of bone regeneration.},
}

@article {pmid34474848,
year = {2021},
author = {Mendhi, J and Ramachandra, SS and Prasadam, I and Ivanovski, S and Yang, Y and Xiao, Y},
title = {Endogenous nitric oxide-generating surfaces via polydopamine-copper coatings for preventing biofilm dispersal and promoting microbial killing.},
journal = {Materials science & engineering. C, Materials for biological applications},
volume = {128},
number = {},
pages = {112297},
doi = {10.1016/j.msec.2021.112297},
pmid = {34474848},
issn = {1873-0191},
abstract = {INTRODUCTION: Peri-implantitis is a bacterially induced inflammatory disease which affects the hard and soft tissues around a dental implant. Microbial biofilm formation is an important causative factor in peri-implantitis. The aim of this study is to develop an effective multifunctional surface coating for antimicrobial property and to counteract oral biofilm-associated infections via a single polydopamine copper coating (PDAM@Cu) on titanium implant surface to regulate endogenous nitric oxide (NO) generation.

METHODS: PDAM@Cu coatings were made with different concentrations of CuCl2 on titanium surfaces with a simple dip coating technique. Coatings were characterised to evaluate Cu concentrations as well as NO release rates from the coatings. Further, salivary biofilms were made on the coatings using Brain Heart Infusion (BHI) media in an anaerobic chamber. Biofilms were prepared with three different mixtures, one of which was saliva only, the second had an addition of sheep's blood, and the third was prepared with NO donors S-nitrosoglutathione (GSNO) and L-glutathione (GSH) in the mixture of saliva and blood to evaluate the effects of endogenously produced NO on biofilms. The effectiveness of coated surfaces on biofilms were assessed using four different methods, namely, crystal violet assay, scanning electron microscopy imaging, 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) metabolic assay, and live/dead staining.

RESULTS: NO release rates could be controlled with different Cu concentration in PDAM@Cu coatings. NO generated from the PDAM@Cu coatings effectively induced dispersal of biofilms shown by the reduction in biofilm biomass as well as reduced biofilm attachment in samples prepared with blood and NO donors. Cu ions released from the PDAM@Cu coatings resulted in killing of the dispersed bacteria, which was evidenced by the live/dead cell staining and reduced metabolic activity noted from the XTT assay. In contrast, samples prepared with saliva showed no significant reduction in biofilms, indicating the important effect of endogenously generated NO on biofilm dispersal.

CONCLUSION: In conclusion, PDAM@Cu coatings with NO generating surfaces have a dual anti-biofilm function, with a synergistic effect on biofilm dispersal from regulated NO generation and bactericidal effects from Cu ions from the coatings.},
}

@article {pmid34473354,
year = {2021},
author = {Leelapornpisid, W and Novak-Frazer, L and Qualtrough, A and Rautemaa-Richardson, R},
title = {Effectiveness of D,L-2-hydroxyisocaproic acid (HICA) and alpha-mangostin against endodontopathogenic microorganisms in a multi-species bacterial-fungal biofilm in an ex vivo tooth model.},
journal = {International endodontic journal},
volume = {},
number = {},
pages = {},
doi = {10.1111/iej.13623},
pmid = {34473354},
issn = {1365-2591},
abstract = {AIMS: To develop a defined multi-species root canal biofilm model ex vivo, and to perform viable compositional analysis following D,L-2-hydroxyisocaproic acid (HICA), alpha-mangostin, Calcicur® , and Odontopaste® exposure.

METHODOLOGY: Time-kill assays were conducted in vitro using HICA, alpha-mangostin, Calcicur® , Odontopaste® , and saline solution on the planktonic cultures of C. albicans, E. faecalis, L. rhamnosus, and S. gordonii. Human root dentine blocks were prepared (n = 100) ex vivo, and multi-species suspensions containing each of 1.5x108 CFU/mL C. albicans, E. faecalis, L. rhamnosus, and S. gordonii in BHI were incubated within the root canals for 21 days. Canals (n = 20/group) were then exposed to medicaments for 7 days. Samples taken from the inner (first 0.1 mm) and deeper (second 0.1 mm) dentine by drilling with Ash Steel Burs No. 5 and No. 6, and residual roots were cultured in broth for 24 hours. Cell growth was detected by spectrophotometry and confirmed by culture on agar. The other set of inner dentine, deeper dentine, and residual root samples were sonicated then exposed with 50 μM PMA before DNA was extracted using the QIAamp DNA mini kit. Real-time quantitative PCR was performed to determine the biofilm composition as well as the number of live and total cells remaining in the biofilm following each treatment. The OD data were analysed with Kruskal-Wallis and Friedman with Wilcoxon signed-rank test between and within groups, respectively, agar culture and qPCR data with Pearson chi-square with Mann-Whitney and Cochran with McNemar tests, respectively (P<0.0001).

RESULTS: Time-kill assays revealed that HICA and Calcicur® killed all planktonic organisms within 24 hours, while alpha-mangostin killed the organisms within 72 hours. However, Odontopaste® was a slow-killing agent: 10 cells of planktonic organisms survived after exposure to the agent for 7 days. The ex vivo tooth model demonstrated that HICA and alpha-mangostin significantly inhibited the cell growth in all sampling depths (p<0.0001). All species-specific data revealed the effectiveness of each medicament on the biofilm composition.

CONCLUSIONS: HICA and alpha-mangostin had antimicrobial activity against multi-species bacterial-fungal biofilms.},
}

@article {pmid34469193,
year = {2021},
author = {Hashidoko, Y and Kim, D},
title = {Bidirectional cell-cell communication via indole and cyclo(Pro-Tyr) modulates interspecies biofilm formation.},
journal = {Applied and environmental microbiology},
volume = {},
number = {},
pages = {AEM0127721},
doi = {10.1128/AEM.01277-21},
pmid = {34469193},
issn = {1098-5336},
abstract = {The extracellular signaling molecule indole plays a pivotal role in biofilm formation by the enteric γ-Proteobacterium Escherichia coli; this process is particularly correlated with extracellular indole concentration. Using indole-biodegrading β-Proteobacterium Burkholderia unamae, we examined the mechanism by which these two bacteria modulate biofilm formation in an indole-dependent manner. We quantified the spatial organization of cocultured microbial communities at the micron-scale through computational image analysis, ultimately identifying how bidirectional cell-to-cell communication modulated the physical relationships between them. Further analysis allowed us to determine the mechanism by which the B. unamae-derived signaling diketopiperazine, cyclo(Pro-Tyr), considerably upregulated indole biosynthesis and enhanced E. coli biofilm formation. We also determined that the presence of unmetabolized indole enhanced production of cyclo(Pro-Tyr). Thus, bidirectional cell-to-cell communication that occurred via interspecies signaling molecules modulated formation of a mixed-species biofilm between indole-producing and indole-consuming species. Importance Indole is a relatively stable N-heterocyclic aromatic compound that is widely found in nature. To date, the correlations between indole-related bidirectional cell-to-cell communications and interspecies communal organization remain poorly understood. In this study, we used an experimental model, which consisted of indole-producing and indole-degrading bacteria, to evaluate how bidirectional cell-to-cell communication modulated interspecies biofilm formation via intrinsic and environmental cues. We identified a unique spatial patterning of indole-producing and indole-degrading bacteria within mixed-species biofilms. This spatial patterning was an active process mediated by bidirectional physico-chemical interactions. Our findings represent an important step in gaining a more thorough understanding of the process of polymicrobial biofilm formation and advance the possibility of using indole degrading bacteria to address biofilm-related health and industry issues.},
}

@article {pmid34469136,
year = {2021},
author = {Liu, M and Han, P and Zhang, L and Zhong, C and You, C},
title = {Biofilm-Mediated Immobilization of a Multienzyme Complex for Accelerating Inositol Production from Starch.},
journal = {Bioconjugate chemistry},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.bioconjchem.1c00338},
pmid = {34469136},
issn = {1520-4812},
abstract = {Bacterial biofilm, as a natural and renewable material, is a promising architecture for enzyme immobilization. In this study, we have demonstrated the feasibility of an Escherichia coli biofilm to immobilize a self-assembly multienzyme complex by the covalent interaction between a peptide SpyTag and its protein partner SpyCatcher. The SpyTag-labeled biofilm is displayed on the surface of E. coli by overexpressing the recombinant CsgA-SpyTag, in which CsgA is capable of forming biofilms. This SpyTag bearing biofilm is used to bind with SpyCatcher bearing synthetic mini-scaffoldin, which also contains a carbohydrate-binding module 3 (CBM3), and four different cohesins from different microorganisms. CBM3 was used to bind with cellulose, while the four different cohesins were used to recruit four dockerin-containing cascade enzymes, which were subsequently applied to convert starch to myo-inositol. Compared to the free enzyme mixture, the biofilm-immobilized enzyme complex exhibited a 4.28 times increase in initial reaction rate in producing myo-inositol from 10 g/L maltodextrin (a derivative of starch). Additionally, this biofilm-immobilized enzyme complex showed much higher recycle ability than the enzyme complex which was immobilized on a regenerated amorphous cellulose (RAC) system. In conclusion, the biofilm-mediated immobilization of the enzymatic biosystem provides a promising strategy to increase the reaction rate and enhance the stability of an in vitro enzymatic biosystem, exhibiting high potential to improve the efficiency of an in vitro biosystem.},
}

@article {pmid34466092,
year = {2021},
author = {El-Tarabily, KA and El-Saadony, MT and Alagawany, M and Arif, M and Batiha, GE and Khafaga, AF and Elwan, HAM and Elnesr, SS and E Abd El-Hack, M},
title = {Using essential oils to overcome bacterial biofilm formation and their antimicrobial resistance.},
journal = {Saudi journal of biological sciences},
volume = {28},
number = {9},
pages = {5145-5156},
doi = {10.1016/j.sjbs.2021.05.033},
pmid = {34466092},
issn = {1319-562X},
abstract = {The increase of resistant bacteria puts a huge pressure on the antimicrobials in current use. Antimicrobial resistance (AMR) results from antibiotic misuse and abuse over many years and is a global financial burden. New polices must be developed for the use of antimicrobials and to continue research efforts to mitigate AMR. It is essential to target the most harmful bacteria and concentrate on their mechanisms of resistance to develop successful antimicrobials. Essential oils (EOs) are occur naturally in plants and have long been used as antimicrobials, but most have not been researched. This review explores EOs as alternative antimicrobials, investigating their ability to decrease or inhibit biofilm formation, and assess their ability to contribute to AMR control. Low concentrations of EOs can inhibit Gram-positive and Gram-negative pathogenic bacteria. Some EOs have demonstrated strong anti-biofilm activities. If EOs are successful against biofilm formation, particularly in bacteria developing AMR, they could be incorporated into new antimicrobials. Therefore, there is a need to investigate these EOs' potential, particularly for surface disinfection, and against bacteria from food, clinical and non-clinical environments.},
}

@article {pmid34466074,
year = {2021},
author = {Alarjani, KM and Almutairi, AM and Flanet Raj, SR and Rajaselvam, J and Chang, SW and Ravindran, B},
title = {Biofilm producing indigenous bacteria isolated from municipal sludge and their nutrient removal ability in moving bed biofilm reactor from the wastewater.},
journal = {Saudi journal of biological sciences},
volume = {28},
number = {9},
pages = {4994-5001},
doi = {10.1016/j.sjbs.2021.06.084},
pmid = {34466074},
issn = {1319-562X},
abstract = {In the present study, improved moving bed biofilm reactor (MBBR) was applied to enhance the nutrient removal ability of the municipal wastewater. A total of 18 indigenous bacterial isolates were screened from the sewage sludge sample and nitrate reductase, nitrite reductase and hydroxylamine oxidase was analyzed. The strains Pseudomonas aeruginosa NU1 and Acinetobacter calcoaceticus K12 produced 0.87 ± 0.05 U/mg and 0.52 ± 0.12 U/mg hydroxylamine oxidase, 1.023 ± 0.062 U/mg and 1.29 ± 0.07 U/mg nitrite reductase, and 0.789 ± 0.031 U/mg and 1.07 ± 0.13 U/mg nitrate reductase. Nitrogen and phosphate removal improved by the addition of nutrient sources and achieved > 80% removal rate. pH and temperature of the medium also affected nutrient removal and improved removal was achieved at optimum level (p < 0.05). MBBR was designed with R1 (aerobic), R2 and R3 (anoxic) reactors. MBBR reactors removed acceptable level phosphorus removal properties up to 7.2 ± 3.8%, 42.4 ± 4.6%, and 84.2 ± 13.1% in the R1, R2, R3 and R4 reactors, respectively. Denitrification rate showed linear relationship at increasing concentrations nitrogen content in the reactor and denitrification rate was 1.43 g NO2-N /m2/day at 1.5 g NO2-N /m2/day. Dehydrogenase activity was assayed in all reactors and maximum amount was detected in the aerobic biofilm reactor. Based on the present findings, MBBRs and the selected bacterial strains are useful for the degradation domestic wastewater with minimum working area.},
}

@article {pmid34464080,
year = {2021},
author = {Motealleh, A and Kart, D and Czieborowski, M and Kehr, NS},
title = {Functional Nanomaterials and 3D-Printable Nanocomposite Hydrogels for Enhanced Cell Proliferation and for the Reduction of Bacterial Biofilm Formation.},
journal = {ACS applied materials & interfaces},
volume = {},
number = {},
pages = {},
doi = {10.1021/acsami.1c13392},
pmid = {34464080},
issn = {1944-8252},
abstract = {Biomaterial-associated infections are a major cause of biomaterial implant failure. To prevent the initial attachment of bacteria to the implant surface, researchers have investigated various surface modification methods. However, most of these approaches also prevent the attachment, spread, and growth of mammalian cells, resulting in tissue integration failure. Therefore, the success of biomaterial implants requires an optimal balance between tissue integration (cell adhesion to biomaterial implants) and inhibition of bacterial colonization. In this regard, we synthesize bifunctional nanomaterials by functionalizing the pores and outer surfaces of periodic mesoporous organosilica (PMO) with antibacterial tetracycline (Tet) and antibacterial and cell-adhesive bipolymer poly-d-lysine (PDL), respectively. Then, the fabricated TetPMO-PDL nanomaterials are incorporated into alginate-based hydrogels to create injectable and 3D-printable nanocomposite (NC) hydrogels (AlgL-TetPMO-PDL). These bifunctional nanomaterial and 3D-printable NC hydrogel show pH-dependent release of Tet over 7 days. They also enhance the proliferation of eukaryotic cells (fibroblasts). TetPMO-PDL is inactive in reducing Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis biofilms. However, AlgL-TetPMO-PDL shows significant antibiofilm activity against P. aeruginosa. These results suggest that the incorporation of TetPMO-PDL into AlgL may have a synergistic effect on the inhibition of the Gram-negative bacterial (P. aeruginosa) biofilm, while this has no effect on the reduction of the Gram-positive bacterial (S. aureus and E. faecalis) biofilm.},
}

@article {pmid34462461,
year = {2021},
author = {Pizauro, LJL and de Almeida, CC and Silva, SR and MacInnes, JI and Kropinski, AM and Zafalon, LF and de Avila, FA and de Mello Varani, A},
title = {Genomic comparisons and phylogenetic analysis of mastitis-related staphylococci with a focus on adhesion, biofilm, and related regulatory genes.},
journal = {Scientific reports},
volume = {11},
number = {1},
pages = {17392},
pmid = {34462461},
issn = {2045-2322},
abstract = {Mastitis is a common and costly disease on dairy farms, commonly caused by Staphylococcus spp. though the various species are associated with different clinical outcomes. In the current study, we performed genomic analyses to determine the prevalence of adhesion, biofilm, and related regulatory genes in 478 staphylococcal species isolated from clinical and subclinical mastitis cases deposited in public databases. The most prevalent adhesin genes (ebpS, atl, pls, sasH and sasF) were found in both clinical and subclinical isolates. However, the ebpS gene was absent in subclinical isolates of Staphylococcus arlettae, S. succinus, S. sciuri, S. equorun, S. galinarum, and S. saprophyticus. In contrast, the coa, eap, emp, efb, and vWbp genes were present more frequently in clinical (vs. subclincal) mastitis isolates and were highly correlated with the presence of the biofim operon (icaABCD) and its transcriptional regulator, icaR. Co-phylogenetic analyses suggested that many of these adhesins, biofilm, and associated regulatory genes could have been horizontally disseminated between clinical and subclinical isolates. Our results further suggest that several adhesins, biofilm, and related regulatory genes, which have been overlooked in previous studies, may be of use for virulence profiling of mastitis-related Staphylococcus strains or as potential targets for vaccine development.},
}

@article {pmid34461541,
year = {2021},
author = {Luo, H and Liu, C and He, D and Xu, J and Sun, J and Li, J and Pan, X},
title = {Environmental behaviors of microplastics in aquatic systems: A systematic review on degradation, adsorption, toxicity and biofilm under aging conditions.},
journal = {Journal of hazardous materials},
volume = {423},
number = {Pt A},
pages = {126915},
doi = {10.1016/j.jhazmat.2021.126915},
pmid = {34461541},
issn = {1873-3336},
abstract = {Microplastics (MPs, < 5 mm) in the environment have attracted worldwide attention due to their wide distribution and difficulty in handling. Aging processes such as UV irradiation, biodegradation, physical abrasion and chemical oxidation can affect the environmental behavior of MPs. This review article summarizes different aging processes of MPs and subsequent effects on the adsorption of pollutants, the leaching of additives, and the toxicity of MPs. In addition, the formation process of biofilm on the surface of MPs and the interactions between biofilm and aged MPs are revealed. MPs can accumulate different environmental pollutants (organic pollutants, heavy metals, microorganisms, etc.) through surface adsorption, pore filling and distribution. Moreover, the aging of MPs affects their adsorption performance toward these pollutants due to a series of changes in their specific surface area and oxygen-containing functional groups. The release of some toxic additives such as phthalates after aging can enhance the toxic effects of MPs. Aging also changes the shape and size of MPs, which can affect the eating habits of the organisms and further increase the potential toxicity of MPs. This article conducts a systematical analysis and summary of the environmental behavior and physicochemical properties of MPs as well as the changes due to MPs aging, which helps to better understand the impact of aging on MPs in the environment. Future research on MPs aging should reduce the knowledge gap between laboratory simulation and actual conditions and increase the environmental relevance.},
}

@article {pmid34461310,
year = {2021},
author = {Rohatgi, A and Gupta, P},
title = {Natural and synthetic plant compounds as anti-biofilm agents against Escherichia coli O157:H7 biofilm.},
journal = {Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases},
volume = {},
number = {},
pages = {105055},
doi = {10.1016/j.meegid.2021.105055},
pmid = {34461310},
issn = {1567-7257},
abstract = {Escherichia coli is a common gram-negative bacterium found in the gut and intestinal tract of warm-blooded animals including humans. An evolved seropathotype E. coli O157:H7 (STEC) came into existence in 1982, since then it has been evolved as a stronger and more robust drug-resistant pathotype of E. coli. This drug resistance is due to horizontal gene transfer, natural gene evolution for survival, and most of the cases due to the ability of STEC to switch to the biofilm growth mode from planktonic lifestyle. During the growth in biofilm mode, Escherichia coli O157:H7 opts more robust ability to grow in adverse environments i.e., in presence of antibiotics and other antimicrobial chemicals. Due to the biofilm matrix, the microbial community acquires drug resistance. This makes the treatment of diseases caused by E. coli O157:H7 a complex challenge. To address the illnesses caused by this biofilm-forming pathogen, there are several possible strategies such as antibiotic therapies, synthetic antimicrobial chemicals, adjunct therapy of synergistic effect of multiple drugs, and more importantly plant originated compounds as a new anti-biofilm candidate. The present review summarizes various phytochemicals and their derivatives reported in the last decade mostly to eliminate the biofilm of STEC. The review will progressively reveal the antibiofilm mechanism of the phytochemicals against STEC and to be a potential candidate for the development of the future antibacterial drugs to STEC induced infections.},
}

@article {pmid34460871,
year = {2021},
author = {Soh, EY and Smith, F and Gimenez, MR and Yang, L and Vejborg, RM and Fletcher, M and Halliday, N and Bleves, S and Heeb, S and Cámara, M and Givskov, M and Hardie, KR and Tolker-Nielsen, T and Ize, B and Williams, P},
title = {Disruption of the Pseudomonas aeruginosa Tat system perturbs PQS-dependent quorum sensing and biofilm maturation through lack of the Rieske cytochrome bc1 sub-unit.},
journal = {PLoS pathogens},
volume = {17},
number = {8},
pages = {e1009425},
doi = {10.1371/journal.ppat.1009425},
pmid = {34460871},
issn = {1553-7374},
abstract = {Extracellular DNA (eDNA) is a major constituent of the extracellular matrix of Pseudomonas aeruginosa biofilms and its release is regulated via pseudomonas quinolone signal (PQS) dependent quorum sensing (QS). By screening a P. aeruginosa transposon library to identify factors required for DNA release, mutants with insertions in the twin-arginine translocation (Tat) pathway were identified as exhibiting reduced eDNA release, and defective biofilm architecture with enhanced susceptibility to tobramycin. P. aeruginosa tat mutants showed substantial reductions in pyocyanin, rhamnolipid and membrane vesicle (MV) production consistent with perturbation of PQS-dependent QS as demonstrated by changes in pqsA expression and 2-alkyl-4-quinolone (AQ) production. Provision of exogenous PQS to the tat mutants did not return pqsA, rhlA or phzA1 expression or pyocyanin production to wild type levels. However, transformation of the tat mutants with the AQ-independent pqs effector pqsE restored phzA1 expression and pyocyanin production. Since mutation or inhibition of Tat prevented PQS-driven auto-induction, we sought to identify the Tat substrate(s) responsible. A pqsA::lux fusion was introduced into each of 34 validated P. aeruginosa Tat substrate deletion mutants. Analysis of each mutant for reduced bioluminescence revealed that the primary signalling defect was associated with the Rieske iron-sulfur subunit of the cytochrome bc1 complex. In common with the parent strain, a Rieske mutant exhibited defective PQS signalling, AQ production, rhlA expression and eDNA release that could be restored by genetic complementation. This defect was also phenocopied by deletion of cytB or cytC1. Thus, either lack of the Rieske sub-unit or mutation of cytochrome bc1 genes results in the perturbation of PQS-dependent autoinduction resulting in eDNA deficient biofilms, reduced antibiotic tolerance and compromised virulence factor production.},
}

@article {pmid34460313,
year = {2021},
author = {Kalamara, M and Stanley-Wall, NR},
title = {The intertwined roles of specialised metabolites within the Bacillus subtilis biofilm.},
journal = {Journal of bacteriology},
volume = {},
number = {},
pages = {JB0043121},
doi = {10.1128/JB.00431-21},
pmid = {34460313},
issn = {1098-5530},
abstract = {Bacteria produce specialised metabolites with a range of functions. In this issue of the Journal of Bacteriology Schoenborn et al. study the production and role of secondary metabolites during biofilm development and sporulation in Bacillus subtilis. Most metabolites studied are produced during differentiation and six are required for the development of biofilms and/or spores. The authors propose a model for the timing of production and role in differentiation exerted by each secondary metabolite.},
}

@article {pmid34459556,
year = {2021},
author = {Rørvik, GH and Naemi, AO and Edvardsen, PKT and Simm, R},
title = {The c-di-AMP signaling system influences stress tolerance and biofilm formation of Streptococcus mitis.},
journal = {MicrobiologyOpen},
volume = {10},
number = {4},
pages = {e1203},
doi = {10.1002/mbo3.1203},
pmid = {34459556},
issn = {2045-8827},
abstract = {Streptococcus mitis is a commensal bacterial species of the oral cavity, with the potential for opportunistic pathogenesis. For successful colonization, S. mitis must be able to adhere to surfaces of the oral cavity and survive and adapt to frequently changing environmental conditions. Cyclic-di-AMP (c-di-AMP) is a nucleotide second messenger, involved in the regulation of stress responses and biofilm formation in several bacterial species. Cyclic-di-AMP is produced by diadenylate cyclases and degraded by phosphodiesterases. We have previously shown that in S. mitis, one diadenylate cyclase (CdaA) and at least two phosphodiesterases (Pde1 and Pde2) regulate the intracellular concentration of c-di-AMP. In this study, we utilized S. mitis deletion mutants of cdaA, pde1, and pde2 to analyze the role of c-di-AMP signaling in various stress responses, biofilm formation, and adhesion to eukaryotic cells. Here, we demonstrate that the Δpde1 mutant displayed a tendency toward increased susceptibility to acetic acid at pH 4.0. Deletion of cdaA increases auto-aggregation of S. mitis but reduces biofilm formation on an abiotic surface. These phenotypes are more pronounced under acidic extracellular conditions. Inactivation of pde1 or pde2 reduced the tolerance to ciprofloxacin, and UV radiation and the Δpde1 mutant was more susceptible to Triton X-100, indicating a role for c-di-AMP signaling in responses to DNA damage and cell membrane perturbation. Finally, the Δpde2 mutant displayed a tendency toward a reduced ability to adhere to oral keratinocytes. Taken together, our results indicate an important role for c-di-AMP signaling in cellular processes important for colonization of the mouth.},
}

@article {pmid34456739,
year = {2021},
author = {Qu, Q and Cui, W and Xing, X and Zou, R and Huang, X and Wang, X and Wu, T and Bello-Onaghise, G and Yuan, S and Li, Y},
title = {Rutin, A Natural Inhibitor of IGPD Protein, Partially Inhibits Biofilm Formation in Staphylococcus xylosus ATCC700404 in vitro and in vivo.},
journal = {Frontiers in pharmacology},
volume = {12},
number = {},
pages = {728354},
doi = {10.3389/fphar.2021.728354},
pmid = {34456739},
issn = {1663-9812},
abstract = {Staphylococcus xylosus (S. xylosus) has become an emerging opportunistic pathogen due to its strong biofilm formation ability. Simultaneously, the biofilm of bacteria plays an important role in antibiotic resistance and chronic infection. Here, we confirmed that rutin can effectively inhibit biofilm formation in S. xylosus, of which the inhibition mechanism involves its ability to interact with imidazole glycerol phosphate dehydratase (IGPD), a key enzyme in the process of biofilm formation. We designed experiments to target IGPD and inhibited its activities against S. xylosus. Our results indicated that the activity of IGPD and the amount of histidine decreased significantly under the condition of 0.8 mg/ml rutin. Moreover, the expression of IGPD mRNA (hisB) and IGPD protein was significantly down-regulated. Meanwhile, the results from molecular dynamic simulation and Bio-layer interferometry (BLI) technique showed that rutin could bind to IGPD strongly. Additionally, in vivo studies demonstrated that rutin treatment reduced inflammation and protect mice from acute mastitis caused by S. xylosus. In summary, our findings provide new insights into the treatment of biofilm mediated persistent infections and chronic bacterial infections. It could be helpful to design next generation antibiotics to against resistant bacteria.},
}

@article {pmid34456615,
year = {2021},
author = {Dos Santos, EMP and Martins, CCB and de Oliveira Santos, JV and da Silva, WRC and Silva, SBC and Pelagio-Flores, MA and Galembeck, A and Cavalcanti, IMF},
title = {Silver nanoparticles-chitosan composites activity against resistant bacteria: tolerance and biofilm inhibition.},
journal = {Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology},
volume = {23},
number = {8},
pages = {196},
doi = {10.1007/s11051-021-05314-1},
pmid = {34456615},
issn = {1388-0764},
abstract = {This study aimed to evaluate the effectiveness of silver nanoparticles-chitosan composites (AgNPs) with different morphologies and particle size distributions against resistant bacteria and biofilm formation. Four different samples were prepared by a two-step procedure using sodium borohydride and ascorbic acid as reducing agents and characterized by UV-Vis absorption spectra, scanning transmission electron microscopy. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the AgNPs were determined according to the Clinical and Laboratory Standards Institute (CLSI) against clinical isolates multidrug-resistant and strains of the American Type Culture Collection (ATCC). An assay was performed to determine the MICs during 20 successive bacteria exposures to AgNPs to investigate whether AgNPs induce tolerance in bacteria. The antibiofilm activities of AgNPs were also evaluated by determining the minimum biofilm inhibitory concentration (MBIC). The spherical AgNPs present diameters ranging from 9.3 to 62.4 nm, and some samples also have rod-, oval-, and triangle-shaped nanoparticles. The MIC and MBC values ranged from 0.8 to 25 μg/mL and 3.1 to 50 μg/mL, respectively. Smaller and spherical AgNPs exhibited the highest activity, but all the AgNPs developed in this study exhibit bactericidal activity. There was no significant MIC increase after 20 passages to the AgNPs. Regarding the antibiofilm activity, MBICs ranged from 12.5 to 50 μg/mL. Again, smaller and spherical nanoparticles presented the best results with phenotypic inhibition of production of slime or exopolysaccharide (EPS) matrix. Thus, it was concluded that AgNPs have a promising potential against resistant bacteria and bacteria that grow on biofilms without inducing tolerance.

Supplementary Information: The online version contains supplementary material available at 10.1007/s11051-021-05314-1.},
}

@article {pmid34455871,
year = {2021},
author = {Gilbert-Girard, S and Reigada, I and Savijoki, K and Yli-Kauhaluoma, J and Fallarero, A},
title = {Screening of natural compounds identifies ferutinin as an antibacterial and anti-biofilm compound.},
journal = {Biofouling},
volume = {},
number = {},
pages = {1-17},
doi = {10.1080/08927014.2021.1971655},
pmid = {34455871},
issn = {1029-2454},
abstract = {Antibacterial screenings are most commonly targeted at planktonic bacteria but less effort is dedicated to the exploration of agents acting on biofilms. Here, a natural compounds library was screened against Staphylococcus aureus using a 384-well plate platform to identify compounds preventing biofilm formation. Five structurally diverse hits were selected for follow-up studies: honokiol, tschimganidin, ferutinin, oridonin and deoxyshikonin. The compounds were evaluated against different bacterial species for their capacity to prevent and disrupt biofilms. The development of resistance and cytotoxicity were also investigated. Ferutinin displayed the best antibacterial activity, with a minimum inhibitory, bactericidal and biofilm preventive concentration of 25 µM against S. aureus. It efficiently disrupted pre-formed biofilms (over 5-log reduction of viable cells) and reduced biofilm formation on a catheter in the presence of neutrophils. This work provides new information on the antibacterial activity of five natural compounds and identified ferutinin as a promising candidate against S. aureus biofilms.},
}

@article {pmid34455869,
year = {2021},
author = {Talluri, SNL and Winter, RM and Salem, DR},
title = {Nanoscale characteristics of conditioning film development on photobioreactor materials: influence on the initial adhesion and biofilm formation by a cyanobacterium.},
journal = {Biofouling},
volume = {},
number = {},
pages = {1-14},
doi = {10.1080/08927014.2021.1971201},
pmid = {34455869},
issn = {1029-2454},
abstract = {Adsorption of conditioning films on a solid surface is the first step in the development of biofilms. With the goal of understanding the preliminary adhesion mechanisms of cyanobacteria on photobioreactor (PBR) materials to prevent biofouling, the physical changes occurring on PBR materials were investigated during the initial adhesion and biofilm formation by Anabaena sp. PCC 7120, a cyanobacterium that is genetically modified to produce linalool. Atomic force microscopy (AFM) revealed that the conditioning film deposition was in the form of spike-like structures on all the materials except PVC. The average heights (in the range 9 - 16 nm) of the conditioning films deposited on glass, PMMA, PC and HDPE were 11 to 20 times higher than on PVC at 96 h. The time dependent change in thickness of conditioning films correlated well with Anabaena cell attachment to the PBR materials. The rapid and significant colonization of Anabaena on glass within 48 h was consistent with the increase in thickness of the conditioning film within this time period. Lack of the conditioning film spike structures and no change in thickness of the conditioning films with time on the PVC together with comparatively delayed cell attachment and conditioning-film protein deposition on this material, indicated that the nanoscale spike structures on the other PBR materials may be accelerating the cell attachment process but are not a prerequisite for cell attachment. These results suggest that PVC should be explored further as an antifouling material for photobioreactors. The thickness of the conditioning films on glass measured by a scratch and scan method was in good agreement with the thickness values measured by an adhesive tape method, indicating that both these methods can be used for fast and reliable AFM thickness determination of bacterial conditioning films.},
}

@article {pmid34455651,
year = {2021},
author = {Saïdi, F and Jolivet, NY and Lemon, DJ and Nakamura, A and Belgrave, AM and Garza, AG and Veyrier, FJ and Islam, ST},
title = {Bacterial glycocalyx integrity drives multicellular swarm biofilm dynamism.},
journal = {Molecular microbiology},
volume = {},
number = {},
pages = {},
doi = {10.1111/mmi.14803},
pmid = {34455651},
issn = {1365-2958},
abstract = {Exopolysaccharide (EPS) layers on the bacterial cell surface are key determinants of biofilm establishment and maintenance, leading to the formation of higher-order 3D structures that confer numerous survival benefits to a cell community. In addition to a specific cell-associated EPS glycocalyx, we recently revealed that the social δ-proteobacterium Myxococcus xanthus secretes a novel biosurfactant polysaccharide (BPS) to the extracellular milieu. Together, secretion of the two polymers (EPS and BPS) is required for type IV pilus (T4P)-dependent swarm expansion via spatio-specific biofilm expression profiles. Thus the synergy between EPS and BPS secretion somehow modulates the multicellular lifecycle of M. xanthus. Herein, we demonstrate that BPS secretion functionally alters the EPS glycocalyx via destabilization of the latter, fundamentally changing the characteristics of the cell surface. This impacts motility behaviours at the single-cell level and the aggregative capacity of cells in groups via cell-surface EPS fibril formation as well as T4P production, stability, and positioning. These changes modulate the structure of swarm biofilms via cell layering, likely contributing to the formation of internal swarm polysaccharide architecture. Together, these data reveal the manner by which the combined secretion of two distinct polymers induces single-cell changes that modulate swarm biofilm communities.},
}

@article {pmid34455348,
year = {2021},
author = {Kim, HJ and Park, JS and Lee, TK and Kang, D and Kang, JH and Shin, K and Jung, SW},
title = {Dynamics of marine bacterial biofouling communities after initial Alteromonas genovensis biofilm attachment to anti-fouling paint substrates.},
journal = {Marine pollution bulletin},
volume = {172},
number = {},
pages = {112895},
doi = {10.1016/j.marpolbul.2021.112895},
pmid = {34455348},
issn = {1879-3363},
abstract = {To determine how bacterial communities succeed after the initial attachment of the bacterial biofilm adhesion using 16S rDNA meta-barcoding in plates coated with copper-based anti-fouling (AF) and non-AF (control) coatings as well as ambient seawater, coated plates were submerged in a marine environment in situ. Alteromonas genovensis (Gammaproteobacteria) in AF coating and Pacificibacter sp. (Alphaproteobacteria) in the control plate were initially abundant. In the AF coating, the abundance of A. genovensis decreased rapidly, whereas that of genus Phaeobacter (Alphaproteobacteria), Serratia (Gammaproteobacteria) and Cupriavidus (Betaproteobacteria) increased. Bacterial community in the control plate had a strong connection to pathogenic Vibrio spp. associated with the growth of invertebrates. Therefore, in the in situ AF coating experiment, A. genovensis accumulation was initially and intensively increased, and the bacteria responded to chemical antagonism, induced the proliferation of specific biofilm bacteria and influenced the interactions and recruitment of additional bacterial communities.},
}

@article {pmid34454228,
year = {2021},
author = {Kostrytsia, A and Papirio, S and Khodzhaev, M and Morrison, L and Collins, G and Lens, PNL and Ijaz, UZ and Esposito, G},
title = {Biofilm carrier type affects biogenic sulfur-driven denitrification performance and microbial community dynamics in moving-bed biofilm reactors.},
journal = {Chemosphere},
volume = {287},
number = {Pt 1},
pages = {131975},
doi = {10.1016/j.chemosphere.2021.131975},
pmid = {34454228},
issn = {1879-1298},
abstract = {Autotrophic denitrification with biosulfur (ADBIOS) provides a sustainable technological solution for biological nitrogen removal from wastewater driven by biogenic S0, derived from biogas desulfurization. In this study, the effect of different biofilm carriers (conventional AnoxK™ 1 and Z-200 with a pre-defined maximum biofilm thickness) on ADBIOS performance and microbiomics was investigated in duplicate moving bed-biofilm reactors (MBBRs). The MBBRs were operated parallelly in continuous mode for 309 days, whilst gradually decreasing the hydraulic retention time (HRT) from 72 to 21 h, and biosulfur was either pumped in suspension (days 92-223) or supplied in powder form. Highest nitrate removal rates were approximately 225 (±11) mg/L·d and 180 (±7) mg NO3--N/L·d in the MBBRs operated with K1 and Z-200 carriers, respectively. Despite having the same protected surface area for biofilm development in each MBBR, the biomass attached onto the K1 carrier was 4.8-fold more than that on the Z-200 carrier, with part of the biogenic S0 kept in the biofilm. The microbial communities of K1 and Z-200 biofilms could also be considered similar at cDNA level in terms of abundance (R = 0.953 with p = 0.042). A relatively stable microbial community was formed on K1 carriers, while the active portion of the microbial community varied significantly over time in the MBBRs using Z-200 carriers.},
}

@article {pmid34452788,
year = {2021},
author = {Panariello, BHD and Cavichioli, EAM and Sochacki, SF and Gandini Junior, LG and Duarte, S},
title = {Blue light & chlorhexidine therapies on Streptococcus mutans biofilm and its regrowth on an in vitro orthodontic model.},
journal = {American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics},
volume = {},
number = {},
pages = {},
doi = {10.1016/j.ajodo.2020.06.050},
pmid = {34452788},
issn = {1097-6752},
abstract = {INTRODUCTION: Fixed orthodontic appliances create areas of stagnation for dental biofilms and make it difficult to clean the teeth; therefore, there is a risk of developing incipient caries lesions during the orthodontic treatment. The objective of this study is to determine if the combination of 2 different therapies, phototherapy by blue light (BL) and the antimicrobial 0.12% chlorhexidine (CHX) on enamel, orthodontic brackets, and elastics, would reduce or inhibit mature Streptococcus mutans biofilms and their regrowth on these substrates 24 hours after the application of the treatment; and if this treatment would interfere with bracket adhesion to the enamel.

METHODS: Biofilms of S. mutans UA159 were formed for 5-days over samples composed of a bovine enamel, orthodontic bracket, and orthodontic elastic. Then, the specimens were treated with 0.89% NaCl for 1 minute, BL for 12 minutes (72 J/cm2), 0.12% CHX for 1 minute, and BL for 12 minutes, followed by 0.12% CHX for 1 minute (BL+CHX). Biofilm was evaluated by colonies forming units and dry weight immediately after treatments and 24 hours after treatments (regrowth). The pH of the spent media was measured on the fifth and sixth days. Biofilm formation on the samples after the treatments and regrowth was visually evaluated by confocal laser scanning microscopy. Shear bond strength (SBS) between bracket and enamel was evaluated using a universal testing machine at a crosshead speed of 1 mm/min. After bonding, specimens were thermocycled (500× at 5-55°C), treated, and thermocycled again.

RESULTS: After 5 days of biofilm formation, BL+CHX significantly reduced the bacterial viability on enamel compared with NaCl (P = 0.004) and BL (P = 0.014). For bracket and elastic, all the treatments resulted in similar bacterial viability (P ≥0.081). In the regrowth, CHX and BL+CHX significantly reduced the bacterial viability in the enamel compared with the NaCl (P ≤0.015) and BL (P ≤0.013). For bracket, BL+CHX significantly reduced the bacterial viability compared with NaCl (P = 0.008) and BL (P = 0.009). For the elastic, BL+CHX eliminated the biofilms from the substrate. CHX and BL+CHX significantly reduced the bacterial viability 24 hours after treatment for all substrates (P ≤0.05). The media pH significantly increased when samples were treated with CHX and BL+CHX (P ≤0.001). Confocal laser scanning microscopy images visually showed an abundant quantity of red cells in the samples treated with BL+CHX. There was no difference in the SBS between the treatments (P ≥0.932).

CONCLUSIONS: The association between BL and CHX reduced S. mutans biofilm and its regrowth on an in vitro orthodontic model and did not influence the bonding strength between bracket and enamel.},
}

@article {pmid34452132,
year = {2021},
author = {Allegrone, G and Ceresa, C and Rinaldi, M and Fracchia, L},
title = {Diverse Effects of Natural and Synthetic Surfactants on the Inhibition of Staphylococcus aureus Biofilm.},
journal = {Pharmaceutics},
volume = {13},
number = {8},
pages = {},
doi = {10.3390/pharmaceutics13081172},
pmid = {34452132},
issn = {1999-4923},
support = {FAR project 2019//Università degli Studi del Piemonte Orientale/ ; },
abstract = {A major challenge in the biomedical field is the creation of materials and coating strategies that effectively limit the onset of biofilm-associated infections on medical devices. Biosurfactants are well known and appreciated for their antimicrobial/anti-adhesive/anti-biofilm properties, low toxicity, and biocompatibility. In this study, the rhamnolipid produced by Pseudomonas aeruginosa 89 (R89BS) was characterized by HPLC-MS/MS and its ability to modify cell surface hydrophobicity and membrane permeability as well as its antimicrobial, anti-adhesive, and anti-biofilm activity against Staphylococcus aureus were compared to two commonly used surfactants of synthetic origin: Tween® 80 and TritonTM X-100. The R89BS crude extract showed a grade of purity of 91.4% and was composed by 70.6% of mono-rhamnolipids and 20.8% of di-rhamnolipids. The biological activities of R89BS towards S. aureus were higher than those of the two synthetic surfactants. In particular, the anti-adhesive and anti-biofilm properties of R89BS and of its purified mono- and di-congeners were similar. R89BS inhibition of S. aureus adhesion and biofilm formation was ~97% and 85%, respectively, and resulted in an increased inhibition of about 33% after 6 h and of about 39% after 72 h when compared to their chemical counterparts. These results suggest a possible applicability of R89BS as a protective coating agent to limit implant colonization.},
}

@article {pmid34451969,
year = {2021},
author = {Su, FJ and Chen, MM},
title = {Protective Efficacy of Novel Oral Biofilm Vaccines against Lactococcus garvieae Infection in Mullet, Mugil cephalus.},
journal = {Vaccines},
volume = {9},
number = {8},
pages = {},
doi = {10.3390/vaccines9080844},
pmid = {34451969},
issn = {2076-393X},
abstract = {Lactococcus garvieae (L. garvieae) is an important pathogen that causes enormous economic losses in both marine and freshwater aquaculture. At present, antibiotics are the only option for farmers to reduce the losses caused by L. garvieae. However, the usage of antibiotics leads to environmental pollution and the production of drug-resistant strains of bacteria. Therefore, vaccination is preferred as an alternative method to prevent infectious diseases. In this study, we describe an effective approach to the production of an oral biofilm vaccine, using bacteria grown on chitosan particles to form biofilms, and thus providing an inactive pathogen that enhances the immune response in fish. We observed the formation of a biofilm on chitosan particles and administered the novel oral biofilm vaccine to fish. We analyzed the immune responses, including antibody production, phagocytic ability, albumin/globulin ratio and immune-related genes, of vaccinated and control groups of black mullet. Our results show that the phagocytic ability of the biofilm vaccine group was 84%, which is significantly higher than that of the control group, and the antibody production in this group was significantly higher compared with the other group. The mRNA expression levels of immune-related genes (TLR2, IL-1β, TNF-α) were significantly upregulated in the spleen after vaccination. In challenge experiments, the relative percent survival (RPS) was 77% in the biofilm vaccine group, 18% in the whole-cell vaccine group, and 0% in the chitosan particle group at 32 days post-vaccination. In addition, we also found that the relative percent survival (RPS) at 1 day post-vaccination was 74% in the biofilm vaccine group, 42% in the whole-cell vaccine group, and 26% in the chitosan particle group. In both long-term and short-term challenge experiments, the viability of the biofilm vaccine group was significantly higher than that of the whole-cell, chitosan particle and PBS groups. We conclude that based on its protective effect, the L. garvieae biofilm vaccine is better than the whole-cell vaccine when challenged several weeks after vaccination. In addition, the biofilm vaccine also has a greater protective effect than the whole-cell vaccine when challenged immediately after vaccination. Therefore, the biofilm vaccine might represent a novel method for the prevention and treatment of L. garvieae infection.},
}

@article {pmid34451434,
year = {2021},
author = {Silva, V and Almeida, L and Gaio, V and Cerca, N and Manageiro, V and Caniça, M and Capelo, JL and Igrejas, G and Poeta, P},
title = {Biofilm Formation of Multidrug-Resistant MRSA Strains Isolated from Different Types of Human Infections.},
journal = {Pathogens (Basel, Switzerland)},
volume = {10},
number = {8},
pages = {},
doi = {10.3390/pathogens10080970},
pmid = {34451434},
issn = {2076-0817},
abstract = {Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main pathogens causing chronic infections, mainly due to its capacity to form biofilms. However, the mechanisms underlying the biofilm formation of MRSA strains from different types of human infections are not fully understood. MRSA strains isolated from distinct human infections were characterized aiming to determine their biofilm-forming capacity, the biofilm resistance to conventional antibiotics and the prevalence of biofilm-related genes, including, icaA, icaB, icaC, icaD, fnbA, fnbB, clfA, clfB, cna, eno, ebpS, fib and bbp. Eighty-three clinical MRSA strains recovered from bacteremia episodes, osteomyelitis and diabetic foot ulcers were used. The biofilm-forming capacity was evaluated by the microtiter biofilm assay and the biofilm structure was analyzed via confocal scanning laser microscopy. The antimicrobial susceptibility of 24-h-old biofilms was assessed against three antibiotics and the biomass reduction was measured. The metabolic activity of biofilms was evaluated by the XTT assay. The presence of biofilm-related genes was investigated by whole-genome sequencing and by PCR. Despite different intensities, all strains showed the capacity to form biofilms. Most strains had also a large number of biofilm-related genes. However, strains isolated from osteomyelitis showed a lower capacity to form biofilms and also a lower prevalence of biofilm-associated genes. There was a significant reduction in the biofilm biomass of some strains tested against antibiotics. Our results provide important information on the biofilm-forming capacity of clinical MRSA strains, which may be essential to understand the influence of different types of infections on biofilm production and chronic infections.},
}

@article {pmid34451352,
year = {2021},
author = {Burgard, N and Kienitz, M and Jourdan, C and Rüttermann, S},
title = {The Influence of Modified Experimental Dental Resin Composites on the Initial In Situ Biofilm-A Triple-Blinded, Randomized, Controlled Split-Mouth Trial.},
journal = {Polymers},
volume = {13},
number = {16},
pages = {},
doi = {10.3390/polym13162814},
pmid = {34451352},
issn = {2073-4360},
support = {RU 825/3-1//Deutsche Forschungsgemeinschaft/ ; },
abstract = {The purpose of the study was to investigate the bacterial viability of the initial biofilm on the surface of experimental modified dental resin composites. Twenty-five healthy individuals with good oral hygiene were included in this study. In a split-mouth design, they received acrylic splints with five experimental composite resin specimens. Four of them were modified with either a novel polymeric hollow-bead delivery system or methacrylated polymerizable Irgasan (Antibacterial B), while one specimen served as an unmodified control (ST). A delivery system based on Poly-Pore® was loaded with one of the active agents: Tego® Protect 5000 (Antiadhesive A), Dimethicone (Antiadhesive B), or Irgasan (Antibacterial A). All study subjects refrained from toothbrushing during the study period. Specimens were detached from the splints after 8 h and given a live/dead staining before fluorescence microscopy. A Friedman test and a post hoc Nemenyi test were applied with a significance level at p < 0.05. In summary, all materials but Antibacterial B showed a significant antibacterial effect compared to ST. The results suggested the role of the materials' chemistry in the dominance of cell adhesion. In conclusion, dental resin composites with Poly-Pore-loaded active agents showed antibacterial effectiveness in situ.},
}

@article {pmid34450330,
year = {2021},
author = {Ruan, X and Deng, X and Tan, M and Wang, Y and Hu, J and Sun, Y and Yu, C and Zhang, M and Jiang, N and Jiang, R},
title = {Effect of resveratrol on the biofilm formation and physiological properties of avian pathogenic Escherichia coli.},
journal = {Journal of proteomics},
volume = {},
number = {},
pages = {104357},
doi = {10.1016/j.jprot.2021.104357},
pmid = {34450330},
issn = {1876-7737},
abstract = {Avian pathogenic Escherichia coli (APEC) is widely distributed, causing great economic losses to the poultry industry. The formation of APEC biofilms causes chronic, persistent, and repeated infections in the clinic, making treatment difficult. Resveratrol is a natural product, which has good health benefits including antimicrobial, anti-inflammatory, and cardiovascular activities. Resveratrol shows efficient inhibition of bacterial biofilm formation. However, a comprehensive understanding of the proteomic properties of APEC treated resveratrol is still lacking. In this study, APEC cells treated by resveratrol were investigated using a label-free differential proteomic method. Several proteins, including those related to a two-component system and chemotaxis, were found to be implicated in APEC biofilm formation. In addition, the physiological properties were significantly changed in terms of purine, pyruvate, and glyoxylate and dicarboxylate metabolism in APEC. Data are available via ProteomeXchange with the identifier PXD025706. We speculated that pyruvate dehydrogenase might be a potential target to inhibit Escherichia coli biofilm formation. Overall, our results indicated that resveratrol inhibits APEC biofilm formation by regulating the levels of proteins in two-component systems, especially chemotaxis proteins. The results showed that resveratrol had a potential application in inhibiting the biofilm formation of APEC. SIGNIFICANCE: This study elucidated the mechanism of resveratrol inhibiting biofilm formation of avian pathogenic Escherichia coli (APEC) based on a label-free differential proteomics. It was indicated that resveratrol inhibits APEC biofilm formation by regulating the levels of proteins in two component systems, especially chemotaxis proteins. Meanwhile, we speculated that pyruvate dehydrogenase might be a potential target to inhibit Escherichia coli biofilm formation. It shows that resveratrol has a potential application prospect in inhibiting the biofilm formation of APEC.},
}

@article {pmid34450163,
year = {2021},
author = {Qi, J and Gong, M and Zhang, R and Song, Y and Liu, Q and Zhou, H and Wang, J and Mei, Y},
title = {Evaluation of the antibacterial effect of tea tree oil on Enterococcus faecalis and biofilm in vitro.},
journal = {Journal of ethnopharmacology},
volume = {},
number = {},
pages = {114566},
doi = {10.1016/j.jep.2021.114566},
pmid = {34450163},
issn = {1872-7573},
abstract = {Tea tree essential oil (TTO) is extracted from the leaves of Melaleuca alternifolia by steam distillation. It is well known for its traditional medicinal uses, particularly for the treatment of bruises, insect bites, skin infections, vertigo, convulsions, toothache, and rheumatism. Earlier research has shown that TTO can effectively inhibit oral microorganisms in the root canals. Enterococcus faecalis (E. faecalis) has been considered to be associated with persistent root canal infections and root canal treatment failure. The biofilm of E. faecalis makes it more vigorous, toxic, and resistant to antibiotics.

AIM OF THE STUDY: In this study, our aim was to evaluate the antimicrobial effects of TTO on planktonic E. faecalis and biofilms compared with 0.2% CHX.

MATERIALS AND METHODS: We explored the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), the bacteriostatic rate by MTT assay, the antimicrobial time by time-kill assay, and the effects on cell integrity, the biomass, and bacterial activity of E. faecalis biofilms. Finally, we investigated the microstructure changes of E. faecalis biofilms using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).

RESULTS: The MIC and MBC values were 0.25% and 0.5%, the bacterial inhibition rate, time-kill was dosage dependent, and TTO can effectively destroy membrane integrity. SEM CLSM images revealed that TTO could reduce bacterial aggregation, biofilm thickness and inhibited biofilm formation. The effect of TTO was the same as that of 0.2% CHX at some specific concentrations. In summary, TTO has the potential to be effective against E. faecalis infections.

CONCLUSIONS: TTO was able to inhibit E. faecalis by destroying cell membrane, inhibiting the formation of E. faecalis biofilms, and eliminating mature formed biofilms. In this study, TTO has the potential to be further developed as a novel antibacterial drug.},
}

@article {pmid34449059,
year = {2021},
author = {Na, SH and Jeon, H and Oh, MH and Kim, YJ and Lee, JC},
title = {Screening of small molecules attenuating biofilm formation of Acinetobacter baumannii by inhibition of ompA promoter activity.},
journal = {Journal of microbiology (Seoul, Korea)},
volume = {59},
number = {9},
pages = {871-878},
pmid = {34449059},
issn = {1976-3794},
abstract = {Anti-virulence therapeutic strategies are promising alternatives against drug-resistant pathogens. Outer membrane protein A (OmpA) plays a versatile role in the pathogenesis and antimicrobial resistance of Acinetobacter baumannii. Therefore, OmpA is an innovative target for anti-virulence therapy against A. baumannii. This study aimed to develop a high-throughput screening (HTS) system to discover small molecules inhibiting the ompA promoter activity of A. baumannii and screen chemical compounds using the bacterial growth-based HTS system. The ompA promoter and open reading frame of nptI fusion plasmids that controlled the expression of nptI encoding resistance to kanamycin by the ompA promoter were constructed and then transformed into A. baumannii ATCC 17978. This reporter strain was applied to screen small molecules inhibiting the ompA promoter activity in a chemical library. Of the 7,520 chemical compounds, 15 exhibited ≥ 70% growth inhibition of the report strain cultured in media containing kanamycin. Three compounds inhibited the expression of ompA and OmpA in the outer membrane of A. baumannii ATCC 17978, which subsequently reduced biofilm formation. In conclusion, our reporter strain is useful for large-scale screening of small molecules inhibiting the ompA expression in A. baumannii. Hit compounds identified by the HTS system are promising scaffolds to develop novel therapeutics against A. baumannii.},
}

@article {pmid34448395,
year = {2021},
author = {Tran, HA and Tran, PA},
title = {In Situ Coatings of Silver Nanoparticles for Biofilm Treatment in Implant-Retention Surgeries: Antimicrobial Activities in Monoculture and Coculture.},
journal = {ACS applied materials & interfaces},
volume = {},
number = {},
pages = {},
doi = {10.1021/acsami.1c08239},
pmid = {34448395},
issn = {1944-8252},
abstract = {Bacterial biofilms are indicated in most medical device-associated infections. Treating these biofilms is challenging yet critically important for applications such as in device-retention surgeries, which can have reinfection rates of up to 80%. This in vitro study centered around our new method of treating biofilm and preventing reinfection. Ionic silver (Ag, in the form of silver nitrate) combined with dopamine and a biofilm-lysing enzyme (α-amylase) were applied to model 4-day-old Staphylococcus aureus biofilms on titanium substrates to degrade the extracellular matrix of the biofilm and kill the biofilm bacteria. In this process, the oxidative self-polymerization of dopamine converted Ag ions into Ag nanoparticles that, together with the resultant self-adhering polydopamine (PDA), formed coatings that strongly bound to the treated substrates. Surprisingly, although these Ag/PDA coatings significantly reduced S. aureus growth in standard bacterial monoculture, they showed much lower antimicrobial activity in coculture of the bacteria and osteoblastic MC3T3-E1 cells in which the bacteria were also found attached to the osteoblasts. This S. aureus- osteoblast interaction was also linked to bacterial survival against gentamicin treatment observed in coculture. Our study thus provided clear evidence suggesting that bacteria's interactions with tissue cells surrounding implants may significantly contribute to their resistance to antimicrobial treatment.},
}

@article {pmid34448102,
year = {2021},
author = {Teren, M and Shagieva, E and Vondrakova, L and Viktorova, J and Svarcova, V and Demnerova, K and Michova, HT},
title = {Mutagenic strategies against luxS gene affect the early stage of biofilm formation of Campylobacter jejuni.},
journal = {Journal of applied genetics},
volume = {},
number = {},
pages = {},
pmid = {34448102},
issn = {2190-3883},
abstract = {Currently, it is clear that the luxS gene has an impact on the process of biofilm formation in Campylobacter jejuni. However, even within the species, naturally occurring strains of Campylobacter lacking the luxS gene exist, which can form biofilms. In order to better understand the genetic determinants and the role of quorum sensing through the LuxS/AI-2 pathway in biofilm formation, a set of mutant/complemented strains of C. jejuni 81-176 were prepared. Additionally, the impact of the mutagenic strategy used against the luxS gene was investigated. Biofilm formation was affected by both the presence and absence of the luxS gene, and by the mutagenic strategy used. Analysis by CLSM showed that all mutant strains formed significantly less biofilm mass when compared to the wild-type. Interestingly, the deletion mutant (∆luxS) showed a larger decrease in biofilm mass than the substitution (∙luxS) and insertional inactivated ([Formula: see text]luxS) mutants, even though all the mutant strains lost the ability to produce autoinducer-2 molecules. Moreover, the biofilm of the ∆luxS mutant lacked the characteristic microcolonies observed in all other strains. The complementation of all mutant strains resulted in restored ability to produce AI-2, to form a complex biofilm, and to develop microcolonies at the level of the wild-type.},
}

@article {pmid34447490,
year = {2021},
author = {Robertsson, C and Svensäter, G and Blum, Z and Jakobsson, ME and Wickström, C},
title = {Proteomic response in Streptococcus gordonii DL1 biofilm cells during attachment to salivary MUC5B.},
journal = {Journal of oral microbiology},
volume = {13},
number = {1},
pages = {1967636},
doi = {10.1080/20002297.2021.1967636},
pmid = {34447490},
issn = {2000-2297},
abstract = {Background: Salivary mucin MUC5B seems to promote biodiversity in dental biofilms, and thereby oral health, for example, by inducing synergistic 'mucolytic' activities in a variety of microbial species that need to cooperate for the release of nutrients from the complex glycoprotein. Knowledge of how early colonizers interact with host salivary proteins is integral to better understand the maturation of putatively harmful oral biofilms and could provide key insights into biofilm physiology.

Methods: The early oral colonizer Streptococcus gordonii DL1 was grown planktonically and in biofilm flow cell systems with uncoated, MUC5B or low-density salivary protein (LDP) coated surfaces. Bacterial cell proteins were extracted and analyzed using a quantitative mass spectrometry-based workflow, and differentially expressed proteins were identified.

Results and conclusions: Overall, the proteomic profiles of S. gordonii DL1 were similar across conditions. Six novel biofilm cell proteins and three planktonic proteins absent in all biofilm cultures were identified. These differences may provide insights into mechanisms for adaptation to biofilm growth in this species. Salivary MUC5B also elicited specific responses in the biofilm cell proteome. These regulations may represent mechanisms by which this mucin could promote colonization of the commensal S. gordonii in oral biofilms.},
}

@article {pmid34445806,
year = {2021},
author = {Campoccia, D and Montanaro, L and Arciola, CR},
title = {Extracellular DNA (eDNA). A Major Ubiquitous Element of the Bacterial Biofilm Architecture.},
journal = {International journal of molecular sciences},
volume = {22},
number = {16},
pages = {},
doi = {10.3390/ijms22169100},
pmid = {34445806},
issn = {1422-0067},
support = {Theory-enhancing Project RF-2018-12368273//Ministry of Health for the IRCCS Rizzoli Orthopaedic Institute of Bologna, Italy/ ; },
abstract = {After the first ancient studies on microbial slime (the name by which the biofilm matrix was initially indicated), multitudes of studies on the morphology, composition and physiology of biofilms have arisen. The emergence of the role that biofilms play in the pathogenesis of recalcitrant and persistent clinical infections, such as periprosthetic orthopedic infections, has reinforced scientific interest. Extracellular DNA (eDNA) is a recently uncovered component that is proving to be almost omnipresent in the extracellular polymeric substance (EPS) of biofilm. This macromolecule is eliciting unprecedented consideration for the critical impact on the pathogenesis of chronic clinical infections. After a systematic review of the literature, an updated description of eDNA in biofilms is presented, with a special focus on the latest findings regarding its fundamental structural role and the contribution it makes to the complex architecture of bacterial biofilms through interactions with a variety of other molecular components of the biofilm matrix.},
}

@article {pmid34445798,
year = {2021},
author = {Mušković, M and Ćavar, I and Lesar, A and Lončarić, M and Malatesti, N and Gobin, I},
title = {Photodynamic Inactivation of Legionella pneumophila Biofilm Formation by Cationic Tetra- and Tripyridylporphyrins in Waters of Different Hardness.},
journal = {International journal of molecular sciences},
volume = {22},
number = {16},
pages = {},
doi = {10.3390/ijms22169095},
pmid = {34445798},
issn = {1422-0067},
support = {KK.01.1.1.01.0001//European Regional Development Fund/ ; uniri-biomed-18-171//University of Rijeka/ ; uniri-prirod-18-173//University of Rijeka/ ; },
abstract = {The bacterium Legionella pneumophila is still one of the probable causes of waterborne diseases, causing serious respiratory illnesses. In the aquatic systems, L. pneumophila exists inside free-living amoebae or can form biofilms. Currently developed disinfection methods are not sufficient for complete eradication of L. pneumophila biofilms in water systems of interest. Photodynamic inactivation (PDI) is a method that results in an antimicrobial effect by using a combination of light and a photosensitizer (PS). In this work, the effect of PDI in waters of natural origin and of different hardness, as a treatment against L. pneumophila biofilm, was investigated. Three cationic tripyridylporphyrins, which were previously described as efficient agents against L. pneumophila alone, were used as PSs. We studied how differences in water hardness affect the PSs' stability, the production of singlet oxygen, and the PDI activity on L. pneumophila adhesion and biofilm formation and in biofilm destruction. Amphiphilic porphyrin showed a stronger tendency for aggregation in hard and soft water, but its production of singlet oxygen was higher in comparison to tri- and tetracationic hydrophilic porphyrins that were stable in all water samples. All three studied porphyrins were shown to be effective as PDI agents against the adhesion of the L. pneumophila to polystyrene, against biofilm formation, and in the destruction of the formed biofilm, in their micromolar concentrations. However, a higher number of dissolved ions, i.e., water hardness, generally reduced somewhat the PDI activity of all the porphyrins at all tested biofilm growth stages.},
}

@article {pmid34445744,
year = {2021},
author = {Salvatore, MM and Maione, A and Albarano, L and de Alteriis, E and Carraturo, F and Andolfi, A and Salvatore, F and Galdiero, E and Guida, M},
title = {An Integrated Analysis of Intracellular Metabolites and Virulence Gene Expression during Biofilm Development of a Clinical Isolate of Candida tropicalis on Distinct Surfaces.},
journal = {International journal of molecular sciences},
volume = {22},
number = {16},
pages = {},
doi = {10.3390/ijms22169038},
pmid = {34445744},
issn = {1422-0067},
abstract = {Emergence of Candida tropicalis, which causes potential life-threatening invasive candidiasis, is often associated with colonization of medical devices as biofilm. Biofilm plays an important role in the virulence of the pathogen because of its complex structure, which provides resistance to conventional antimicrobials. In this study, the metabolic response of a clinical strain of C. tropicalis colonizing three distinct surfaces (polytetrafluoroethylene (PTFE), polystyrene, and polycarbonate) as well as the expression of virulence and stress related genes (ALS3, Hsp21, SAP1, SAP2, SAP3, and CYR1), were explored. Our results showed that lesser biofilm was developed on PTFE compared to polystyrene and polycarbonate. GS-MS metabolic analysis identified a total of 36 metabolites in the intracellular extract of cells grown on polystyrene, polycarbonate, and PTFE, essentially belonging to central carbon metabolism, amino acids, and lipids metabolism. The metabolic analysis showed that saturated and unsaturated fatty acids are preferentially produced during biofilm development on polycarbonate, whereas trehalose and vitamin B6, known as cellular protectors against a variety of stressors, were characteristic of biofilm on PTFE. The results of the transcriptomic analysis consider the different degrees of colonization of the three substrates, being CYR1, which encodes the component of signaling pathway of hyphal formation-cAMP-PKA, downregulated in PTFE biofilm compared to polycarbonate or polystyrene biofilms, while Hsp21 was upregulated in concomitance with the potential unfavorable conditions for biofilm formation on PTFE. Overall, this work provides new insights into the knowledge of C. tropicalis biofilm development on surfaces of medical relevance in the perspective of improving the management of Candida infections.},
}

@article {pmid34443617,
year = {2021},
author = {Rusakov, A and Kuz'mina, M and Frank-Kamenetskaya, O},
title = {Biofilm Medium Chemistry and Calcium Oxalate Morphogenesis.},
journal = {Molecules (Basel, Switzerland)},
volume = {26},
number = {16},
pages = {},
doi = {10.3390/molecules26165030},
pmid = {34443617},
issn = {1420-3049},
support = {19-17-00141//Russian Science Foundation/ ; },
abstract = {The present study is focused on the effect of biofilm medium chemistry on oxalate crystallization and contributes to the study of the patterns of microbial biomineralization and the development of nature-like technologies, using the metabolism of microscopic fungi. Calcium oxalates (weddellite and whewellite in different ratios) were synthesized by chemical precipitation in a weakly acidic environment (pH = 4-6), as is typical for the stationary phase of micromycetes growth, with a ratio of Ca2+/C2O42- = 4.0-5.5, at room temperature. Additives, which are common for biofilms on the surface of stone in an urban environment (citric, malic, succinic and fumaric acids; and K+, Mg2+, Fe3+, Sr2+, SO42+, PO43+ and CO32+ ions), were added to the solutions. The resulting precipitates were studied via X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). It was revealed that organic acids, excreted by micromicetes, and some environmental ions, as well as their combinations, significantly affect the weddellite/whewellite ratio and the morphology of their phases (including the appearance of tetragonal prism faces of weddellite). The strongest unique effect leading to intensive crystallization of weddellite was only caused by the presence of citric acid additive in the medium. Minor changes in the composition of the additive components can lead to significant changes in the weddellite/whewellite ratio. The effect of the combination of additives on this ratio does not obey the law of additivity. The content of weddellite in the systems containing a representative set of both organic acids and environmental ions is ~20 wt%, which is in good agreement with natural systems.},
}

@article {pmid34443457,
year = {2021},
author = {Di Salle, A and Viscusi, G and Di Cristo, F and Valentino, A and Gorrasi, G and Lamberti, E and Vittoria, V and Calarco, A and Peluso, G},
title = {Antimicrobial and Antibiofilm Activity of Curcumin-Loaded Electrospun Nanofibers for the Prevention of the Biofilm-Associated Infections.},
journal = {Molecules (Basel, Switzerland)},
volume = {26},
number = {16},
pages = {},
doi = {10.3390/molecules26164866},
pmid = {34443457},
issn = {1420-3049},
support = {PON 03 PE_00110_1/ptd1_000410//Regione Campania/ ; },
abstract = {Curcumin extracted from the rhizome of Curcuma Longa has been used in therapeutic preparations for centuries in different parts of the world. However, its bioactivity is limited by chemical instability, water insolubility, low bioavailability, and extensive metabolism. In this study, the coaxial electrospinning technique was used to produce both poly (ε-caprolactone) (PCL)-curcumin and core-shell nanofibers composed of PCL and curcumin in the core and poly (lactic acid) (PLA) in the shell. Morphology and physical properties, as well as the release of curcumin were studied and compared with neat PCL, showing the formation of randomly oriented, defect-free cylindrical fibers with a narrow distribution of the dimensions. The antibacterial and antibiofilm potential, including the capacity to interfere with the quorum-sensing mechanism, was evaluated on Pseudomonas aeruginosa PAO1, and Streptococcus mutans, two opportunistic pathogenic bacteria frequently associated with infections. The reported results demonstrated the ability of the Curcumin-loading membranes to inhibit both PAO1 and S. mutans biofilm growth and activity, thus representing a promising solution for the prevention of biofilm-associated infections. Moreover, the high biocompatibility and the ability to control the oxidative stress of damaged tissue, make the synthesized membranes useful as scaffolds in tissue engineering regeneration, helping to accelerate the healing process.},
}

@article {pmid34443349,
year = {2021},
author = {Fournière, M and Bedoux, G and Souak, D and Bourgougnon, N and Feuilloley, MGJ and Latire, T},
title = {Effects of Ulva sp. Extracts on the Growth, Biofilm Production, and Virulence of Skin Bacteria Microbiota: Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes Strains.},
journal = {Molecules (Basel, Switzerland)},
volume = {26},
number = {16},
pages = {},
doi = {10.3390/molecules26164763},
pmid = {34443349},
issn = {1420-3049},
support = {643 [INR00089]//"Conseil départemental des Côtes d'Armor (CD22)" and "Guingamp Paimpol Agglomération (GPA)"/ ; },
abstract = {Ulva sp. is known to be a source of bioactive compounds such as ulvans, but to date, their biological activity on skin commensal and/or opportunistic pathogen bacteria has not been reported. In this study, the effects of poly- and oligosaccharide fractions produced by enzyme-assisted extraction and depolymerization were investigated, for the first time in vitro, on cutaneous bacteria: Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes. At 1000 μg/mL, poly- and oligosaccharide fractions did not affect the growth of the bacteria regarding their generation time. Polysaccharide Ulva sp. fractions at 1000 μg/mL did not alter the bacterial biofilm formation, while oligosaccharide fractions modified S. epidermidis and C. acnes biofilm structures. None of the fractions at 1000 μg/mL significantly modified the cytotoxic potential of S. epidermidis and S. aureus towards keratinocytes. However, poly- and oligosaccharide fractions at 1000 μg/mL induced a decrease in the inflammatory potential of both acneic and non-acneic C. acnes strains on keratinocytes of up to 39.8%; the strongest and most significant effect occurred when the bacteria were grown in the presence of polysaccharide fractions. Our research shows that poly- and oligosaccharide Ulva sp. fractions present notable biological activities on cutaneous bacteria, especially towards C. acnes acneic and non-acneic strains, which supports their potential use for dermo-cosmetic applications.},
}

@article {pmid34443301,
year = {2021},
author = {Yang, W and Wang, Z and Li, Q and Jia, Y and Song, S and Ma, Z and Liu, J and Wang, J},
title = {Photodynamic Inactivation Using Natural Bioactive Compound Prevents and Disrupts the Biofilm Produced by Staphylococcus saprophyticus.},
journal = {Molecules (Basel, Switzerland)},
volume = {26},
number = {16},
pages = {},
doi = {10.3390/molecules26164713},
pmid = {34443301},
issn = {1420-3049},
abstract = {Staphylococcus saprophyticus, the food-borne bacteria present in dairy products, ready-to-eat food and environmental sources, has been reported with antibiotic resistance, raising concerns about food microbial safety. The antimicrobial resistance of S. saprophyticus requires the development of new strategies. Light- and photosensitizer-based antimicrobial photodynamic inactivation (PDI) is a promising approach to control microbial contamination, whereas there is limited information regarding the effectiveness of PDI on S. saprophyticus biofilm control. In this study, PDI mediated by natural bioactive compound (curcumin) associated with LED was evaluated for its potential to prevent and disrupt S. saprophyticus biofilms. Biofilms were treated with curcumin (50, 100, 200 µM) and LED fluence (4.32 J/cm2, 8.64 J/cm2, 17.28 J/cm2). Control groups included samples treated only with curcumin or light, and samples received neither curcumin nor light. The action was examined on biofilm mass, viability, cellular metabolic activity and cytoplasmic membrane integrity. PDI using curcumin associated with LED exhibited significant antibiofilm activities, inducing biofilm prevention and removal, metabolic inactivation, intracellular membrane damage and cell death. Likewise, scanning electronic microscopy observations demonstrated obvious structural injury and morphological alteration of S. saprophyticus biofilm after PDI application. In conclusion, curcumin is an effective photosensitizer for the photodynamic control of S. saprophyticus biofilm.},
}

@article {pmid34443242,
year = {2021},
author = {Ajdnik, U and Luxbacher, T and Vesel, A and Štern, A and Žegura, B and Trček, J and Fras Zemljič, L},
title = {Polysaccharide-Based Bilayer Coatings for Biofilm-Inhibiting Surfaces of Medical Devices.},
journal = {Materials (Basel, Switzerland)},
volume = {14},
number = {16},
pages = {},
doi = {10.3390/ma14164720},
pmid = {34443242},
issn = {1996-1944},
support = {J1 9169 and P2-0118//Javna Agencija za Raziskovalno Dejavnost RS/ ; },
abstract = {Chitosan (Chi) and 77KS, a lysine-derived surfactant, form polyelectrolyte complexes that reverse their charge from positive to negative at higher 77KS concentrations, forming aggregates that have been embedded with amoxicillin (AMOX). Dispersion of this complex was used to coat polydimethylsiloxane (PDMS) films, with an additional layer of anionic and hydrophilic hyaluronic acid (HA) as an outer adsorbate layer to enhance protein repulsion in addition to antimicrobial activity by forming a highly hydrated layer in combination with steric hindrance. The formed polysaccharide-based bilayer on PDMS was analyzed by water contact angle measurements, X-ray photoelectron spectroscopy (XPS), and surface zeta (ζ)-potential. All measurements show the existence and adhesion of the two layers on the PDMS surface. Part of this study was devoted to understanding the underlying protein adsorption phenomena and identifying the mechanisms associated with biofouling. Thus, the adsorption of a mixed-protein solution (bovine serum albumin, fibrinogen, γ-globulin) on PDMS surfaces was studied to test the antifouling properties. The adsorption experiments were performed using a quartz crystal microbalance with dissipation monitoring (QCM-D) and showed improved antifouling properties by these polysaccharide-based bilayer coatings compared to a reference or for only one layer, i.e., the complex. This proves the benefit of a second hyaluronic acid layer. Microbiological and biocompatibility tests were also performed on real samples, i.e., silicone discs, showing the perspective of the prepared bilayer coating for medical devices such as prostheses, catheters (balloon angioplasty, intravascular), delivery systems (sheaths, implants), and stents.},
}

@article {pmid34443123,
year = {2021},
author = {Pavlic, A and Begic, G and Tota, M and Abram, M and Spalj, S and Gobin, I},
title = {Bacterial Exposure to Nickel: Influence on Adhesion and Biofilm Formation on Orthodontic Archwires and Sensitivity to Antimicrobial Agents.},
journal = {Materials (Basel, Switzerland)},
volume = {14},
number = {16},
pages = {},
doi = {10.3390/ma14164603},
pmid = {34443123},
issn = {1996-1944},
support = {IP-2020-02-4027//Hrvatska Zaklada za Znanost/ ; IP-2014-09-7500//Hrvatska Zaklada za Znanost/ ; },
abstract = {The presence of nickel could modify bacterial behavior and susceptibility to antimicrobial agents. Adhesion and biofilm formation on orthodontic archwires can be a source of bacterial colonization and possible health hazards. Staphylococcus aureus was subjected to exposure and adaptation to various sub-inhibitory concentrations of nickel. Five strains of bacteria adapted to nickel in concentrations of 62.5-1000 μg/mL were tested for adhesion and biofilm formation on nickel-titanium archwires. Archwires were previously incubated in artificial saliva. Bacteria were incubated with orthodontic wire with stirring for 4 h (adhesion) and 24 h (biofilm formation). The number of adherent bacteria was determined after sonication and cultivation on the Muller-Hinton agar. Disk diffusion method was performed on all bacteria to assess the differences in antimicrobial susceptibility. Bacteria adapted to lower concentrations of nickel adhered better to nickel-titanium than strains adapted to higher concentrations of nickel (p < 0.05). Biofilm formation was highest in strains adapted to 250 and 500 μg/mL of nickel (p < 0.05). The highest biofilm biomass was measured for strains adapted to 250 μg/mL, followed by those adapted to 1000 μg/mL. Bacteria adapted to lower concentrations of nickel demonstrated lower inhibition zone diameters in the disk diffusion method (p < 0.05), indicating increased antimicrobial resistance. In conclusion, bacteria adapted to 250 μg/mL of nickel ions adhered better, demonstrated higher biofilm formation and often had higher antimicrobial resistance than other adapted and non-adapted strains.},
}

@article {pmid34442858,
year = {2021},
author = {Di Fermo, P and Ciociola, T and Di Lodovico, S and D'Ercole, S and Petrini, M and Giovati, L and Conti, S and Di Giulio, M and Cellini, L},
title = {Antimicrobial Peptide L18R Displays a Modulating Action against Inter-Kingdom Biofilms in the Lubbock Chronic Wound Biofilm Model.},
journal = {Microorganisms},
volume = {9},
number = {8},
pages = {},
doi = {10.3390/microorganisms9081779},
pmid = {34442858},
issn = {2076-2607},
support = {Luigina Cellini and Mara Di Giulio FAR 2020//Ministero dell'Istruzione, dell'Università e della Ricerca/ ; Research Grant PRIN 2017 SFBFER from MIUR, Italy.//Ministero dell'Istruzione, dell'Università e della Ricerca/ ; },
abstract = {Chronic wound infections represent an important health problem due to the reduced response to antimicrobial treatment of the pathogens organized in structured biofilms. This study investigated the effects of the previously described antifungal peptide L18R against three representative wound pathogens: Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The antimicrobial activity of L18R was evaluated (i) against single planktonic microbial populations; (ii) on single, dual, and triadic species of biofilms in both the early stage and mature stage; and (iii) in the polymicrobial Lubbock chronic wound biofilm (LCWB) model, mimicking spatial microbial colonization. This study used the evaluation of CFUs, biofilm biomass detection, and confocal and scanning electron microscopy analysis. L18R showed a significant antimicrobial activity against planktonic microorganisms and was able to differentially reduce the biomass of monomicrobial biofilms. No reduction of biomass was observed against the polymicrobial biofilm. In mature LCWB, L18R caused a moderate reduction in total CFU number, with a variable effect on the different microorganisms. Microscopy images confirmed a predominant presence of P.aeruginosa and a lower percentage of C. albicans cells. These findings suggest a modulating action of L18R and recommend further studies on its potential role in chronic wound management in association with conventional antibiotics or alternative treatments.},
}

@article {pmid34442788,
year = {2021},
author = {Johnson, E and Petersen, T and Goeres, DM},
title = {Characterizing the Shearing Stresses within the CDC Biofilm Reactor Using Computational Fluid Dynamics.},
journal = {Microorganisms},
volume = {9},
number = {8},
pages = {},
doi = {10.3390/microorganisms9081709},
pmid = {34442788},
issn = {2076-2607},
support = {NA//BioSurface Technologies Corporation/ ; },
abstract = {Shearing stresses are known to be a critical factor impacting the growth and physiology of biofilms, but the underlying fluid dynamics within biofilm reactors are rarely well characterized and not always considered when a researcher decides which biofilm reactor to use. The CDC biofilm reactor is referenced in validated Standard Test Methods and US EPA guidance documents. The driving fluid dynamics within the CDC biofilm reactor were investigated using computational fluid dynamics. An unsteady, three-dimensional model of the CDC reactor was simulated at a rotation rate of 125 RPM. The reactor showed turbulent structures, with shear stresses averaging near 0.365 ± 0.074 Pa across all 24 coupons. The pressure variation on the coupon surfaces was found to be larger, with a continuous 2-3 Pa amplitude, coinciding with the baffle passage. Computational fluid dynamics was shown to be a powerful tool for defining key fluid dynamic parameters at a high fidelity within the CDC biofilm reactor. The consistency of the shear stresses and pressures and the unsteadiness of the flow within the CDC reactor may help explain its reproducibility in laboratory studies. The computational model will enable researchers to make an informed decision whether the fluid dynamics present in the CDC biofilm reactor are appropriate for their research.},
}

@article {pmid34442690,
year = {2021},
author = {Jin, F and Yang, H},
title = {Effects of Lactobacillus salivarius LN12 in Combination with Amoxicillin and Clarithromycin on Helicobacter pylori Biofilm In Vitro.},
journal = {Microorganisms},
volume = {9},
number = {8},
pages = {},
doi = {10.3390/microorganisms9081611},
pmid = {34442690},
issn = {2076-2607},
support = {HUCXY-2016-010//Shanghai Industry-University Joint Research Program/ ; },
abstract = {Helicobacter pylori is a highly prevalent and harmful gastrointestinal pathogen. Antibiotic resistance and biofilm complexity have led to a decrease in the cure rate. Probiotics are considered to be an adjuvant therapy for clinical Helicobacter pylori infections. However, there is no substantial explanation for the adjuvant role of probiotics on H. pylori biofilm. In this study, the effects of probiotics in combination with amoxicillin (AMX) and clarithromycin (CLR) on H. pylori biofilms were explored in vitro for the first time. The minimum inhibitory concentration (MIC) and the fractional inhibitory concentration (FIC) for H. pylori was determined by the microbroth dilution method, and the plate counting method was used to determine the minimum biofilm removal concentration (MBEC) and survival rate for H. pylori biofilm. The biofilm structure was observed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), protein and polysaccharide contents in extracellular polymeric substances (EPS) were determined by the Bradford method and the phenol-sulfate method, respectively. The gene expression levels of cagA and vacA were evaluated by real-time qPCR. Among the ten H. pylori strains, the clinical strain 3192 showed the strongest film-forming ability, the 3192 biofilms significantly improved the resistance to AMX and CLR, and AMX and CLR showed antagonistic effects on planktonic 3192 cells. When the Lactobacillus salivarius LN12 cell-free supernatant (CFS) was in combination with AMX and CLR, the 3192 biofilm structure was destroyed to a greater extent than when separately; more biofilm biomass and protein in EPS was decreased; and the downregulation effect of the virulence gene vacA was also greater than that of single use. In this study, we suggest that the addition of LN12 to AMX and CLR may enhance the therapeutic effect of triple therapy, especially for the treatment of H. pylori biofilms.},
}

@article {pmid34442682,
year = {2021},
author = {Chamarande, J and Cunat, L and Caillet, C and Mathieu, L and Duval, JFL and Lozniewski, A and Frippiat, JP and Alauzet, C and Cailliez-Grimal, C},
title = {Surface Properties of Parabacteroides distasonis and Impacts of Stress-Induced Molecules on Its Surface Adhesion and Biofilm Formation Capacities.},
journal = {Microorganisms},
volume = {9},
number = {8},
pages = {},
doi = {10.3390/microorganisms9081602},
pmid = {34442682},
issn = {2076-2607},
abstract = {The gut microbiota is a complex and dynamic ecosystem whose balance and homeostasis are essential to the host's well-being and whose composition can be critically affected by various factors, including host stress. Parabacteroides distasonis causes well-known beneficial roles for its host, but is negatively impacted by stress. However, the mechanisms explaining its maintenance in the gut have not yet been explored, in particular its capacities to adhere onto (bio)surfaces, form biofilms and the way its physicochemical surface properties are affected by stressing conditions. In this paper, we reported adhesion and biofilm formation capacities of 14 unrelated strains of P. distasonis using a steam-based washing procedure, and the electrokinetic features of its surface. Results evidenced an important inter-strain variability for all experiments including the response to stress hormones. In fact, stress-induced molecules significantly impact P. distasonis adhesion and biofilm formation capacities in 35% and 23% of assays, respectively. This study not only provides basic data on the adhesion and biofilm formation capacities of P. distasonis to abiotic substrates but also paves the way for further research on how stress-molecules could be implicated in P. distasonis maintenance within the gut microbiota, which is a prerequisite for designing efficient solutions to optimize its survival within gut environment.},
}