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14 Nov 2022 at 01:59
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Bibliography on: Biofilm


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RJR: Recommended Bibliography 14 Nov 2022 at 01:59 Created: 


Wikipedia: Biofilm A biofilm is any group of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPS). The EPS components are produced by the cells within the biofilm and are typically a polymeric conglomeration of extracellular DNA, proteins, and polysaccharides. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, biofilms are frequently described metaphorically as cities for microbes. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium. Biofilms can be present on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

Created with PubMed® Query: biofilm[title] NOT 28392838[PMID] NOT 31293528[PMID] NOT 29372251[PMID] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2022-11-09

Martínez-Campos S, González-Pleiter M, Rico A, et al (2022)

Time-course biofilm formation and presence of antibiotic resistance genes on everyday plastic items deployed in river waters.

Journal of hazardous materials, 443(Pt B):130271 pii:S0304-3894(22)02065-9 [Epub ahead of print].

The plastisphere has been widely studied in the oceans; however, there is little information on how living organisms interact with the plastisphere in freshwater ecosystems, and particularly on how this interaction changes over time. We have characterized, over one year, the evolution of the eukaryotic and bacterial communities colonizing four everyday plastic items deployed in two sites of the same river with different anthropogenic impact. α-diversity analyses showed that site had a significant role in bacterial and eukaryotic diversity, with the most impacted site having higher values of the Shannon diversity index. β-diversity analyses showed that site explained most of the sample variation followed by substrate type (i.e., plastic item) and time since first colonization. In this regard, core microbiomes/biomes in each plastic at 1, 3, 6 and 12 months could be identified at genus level, giving a global overview of the evolution of the plastisphere over time. The measured concentration of antibiotics in the river water positively correlated with the abundance of antibiotic resistance genes (ARGs) on the plastics. These results provide relevant information on the temporal dynamics of the plastisphere in freshwater ecosystems and emphasize the potential contribution of plastic items to the global spread of antibiotic resistance.

RevDate: 2022-11-09

Alba MLS, Durán-Rodriguez AT, Pulido LMS, et al (2022)

Peptides DLL37-1 and LL37-1, an alternative to inhibit biofilm formation in clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis.

Anais da Academia Brasileira de Ciencias, 94(3):e20210848 pii:S0001-37652022000500706.

Staphylococcus aureus and Staphylococcus epidermidis have microbial surface components recognizing adhesive matrix molecules (MSCRAMM) adhesion proteins that enhance their biofilm formation ability, as well as virulence factors that influence morbidity and mortality in hospital settings. In this work, four peptides analogous of the peptide LL-37 that were evaluated to inhibit biofilm formation and its action potential on the expression of MSCRAMM proteins in clinical isolates through different tests, such as crystal violet, PCR and qPCR. In total, 96.8% of S. aureus were strong in biofilm formation in contrast to 48.4% of S. epidermidis. sdrG and sdrF genes were present in 100% of S. epidermidis strains and in all isolates. In S. aureus, specific genes that code for MSCRAMM proteins were detected: clfA (89%), clFB, sdrC and fnBA (94%). The peptides did not show hemolytic or cytotoxic activity. In this study, it was evidenced that of the peptides DLL37-1 at a 5 µM concentration was an efficacious antimicrobial agent and depicted greater biofilm inhibition in both bacterial species. Exhibiting a significant inhibition rate in S. aureus, this peptide caused a negative regulation in the expression of the genes clfA and sdrC, showed greater biological activity.

RevDate: 2022-11-09

Mirzaei R, Yousefimashouf R, Arabestani MR, et al (2022)

The issue beyond resistance: Methicillin-resistant Staphylococcus epidermidis biofilm formation is induced by subinhibitory concentrations of cloxacillin, cefazolin, and clindamycin.

PloS one, 17(11):e0277287 pii:PONE-D-22-04775.

Staphylococcus epidermis is one of the most frequent causes of device-associated infections due to biofilm formation. Current reports noted that subinhibitory concentrations of antibiotics induce biofilm production in some bacteria. Accordingly, we evaluated the effect of exposure of different subinhibitory concentrations of cloxacillin, cefazolin, clindamycin, and vancomycin on the biofilm formation of methicillin-resistant S. epidermidis (MRSE). Antimicrobial susceptibility testing and minimum inhibitory/bactericidal concentration of antimicrobial agents were determined. MRSE isolates were selected, and their biofilm formation ability was evaluated. The effect of subinhibitory concentrations of cloxacillin, cefazolin, clindamycin, and vancomycin, antibiotics selected among common choices in the clinic, on MRSE biofilm formation was determined by the microtitre method. Besides, the effect of subinhibitory concentrations of cloxacillin, cefazolin, clindamycin, and vancomycin on the expression of the biofilm-associated genes icaA and atlE was evaluated by Reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR). Antimicrobial susceptibility patterns of MRSE strains showed a high level of resistance as follows: 80%, 53.3%, 33.3%, 33.3%, and 26.6%, for erythromycin, trimethoprim-sulfamethoxazole, tetracycline, clindamycin, and gentamicin, respectively. Besides, 73.3% of S. epidermidis strains were Multidrug-resistant (MDR). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were in the range of 0.5 to512 μg/mL and 1 to1024 μg/mL for cloxacillin, 0.125 to256 μg/mL and 1 to512 μg/mL for cefazolin, 0.125 to64 μg/mL and 4 to>1024 μg/mL for clindamycin, and 2 to32 μg/mL and 4 to32 μg/mL for vancomycin, respectively. The findings showed that subinhibitory concentrations of cloxacillin, cefazolin, and clindamycin induce biofilm production in MRSE strains. In particular, the OD values of strains were in the range of 0.09-0.95, 0.05-0.86, and 0.06-1 toward cloxacillin, cefazolin, and clindamycin, respectively. On the other hand, exposure to subinhibitory vancomycin concentrations did not increase the biofilm formation in MRSE strains. The findings also demonstrated that sub-MIC of antibiotics up-regulated biofilm-associated genes. In particular, atlE and icaA were up-regulated 0.062 to 1.16 and 0.078 to 1.48 folds, respectively, for cloxacillin, 0.11 to 0.8, and 0.1 to 1.3 folds for cefazolin, 0.18 to 0.98, and 0.19 to 1.4 folds, respectively, for clindamycin. In contrast, the results showed that sub-MIC of vancomycin did not increase the biofilm-associated genes. These findings overall show that exposure to sub-MIC of traditional antibiotics can cause biofilm induction in MRSE, thereby increasing the survival and persistence on various surfaces that worsen the condition of comorbid infections.

RevDate: 2022-11-09

Li M, Mai B, Wang A, et al (2022)

Correction: Photodynamic antimicrobial chemotherapy with cationic phthalocyanines against Escherichia coli planktonic and biofilm cultures.

RSC advances, 12(48):31091-31092 pii:d2ra90106d.

[This corrects the article DOI: 10.1039/C7RA06073D.].

RevDate: 2022-11-09

Zhou G, Wang YS, Peng H, et al (2022)

ompX contribute to biofilm formation, osmotic response and swimming motility in Citrobacter werkmanii.

Gene, 851:147019 pii:S0378-1119(22)00839-3 [Epub ahead of print].

Citrobacter werkmanii, an aerobe and mesophilic Proteobacterium, is universal in industrial putrefaction, coastal water, and human blood. Our previous studies have discovered that outer membrane protein X (OmpX) of C. werkmanii is involved in calcium response, but the underlying mechanisms and its molecular characteristics remain elusive. To that end, the ompX gene was deleted from the genome of C. werkmanii and its phenotypic variations were thoroughly investigated in conjunction with the wild type (WT) and complementary strains using biochemical and molecular techniques such as RNA-Seq, respectively. The results demonstrated that deleting ompX reduces biofilm formation on polystyrene and glass surfaces. Meanwhile, ΔompX's swimming ability but not for its twitching or swarming abilities, was also reduced on semi-solid plates compared with WT, which was caused by inhibition of flagellar assembly genes, such as flgC, flhB, and fliE, etc. Furthermore, ompX inactivation altered susceptibility to various bactericide classes, as well as responses to Ca2+ and Mg2+ stress. In addition, when compared to WT, ΔompX captures a total of 1,357 deferentially expressed genes (DEGs), of which 465 were up-regulated and 892 were down-regulated, which can be enriched into various GO ontology and KEGG pathway terms. Furthermore, ompX, as well as ompD and ompW, can be modulated at the transcriptional levels by rbsR and tdcA. Overall, the ompX gene contributed to a variety of biological functions in C. werkmanii and could be served as a targeted site for controlling biofilm formation and developing new bactericides.

RevDate: 2022-11-08

Buzzá HH, Alves F, Tomé AJB, et al (2022)

Porphyrin nanoemulsion for antimicrobial photodynamic therapy: effective delivery to inactivate biofilm-related infections.

Proceedings of the National Academy of Sciences of the United States of America, 119(46):e2216239119.

The management of biofilm-related infections is a challenge in healthcare, and antimicrobial photodynamic therapy (aPDT) is a powerful tool that has demonstrated a broad-spectrum activity. Nanotechnology has been used to increase the aPDT effectiveness by improving the photosensitizer's delivery properties. NewPS is a simple, versatile, and safe surfactant-free nanoemulsion with a porphyrin salt shell encapsulating a food-grade oil core with promising photodynamic action. This study evaluated the use of NewPS for aPDT against microorganisms in planktonic, biofilm, and in vivo models of infected wounds. First, the potential of NewPS-mediated aPDT to inactivate Streptococcus pneumoniae and Staphylococcus aureus suspensions was evaluated. Then, a series of protocols were assessed against S. aureus biofilms by means of cell viability and confocal microscopy. Finally, the best biofilm protocol was used for the treatment of S. aureus in a murine-infected wound model. A high NewPS-bacteria cell interaction was achieved since 0.5 nM and 30 J/cm2 was able to kill S. pneumoniae suspension. In the S. aureus biofilm, enhanced efficacy of NewPS-aPDT was achieved when 100 µM of NewPS was applied with longer periods of incubation at the light dose of 60 J/cm2. The best single and double-session protocol reduced 5.56 logs and 6.03 logs, respectively, homogeneous NewPS distribution, resulting in a high number of dead cells after aPDT. The in vivo model showed that one aPDT session enabled a reduction of 6 logs and faster tissue healing than the other groups. In conclusion, NewPS-aPDT may be considered a safe and effective anti-biofilm antimicrobial photosensitizer.

RevDate: 2022-11-08

Wang Y, Xu H, Yao H, et al (2022)

Insights into the role of prechlorination in algae-laden raw water distribution process: Algal organic matter and microcystin-LR release, extracellular polymeric substances (EPS) aggregation, and pipeline biofilm communities.

Journal of hazardous materials, 443(Pt B):130306 pii:S0304-3894(22)02100-8 [Epub ahead of print].

Prechlorination routinely applied for the treatment of algae-laden raw water has received extensive attention due to its influence on water quality and aquatic microbes. In this study, prechlorination experiments with different doses were conducted in sets of model raw water distribution systems. With the elevated dose of chlorine and prolonged hydraulic retention time (HRT), the ratio of intact algal cells decreased, and the stability of water enhanced. Dissolved organic carbon (DOC) and nitrogen (DON) increased when chlorine dose elevated from 0 to 0.5 mg/L but decreased with elevations from 0.5 to 2.0 mg/L, while UV254 showed a monotonically increasing tendency. DOC, DON and extracellular microcystin-LR increase initially and decrease thereafter with the prolonged HRT. Notably, the effects of prechlorination on extracellular polymeric substances aggregation behavior on pipe walls and microbial community composition was revealed, providing more profound understanding of the community dynamics in this engineered system. This study helped optimize strategies to improve the stability and efficiency of pretreatment of algae-laden water.

RevDate: 2022-11-07

Rathi B, Gupta S, Kumar P, et al (2022)

Anti-biofilm activity of caffeine against uropathogenic E. coli is mediated by curli biogenesis.

Scientific reports, 12(1):18903.

Biofilms are assemblages of sessile microorganisms that form an extracellular matrix around themselves and mediate attachment to surfaces. The major component of the extracellular matrix of Uropathogenic E. coli and other Enterobacteriaceae are curli fibers, making biofilms robust and resistant to antimicrobials. It is therefore imperative to screen antibiofilm compounds that can impair biofilm formation. In the present study, we investigated the curli-dependent antibiofilm activity of caffeine against UPEC strain CFT073 and commensal strain E. coli K-12MG1655.Caffeine significantly reduced the biofilm formation of both UPEC and E. coli K-12 by 86.58% and 91.80% respectively at 48 mM caffeine as determined by Crystal Violet assay. These results were further confirmed by fluorescence microscopy and Scanning Electron Microscope (SEM). Caffeine significantly reduced the cytotoxicity and survivability of UPEC. Molecular docking analysis revealed a strong interaction between caffeine and curli regulator protein (Csg D) of E. coli. The qRT-PCR data also showed significant downregulation in the expression of CsgBA and the CsgDEFG operon at both 24 mM and 48 mM caffeine. The findings revealed that caffeine could inhibit E. coli biofilm formation by regulating curli assembly and thus may be used as an alternative therapeutic strategy for the treatment of chronic E. coli biofilm-related infections.

RevDate: 2022-11-07

Oda S, A Tanikawa (2022)

A new plate-hanging method for biofilm quantification and its application to evaluate the role of surface hydrophobicity.

Journal of microbiological methods pii:S0167-7012(22)00203-2 [Epub ahead of print].

A novel procedure for the quantitative analysis of biofilm formation by bacteria and yeasts, the Plate-hanging method, was developed. In this system, various polymer disks were hung from the lid of a 6-well plate, immersed in a cell suspension, and moderately shaken (70 rpm). In order to verify the validity of the procedure, the effects of the solid surface hydrophobicity of the test disks and the cell surface hydrophobicities of microorganisms on biofilm formation were investigated. Biofilm formation of bacteria and yeasts on the solid surface strongly depended on hydrophobic interactions between the solid surface and the cell surface. A positive correlation between the hydrophobic properties of substratum and cell surfaces was observed. On the other hand, hydrophilic yeasts preferentially adsorbed onto relatively hydrophilic surfaces. Moreover, the plate-hanging method coupled with the periodic exchange of the liquid medium enabled the quantification of long-term biofilm growth.

RevDate: 2022-11-07

Wu B, Ren Q, Xia L, et al (2022)

pH-dependent microbial niches succession and antibiotic resistance genes distribution in an oxygen-based membrane biofilm reactor treating greywater.

Environmental research pii:S0013-9351(22)02052-7 [Epub ahead of print].

System pH is found to crucially affect biofilm growth and microorganisms' activity in the biofilm-based wastewater treatment system. This study investigated the pH-dependent pollutants removal, microbial niches succession and antibiotic resistance genes (ARGs) accumulation in an oxygen-based membrane biofilm reactor treating greywater. Results indicated that neutral conditions achieved the highest biofilm concentration and living cells, which enabled the highest pollutants removal rates; multifarious functional groups in biofilm enabled pollutants adsorption, which favored its continuous bio-removal. Microbial communities under acidic condition (pH = 5.0) were significantly different with that under other conditions (p < 0.05). The neutral and alkaline niches (pH = 7.0 and 9.0) were predominant by organics biodegradation and nitrogen reduction bacteria (e.g. Sphingobacteriales, Pseudomonas, Flavobacterium and Phenylobacterium), but which were significantly dropped under acidic conditions, leading to the declined reactor performance. ARGs in biofilm (predominant by korB, intI-1, sul1 and sul2) were much higher than that in the cell-free liquid and the target ARGs accumulation (korB, intI-1, blaCTX-M, qnrS) had nearly linear positive relationships (R2 > 0.95, P < 0.01) with biofilm-attached linear alkylbenzene sulfonate (LAS). LAS stimulate ARGs proliferation in functional microorganisms (korB, sul-1 and intI-1 were significantly associated with related microbial genus) and biofilm played a key role in ARGs dissemination. The relatively low ARGs in both biofilm and effluent under neutral conditions suggested that pH controlling can be an effective strategy to inhibit ARGs dissemination and proliferation in the system.

RevDate: 2022-11-07

Schestakow A, Meyer-Probst CT, Hannig C, et al (2022)

Prevention of Dental Biofilm Formation with Polyphenols: A Systematic Review.

Planta medica [Epub ahead of print].

Polyphenols are plant secondary products with health-promoting properties against various degenerative or infectious diseases, and thus may help in the prevention of oral diseases. The aim of the present systematic review was to investigate polyphenols as a possible adjuvant in inhibiting dental biofilm formation, which is an important precondition for the most prevalent oral disease - caries and periodontitis. A literature search was conducted using the databases PubMed, CENTRAL and Scopus. Only studies with oral healthy participants and plaque level as outcome were included. Data search and extraction was conducted by two authors independently. Of the 211 initially identified studies, only six met all inclusion criteria. Meta-analysis was performed with five studies using the random effect model. Treatment with polyphenols reduced the plaque level in comparison to a negative control, but not significantly. Strong evidence of heterogeneity was observed. The diversity and complexity of polyphenols and their preparation need to be considered. There is no clear evidence that clinical use of polyphenols can prevent dental biofilm formation. Additional research with more and larger randomized controlled trials are required.

RevDate: 2022-11-07

Podnar E, Erega A, Danevčič T, et al (2022)

Nutrient Availability and Biofilm Polysaccharide Shape the Bacillaene-Dependent Antagonism of Bacillus subtilis against Salmonella Typhimurium.

Microbiology spectrum [Epub ahead of print].

Salmonella enterica is one of the most common foodborne pathogens and, due to the spread of antibiotic resistance, new antimicrobial strategies are urgently needed to control it. In this study, we explored the probiotic potential of Bacillus subtilis PS-216 and elucidated the mechanisms that underlie the interactions between this soil isolate and the model pathogenic strain S. Typhimurium SL1344. The results reveal that B. subtilis PS-216 inhibits the growth and biofilm formation of S. Typhimurium through the production of the pks cluster-dependent polyketide bacillaene. The presence of S. Typhimurium enhanced the activity of the PpksC promoter that controls bacillaene production, suggesting that B. subtilis senses and responds to Salmonella. The level of Salmonella inhibition, overall PpksC activity, and PpksC induction by Salmonella were all higher in nutrient-rich conditions than in nutrient-depleted conditions. Although eliminating the extracellular polysaccharide production of B. subtilis via deletion of the epsA-O operon had no significant effect on inhibitory activity against Salmonella in nutrient-rich conditions, this deletion mutant showed an enhanced antagonism against Salmonella in nutrient-depleted conditions, revealing an intricate relationship between exopolysaccharide production, nutrient availability, and bacillaene synthesis. Overall, this work provides evidence on the regulatory role of nutrient availability, sensing of the competitor, and EpsA-O polysaccharide in the social outcome of bacillaene-dependent competition between B. subtilis and S. Typhimurium. IMPORTANCE Probiotic bacteria represent an alternative for controlling foodborne disease caused by Salmonella enterica, which constitutes a serious concern during food production due to its antibiotic resistance and resilience to environmental stress. Bacillus subtilis is gaining popularity as a probiotic, but its behavior in biofilms with pathogens such as Salmonella remains to be elucidated. Here, we show that the antagonism of B. subtilis is mediated by the polyketide bacillaene and that the production of bacillaene is a highly dynamic trait which depends on environmental factors such as nutrient availability and the presence of competitors. Moreover, the production of extracellular polysaccharides by B. subtilis further alters the influence of these factors. Hence, this work highlights the inhibitory effect of B. subtilis, which is condition-dependent, and the importance of evaluating probiotic strains under conditions relevant to the intended use.

RevDate: 2022-11-07

Wang DY, Yang G, Zhang XX, et al (2022)

Proton-mediated burst of dual-drug loaded liposomes for biofilm dispersal and bacterial killing.

Journal of controlled release : official journal of the Controlled Release Society, 352:460-471 pii:S0168-3659(22)00727-1 [Epub ahead of print].

Exposure of infectious biofilms to dispersants induces high bacterial concentrations in blood that may cause sepsis. Preventing sepsis requires simultaneous biofilm dispersal and bacterial killing. Here, self-targeting DCPA(2-(4-((1,5-bis(octadecenoyl)1,5-dioxopentan-2-yl)carbamoyl)pyridin-1-ium-1-yl)acetate) liposomes with complexed water were self-assembled with ciprofloxacin loaded in-membrane and PEGylated as a lipid-membrane component, together with bromelain loaded in-core. Inside biofilms, DCPA-H2O and PEGylated ciprofloxacin became protonated, disturbing the balance in the lipid-membrane to cause liposome-burst and simultaneous release of bromelain and ciprofloxacin. Simultaneous release of bromelain and ciprofloxacin enhanced bacterial killing in Staphylococcus aureus biofilms as compared with free bromelain and/or ciprofloxacin. After tail-vein injection in mice, liposomes accumulated inside intra-abdominal staphylococcal biofilms. Subsequent liposome-burst and simultaneous release of bromelain and ciprofloxacin yielded degradation of the biofilm matrix by bromelain and higher bacterial killing without inducing septic symptoms as obtained by injection of free bromelain and ciprofloxacin. This shows the advantage of simultaneous release from liposomes of bromelain and ciprofloxacin inside a biofilm.

RevDate: 2022-11-07

Sadaqat MH, Mobarez AM, M Nikkhah (2022)

Curcumin carbon dots inhibit biofilm formation and expression of esp and gelE genes of Enterococcusfaecium.

Microbial pathogenesis, 173(Pt A):105860 pii:S0882-4010(22)00473-9 [Epub ahead of print].

The increasing prevalence of vancomycin-resistant Enterococcus faecium, along with the ability of this bacterium to form biofilm on biotic surfaces and medical devices, has created a serious challenge. Therefore, the development of new antibacterial agents is an urgent need. In this study, curcumin carbon dots (Cur-CDs) were synthesized by a one-step hydrothermal method, and its antibacterial and antibiofilm effects were investigated. By broth microdilution method, the minimal inhibitory concentration (MIC) against vancomycin-resistant and sensitive clinical isolates of Enterococcus faecium (two clinical isolates in total) and standard strain of Enterococcus faecalis ATCC 29212 was determined, which were 1000, 1000, and 125 μg/ml, respectively. The inhibitory effect of Cur-CDs on biofilm formation of vancomycin-resistant E. faecium clinical isolates were evaluated by microtiter plate assay. Cur-CDs (1000 μg/ml) significantly prevented (p = 0.009) the biofilm formation of E. faecium isolates. Real-time PCR results showed that Cur-CDs (1000 μg/ml) significantly downregulated the expression of esp and gelE genes (p = 0.001 and p = 000000002, respectively) in clinical isolates of E. faecium, while Cur-CDs did not affect acm gene expression (p = 0.086). This study revealed that Cur-CDs can be effective antibacterial and antibiofilm agents against vancomycin-resistant and biofilm producer E. faecium, which makes them interesting candidates for treating or preventing bacterial infections.

RevDate: 2022-11-07

Xu T, Zhu H, Liu R, et al (2022)

The protective role of caffeic acid on bovine mammary epithelial cells and the inhibition of growth and biofilm formation of Gram-negative bacteria isolated from clinical mastitis milk.

Frontiers in immunology, 13:1005430.

As a first-line barrier against bacterial infection of mammary tissues, bovine mammary epithelial cells (bMECs) are generally believed to be involved in the immune response due to exogenous stress. Due to the escalating crisis of antibiotic resistance, there is an urgent need for new strategies to combat pathogenic bacteria-infected bovine mastitis. In this study, isolated bMECs and Institute of Cancer Research (ICR) mice were used for Escherichia coli infection and caffeic acid (CA) pretreatment experiments in vitro and in vivo. The inhibitory effect of CA on bacterial growth and biofilm formation was also demonstrated with bacteria strains isolated from mastitis-infected milk. It was demonstrated that CA supplementation prohibits the growth of the predominant strains of bacteria isolated from clinical bovine mastitis milk samples. CA was found to disrupt the biofilm formation of E. coli B1 in a sub-minimum inhibitory concentration (sub-MIC) and inhibited the adherence property of E. coli on bMECs by decreasing the staining of bacteria on cell surfaces in vitro. In addition, CA was found to attenuate proinflammatory and oxidative responses in cells infected with E. coli. The pretreatment of bMECs with CA also restored altered lipid homeostasis caused by E. coli stimulation. The protective role of CA was further confirmed via the administration of CA in mice followed by representative Gram-negative bacterial infection. Collectively, these findings highlight the potential of CA to mediate Gram-negative infections and indicate that it has the potential to be developed as a novel antibacterial drug.

RevDate: 2022-11-07

Lv M, Ye S, Hu M, et al (2022)

Two-component system ArcBA modulates cell motility and biofilm formation in Dickeya oryzae.

Frontiers in plant science, 13:1033192.

Phytopathogen Dickeya oryzae is a causal agent of rice foot rot disease and the pathogen has an array of virulence factors, such as phytotoxin zeamines, plant cell wall degrading enzymes, cell motility, and biofilms, collectively contributing to the bacterial pathogenesis. In this study, through deletion analysis of predicted regulatory genes in D. oryzae EC1, we identified a two-component system associated with the regulation of bacterial virulence. The two-component system contains a histidine kinase ArcB and a response regulator ArcA, and deletion of their coding genes resulted in changed phenotypes in cell motility, biofilm formation, and bacterial virulence. Electrophoretic mobility shift assay revealed that ArcA bound to the promoters of the bcs operon and bssS, which respectively encode enzymes for the synthesis of celluloses and a biofilm formation regulatory protein. ArcA could also bind to the promoters of three virulence associated transcriptional regulatory genes, i.e., fis, slyA and ohrR. Surprisingly, although these three regulators were shown to modulate the production of cell wall degrading enzymes and zeamines, deletion of arcB and arcA did not seem to affect these phenotypes. Taken together, the findings from this study unveiled a new two-component system associated with the bacterial pathogenesis, which contributes to the virulence of D. oryzae mainly through its action on bacterial motility and biofilm formation.

RevDate: 2022-11-07

Ciancio Casalini L, Piazza A, Masotti F, et al (2022)

Manganese oxidation counteracts the deleterious effect of low temperatures on biofilm formation in Pseudomonas sp. MOB-449.

Frontiers in molecular biosciences, 9:1015582 pii:1015582.

Mn removal from groundwater by biological sand filter technology is negatively impacted by low temperatures in winter periods. Therefore, the need to study Mn(II)-oxidizing bacteria (MOB) having the potential to oxidize Mn(II) and form biofilms at low temperatures is imperative. These MOB can have potential as inocula for sand filter bioaugmentation strategies to optimize Mn removal during winter periods. We previously showed that a Pseudomonas sp. MOB-449 (MOB-449), isolated from a Mn biofilter, oxidizes Mn(II) in a biofilm-dependent way at low temperatures. In this work, MOB-449 Mn(II) oxidation and growth capacities were evaluated under planktonic and biofilm conditions at different temperatures. At 18°C, MOB-449 showed enhanced biofilm formation due to the addition of Mn(II) to the medium correlating with Mn(II) oxidation, compared to biofilms grown in control medium. Moreover, this enhancement on biofilm formation due to the addition of Mn(II) was only observed at 18°C. At this temperature, Mn(II) oxidation in membrane fractions collected from biofilms was induced by uncoupling oxidative phosphorylation from the electron transport chain with 2,4-Dinitrophenol. In Pseudomonas, a role for c-type cytochrome in Mn(II) oxidation has been demonstrated. Accordingly, transcriptional profiles of all terminal oxidases genes found in MOB-449 showed an induction of cytochrome c terminal oxidases expression mediated by Mn(II) oxidation at 18°C. Finally, heme peroxidase activity assays and MS analysis revealed that PetC, a cytochrome c5, and also CcmE, involved in the cytochrome c biogenesis machinery, are induced at 18°C only in the presence of Mn(II). These results present evidence supporting that cytochromes c and also the cytochrome c terminal oxidases are activated at low temperatures in the presence of Mn(II). Overall, this work demonstrate that in MOB-449 Mn(II) oxidation is activated at low temperatures to gain energy, suggesting that this process is important for survival under adverse environmental conditions and contributing to the understanding of the physiological role of bacterial Mn(II) oxidation.

RevDate: 2022-11-07

Liu D, Wang Y, Wang X, et al (2021)

Role of the multiple efflux pump protein TolC on growth, morphology, and biofilm formation under nitric oxide stress in Cronobacter malonaticus.

JDS communications, 2(3):98-103 pii:S2666-9102(21)00039-9.

Nitric oxide (NO) is a biological signal molecule that can control and prevent the growth of most pathogens. Cronobacter species are a group of gram-negative foodborne pathogens that cause severe diseases, including neonatal meningitis, septicemia, and necrotizing enterocolitis, especially among newborns and infants consuming contaminated powdered infant formula. Cronobacter species might be tolerant to NO, resulting in severe infections. However, the specific mechanism of tolerance to NO in Cronobacter species is unclear. Here, we explore the effects of a key component, the protein TolC, of a multiple efflux pump on the growth, morphological changes, and biofilm formation of Cronobacter malonaticus under NO stress. We found that deletion of tolC resulted in a decreased growth rate under 100 mM sodium nitroprusside (NO donor) and led to more disruptive morphological injury to the bacterial cells. Furthermore, C. malonaticus lacking the TolC protein (ΔtolC mutant) showed weaker biofilm formation than the wild-type strain under normal or NO stress conditions. We have proved that TolC plays an important role in cell growth and biofilm formation of C. malonaticus. Therefore, our results may provide valuable theoretical basis for formulating clinical guidelines for treatment of disease caused by C. malonaticus and ensuring food safety.

RevDate: 2022-11-07

Liu Q, Zhu J, Liu N, et al (2022)

Type I fimbriae subunit fimA enhances Escherichia coli biofilm formation but affects L-threonine carbon distribution.

Frontiers in bioengineering and biotechnology, 10:904636 pii:904636.

The biofilm (BF) provides favorable growth conditions to cells, which has been exploited in the field of industrial biotechnology. Based on our previous research works on type I fimbriae for the biosynthesis of L-threonine (LT) in Escherichia coli, in this study, a fimA-overexpressing strain was engineered, which improved BF formation under industrial fermentation conditions. The morphological observation and characterization of BF formation were conducted to verify the function of the subunit FimA. However, it was not suitable for repeated-batch immobilized fermentation as the LT titer was not elevated significantly. The underlying molecular mechanisms of BF formation and the LT carbon flux were explored by transcriptomic analysis. The results showed that fimA regulated E. coli BF formation but affected LT carbon distribution. This study will stimulate thoughts about how the fimbriae gene regulated biofilms and amino acid excretion and will bring some consideration and provide a reference for the development of BF-based biomanufacturing processes in E. coli.

RevDate: 2022-11-07

Liu X, Xiong Y, Shi Y, et al (2022)

In vitro activities of licochalcone A against planktonic cells and biofilm of Enterococcus faecalis.

Frontiers in microbiology, 13:970901.

This study aims to evaluate the in vitro antibacterial and anti-biofilm activities of licochalcone A on Enterococcus faecalis and to investigate the possible target genes of licochalcone A in E. faecalis. This study found that licochalcone A had antibacterial activities against E. faecalis, with the MIC50 and MIC90 were 25 μM. Licochalcone A (at 4 × MIC) indicated a rapid bactericidal effect on E. faecalis planktonic cells, and killed more E. faecalis planktonic cells (at least 3-log10 cfu/ml) than vancomycin, linezolid, or ampicillin at the 2, 4, and 6 h of the time-killing test. Licochalcone A (at 10 × MIC) significantly reduced the production of E. faecalis persister cells (at least 2-log10 cfu/ml) than vancomycin, linezolid, or ampicillin at the 24, 48, 72, and 96 h of the time-killing test. Licochalcone A (at 1/4 × MIC) significantly inhibited the biofilm formation of E. faecalis. The RNA levels of biofilm formation-related genes, agg, esp, and srtA, markedly decreased when the E. faecalis isolates were treated with licochalcone A at 1/4 × MIC for 6 h. To explore the possible target genes of licochalcone A in E. faecalis, the licochalcone A non-sensitive E. faecalis clones were selected in vitro by induction of wildtype strains for about 140 days under the pressure of licochalcone A, and mutations in the possible target genes were detected by whole-genome sequencing. This study found that there were 11 nucleotide mutations leading to nonsynonymous mutations of 8 amino acids, and among these amino acid mutations, there were 3 mutations located in transcriptional regulator genes (MarR family transcriptional regulator, TetR family transcriptional regulator, and MerR family transcriptional regulator). In conclusion, this study found that licochalcone A had an antibacterial effect on E. faecalis, and significantly inhibited the biofilm formation of E. faecalis at subinhibitory concentrations.

RevDate: 2022-11-06

Farto-Vaamonde X, Diaz-Gomez L, Parga A, et al (2022)

Perimeter and carvacrol-loading regulate angiogenesis and biofilm growth in 3D printed PLA scaffolds.

Journal of controlled release : official journal of the Controlled Release Society pii:S0168-3659(22)00738-6 [Epub ahead of print].

Carvacrol is a natural low-cost compound derived from oregano which presents anti-bacterial properties against both Gram-positive and Gram-negative bacteria. In this work, carvacrol-loaded PLA scaffolds were fabricated by 3D printing as platforms to support bone tissue regeneration while preventing biofilm development. Scaffolds were printed with or without a perimeter (lateral wall) mimicking the cortical structure of bone tissue to further evaluate if the lateral interconnectivity could affect the biological or antimicrobial properties of the scaffolds. Carvacrol incorporation was performed by loading either the PLA filament prior to 3D printing or the already printed PLA scaffold. The loading method determined carvacrol localization in the scaffolds and its release profile. Biphasic profiles were recorded in all cases, but scaffolds loaded post-printed released carvacrol much faster, with 50-80% released in the first day, compared to those containing carvacrol in PLA filament before printing which sustained the release for several weeks. The presence or absence of the perimeter did not affect the release rate, but total amount released. Tissue integration and vascularization of carvacrol-loaded scaffolds were evaluated in a chorioallantoic membrane model (CAM) using a novel quantitative micro-computed tomography (micro-CT) analysis approach. The obtained results confirmed the CAM tissue ingrowth and new vessel formation within the porous structure of the scaffolds after 7 days of incubation, without leading to hemorrhagic or cytotoxic effects. The absence of lateral wall facilitated lateral integration of the scaffolds in the host tissue, although increased the anisotropy of the mechanical properties. Scaffolds loaded with carvacrol post-printing showed antibiofilm activity against Staphylococcus aureus and Pseudomonas aeruginosa as observed in a decrease in CFU counting after biofilm detachment, changes in metabolic heat measured by calorimetry, and increased contact killing efficiency. In summary, this work demonstrated the feasibility of tuning carvacrol release rate and amount released from PLA scaffolds to achieve antibiofilm protection without altering angiogenesis, which was mostly dependent on the perimeter density of the scaffolds.

RevDate: 2022-11-06

Duc HM, Zhang Y, Son HM, et al (2022)

Genomic characterization and application of a novel bacteriophage STG2 capable of reducing planktonic and biofilm cells of Salmonella.

International journal of food microbiology, 385:109999 pii:S0168-1605(22)00471-8 [Epub ahead of print].

As one major foodborne pathogen, Salmonella can cause serious food poisoning outbreaks worldwide. Bacteriophage therapy is increasingly considered as one of the promising antibacterial agents for the biocontrol of foodborne pathogens. In the current study, a lytic phage STG2 capable of infecting S. enteritidis and S. typhimurium was characterized, and its efficacy in reducing these foodborne pathogens in both planktonic and biofilm forms was evaluated on cabbage and various surfaces. Genomic characterization revealed that phage STG2 was Siphoviridae phage (Epseptimavirus genus) with a dsDNA genome comprising of 114,275 bp and its genome does not contain any genes associated to antibiotic resistance, toxins, lysogeny, or virulence factors. Additionally, phage STG2 exhibited great efficacy in reducing (>2 Log) planktonic cells on cabbage as well as the biofilms formed on cabbage, polystyrene, and stainless steel, suggesting that phage STG2 is capable of simultaneously controlling both S. enteritidis and S. typhimurium contaminations on food and food-related surfaces.

RevDate: 2022-11-05

Tian L, Wang L, Zhang X, et al (2022)

Multi-omics analysis on seasonal variations of the biofilm microbial community in a full-scale pre-denitrification biofilter.

Environmental science and pollution research international [Epub ahead of print].

The seasonal variations of biofilm communities in a municipal wastewater treatment plant were investigated using multi-omics techniques. The abundance of the main phyla of microorganisms varied with summer (July 2019) and winter (January 2019) samples considerably, the Bacteroidetes enriched in winter and Chloroflexi in summer. The results of metaproteomic and metagenomic showed that most of the functional microorganisms belonged to the Betaproteobacteria class, and the enrichment of Flavobacteria class in winter guaranteed the stability of denitrification performance to some extent. Seasonal variations affected the proteomic expression profiling, a total of 2835 differentially expressed proteins identified were significantly enriched in quorum sensing, two-component system, ribosome, benzoate degradation, butanoate metabolism, tricarboxylic acid cycle (TCA cycle), and cysteine and methionine metabolism pathways. With the expression of nitrogen metabolic proteins decreases in winter, the overall expression of denitrification-related enzymes in winter was much lower than that in summer, the nitrogen metabolism pathway varied significantly. Seasonal variations also induced the alteration of the biofilm metabolite profile; a total of 66 differential metabolites, 8 potential biomarkers, and 8 perturbed metabolic pathways such as TCA cycle were detected. It was found that most of the perturbed pathways are directly related to nitrogen metabolism, and several amino acids and organic acids associated with the TCA cycle were significantly perturbed, the accumulation of TCA cycle intermediates, ornithine, and L-histidine in winter might be conducive to resisting cold temperatures. Furthermore, the correlation between biofilm microbial communities and metabolites was identified by the combined analysis of metabolomic and metaproteomic. The differences of microbial community structure, function, and metabolism between winter and summer in a full-scale pre-denitrification biofilter were revealed for the first time, strengthening our understanding of the microbial ecology of biofilm communities.

RevDate: 2022-11-05

Cho JA, Roh YJ, Son HR, et al (2022)

Assessment of the biofilm-forming ability on solid surfaces of periprosthetic infection-associated pathogens.

Scientific reports, 12(1):18669.

Biofilm formation is one of the leading causes of complications after surgery in clinical settings. In this study, we profiled the biofilm-forming ability of various periprosthetic infection-associated pathogens on medically relevant surfaces, polystyrene (PS) and titanium (Ti). We also explored how a specific environmental stressor, epigallocatechin gallate (EGCG), affected biofilm formation. First, Congo red tests revealed that all microorganisms formed biofilms within 72 h. Then, the amounts of biofilm formation on PS at 24, 48 and 72 h and also on a Ti plate for 72 h were determined. Some microbes preferred one surface over the other, whereas other microbes formed consistent levels of biofilm regardless of the surface material. Staphylococcus lugdunenensis was the most potent, while Enterococcus faecalis and Staphylococcus aureus were the weakest. Bacterial adhesion to hydrocarbon (BATH) tests indicated that the biofilm-forming abilities were not directly correlated with cell surface hydrophobicity (CSH). Finally, an external signal, EGCG, was applied to challenge the biofilm formation of each microorganism. EGCG regulated each microorganism's ability differently, though the change was consistent across surfaces for most pathogens. This study can help a better understanding of a broad spectrum of periprosthetic infection-associated pathogens by relative comparison of their biofilm-forming abilities.

RevDate: 2022-11-04

Charlton SGV, Kurz DL, Geisel S, et al (2022)

The role of biofilm matrix composition in controlling colony expansion and morphology.

Interface focus, 12(6):20220035 pii:rsfs20220035.

Biofilms are biological viscoelastic gels composed of bacterial cells embedded in a self-secreted polymeric extracellular matrix (ECM). In environmental settings, such as in the rhizosphere and phyllosphere, biofilm colonization occurs at the solid-air interface. The biofilms' ability to colonize and expand over these surfaces depends on the formation of osmotic gradients and ECM viscoelastic properties. In this work, we study the influence of biofilm ECM components on its viscoelasticity and expansion, using the model organism Bacillus subtilis and deletion mutants of its three major ECM components, TasA, EPS and BslA. Using a multi-scale approach, we quantified macro-scale viscoelasticity and expansion dynamics. Furthermore, we used a microsphere assay to visualize the micro-scale expansion patterns. We find that the viscoelastic phase angle Φ is likely the best viscoelastic parameter correlating to biofilm expansion dynamics. Moreover, we quantify the sensitivity of the biofilm to changes in substrate water potential as a function of ECM composition. Finally, we find that the deletion of ECM components significantly increases the coherence of micro-scale colony expansion patterns. These results demonstrate the influence of ECM viscoelasticity and substrate water potential on the expansion of biofilm colonies on wet surfaces at the air-solid interface, commonly found in natural environments.

RevDate: 2022-11-04

Zhang Y, Wang Y, Zhao X, et al (2022)

Study on the anti-biofilm mechanism of 1,8-cineole against Fusarium solani species complex.

Frontiers in pharmacology, 13:1010593 pii:1010593.

Fungal-infections are mostly due to fungi in an adhering, biofilm-mode of growth and not due to planktonically growing, suspended-fungi. 1, 8-cineole is a natural product, which has been shown to possess antifungal effect. However, the anti-biofilm effect and mechanism of 1,8-cineole against Fusarium solani species complex has not reported previously. In this study, we found that 1,8-cineole has a good antifungal activity against F. solani with an MIC value of 46.1 μg/ml. Notably, 1,8-cineole showed good anti-biofilm formation activity against F. solani via inhibiting cell adhesion, hypha formation and decreasing the secretion of extracellular matrix at the concentration of ≥5.76 μg/ml. In addition, transcriptome sequencing analysis results showed that F. solani species complex genes related to ECM, protein synthesis and energy metabolism were down-expressed in the biofilms formation process treated with 1,8-cineole. In conclusion, these results show that 1,8-cineole has good anti-biofilm formation activity against F. solani species complex, and it exerts its anti-biofilm formation activity by downregulating of ergosterol biosynthetic genes, inhibiting adhesion, hindering the synthesis of ECM and interfering mitochondrial activity. This study suggests that 1,8-cineole is a promising anti-biofilm agent against F. solani species complex.

RevDate: 2022-11-04

Wang Y, Zhang Y, Song X, et al (2022)

1,8-Cineole inhibits biofilm formation and bacterial pathogenicity by suppressing luxS gene expression in Escherichia coli.

Frontiers in pharmacology, 13:988245 pii:988245.

In recent years, with frequent reports of multi-drug resistant strains, bacteria antibiotic resistance has become an increasingly serious health problem worldwide. One of the most promising ways for combating bacterial infections and antibiotic resistance is development of quorum-sensing (QS) interfering drugs. In this study, the results show that 1,8-cineole inhibited the expression of QS as well as the virulence genes in Escherichia coli O101 (E. coli O101) with a 65% inhibition rate against luxS gene. Therefore, we hypothesized that 1,8-cineole may inhibit the biofilm formation and reduce the pathogenicity of E. coli O101 by inhibiting the expression of luxS gene. To confirm our hypotheses, a luxS gene deleted E. coli O101 was constructed. The results show that the biofilm formation, motility, structure and pathogenicity of E. coli O101 were significantly inhibited following deletion of the luxS gene. In addition, the transcript levels of QS and virulence genes of E. coli O101 were also significantly down-regulated. Interestingly, 1,8-cineole no longer had a significant inhibitory effect on the related phenotype and gene expression of E. coli O101 without luxS gene. In conclusion, the results show that 1,8-cineole can affect bacterial biofilm formation and pathogenicity by suppressing the expression of luxS gene in E. coli O101, which could provide a new perspective for dealing with the biofilm problem of pathogenic bacteria.

RevDate: 2022-11-04

Pajohesh R, Tajbakhsh E, Momtaz H, et al (2022)

Relationship between Biofilm Formation and Antibiotic Resistance and Adherence Genes in Staphylococcus aureus Strains Isolated from Raw Cow Milk in Shahrekord, Iran.

International journal of microbiology, 2022:6435774.

The production of biofilms by S. aureus contributes significantly to treatment failures. The present study aims to establish the relationship between biofilm formation and antibiotic resistance and adhesion genes in Staphylococcus aureus strains isolated from raw cow milk in Shahrekord, Iran. A total of 90 samples of raw cow's milk were collected. Presumptive S. aureus strains were obtained using Baird-Parker plates after enrichment in tryptone soy broth, and final colonies were selected from brain heart infusion. Additional tests such as coagulase were done, and the identification was confirmed by the detection of the aroA gene. Biofilm producing strains were screened using a spectrophotometry method applied to microplates. Crystal violet staining was used to quantify the formation of biofilm. An antibiotic susceptibility test was performed using the Kirby-Bauer disc diffusion method. PCR was used to detect several biofilm and antibiotics resistance related genes. The chi-square test and Fisher's exact test were used to establish a statistically significant relationship between biofilm reaction and antibiotic resistance (p value <0.05). Results show a moderate (38.88%) recovery rate of S. aureus in milk and 65.71% of the isolates were strong biofilm producers. Antibiotic susceptibility tests show an alarming rate of resistance to beta-lactam antibiotics, especially penicillin (100%), ampicillin (91.42%), and oxacillin (71.42%). This finding correlates with antibiotic resistance gene detection, in which the gene blaZ was most found (71.42%), followed by mecA and Aac-D (42.85%). Detection of biofilm-related genes shows that all the genes targeted were found among S. aureus isolates. Statistical tests show a significant correlation between biofilm production and antibiotic resistance in S. aureus. This study revealed that there is a significant correlation between biofilm production and antibiotic resistance in S. aureus isolated from raw milk. These results highlight the need for regular surveillance of the occurrence of S. aureus strains in milk and milk products in Iran.

RevDate: 2022-11-04

Ravichandran S, Avatapalli S, Narasimhan Y, et al (2022)

'Targeting' the search: An upgraded structural and functional repository of antimicrobial peptides for biofilm studies (B-AMP v2.0) with a focus on biofilm protein targets.

Frontiers in cellular and infection microbiology, 12:1020391.

Bacterial biofilms, often as multispecies communities, are recalcitrant to conventional antibiotics, making the treatment of biofilm infections a challenge. There is a push towards developing novel anti-biofilm approaches, such as antimicrobial peptides (AMPs), with activity against specific biofilm targets. In previous work, we developed Biofilm-AMP, a structural and functional repository of AMPs for biofilm studies (B-AMP v1.0) with more than 5000 structural models of AMPs and a vast library of AMP annotations to existing biofilm literature. In this study, we present an upgraded version of B-AMP, with a focus on existing and novel bacterial biofilm targets. B-AMP v2.0 hosts a curated collection of 2502 biofilm protein targets across 473 bacterial species, with structural protein models and functional annotations from PDB, UniProt, and PubMed databases. The biofilm targets can be searched for using the name of the source organism, and function and type of protein, and results include designated Target IDs (unique to B-AMP v2.0), UniProt IDs, 3D predicted protein structures, PDBQT files, pre-defined protein functions, and relevant scientific literature. To present an example of the combined applicability of both, the AMP and biofilm target libraries in the repository, we present two case studies. In the first case study, we expand an in silico pipeline to evaluate AMPs against a single biofilm target in the multidrug resistant, bacterial pathogen Corynebacterium striatum, using 3D protein-peptide docking models from previous work and Molecular Dynamics simulations (~1.2µs). In the second case study, we build an in silico pipeline to identify candidate AMPs (using AMPs with both anti-Gram positive and anti-Gram negative activity) against two biofilm targets with a common functional annotation in Pseudomonas aeruginosa and Staphylococcus aureus, widely-encountered bacterial co-pathogens. With its enhanced structural and functional capabilities, B-AMP v2.0 serves as a comprehensive resource for AMP investigations related to biofilm studies. B-AMP v2.0 is freely available at https://b-amp.karishmakaushiklab.com and will be regularly updated with structural models of AMPs and biofilm targets, as well as 3D protein-peptide interaction models for key biofilm-forming pathogens.

RevDate: 2022-11-04

Jin X, An S, Kightlinger W, et al (2021)

Engineering Escherichia coli to produce and secrete colicins for rapid and selective biofilm cell killing.

AIChE journal. American Institute of Chemical Engineers, 67(12):.

Bacterial biofilms are associated with chronic infectious diseases and are highly resistant to conventional antibiotics. Antimicrobial bacteriocins are alternatives to conventional antibiotics and are characterized by unique cell-killing mechanisms, including pore formation on cell membranes, nuclease activity, and cell wall synthesis inhibition. Here, we used cell-free protein synthesis to rapidly evaluate the anti-biofilm activities of colicins E1, E2, and E3. We found that E2 (with DNase activity) most effectively killed target biofilm cells (i.e., the K361 strain) while leaving non-targeted biofilms intact. We then engineered probiotic Escherichia coli microorganisms with genetic circuits to controllably synthesize and secrete colicin E2, which successfully inhibited biofilms and killed pre-formed indicator biofilms. Our findings suggest that colicins rapidly and selectively kill target biofilm cells in multispecies biofilms and demonstrate the potential of using microorganisms engineered to produce antimicrobial colicin proteins as live therapeutic strategies to treat biofilm-associated infections.

RevDate: 2022-11-04

Wiguna OD, Waturangi DE, Yogiara (2022)

Bacteriophage DW-EC with the capability to destruct and inhibit biofilm formed by several pathogenic bacteria.

Scientific reports, 12(1):18539.

Biofilm formation by pathogenic bacteria is a major challenge in the food industry. Once a biofilm is established, such as on food processing equipment, it becomes more difficult to eradicate. Although physical and chemical treatments are often used to control biofilm formation, these treatments can have significant drawbacks. Alternative biofilm treatments are needed. Phage DW-EC was isolated from dawet, an Indonesian traditional Ready-To-Eat food, which has high specificity for Enterohaemorrhagic Escherichia coli (EHEC), Enteropathogenic E. coli (EPEC), and Enterotoxigenic E. coli (ETEC). Phage DW-EC produces several enzymes that can prevent the development of biofilm and biofilm eradication. Depolymerase enzymes break down the polysaccharides layer on the biofilms can lead to biofilm damage. On the other hand, endolysin and putative like-T4 lysozyme will lyse and kill a bacterial cell, thereby preventing biofilm growth. This research aims to determine the capability of previously identified phage DW-EC to inhibit and destroy biofilms produced by several foodborne pathogens. Phage DW-EC formed plaques on the bacterial lawns of EHEC, EPEC, and ETEC. The efficiency of plating (EOP) values for EHEC, EPEC, ETEC, and Bacillus cereus were 1.06, 0.78. 0.70, and 0.00, demonstrating that DW-EC was effective in controlling pathogenic E. coli populations. Furthermore, phage DW-EC showed anti-biofilm activity against foodborne pathogenic bacteria on polystyrene and stainless-steel substrates. DW-EC biofilm inhibition and destruction activities against pathogenic E. coli were significantly higher than against B. cereus biofilms, which was indicated by a lower density of the biofilm than B. cereus. Microscopic visualization verified that bacteriophage DW-EC effectively controlled EHEC, EPEC, and ETEC biofilms. The results showed that DW-EC could inhibit and destroy biofilm, making it promising to be used as an anti-biofilm candidate for polystyrene and stainless steel equipment in the food industry.

RevDate: 2022-11-03

Surya T, Jeyasekaran G, Shakila RJ, et al (2022)

Prevalence of biofilm forming Salmonella in different seafood contact surfaces of fishing boats, fish landing centres, fish markets and seafood processing plants.

Marine pollution bulletin, 185(Pt A):114285 pii:S0025-326X(22)00967-5 [Epub ahead of print].

The prevalence of biofilm forming Salmonella on different seafood contact surfaces was investigated. Out of 384 swab samples, 16.14 % and 1 % were confirmed biochemically and molecularly as Salmonella respectively. One out of four isolates was from the boat deck, and three were from the seafood processing plant. Salmonella was more prevalent in January, June, and September months. Different assays investigated the biofilm forming ability of isolates. Two out of four isolates have shown strong biofilms, and the others were moderate biofilm formers by microtitre plate assay. In the CRA assay, three isolates showed 'rdar' morphotype, and one showed 'bdar' morphotype. All isolates were positive for gcpA gene (~1700 bp), a critical gene found in Salmonella biofilms. The microbial load of Salmonella biofilms on different contact surfaces were determined, stainless steel and HDPE were found prone to biofilms. With this, a suitable mechanism shall be formulated to control the biofilms of Salmonella.

RevDate: 2022-11-03

Naziri Z, M Majlesi (2022)

Comparison of the prevalence, antibiotic resistance patterns, and biofilm formation ability of methicillin-resistant Staphylococcus pseudintermedius in healthy dogs and dogs with skin infections.

Veterinary research communications [Epub ahead of print].

Staphylococcus pseudintermedius (S. pseudintermedius), found on dogs' skin and mucous membranes, can act as an opportunistic pathogen causing skin, ear, and other tissue infections. Due to the possibility of zoonotic transmission of them, it is necessary to investigate the prevalence of S. pseudintermedius, especially the antimicrobial-resistant strains, in pets. In this study, the prevalence, antimicrobial resistance patterns, and biofilm formation ability of methicillin-resistant S. pseudintermedius (MRSP) were investigated and compared in 50 healthy dogs and 50 dogs with skin infections. The prevalence of S. pseudintermedius was not significantly different between healthy dogs (40%) and dogs with skin infections (50%). No significant difference was found in the prevalence of MRSP between healthy dogs (12%) and dogs with skin infections (18%). A total of 81.8% of S. pseudintermedius isolates were biofilm producers. The frequencies of antibiotic resistance (except for gentamicin), multidrug resistance (MDR), and biofilm formation ability were not significantly different between S. pseudintermedius isolates of healthy dogs and dogs with skin infections. The frequencies of resistance to penicillin and tetracycline, MDR, and biofilm production abilities were significantly higher among MRSP than methicillin-susceptible S. pseudintermedius (MSSP). The frequency of oxacillin resistance was significantly higher among weak or moderate biofilm producers than non-biofilm producers. The frequency of resistance to erythromycin was significantly higher among moderate biofilm producers than non-biofilm producers or weak biofilm producers. High frequencies of biofilm-producer S. pseudintermedius isolates and their resistance to antibiotics can affect the success of treatment of infections caused by these strains.

RevDate: 2022-11-03

Holden ER, Yasir M, Turner AK, et al (2022)

Comparison of the genetic basis of biofilm formation between Salmonella Typhimurium and Escherichia coli.

Microbial genomics, 8(11):.

Most bacteria can form biofilms, which typically have a life cycle from cells initially attaching to a surface before aggregation and growth produces biomass and an extracellular matrix before finally cells disperse. To maximize fitness at each stage of this life cycle and given the different events taking place within a biofilm, temporal regulation of gene expression is essential. We recently described the genes required for optimal fitness over time during biofilm formation in Escherichia coli using a massively parallel transposon mutagenesis approach called TraDIS-Xpress. We have now repeated this study in Salmonella enterica serovar Typhimurium to determine the similarities and differences in biofilm formation through time between these species. A core set of pathways involved in biofilm formation in both species included matrix production, nucleotide biosynthesis, flagella assembly and LPS biosynthesis. We also identified several differences between the species, including a divergent impact of the antitoxin TomB on biofilm formation in each species. We observed deletion of tomB to be detrimental throughout the development of the E. coli biofilms but increased biofilm biomass in S. Typhimurium. We also found a more pronounced role for genes involved in respiration, specifically the electron transport chain, on the fitness of mature biofilms in S. Typhimurium than in E. coli and this was linked to matrix production. This work deepens understanding of the core requirements for biofilm formation in the Enterobacteriaceae whilst also identifying some genes with specialised roles in biofilm formation in each species.

RevDate: 2022-11-03

Guillaume O, Butnarasu C, Visentin S, et al (2022)

Interplay between biofilm microenvironment and pathogenicity of Pseudomonas aeruginosa in cystic fibrosis lung chronic infection.

Biofilm, 4:100089 pii:S2590-2075(22)00023-5.

Pseudomonas aeruginosa (PA) is a highly, if not the most, versatile microorganism capable of colonizing diverse environments. One of the niches in which PA is able to thrive is the lung of cystic fibrosis (CF) patients. Due to a genetic aberration, the lungs of CF-affected patients exhibit impaired functions, rendering them highly susceptible to bacterial colonization. Once PA attaches to the epithelial surface and transitions to a mucoid phenotype, the infection becomes chronic, and antibiotic treatments become inefficient. Due to the high number of affected people and the severity of this infection, CF-chronic infection is a well-documented disease. Still, numerous aspects of PA CF infection remain unclear. The scientific reports published over the last decades have stressed how PA can adapt to CF microenvironmental conditions and how its surrounding matrix of extracellular polymeric substances (EPS) plays a key role in its pathogenicity. In this context, it is of paramount interest to present the nature of the EPS together with the local CF-biofilm microenvironment. We review how the PA biofilm microenvironment interacts with drugs to contribute to the pathogenicity of CF-lung infection. Understanding why so many drugs are inefficient in treating CF chronic infection while effectively treating planktonic PA is essential to devising better therapeutic targets and drug formulations.

RevDate: 2022-11-02

Huang Y, Zhang B, Chen K, et al (2022)

Temperature-controlled microalgae biofilm adsorption/desorption in a thermo-responsive light-guided 3D porous photo-bioreactor for CO2 fixation.

Environmental research pii:S0013-9351(22)01972-7 [Epub ahead of print].

Microalgae biofilm-based culture provides an efficient CO2 reduction and wastewater treatment method for its high photosynthetic efficiency and density. As supporting substrates for microalgae biofilm, porous materials have a big available adsorption area, but mutual shading makes it difficult to transmit external light to the internal surface for attached cells' photosynthesis. Thus, light-guided particles (SiO2) were introduced into photosensitive resin to fabricate a light-guided ordered porous photobioreactor (PBR) by 3D printing technology in this study. The space utilization of the PBR was significantly enhanced and the effective microalgae adsorption area was increased by 13.6 times. Further, a thermo-responsive hydrogel was grafted onto the surface of the substrate to form a smart temperature-controllable interface that could enhance microalgae adsorption and desorption in both directions. When the thermo-responsive layer received light, it would generate heat due to the hydrogel's photo-thermal effect. And the surface temperature would then raise to 33 °C, higher than the hydrogel phase transition point of 32 °C, making the surface shrinking and more hydrophobicity for microalgae cells attachment. The microalgae cells' adsorption capacity increased by 103%, resulting in a high microalgae growth rate of 3.572 g m-2 d-1. When turning off the light, the surface temperature would cool down to below 20 °C, the surface would shrink. And the biofilm shows a 564.7% increase in desorption ability, realizing temperature-controlled microalgae harvesting.

RevDate: 2022-11-02

Chackartchi T, Zaydel L, Shapira L, et al (2022)

Biofilm formation, its removal and consequent effect on the osteoblast response to titanium surfaces: A model for re-osseointegration.

Journal of periodontology [Epub ahead of print].

BACKGROUND: The aim of the study was to characterize pathogenic biofilm formation on titanium surfaces, the ability to remove the biofilm and the osteoblast response to infected and cleaned titanium surfaces as a model for re-osseointegration.

METHODS: Multispecies biofilm composed of Pseudomonas. gingivalis, F. nucleatum, S. sanguis and A. naeslundii was grown on smooth, acid-etched, and acid-etched-aluminum-sprayed titanium surfaces. Bacterial viability was determined with live/dead staining. The biofilm was removed mechanically or together with adjunctive antibiotics. The osteoblast (Saos2) response to previously infected, treated and non-infected titanium surfaces was measured according to 4'-6-diamidino-2-phenylindole staining. Alkaline phosphatase levels and Receptor activator of nuclear factor kappa-Β ligand/Osteoprotegerin expression were measured with ELISA and immunofluorescence staining, respectively The inflammatory environment was established by using differentiated HL-60 cells (neutrophils) pre-inoculated onto the biofilm clusters that were more prominent and less scattered on infected titanium surfaces before osteoblast attachment.

RESULTS: Biofilm formed on all the tested surfaces, with an increased thickness on rough surfaces and no differences in bacterial viability. All the treatments reduced the amount of biofilm, but none led to bacteria-free surfaces. The treated surfaces showed reduced osteoblast attachment and reduced alkaline phosphatase activity compared with non-infected surfaces. Additionally, treated surfaces showed an osteoblast shift to a pro-osteoclastic-induction phenotype, compared with non-infected surfaces. The presence of experiomental inflammation before osteoblast attachment reduced the levels of osteoblast attachment compared with that of the non-inflamed control.

CONCLUSIONS: Biofilm removal from titanium surfaces is incomplete when hand instruments are used alone or in combination with antibiotics. The treated surfaces showed impaired osteoblast attachment and function, particularly in the presence of inflammation, which may prevent or decrease the ability for re-osseointegration. This article is protected by copyright. All rights reserved.

RevDate: 2022-10-31

Mazioti AA, I Vyrides (2022)

Treatment of high-strength saline bilge wastewater by four pilot-scale aerobic moving bed biofilm reactors and comparison of the microbial communities.

Environmental technology [Epub ahead of print].

Four Pilot-scale Moving Bed Biofilm Reactors (MBBRs) were operated for the treatment of real, saline, bilge wastewater. The MBBRs were connected in pairs to create two system configurations with different filling ratios (20%, 40%) and were operated in parallel. The inflow organic loading rate (OLR) varied from 3.6 ± 0.2 to 7.8 ± 0.6 g COD L-1 d-1, salinity was >15 ppt and three hydraulic residence times (HRTs) were tested 48, 30 and 24 h. In both systems, the first-stage bioreactors (R1 and R3) eliminated the higher part of the organic load (57%-65%). The second-stage bioreactors (R2 and R4) removed an additional fraction (18%-31%) of the organic load received by the effluent of R1 and R3, respectively. The microbial communities of the influent wastewater, suspended, and attached biomass were determined using 16S rRNA gene amplicon sequencing analysis. The evolution of the microbial communities was investigated and compared over the different operational phases. The microbial communities of the biofilm presented higher diversity and greater stability in composition over time, while the suspended biomass exhibited intense and rapid changes in the dominance of genera. Proteobacteria, Bacteroidetes and Firmicutes were highly present in the biofilm. The genera Celeribacter, Novispirillum, Roseovarius (class: Alphaproteobacteria) and Formosa (class: Flavobacteriia) were highly present during all operational phases. Principal Component Analysis (PCA) was used to identify similarities between samples, exhibiting high relation of samples according to the series of the bioreactor (1st, 2nd).

RevDate: 2022-10-31

Shipitsyna IV, EV Osipova (2022)

Influence of ß-lactam antibiotics on the activity of K. pneumoniae bacteria biofilm forms isolated from wounds of patients with chronic osteomyelitis.

Klinicheskaia laboratornaia diagnostika, 67(10):594-599.

One of the reasons for the emergence of highly resistant strains is associated with the ability of bacteria to form biofilms on various surfaces. The formation of a biofilm by pathogens leads to a decrease in the activity of the antibiotic, an increase in the time for the production of stress response genes by bacteria, and, as a result, an increase in antimicrobial tolerance. To investigate the effect of imipenem and cefepime on the activity of biofilm forms of K. pneumoniae bacteria isolated from the wounds of patients with chronic osteomyelitis. The object of the study is clinical strains of K. pneumoniae isolated from the wounds of patients with chronic osteomyelitis. In the control series, the level of biofilm formation of K. pneumoniae strains was assessed after 48 hours of cultivation on coverslips and 96-well polystyrene plates. In the second and third series, the biofilm form of K. pneumoniae bacteria was exposed to imipenem and cefepime, and after 24 hours the activity of biofilm formation was assessed according to previously developed criteria. The structure of the emerging biofilm on the surface of the coverslip in all series of the experiment was represented by single adherent cells and microcolonies of various sizes. Cultivation with antibiotics led to a decrease in the number of microcolonies ranging in size from 10 to 10,000 µm2 in the second and third series, however, significant differences from the control series were found only when exposed to cefepime. The intensity of film formation of K. pneumoniae in the control series by the tablet method was 0.350 (0.334; 0.368) units opt.pl. When cultivating biofilms together with antibacterial drugs, the biofilm-forming activity after 24 hours of the experiment was significantly lower than in the control group in all experimental series. K. pneumoniae bacteria isolated from patients with chronic osteomyelitis, when cultivated on polystyrene plates and on the surface of coverslips, actively form a biofilm, exhibiting highly adhesive properties. The studied antibiotics were shown to have a bacteriostatic effect on biofilm forms of K. pneumoniae bacteria. The bactericidal effect of imipenem and cefepime on biofilm forms was not revealed.

RevDate: 2022-10-31

Wagner BM, Daigger GT, NG Love (2022)

Design methodologies to determine optimal staging of membrane-aerated biofilm reactors for mainstream treatment with anammox.

Water science and technology : a journal of the International Association on Water Pollution Research, 86(8):1887-1903.

Partial nitritation anammox (PNA) membrane-aerated biofilm reactors (MABRs) can be used in mainstream nitrogen removal to help facilities reduce their energy consumption. Previous PNA MABR research has not investigated the impacts of staging, i.e. arraying MABRs in series, on their nitrogen removal performance, operation, and ability to suppress nitrite oxidizing bacteria. In this paper, a mathematical model simulated PNA MABR performance at different influent total ammonia concentrations and loadings. A design methodology for staging PNA MABRs was created and found that the amount of membrane surface area is dependent upon the total ammonia-nitrogen concentration and loading, and the air loading to the membrane must be proportional to the total ammonia-nitrogen loading to maximize the total inorganic nitrogen (TIN) removal rate. This led to approximately equal-sized stages that each had a TIN removal percentage of 71% of the influent total ammonia nitrogen. Staging a treatment train resulted in 9.8% larger total ammonia and 9.3% larger total nitrogen removal rates when compared with an un-staged reactor. The un-staged reactor also was not able to produce an effluent total ammonia concentration below 5 mg N/L which would be necessary for many facilities' permits.

RevDate: 2022-10-31

Dostert M, Belanger CR, Pedraz L, et al (2022)

BosR: A novel biofilm-specific regulator in Pseudomonas aeruginosa.

Frontiers in microbiology, 13:1021021.

Biofilms are the most common cause of bacterial infections in humans and notoriously hard to treat due to their ability to withstand antibiotics and host immune defenses. To overcome the current lack of effective antibiofilm therapies and guide future design, the identification of novel biofilm-specific gene targets is crucial. In this regard, transcriptional regulators have been proposed as promising targets for antimicrobial drug design. Therefore, a Transposon insertion sequencing approach was employed to systematically identify regulators phenotypically affecting biofilm growth in Pseudomonas aeruginosa PA14 using the TnSeq analysis tools Bio-TraDIS and TRANSIT. A screen of a pool of 300,000 transposon insertion mutants identified 349 genes involved in biofilm growth on hydroxyapatite, including 47 regulators. Detection of 19 regulatory genes participating in well-established biofilm pathways validated the results. An additional 28 novel prospective biofilm regulators suggested the requirement for multiple one-component transcriptional regulators. Biofilm-defective phenotypes were confirmed for five one-component transcriptional regulators and a protein kinase, which did not affect motility phenotypes. The one-component transcriptional regulator bosR displayed a conserved role in P. aeruginosa biofilm growth since its ortholog in P. aeruginosa strain PAO1 was also required for biofilm growth. Microscopic analysis of a chromosomal deletion mutant of bosR confirmed the role of this regulator in biofilm growth. Overall, our results highlighted that the gene network driving biofilm growth is complex and involves regulators beyond the primarily studied groups of two-component systems and cyclic diguanylate signaling proteins. Furthermore, biofilm-specific regulators, such as bosR, might constitute prospective new drug targets to overcome biofilm infections.

RevDate: 2022-10-31

Rindi L, He J, L Benedetti-Cecchi (2022)

Spatial correlation reverses the compound effect of multiple stressors on rocky shore biofilm.

Ecology and evolution, 12(10):e9418 pii:ECE39418.

Understanding how multifactorial fluctuating environments affect species and communities remains one of the major challenges in ecology. The spatial configuration of the environment is known to generate complex patterns of correlation among multiple stressors. However, to what extent the spatial correlation between simultaneously fluctuating variables affects ecological assemblages in real-world conditions remains poorly understood. Here, we use field experiments and simulations to assess the influence of spatial correlation of two relevant climate variables - warming and sediment deposition following heavy precipitation - on the biomass and photosynthetic activity of rocky intertidal biofilm. First, we used a response-surface design experiment to establish the relation between biofilm, warming, and sediment deposition in the field. Second, we used the response surface to generate predictions of biofilm performance under different scenarios of warming and sediment correlation. Finally, we tested the predicted outcomes by manipulating the degree of correlation between the two climate variables in a second field experiment. Simulations stemming from the experimentally derived response surface showed how the degree and direction (positive or negative) of spatial correlation between warming and sediment deposition ultimately determined the nonlinear response of biofilm biomass (but not photosynthetic activity) to fluctuating levels of the two climate variables. Experimental results corroborated these predictions, probing the buffering effect of negative spatial correlation against extreme levels of warming and sediment deposition. Together, these results indicate that consideration of nonlinear response functions and local-scale patterns of correlation between climate drivers can improve our understanding and ability to predict ecological responses to multiple processes in heterogeneous environments.

RevDate: 2022-10-31

Samreen , Qais FA, I Ahmad (2022)

Anti-quorum sensing and biofilm inhibitory effect of some medicinal plants against gram-negative bacterial pathogens: in vitro and in silico investigations.

Heliyon, 8(10):e11113 pii:S2405-8440(22)02401-X.

Multidrug resistance (MDR) in pathogenic bacteria have become a major clinical issue. Quorum sensing regulated bacterial virulence is a promising key drug target for MDR infections. Therefore, the aim of the present work was to assess the anti-quorum sensing properties of selected medicinal plants against bacterial pathogens as well in silico interaction of selected bioactive phytocompounds with QS and biofilm-associated proteins. Based on the ethnopharmacological usage, 18 plants were selected using methanolic extract against Chromobacterium violaceum 12472. The most active extract (Acacia nilotica) was fractionated in increasing polarity solvents (n-hexane, chloroform and ethyl acetate) and tested for anti-QS activity. The most active fraction i.e. ethyl acetate fraction was evaluated for their activity at sub-MICs against QS-associated virulence factors of Pseudomonas aeruginosa PAO1 and Serretia marcescens MTCC 97. Microtiter plate assay and light microscopy was used to determine inhibition of biofilm. Phytochemicals of the ethyl acetate fraction were analysed by GC/MS and LC/MS. Phytocompounds were docked with QS (LasI, LasR, CviR, and rhlR) and biofilm proteins (PilY1 and PilT) using Auto dock vina. The MIC of ethyl acetate fraction determined was 250, 500, and 1000 μg/ml against C. violaceum 12472, P. aeruginosa PAO1, and S. marcescens MTCC97 respectively. At sub-MICs QS regulated virulence factors production and inhibited biofilms broadly (more than 50 percent). GC/MS detected the major bioactive compound benzoic acid, 3,4,5-trihydroxy-, methyl ester (61.24 %) and LC-MS detected Retronecine for the first time in A. nilotica pods. In silico, dehydroabietic acid occupied the same cavity as its antagonist in the CviR ligand binding domain. Also, betulin and epicatechin gallate interact with biofilm proteins PilY1 and PilT, preventing biofilm formation. The findings suggest that the phytochemicals of A. nilotica pod could be exploited as an anti-QS agent against Gram-negative pathogens. To discover therapeutic efficacy of standardised bioactive extract/phytochemicals must be tested under in vivo condition.

RevDate: 2022-10-31

Deng W, Lei Y, Tang X, et al (2022)

DNase inhibits early biofilm formation in Pseudomonas aeruginosa- or Staphylococcus aureus-induced empyema models.

Frontiers in cellular and infection microbiology, 12:917038.

Anti-infection strategies against pleural empyema include the use of antibiotics and drainage treatments, but bacterial eradication rates remain low. A major challenge is the formation of biofilms in the pleural cavity. DNase has antibiofilm efficacy in vitro, and intrapleural therapy with DNase is recommended to treat pleural empyema, but the relevant mechanisms remain limited. Our aim was to investigate whether DNase I inhibit the early biofilm formation in Pseudomonas aeruginosa- or Staphylococcus aureus-induced empyema models. We used various assays, such as crystal violet staining, confocal laser scanning microscopy (CLSM) analysis, peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH), and scanning electron microscopy (SEM) analysis. Our results suggested that DNase I significantly inhibited early biofilm formation in a dose-dependent manner, without affecting the growth of P. aeruginosa or S. aureus in vitro. CLSM analysis confirmed that DNase I decreased the biomass and thickness of both bacterial biofilms. The PNA-FISH and SEM analyses also revealed that DNase I inhibited early (24h) biofilm formation in two empyema models. Thus, the results indicated that DNase inhibited early (24h) biofilm formation in P. aeruginosa- or S. aureus-induced rabbit empyema models and showed its therapeutic potential against empyema biofilms.

RevDate: 2022-10-29

Agustín MDR, Tarifa MC, Vela-Gurovic MS, et al (2023)

Application of natamycin and farnesol as bioprotection agents to inhibit biofilm formation of yeasts and foodborne bacterial pathogens in apple juice processing lines.

Food microbiology, 109:104123.

Biofilms serve as a reservoir for pathogenic and spoilage microorganisms, and their removal from different surfaces is a recurring problem in the beverage industry. This study aimed to investigate the effect of a combination of natamycin (NAT, 0.01 mmol/l) and farnesol (FAR, 0.6 mmol/l) against biofilms on ultrafiltration (UF) membranes and stainless steel (SS) surfaces using apple juice as food matrix. The co-adhesion of Rhodotorula mucilaginosa, Candida tropicalis, C. krusei and C. kefyr (mixed-yeast) with Listeria monocytogenes, Salmonella enterica or Escherichia coli O157:H7 (multi-species) in presence of NAT + FAR was evaluated for 2, 24, 48 h. In biofilms treated with NAT + FAR were observed by cell quantification and microscopy, inhibition of the filamentous yeast forms, disruption of the tri-dimensional structure and a high detachment of yeast cells. NAT + FAR affected the biofilms independently of the surfaces used and the presence (or not) of bacteria. L. monocytogenes was the most susceptible (p < 0.001) in multi-species biofilms, followed by E. coli O157:H7 on both surfaces (p < 0.001), whereas the growth of S. enterica was reduced (p < 0.05) in SS but not in UF-membranes (p > 0.05). Since the combination NAT + FAR affected the structure and viability of yeast species and foodborne pathogens in multi-species biofilms developed on UF-membranes and SS surfaces, the combination proposed could be considered a promising control agent to prevent biofilms in apple juice processing lines.

RevDate: 2022-10-29

Chen J, Sun Z, Jin J, et al (2023)

Role of siderophore in Pseudomonas fluorescens biofilm formation and spoilage potential function.

Food microbiology, 109:104151.

We investigated the function of pyoverdine in the biofilm formation, motility, and spoilage potential of Pseudomonas fluorescens. We targeted and identified two major genes (pvdA and pvdE) that are involved in the biosynthesis of siderophores. We next constructed ΔpvdA and ΔpvdE mutants of P. fluorescens PF08 and found that the deletion of pyoverdine led to a biofilm-to-motivity transition as both ΔpvdA and ΔpvdE mutants displayed enhanced motility, reduced level of exopolysaccharides (EPSs), and attenuated biofilm formation. In addition, the lack of synthesis of pyoverdine promoted the spoilage of fish fillets stored at 4 °C. Based on the effect of pyoverdine deletion on the phenotype; we report that pyoverdine regulates the transcription levels of htpX, phoA, flip, flgA, and RpoS, suggesting that pyoverdine-mediated iron absorption may affect the regulation of flagellum and stress resistance. This study emphasizes the important role of pyoverdine in the formation of biofilm, motility, and spoilage of P. fluorescens PF08.

RevDate: 2022-10-29

Ye Y, Ma S, Peng H, et al (2022)

Insight into the comprehensive effect of carbon dioxide, light intensity and glucose on heterotrophic-assisted phototrophic microalgae biofilm growth: A multifactorial kinetic model.

Journal of environmental management, 325(Pt B):116582 pii:S0301-4797(22)02155-7 [Epub ahead of print].

Heterotrophic-assisted photoautotrophic microalgae biofilm cultivation was an alternative way to realize CO2 reduction and wastewater treatment. Growth kinetics supplied a channel to better understand how the cultivation conditions affect microalgal growth and CO2 reduction. However, the two growth modes (heterotroph and photoautotroph) have different needs for organic and inorganic nutrients. Thus, combining the threshold theory and multiplication theory, an integral multifactorial kinetic model that looking insight into the comprehensive effect of glucose, CO2, light intensity, and nitrate was developed for heterotrophic-assisted photoautotrophic microalgae biofilm growth in this study. R2 between model and experiment was 0.99. It predicted the maximum specific growth rate and maximum CO2 consumption rate of heterotrophic-assisted photoautotrophic microalgae biofilm was 1.868 h-1 and 1.02 h-1, respectively. This model fully explained the influence of the main factors on microalgae biofilm growth and reasonably predicted the growth rate of microalgae biofilm under different growth conditions.

RevDate: 2022-10-29

Zhang H, Zhang SS, Zhang W, et al (2022)

Biomineralization and AHLs-guided quorum sensing enhanced phosphorus recovery in the alternating aerobic/anaerobic biofilm system under metal ion stress.

Journal of environmental management, 325(Pt B):116583 pii:S0301-4797(22)02156-9 [Epub ahead of print].

The alternating aerobic/anaerobic biofilm system had been applied for phosphorus (P) enrichment and recovery because of the advantage of low energy consumption and high efficiency. The metal ions and N-acyl-L-homoserine lactones (AHLs) in system were studied to better clarify the mechanism of P uptake/release under metal ion stress. The results indicated that the increase of metal ions stimulated the release of AHLs, and AHLs-guided quorum sensing (QS) enhanced P uptake. Moreover, biomineralization could stimulate the increase of P content in biofilm (Pbiofilm). Meanwhile, some ortho-p was converted to short-chain poly-p in extracellular polymer substance (EPS), and others were transferred into cell through EPS to synthesize poly-p. With the Pbiofilm increased, more P could be absorbed/released due to the shift in the metabolic model of polyphosphate accumulating organisms (PAOs). The release of AHLs between microorganisms was also inhibited when PAOs reached the state of P saturation (75.6 ± 2.5 mg/g SS), which meant that the effect of signaling function would tend to stabilize, and the 169.2 ± 2.6 mg/L P concentration in the enriched solution was obtained due to the P release was inhibited. Moreover, P was rapidly transferred to the new enriched solution after the P was recovered, and PAOs restored its capability of P uptake/release. In addition, 31P-NMR analysis demonstrated that EPS played a major role in PAOs compared to cell, and inorganic phosphorus (IP) played an essential role in the uptake/release of P compared to organic phosphorus (OP). Furthermore, the microbiological analysis showed that Candidatus Accumulibacter was positively correlated with AHLs (P < 0.05). This study provided essential support for clarifying the P metabolism mechanism of PAOs.

RevDate: 2022-10-29

Zhang Y, Huang Y, Ding H, et al (2022)

A σE-mediated temperature gauge orchestrates type VI secretion system, biofilm formation and cell invasion in pathogen Pseudomonas plecoglossicida.

Microbiological research, 266:127220 pii:S0944-5013(22)00260-9 [Epub ahead of print].

Pseudomonas plecoglossicida is a temperature-dependent opportunistic pathogen mediating visceral granulomas in many piscine species including the large yellow croaker (Larimichthys crocea) but the underlying mechanisms are unclear. RpoE is an alternative sigma (σ) factor involved in regulated intramembrane proteolytic (RIP) cascade, enabling bacterial pathogens to coordinate the expression of genetic traits associated with stress adaptation and virulence determinants in response to diverse stimuli in vitro and in vivo of the hosts. In this study, genes associated to RIP cascade in P. plecoglossicida were identified and characterized to show various sequence similarities to their counterparts in Escherichia coli and P. aeruginosa. The expression of P. plecoglossicida RIP locus was induced by higher temperatures. Moreover, RNA sequencing approach revealed that RpoE regulated the expression of ∼297 and ∼261 genes at virulent (18 °C) and non-virulent (28 °C) temperatures, respectively. RpoE regulon genes are involved in various processes associated with bacterial signal transduction, membrane homeostasis, energy metabolism and virulence. In particular, RpoE positively controlled expression of csrA encoding an RNA binding protein essential for central carbon metabolism. In addition, P. plecoglossicida RpoE was validated to regulate type VI secretion system (T6SS) expression, bacteria competition, biofilm formation and reproduction in macrophages. Collectively, RpoE-centered RIP cascade appeared to play important roles in control of the expression of genes involved in adaptation in vivo and in vitro niches by thermal sensing in P. plecoglossicida. These results facilitates to reveal the pathogenic mechanisms of P. plecoglossicida causing fish diseases and provides new perspectives to control bacterial infection.

RevDate: 2022-10-29

Farjami A, Jalilzadeh S, Siahi-Shadbad M, et al (2022)

The anti-biofilm activity of hydrogen peroxide against Escherichia coli strain FL-Tbz isolated from a pharmaceutical water system.

Journal of water and health, 20(10):1497-1505.

Biofilms are considered a significant reason for the failure of disinfection strategies in industrial water systems due to their resistance to antimicrobial agents. This study is designed to investigate the anti-biofilm activity of hydrogen peroxide (H2O2) at combinations of temperatures and contact times. For this purpose, an in vitro microtiter plate (MTP)-based model system was used for biofilm formation using Escherichia coli (E. coli) strain FL-Tbz isolated from the water system of a pharmaceutical plant. To investigate the anti-biofilm activity of H2O2, it was added at different concentrations (2-7% v/v) to biofilms and incubated at different temperatures (20-60 °C) for 10-40 min to find effective conditions to eradicate biofilms. Maximum biofilms were formed when bacterial suspensions were incubated at 37 °C for 96 h. The rate of biofilm formation using an environmental isolate was higher than that of standard strain. H2O2 at concentrations of ≥6.25% (v/v) at temperatures of ≥40 °C incubated for ≥25 min significantly eradicated the biofilms.

RevDate: 2022-10-29

Yao X, Sun J, Bai X, et al (2022)

A high-efficiency mixotrophic photoelectroactive biofilm reactor (MPBR) for enhanced simultaneous removal of nutrients and antibiotics by integrating light intensity regulation and microbial extracellular electron extraction.

Journal of environmental management, 325(Pt A):116520 pii:S0301-4797(22)02093-X [Epub ahead of print].

The performance of a mixotrophic photoelectroactive biofilm reactor (MPBR) was improved in order to achieve enhanced simultaneous removal of multiple aqueous pollutants and the production of valuable biomass. The MPBR was optimized by integrating the regulation of light intensity (3000, 8000 and 23000 lux) and microbial extracellular electron extraction (using an electrode at -0.3, 0 and 0.3 V). Results showed that the MPBR operated at a high light intensity (23000 lux) with a potential of -0.3 V (Coulomb efficiency (CE) of 9.65%) achieved maximum pollutant removal efficiencies, effectively removing 65% NH4+-N, 95% PO43--P and 52% sulfadiazine (SDZ) within 72 h, exhibiting an increase by 30%, 56% and 26% compared to an MPBR operated at the same light intensity but without an externally applied potential. The use of an electrode with an applied potential of -0.3V was most suitable for the extraction of photosynthetic electrons from the photoelectroactive biofilm, in which Rhodocyclaceae was highly enriched, effectively alleviating photoinhibition and thereby enhancing N, P assimilation and SDZ degradation under high light conditions. A maximum lipid content of 409.28 mg/g was obtained under low light intensity (3000 lux) conditions with an applied potential of 0.3 V (CE 9.08%), while a maximum protein content of 362.29 mg/g was obtained at a low light intensity (3000 lux) and 0 V (CE 10.71%). The selective enrichment of Chlorobium and the subsequent enhanced conversion of excess available carbon under low light and positive potential stimulation conditions, were responsible for the enhanced accumulation of proteins and lipids in biomass.

RevDate: 2022-10-28

Cesaria M, Alfinito E, Arima V, et al (2022)

MEED: A novel robust contrast enhancement procedure yielding highly-convergent thresholding of biofilm images.

Computers in biology and medicine, 151(Pt A):106217 pii:S0010-4825(22)00925-8 [Epub ahead of print].

Morphological and statistical investigation of biofilm images may be even more critical than the image acquisition itself, in particular in the presence of morphologically complex distributions, due to the unavoidable impact of the measurement technique too. Hence, digital image pre-processing is mandatory for reliable feature extraction and enhancement preliminary to segmentation. Also, pattern recognition in automated deep learning (both supervised and unsupervised) models often requires a preliminary effective contrast-enhancement. However, no universal consensus exists on the optimal contrast enhancement approach. This paper presents and discusses a new general, robust, reproducible, accurate and easy to implement contrast enhancement procedure, briefly named MEED-procedure, able to work on images with different bacterial coverages and biofilm structures, coming from different imaging instrumentations (herein stereomicroscope and transmission microscope). It exploits a proper succession of basic morphological operations (erosion and dilation) and a horizontal line structuring element, to minimize the impact on size and shape of the even finer bacterial features. It systematically enhances the objects of interest, without histogram stretching and/or undesirable artifacts yielded by common automated methods. The quality of the MEED-procedure is ascertained by segmentation tests which demonstrate its robustness regarding the determination of threshold and convergence of the thresholding algorithm. Extensive validation tests over a rich image database, comparison with the literature and comprehensive discussion of the conceptual background support the superiority of the MEED-procedure over the existing methods and demonstrate it is not a routine application of morphological operators.

RevDate: 2022-10-28

Gu M, Nguyen HT, Cho JH, et al (2022)

Characterization of Leuconostoc mesenteroides MJM60376 as an oral probiotic and its anti-biofilm activity.

Molecular oral microbiology [Epub ahead of print].

Lactic acid bacteria have been widely used as probiotics for improving gut health. However, studies on oral probiotics were very limited. In this study, 67 lactic acid bacteria (LAB) were isolated from fermented food and screened for antagonistic activity against Streptococcus mutans, the causative pathogen of dental caries. Leuconostoc mesenteroides MJM60376 showed the highest antagonistic activity against S. mutans KCTC3065. L. mesenteroides MJM60376 also showed oral probiotic characteristics including weak acid production, lysozyme tolerance, adhesion to oral epithelial cell (YD-38), antibiotic susceptibility, and good co-aggregation ability with S. mutans. Furthermore, the biofilm formation of S. mutans was significantly reduced when co-cultured with L. mesenteroides. Scanning electron microscopy analysis showed that amounts of attached bacteria of S. mutans and network-like structures were significantly reduced by L. mesenteroides MJM60376. Cell-free supernatant (CFS) of L. mesenteroides MJM60376 also greatly inhibited biofilm formation of S. mutans from the adherent stage, the activity remained even after it was treated with catalase, trypsin, or pH neutralized. Expression levels of biofilm formation-related genes were significantly reduced in S. mutans when it was treated with the CFS of L. mesenteroides MJM60376. Therefore, L. mesenteroides MJM60376 has great potential to be used as a multifunctional oral health ingredient. This article is protected by copyright. All rights reserved.

RevDate: 2022-10-28

Li M, Nahum Y, Matouš K, et al (2022)

Effects of biofilm heterogeneity on the apparent mechanical properties obtained by shear rheometry.

Biotechnology and bioengineering [Epub ahead of print].

Rheometry is an experimental technique widely used to determine the mechanical properties of biofilms. However, it characterizes the bulk mechanical behavior of the whole biofilm. The effects of biofilm mechanical heterogeneity on rheometry measurements are not known. We used laboratory experiments and computer modeling to explore the effects of biofilm mechanical heterogeneity on the results obtained by rheometry. A synthetic biofilm with layered mechanical properties was studied, and a viscoelastic biofilm theory was employed using the Kelvin-Voigt model. Agar gels with different concentrations were used to prepare the layered, heterogenous biofilm, which was characterized for mechanical properties in shear mode with a rheometer. Both experiments and simulations indicated that the biofilm properties from rheometry were strongly biased by the weakest portion of the biofilm. The simulation results using linearly stratified mechanical properties from a previous study also showed that the weaker portions of the biofilm dominated the mechanical properties in creep tests. We note that the model can be used as a predictive tool to explore the mechanical behavior of complex biofilm structures beyond those accessible to experiments. Since most biofilms display some degree of mechanical heterogeneity, our results suggest caution should be used in the interpretation of rheometry data. It does not necessarily provide the "average" of the mechanical properties of the entire biofilm if the sample is vertically stratified. This article is protected by copyright. All rights reserved.

RevDate: 2022-10-29

Ahmed B, Jailani A, Lee JH, et al (2022)

Inhibition of growth, biofilm formation, virulence, and surface attachment of Agrobacterium tumefaciens by cinnamaldehyde derivatives.

Frontiers in microbiology, 13:1001865.

Agrobacterium tumefaciens, a soil-borne, saprophytic plant pathogen that colonizes plant surfaces and induces tumors in a wide range of dicotyledonous plants by transferring and expressing its T-DNA genes. The limited availabilities and efficacies of current treatments necessitate the exploration of new anti-Agrobacterium agents. We examined the effects of trans-cinnamaldehyde (t-CNMA) and its derivatives on the cell surface hydrophobicity, exopolysaccharide and exo-protease production, swimming motility on agar, and biofilm forming ability of A. tumefaciens. Based on initial biofilm inhibition results and minimum inhibitory concentration (MIC) data, 4-nitro, 4-chloro, and 4-fluoro CNMAs were further tested. 4-Nitro, 4-chloro, and 4-fluoro CNMA at ≥150 μg/ml significantly inhibited biofilm formation by 94-99%. Similarly, biofilm formation on polystyrene or nylon was substantially reduced by 4-nitro and 4-chloro CNMAs as determined by optical microscopy and scanning electron microscopy (SEM) and 3-D spectrum plots. 4-Nitro and 4-chloro CNMAs induced cell shortening and concentration- and time-dependently reduced cell growth. Virulence factors were significantly and dose-dependently suppressed by 4-nitro and 4-chloro CNMAs (P ≤ 0.05). Gene expressional changes were greater after 4-nitro CNMA than t-CNMA treatment, as determined by qRT-PCR. Furthermore, some genes essential for biofilm formation, motility, and virulence genes significantly downregulated by 4-nitro CNMA. Seed germination of Raphanus sativus was not hindered by 4-nitro or 4-fluoro CNMA at concentrations ≤200 μg/ml, but root surface biofilm formation was severely inhibited. This study is the first to report the anti-Agrobacterium biofilm and anti-virulence effects of 4-nitro, 4-chloro, and 4-fluoro CNMAs and t-CNMA and indicates that they should be considered starting points for the development of anti-Agrobacterium agents.

RevDate: 2022-10-29

Wu S, Qin B, Deng S, et al (2022)

CodY is modulated by YycF and affects biofilm formation in Staphylococcus aureus.

Frontiers in microbiology, 13:967567.

Background: Staphylococcus aureus (S. aureus) is the leading cause of various infective diseases, including topical soft tissue infections. The goals of this study were to investigate the roles of YycF and CodY in the regulation of biofilm formation and pathogenicity.

Methods: Electrophoretic mobility shift assay (EMSA) was conducted to validate the bound promoter regions of YycF protein. We constructed the codY up-regulated or down-regulated S. aureus mutants. The biofilm biomass was determined by crystal violet microtiter assay and scanning electron microscopy (SEM). Quantitative RT-PCR analysis was used to detect the transcripts of biofilm-related genes. The live and dead cells of S. aureus biofilm were also investigated by confocal laser scanning microscopy (CLSM). We constructed an abscess infection in Sprague Dawley (SD) rat models to determine the effect of CodY on bacterial pathogenicity. We further used the RAW264.7, which were cocultured with S. aureus, to evaluate the effect of CodY on macrophages apoptosis.

Result: Quantitative RT-PCR analyses reveled that YycF negatively regulates codY expression. EMSA assays indicated that YycF protein directly binds to the promoter regions of codY gene. Quantitative RT-PCR confirmed the construction of dual- mutant stains codY + ASyycF and codY-ASyycF. The SEM results showed that the biofilm formation in the codY + ASyycF group was sparser than those in the other groups. The crystal violet assays indicated that the codY + ASyycF group formed less biofilms, which was consistent with the immunofluorescence results of the lowest live cell ration in the codY + ASyycF group. The expression levels of biofilm-associated icaA gene were significantly reduced in the codY + strain, indicating codY negatively regulates the biofilm formation. Furthermore, CodY impedes the pathogenicity in a rat-infection model. After cocultured with bacteria or 4-h in vitro, the apoptosis rates of macrophage cells were lowest in the codY + group.

Conclusions: YycF negatively regulate the expression of codY. By interaction with codY, YycF could modulate S. aureus biofilm formation via both eDNA- dependent and PIA- dependent pathways, which can be a significant target for antibiofilm. CodY not only impedes the pathogenicity but also has a role on immunoregulation. Thus, the current evidence may provide a supplementary strategy for managing biofilm infections.

RevDate: 2022-10-29

Caixeta Magalhães Tibúrcio AA, Paiva AD, Pedrosa AL, et al (2022)

Effect of sub-inhibitory concentrations of antibiotics on biofilm formation and expression of virulence genes in penicillin-resistant, ampicillin-susceptible Enterococcus faecalis.

Heliyon, 8(10):e11154.

Biofilm formation is a key factor in the pathogenesis of enterococcal infections. Thus, the biofilm-forming ability and frequency of biofilm-related genes in penicillin-resistant, ampicillin-susceptible Enterococcus faecalis (PRASEF) compared to penicillin- and ampicillin-susceptible E. faecalis (PSASEF) were assessed in the present study. In addition, the effect of sub-inhibitory concentrations (sub-MICs) of antibiotics on biofilm formation and expression of virulence genes was evaluated. Twenty PRASEF and 21 PSASEF clinical isolates were used to determine the effect of sub-MICs of antibiotics (ampicillin, penicillin, and gentamicin) on biofilm formation, and ten selected isolates were subjected to RT-qPCR to detect the transcript levels of virulence genes (efaA, asa1, esp, and ace). Antibiotic susceptibility was evaluated by the microdilution broth method. Biofilm formation assay was performed using the microtiter plate method. All PSASEF and PRASEF isolates produced biofilms in vitro. Most isolates had three or four virulence genes. Sub-MICs of ampicillin significantly decreased biofilm production and expression of ace and asa1 genes, although the transcript levels were significantly lower (-350% and -606.2%, respectively) among the PSASEF isolates only. Sub-MICs of gentamicin did not have any significant effect on biofilm formation, but slightly increased the transcript levels of efaA. In conclusion, this study showed that the biofilm-forming ability and frequency of the evaluated virulence genes were similar among the PRASEF and PSASEF isolates. Further, in vitro antibiotic sub-MICs were confirmed to interfere with the expression pattern of virulence genes and biofilm formation by E. faecalis. However, further studies are required to clarify the role of sublethal doses of antibiotics on enterococcal biofilms.

RevDate: 2022-10-29

Halsted MC, Bible AN, Morrell-Falvey JL, et al (2022)

Quantifying biofilm propagation on chemically modified surfaces.

Biofilm, 4:100088.

Conditions affecting biofilm formation differ among bacterial species and this presents a challenge to studying biofilms in the lab. This work leverages functionalized silanes to control surface chemistry in the study of early biofilm propagation, quantified with a semi-automated image processing algorithm. These methods support the study of Pantoea sp. YR343, a gram-negative bacterium isolated from the poplar rhizosphere. We found that Pantoea sp. YR343 does not readily attach to hydrophilic surfaces but will form biofilms with a "honeycomb" morphology on hydrophobic surfaces. Our image processing algorithm described here quantified the evolution of the honeycomb morphology over time, and found the propagation to display a logarithmic behavior. This methodology was repeated with a flagella-deficient fliR mutant of Pantoea sp. YR343 which resulted in reduced surface attachment. Quantifiable differences between Pantoea WT and ΔfliR biofilm morphologies were captured by the image processing algorithm, further demonstrating the insight gained from these methods.

RevDate: 2022-10-28

He S, Tong J, Xiong W, et al (2023)

Microplastics influence the fate of antibiotics in freshwater environments: Biofilm formation and its effect on adsorption behavior.

Journal of hazardous materials, 442:130078.

Microplastics (MPs) are substrates available for biofilms colonization in natural water environments. The biofilms formation may enhance the ability of MPs to adsorb harmful contaminants. Herein, we investigated the biofilms formation of three different MPs (PVC, PA and HDPE) in simulated natural environment, and observed the chemical structure, charge property, hydrophobicity and other properties of MPs affect microbial biomass and community composition. More importantly, potential pathogens were found in all three MPs biofilms. Furthermore, the adsorption capacities of original MPs and biological aging MPs for norfloxacin (NOR) was compared. HDPE has the largest adsorption capacity for NOR, while PA has the smallest adsorption capacity for NOR. It was concluded that the formation of biofilms enhanced the adsorption of NOR by 50.60 %, 24.17 % and 46.02 % for PVC, PA and HDPE, respectively. In addition, hydrogen-bond interaction, electrostatic interaction and hydrophobic interaction were found to dominate the adsorption of NOR by MPs. Our study contributed to improve the understanding of the interactions between aging MPs and contaminants in the natural water environments, and provided essential information for ecological risk assessment of MPs.

RevDate: 2022-10-27

Łysik D, Deptuła P, Chmielewska S, et al (2022)

Modulation of Biofilm Mechanics by DNA Structure and Cell Type.

ACS biomaterials science & engineering [Epub ahead of print].

Deoxyribonucleic acid (DNA) evolved as a tool for storing and transmitting genetic information within cells, but outside the cell, DNA can also serve as "construction material" present in microbial biofilms or various body fluids, such as cystic fibrosis, sputum, and pus. In the present work, we investigate the mechanics of biofilms formed from Pseudomonas aeruginosa Xen 5, Staphylococcus aureus Xen 30, and Candida albicans 1408 using oscillatory shear rheometry at different levels of compression and recreate these mechanics in systems of entangled DNA and cells. The results show that the compression-stiffening and shear-softening effects observed in biofilms can be reproduced in DNA networks with the addition of an appropriate number of microbial cells. Additionally, we observe that these effects are cell-type dependent. We also identify other mechanisms that may significantly impact the viscoelastic behavior of biofilms, such as the compression-stiffening effect of DNA cross-linking by bivalent cations (Mg2+, Ca2+, and Cu2+) and the stiffness-increasing interactions of P. aeruginosa Xen 5 biofilm with Pf1 bacteriophage produced by P. aeruginosa. This work extends the knowledge of biofilm mechanobiology and demonstrates the possibility of modifying biopolymers toward obtaining the desired biophysical properties.

RevDate: 2022-10-27

Wang S, Zhu H, Zheng G, et al (2022)

Dynamic Changes in Biofilm Structures under Dynamic Flow Conditions.

Applied and environmental microbiology [Epub ahead of print].

Quantitative assessment of the responses of biofilm structure to external hydrodynamics is critical for understanding biofilm detachment mechanisms. This study used multidimensional imaging and numerical simulation approaches to elucidate the complex relationships between biofilm detachment and hydrodynamics with Shewanella oneidensis MR-1. By integrating real-time confocal laser scanning microscopy (CLSM) images with image analysis tools, the three-dimensional structural changes occurring in thin MR-1 biofilms (<10 μm) under hydrodynamic treatment at a flow velocity of 0.42 × 10-3 to 3.3 × 10-3 m/s in the laminar flow regime were visualized in situ and quantified with single-cell resolution. Analyses of the imaging results revealed high spatial heterogeneity in the degree and intensity of biofilm detachment. Spots with thick and rough biofilm surfaces or high flow rates had high detachment rates, indicating that local biofilm morphology, including thickness and roughness, and hydrodynamic flow conditions collectively controlled the detachment rate. Numerical simulations revealed a significant correlation between local detachment events and the shear stress induced by hydraulic flow at the three-dimensional level. Compared to the even or thin biofilm, a thick or rough structure might induce a 2-fold increase in shear stress over local biofilm surfaces at a microscale dimension. The results provide quantitative and microscopic insights into biofilm detachment processes in subsurface environments, especially in domains under dynamic flow conditions, such as those in hyporheic zones. The relationship between biofilm detachment and hydrodynamics and biofilm structural factors can be integrated into reactive transport models used to describe microbial growth and transport in porous media. IMPORTANCE Detachment is an important process determining the structure and function of bacterial biofilm, which has significant implications for biogeochemical cycling of elements, biofilm application, and infection control in clinical settings. Quantifying the responses of biofilm structure to hydrodynamics is crucial for understanding biofilm detachment mechanisms in aquatic environments. In this work, the spatial and temporal changes occurring in biofilm structures in response to different hydrodynamic conditions were studied by using flow cell reactors. We established the quantitative relationships among detachment, biofilm morphology, and shear stress induced by changes in hydrodynamic conditions. This work provides a quantitative understanding of the complex relationship between biofilm detachment and hydrodynamics in natural environments.

RevDate: 2022-10-27

Koley D (2022)

Electrochemical Sensors for Oral Biofilm-Biomaterials Interface Characterization: a review.

Molecular oral microbiology [Epub ahead of print].

Important processes related to the interaction of the oral microbiome with the tooth surface happen directly at the interface. For example, the chemical microenvironment that exists at the interface of microbial biofilms and the native tooth structure is directly involved in caries development. Consequentially, a critical understanding of this interface and its chemical microenvironment would provide novel avenues in caries prevention, including secondary caries that often occurs at the interface of the dental biofilm, tooth structure and dental material. Electrochemical sensors are a unique quantitative tool and have the inherent advantages of miniaturization, stability, and selectivity. That makes the electrochemical sensors ideal tools for studying these critical biofilm microenvironments with high precision. This review highlights the development and applications of several novel electrochemical sensors such as pH, Ca2+ , and hydrogen peroxide sensors as scanning electrochemical microscope (SECM) probes in addition to flexible pH wire sensors for real-time bacterial biofilm-dental surface and dental materials interface studies. This article is protected by copyright. All rights reserved.

RevDate: 2022-10-27

Zhang H, Yan Q, An Z, et al (2022)

A revolving algae biofilm based photosynthetic microbial fuel cell for simultaneous energy recovery, pollutants removal, and algae production.

Frontiers in microbiology, 13:990807.

Photosynthetic microbial fuel cell (PMFC) based on algal cathode can integrate of wastewater treatment with microalgal biomass production. However, both the traditional suspended algae and the immobilized algae cathode systems have the problems of high cost caused by Pt catalyst and ion-exchange membrane. In this work, a new equipment for membrane-free PMFC is reported based on the optimization of the most expensive MFC components: the separator and the cathode. Using a revolving algae-bacteria biofilm cathode in a photosynthetic membrane-free microbial fuel cell (RAB-MFC) can obtain pollutants removal and algal biomass production as well as electrons generation. The highest chemical oxygen demand (COD) removal rates of the anode and cathode chambers reached 93.5 ± 2.6% and 95.8% ± 0.8%, respectively. The ammonia removal efficiency in anode and cathode chambers was 91.1 ± 1.3% and 98.0 ± 0.6%, respectively, corresponding to an ammonia removal rate of 0.92 ± 0.02 mg/L/h. The maximum current density and power density were 136.1 mA/m2 and 33.1 mW/m2. The average biomass production of algae biofilm was higher than 30 g/m2. The 18S rDNA sequencing analysis the eukaryotic community and revealed high operational taxonomic units (OTUs) of Chlorophyta (44.43%) was dominant phyla with low COD level, while Ciliophora (54.36%) replaced Chlorophyta as the dominant phyla when COD increased. 16S rDNA high-throughput sequencing revealed that biofilms on the cathode contained a variety of prokaryote taxa, including Proteobacteria, Bacteroidota, Firmicutes, while there was only 0.23-0.26% photosynthesizing prokaryote found in the cathode biofilm. Collectively, this work demonstrated that RAB can be used as a bio-cathode in PMFC for pollutants removal from wastewater as well as electricity generation.

RevDate: 2022-10-27

Yang J, Zhang Y, Chang W, et al (2022)

Microbiologically influenced corrosion of FeCoNiCrMn high-entropy alloys by Pseudomonas aeruginosa biofilm.

Frontiers in microbiology, 13:1009310.

Pseudomonas aeruginosa is widely found in industrial water and seawater. Microbiologically influenced corrosion (MIC) caused by P. aeruginosa is a serious threat and damage to the safe service of steel materials. In this study, the MIC behavior of FeCoNiCrMn high-entropy alloy (HEA) by P. aeruginosa biofilm was investigated in the simulated marine medium. The maximum pitting depth of the HEA coupons in the P. aeruginosa-inoculated medium was ~4.77 μm, which was 1.5 times that in the sterile medium. EIS and potentiodynamic polarization results indicated that P. aeruginosa biofilm reduced the corrosion resistance of the passive film of HEA coupons and promoted its anodic dissolution process. XPS and AES results further demonstrated that P. aeruginosa interfered with the distribution of elements in the passive film and significantly promoted the dissolution of Fe.

RevDate: 2022-10-27

Aldossary HA, Rehman S, Jermy BR, et al (2022)

Therapeutic Intervention for Various Hospital Setting Strains of Biofilm Forming Candida auris with Multiple Drug Resistance Mutations Using Nanomaterial Ag-Silicalite-1 Zeolite.

Pharmaceutics, 14(10): pii:pharmaceutics14102251.

Candida auris (C. auris), an emerging multidrug-resistant microorganism, with limited therapeutical options, is one of the leading causes of nosocomial infections. The current study includes 19 C. auris strains collected from King Fahd Hospital of the University and King Fahad Specialist Hospital in Dammam, identified by 18S rRNA gene and ITS region sequencing. Drug-resistance-associated mutations in ERG11, TAC1B and FUR1 genes were screened to gain insight into the pattern of drug resistance. Molecular identification was successfully achieved using 18S rRNA gene and ITS region and 5 drug-resistance-associated missense variants identified in the ERG11 (F132Y and K143R) and TAC1B (H608Y, P611S and A640V) genes of C. auris strains, grouped into 3 clades. The prophylactic and therapeutic application of hydrothermally synthesized Ag-silicalite-1 (Si/Ag ratio 25) nanomaterial was tested against the 3 clades of clinical C. auris strains. 4wt%Ag/TiZSM-5 prepared using conventional impregnation technique was used for comparative study, and nano formulations were characterized using different techniques. The antibiofilm activity of nanomaterials was tested by cell kill assay, scanning electron microscopy (SEM) and light microscopy. Across all the clades of C. auris strains, 4 wt%Ag/TiZSM-5 and Ag-silicalite-1 demonstrated a significant (p = 1.1102 × 10-16) inhibitory effect on the biofilm's survival rate: the lowest inhibition value was (10%) with Ag-silicalite-1 at 24 and 48 h incubation. A profound change in morphogenesis in addition to the reduction in the number of C.auris cells was shown by SEM and light microscopy. The presence of a high surface area and the uniform dispersion of nanosized Ag species displays enhanced anti-Candida activity, and therefore it has great potential against the emerging multidrug-resistant C. auris.

RevDate: 2022-10-27

Alfei S, D Caviglia (2022)

Prevention and Eradication of Biofilm by Dendrimers: A Possibility Still Little Explored.

Pharmaceutics, 14(10): pii:pharmaceutics14102016.

Multidrug resistance (MDR) among pathogens and the associated infections represent an escalating global public health problem that translates into raised mortality and healthcare costs. MDR bacteria, with both intrinsic abilities to resist antibiotics treatments and capabilities to transmit genetic material coding for further resistance to other bacteria, dramatically decrease the number of available effective antibiotics, especially in nosocomial environments. Moreover, the capability of several bacterial species to form biofilms (BFs) is an added alarming mechanism through which resistance develops. BF, made of bacterial communities organized and incorporated into an extracellular polymeric matrix, self-produced by bacteria, provides protection from the antibiotics' action, resulting in the antibiotic being ineffective. By adhering to living or abiotic surfaces present both in the environment and in the healthcare setting, BF causes the onset of difficult-to-eradicate infections, since it is difficult to prevent its formation and even more difficult to promote its disintegration. Inspired by natural antimicrobial peptides (NAMPs) acting as membrane disruptors, with a low tendency to develop resistance and demonstrated antibiofilm potentialities, cationic polymers and dendrimers, with similar or even higher potency than NAMPs and with low toxicity, have been developed, some of which have shown in vitro antibiofilm activity. Here, aiming to incite further development of new antibacterial agents capable of inhibiting BF formation and dispersing mature BF, we review all dendrimers developed to this end in the last fifteen years. The extension of the knowledge about these still little-explored materials could be a successful approach to find effective weapons for treating chronic infections and biomaterial-associated infections (BAIs) sustained by BF-producing MDR bacteria.

RevDate: 2022-10-27

Bu F, Liu M, Xie Z, et al (2022)

Targeted Anti-Biofilm Therapy: Dissecting Targets in the Biofilm Life Cycle.

Pharmaceuticals (Basel, Switzerland), 15(10): pii:ph15101253.

Biofilm is a crucial virulence factor for microorganisms that causes chronic infection. After biofilm formation, the bacteria present improve drug tolerance and multifactorial defense mechanisms, which impose significant challenges for the use of antimicrobials. This indicates the urgent need for new targeted technologies and emerging therapeutic strategies. In this review, we focus on the current biofilm-targeting strategies and those under development, including targeting persistent cells, quorum quenching, and phage therapy. We emphasize biofilm-targeting technologies that are supported by blocking the biofilm life cycle, providing a theoretical basis for design of targeting technology that disrupts the biofilm and promotes practical application of antibacterial materials.

RevDate: 2022-10-27

Jiang Q, Jing Q, Ren B, et al (2022)

Culture Supernatant of Enterococcus faecalis Promotes the Hyphal Morphogenesis and Biofilm Formation of Candida albicans.

Pathogens (Basel, Switzerland), 11(10): pii:pathogens11101177.

(1) Background: Enterococcus faecalis and Candida albicans are often isolated from infected root canals. The interaction between these two species is not clear enough. Therefore, the objective of this study was to investigate the effect of E. faecalis on the biofilm formation, hyphal morphogenesis and virulence gene expression of C. albicans. (2) Methods: We used the culture supernatant of E. faecalis (CSE) to treat the biofilms of C. albicans. Then, crystal violet staining and colony-forming unit (CFU) counting were performed to evaluate biofilm biomass. Scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) were applied to observe fungal morphology. Subsequently, exopolymeric substances (EPS) production, cellular surface hydrophobicity (CSH) and adhesion force of biofilms were investigated by CLSM, water-hydrocarbon two-phase assay and atomic force microscopy (AFM), respectively. Finally, the expression of C. albicans virulence genes (ALS1, ALS3, HWP1 and EFG1) were measured by RT-qPCR assay. (3) Results: The exposure of CSE promoted the biofilm formation and hyphal morphogenesis of C. albicans, increased the EPS production, CSH and adhesion force of C. albicans biofilms, and increased the expression level of EFG1. (4) Conclusions: Our data indicated that CSE promoted the hyphal morphogenesis and biofilm formation of C. albicans.

RevDate: 2022-10-27

Wang L, Ji C, Xia X, et al (2022)

A Regulatory SRNA Rli43 Is Involved in the Modulation of Biofilm Formation and Virulence in Listeria monocytogenes.

Pathogens (Basel, Switzerland), 11(10): pii:pathogens11101137.

Small RNAs (sRNAs) are a kind of regulatory molecule that can modulate gene expression at the post-transcriptional level, thereby involving alteration of the physiological characteristics of bacteria. However, the regulatory roles and mechanisms of most sRNAs remain unknown in Listeria monocytogenes(L. monocytogenes). To explore the regulatory roles of sRNA Rli43 in L. monocytogenes, the rli43 gene deletion strain LM-Δrli43 and complementation strain LM-Δrli43-rli43 were constructed to investigate the effects of Rli43 on responses to environmental stress, biofilm formation, and virulence, respectively. Additionally, Rli43-regulated target genes were identified using bioinformatic analysis tools and a bacterial dual plasmid reporter system based on E. coli. The results showed that the intracellular expression level of the rli43 gene was significantly upregulated compared with those under extracellular conditions. Compared with the parental and complementation strains, the environmental adaptation, motility, biofilm formation, adhesion, invasion, and intracellular survival of LM-Δrli43 were significantly reduced, respectively, whereas the LD50 of LM-Δrli43 was significantly elevated in BALB/c mice. Furthermore, the bacterial loads and pathological damages were alleviated, suggesting that sRNA Rli43 was involved in the modulation of the virulence of L. monocytogenes. It was confirmed that Rli43 may complementarily pair with the 5'-UTR (-47--55) of HtrA mRNA, thereby regulating the expression level of HtrA protein at the post-transcriptional level. These findings suggest that Rli43-mediated control was involved in the modulation of environmental adaptation, biofilm formation, and virulence in L. monocytogenes.

RevDate: 2022-10-27

Silva V, Pereira JE, Maltez L, et al (2022)

Influence of Environmental Factors on Biofilm Formation of Staphylococci Isolated from Wastewater and Surface Water.

Pathogens (Basel, Switzerland), 11(10): pii:pathogens11101069.

The presence of biofilms can negatively affect several different areas, such as the food industry, environment, and biomedical sectors. Conditions under which bacteria grow and develop, such as temperature, nutrients, and pH, among others, can largely influence biofilm production. Staphylococcus species survive in the natural environment due to their tolerance to a wide range of temperatures, dryness, dehydration, and low water activity. Therefore, we aimed to evaluate the influence of external environmental factors on the formation of biofilm of staphylococci isolated from hospital wastewater and surface waters. We investigated the biofilm formation of methicillin-resistant and -susceptible S. aureus (MRSA and MSSA) and coagulase-negative staphylococci (CoNS) under various temperatures, pH values, salt concentrations, glucose concentrations, and under anaerobic and aerobic conditions. CoNS had the ability to produce more biofilm biomass than MSSA and MRSA. All environmental factors studied influenced the biofilm formation of staphylococci isolates after 24 h of incubation. Higher biofilm formation was achieved at 4% of NaCl and 0.5% of glucose for MSSA and CoNS, and 1% of NaCl and 1.5% of glucose for MRSA isolates. Biofilm formation of isolates was greater at 25 °C and 37 °C than at 10 °C and 4 °C. pH values between 6 and 8 led to more robust biofilm formation than pH levels of 9 and 5. Although staphylococci are facultative anaerobes, biofilm formation was higher in the presence of oxygen. The results demonstrated that multiple environmental factors affect staphylococci biofilm formation. Different conditions affect differently the biofilm formation of MRSA, MSSA, and CoNS strains.

RevDate: 2022-10-27

Hata Y, Bouda Y, Hiruma S, et al (2022)

Biofilm Degradation by Seashell-Derived Calcium Hydroxide and Hydrogen Peroxide.

Nanomaterials (Basel, Switzerland), 12(20): pii:nano12203681.

Microbial cells and self-produced extracellular polymeric substances assembled to form biofilms that are difficult to remove from surfaces, causing problems in various fields. Seashell-derived calcium hydroxide, a sustainable inorganic material, has shown high bactericidal activity even for biofilms due to its alkalinity. However, its biofilm removal efficacy is relatively low. Herein, we report a biofilm degradation strategy that includes two environmentally friendly reagents: seashell-derived calcium hydroxide and hydrogen peroxide. A biofilm model of Escherichia coli was prepared in vitro, treated with calcium hydroxide-hydrogen peroxide solutions, and semi-quantified by the crystal violet stain method. The treatment significantly improved biofilm removal efficacy compared with treatments by calcium hydroxide alone and hydrogen peroxide alone. The mechanism was elucidated from calcium hydroxide-hydrogen peroxide solutions, which suggested that perhydroxyl anion and hydroxyl radical generated from hydrogen peroxide, as well as the alkalinity of calcium hydroxide, enhanced biofilm degradation. This study showed that concurrent use of other reagents, such as hydrogen peroxide, is a promising strategy for improving the biofilm degradation activity of seashell-derived calcium hydroxide and will contribute to developing efficient biofilm removal methods.

RevDate: 2022-10-27

Mastoor S, Nazim F, Rizwan-Ul-Hasan S, et al (2022)

Analysis of the Antimicrobial and Anti-Biofilm Activity of Natural Compounds and Their Analogues against Staphylococcus aureus Isolates.

Molecules (Basel, Switzerland), 27(20): pii:molecules27206874.

(1) Background: Staphylococcus aureus (S. aureus) is one of the most frequent causes of biofilm-associated infections. With the emergence of antibiotic-resistant, especially methicillin-resistant S. aureus (MRSA), there is an urgent need to discover novel inhibitory compounds against this clinically important pathogen. In this study, we evaluated the antimicrobial and anti-biofilm activity of 11 compounds, including phenyl propenes and phenolic aldehydes, eugenol, ferulic acid, sinapic acid, salicylaldehyde, vanillin, cinnamoyl acid, and aldehydes, against drug-resistant S. aureus isolates. (2) Methods: Thirty-two clinical S. aureus isolates were obtained from Alkhidmat Diagnostic Center and Blood Bank, Karachi, Pakistan, and screened for biofilm-forming potential, and susceptibility/resistance against ciprofloxacin, chloramphenicol, ampicillin, amikacin, cephalothin, clindamycin, streptomycin, and gentamicin using the Kirby-Bauer disk diffusion method. Subsequently, 5 representative clinical isolates were selected and used to test the antimicrobial and anti-biofilm potential of 11 compounds using both qualitative and quantitative assays, followed by qPCR analysis to examine the differences in the expression levels of biofilm-forming genes (ica-A, fnb-B, clf-A and cna) in treated (with natural compounds and their derivatives) and untreated isolates. (3) Results: All isolates were found to be multi-drug resistant and dominant biofilm formers. The individual Minimum Inhibitory Concentration (MIC) of natural compounds and their analogues ranged from 0.75-160 mg/mL. Furthermore, the compounds, Salicylaldehyde (SALI), Vanillin (VAN), α-methyl-trans-cinnamaldehyde (A-MT), and trans-4-nitrocinnamic acid (T4N) exhibited significant (15-92%) biofilm inhibition/reduction percentage capacity at the concentration of 1-10 mg/mL. Gene expression analysis showed that salicylaldehyde, α-methyl-trans-cinnamaldehyde, and α-bromo-trans-cinnamaldehyde resulted in a significant (p < 0.05) downregulation of the expression of ica-A, clf-A, and fnb-A genes compared to the untreated resistant isolate. (4) Conclusions: The natural compounds and their analogues used in this study exhibited significant antimicrobial and anti-biofilm activity against S. aureus. Biofilms persist as the main concern in clinical settings. These compounds may serve as potential candidate drug molecules against biofilm forming S. aureus.

RevDate: 2022-10-27

Hrichi S, Chaâbane-Banaoues R, Alibrando F, et al (2022)

Chemical Composition, Antifungal and Anti-Biofilm Activities of Volatile Fractions of Convolvulus althaeoides L. Roots from Tunisia.

Molecules (Basel, Switzerland), 27(20): pii:molecules27206834.

The antifungal drugs currently available and mostly used for the treatment of candidiasis exhibit the phenomena of toxicity and increasing resistance. In this context, plant materials might represent promising sources of antifungal agents. The aim of this study is to evaluate for the first time the chemical content of the volatile fractions (VFs) along with the antifungal and anti-biofilm of Convolvulus althaeoides L. roots. The chemical composition was determined by gas chromatography coupled to a flame ionization detector and mass spectrometry. In total, 73 and 86 chemical compounds were detected in the n-hexane (VF1) and chloroform (VF2) fractions, respectively. Analysis revealed the presence of four main compounds: n-hexadecenoic acid (29.77%), 4-vinyl guaiacol (12.2%), bis(2-ethylhexyl)-adipate (9.69%) and eicosane (3.98%) in the VF extracted by hexane (VF1). n-hexadecenoic acid (34.04%), benzyl alcohol (7.86%) and linoleic acid (7.30%) were the main compounds found in the VF extracted with chloroform (VF2). The antifungal minimum inhibitory concentrations (MICs) of the obtained fractions against Candida albicans, Candida glabrata and Candida tropicalis were determined by the micro-dilution technique and values against Candida spp. ranged from 0.87 to 3.5 mg/mL. The biofilm inhibitory concentrations (IBF) and sustained inhibition (BSI) assays on C. albicans, C. glabrata and C. tropicalis were also investigated. The VFs inhibited biofilm formation up to 0.87 mg/mL for C. albicans, up to 1.75 mg/mL against C. glabrata and up to 0.87 mg/mL against C. tropicalis. The obtained results highlighted the synergistic mechanism of the detected molecules in the prevention of candidosic biofilm formation.

RevDate: 2022-10-27

Parolin C, Croatti V, Giordani B, et al (2022)

Vaginal Lactobacillus Impair Candida Dimorphic Switching and Biofilm Formation.

Microorganisms, 10(10): pii:microorganisms10102091.

Lactobacillus spp. generally dominate the vaginal microbiota and prevent pathogen adhesion and overgrowth, including Candida spp., by various mechanisms. Although Candida spp. can be commensal, in certain conditions they can become pathogenic, causing vulvovaginal candidiasis. The insurgence of candidiasis is related to the expression of Candida virulence factors, including morphologic switching and biofilm formation. Germ tubes, pseudohyphae, and hyphae promote Candida tissue invasion, biofilms increase persistence and are often resistant to antifungals and host immune response. Here, we explored the inhibitory activity of vaginal Lactobacillus strains belonging to Lactobacillus crispatus, Lactobacillus gasseri, Limosilactobacillus vaginalis, and Lactiplantibacillus plantarum species towards Candida virulence factors. With the aim to investigate the interrelation between mode of growth and functionality, supernatants were collected from lactobacilli planktonic cultures and, for the first time, from adherent ones, and were evaluated towards Candida dimorphic switching and biofilm. Candida biofilms were analyzed by multiple methodologies, i.e., crystal violet staining, MTT assay, and confocal microscopy. Lactobacillus supernatants reduce Candida switching and biofilm formation. Importantly, L. crispatus supernatants showed the best profile of virulence suppression, especially when grown in adherence. These results highlight the role of such species as a hallmark of vaginal eubiosis and prompt its employment in new probiotics for women's health.

RevDate: 2022-10-27

Elgamoudi BA, Starr KS, V Korolik (2022)

Extracellular c-di-GMP Plays a Role in Biofilm Formation and Dispersion of Campylobacter jejuni.

Microorganisms, 10(10): pii:microorganisms10102030.

Cyclic diguanosine monophosphate (c-diGMP) is a ubiquitous second messenger involved in the regulation of many signalling systems in bacteria, including motility and biofilm formation. Recently, it has been reported that c-di-GMP was detected in C.&nbsp;jejuni DRH212; however, the presence and the role of c-di-GMP in other C. jejuni strains are unknown. Here, we investigated extracellular c-di-GMP as an environmental signal that potentially triggers biofilm formation in C. jejuni NCTC 11168 using a crystal violet-based assay, motility-based plate assay, RT-PCR and confocal laser scanning microscopy (CLSM). We found that, in presence of extracellular c-di-GMP, the biofilm formation was significantly reduced (>50%) and biofilm dispersion enhanced (up to 60%) with no effect on growth. In addition, the presence of extracellular c-di-GMP promoted chemotactic motility, inhibited the adherence of C. jejuni NCTC 11168-O to Caco-2 cells and upregulated the expression of Cj1198 (luxS, encoding quarum sensing pathway component, autoinducer-2), as well as chemotaxis genes Cj0284c (cheA) and Cj0448c (tlp6). Unexpectedly, the expression of Cj0643 (cbrR), containing a GGDEF-like domain and recently identified as a potential diguanylate cyclase gene, required for the synthesis of c-di-GMP, was not affected. Our findings suggest that extracellular c-di-GMP could be involved in C. jejuni gene regulation, sensing and biofilm dispersion.

RevDate: 2022-10-27

Reddersen K, Tittelbach J, C Wiegand (2022)

3D Biofilm Models Containing Multiple Species for Antimicrobial Testing of Wound Dressings.

Microorganisms, 10(10): pii:microorganisms10102027.

The treatment of chronic wounds presents a major challenge in medical care. In particular, the effective treatment of bacterial infections that occur in the form of biofilms is of crucial importance. To develop successful antibiofilm strategies for chronic wound treatment, biofilm models are needed that resemble the in vivo situation, are easy to handle, standardizable, and where results are readily transferable to the clinical situation. We established two 3D biofilm models to distinguish the effectiveness of wound dressings on important microorganisms present in chronic wounds. The first 3D biofilm model contains Staphylococcus aureus, Escherichia coli, and Acinetobacter baumannii, while the second is based on Pseudomonas aeruginosa. Bacteria are cultivated in a nutrient-rich agar/gelatin mix, into which air bubbles are incorporated. This results in a mature biofilm growing in clusters similar to its organization in chronic wounds. The models are convenient to use, have low variability and are easy to establish in the laboratory. Treatment with polihexanide and silver-containing wound dressings showed that the models are very well suited for antimicrobial testing and that they can detect differences in the efficacy of antimicrobial substances. Therefore, these models present valuable tools in the development of effective antibiofilm strategies in chronic wounds.

RevDate: 2022-10-27

Carmona-Torre F, Fernández-Ciriza L, Berniz C, et al (2022)

An Experimental Murine Model to Assess Biofilm Persistence on Commercial Breast Implant Surfaces.

Microorganisms, 10(10): pii:microorganisms10102004.

Capsular contracture is the most frequently associated complication following breast implant placement. Biofilm formation on the surface of such implants could significantly influence the pathogenesis of this complication. The objective of this study was to design an experimental model of breast implant infection that allowed us to compare the in vivo S. epidermidis ability to form and perpetuate biofilms on commonly used types of breast implants (i.e., macrotexturized, microtexturized, and smooth). A biofilm forming S. epidermidis strain (ATCC 35984) was used for all experiments. Three different implant surface types were tested: McGhan BIOCELL® (i.e., macrotexturized); Mentor Siltex® (i.e., microtexturized); and Allergan Natrelle Smooth® (i.e., smooth). Two different infection scenarios were simulated. The ability to form biofilm on capsules and implants over time was evaluated by quantitative post-sonication culture of implants and capsules biopsies. This experimental model allows the generation of a subclinical staphylococcal infection associated with a breast implant placed in the subcutaneous tissue of Wistar rats. The probability of generating an infection was different according to the type of implant studied and to the time from implantation to implant removal. Infection was achieved in 88.9% of macrotextured implants (i.e., McGhan), 37.0% of microtexturized implants (i.e., Mentor), and 18.5% of smooth implants (i.e., Allergan Smooth) in the short-term (p < 0.001). Infection was achieved in 47.2% of macrotextured implants, 2.8% of microtexturized implants, and 2.8% of smooth implants (i.e., Allergan Smooth) in the long-term (p < 0.001). There was a clear positive correlation between biofilm formation on any type of implant and capsule colonization/infection. Uniformly, the capsules formed around the macro- or microtexturized implants were consistently macroscopically thicker than those formed around the smooth implants regardless of the time at which they were removed (i.e., 1-2 weeks or 3-5 weeks). We have shown that there is a difference in the ability of S epidermidis to develop in vivo biofilms on macrotextured, microtextured, and smooth implants. Smooth implants clearly thwart bacterial adherence and, consequently, biofilm formation and persistence are hindered.

RevDate: 2022-10-27

Mohamed HMA, Alnasser SM, Abd-Elhafeez HH, et al (2022)

Detection of β-Lactamase Resistance and Biofilm Genes in Pseudomonas Species Isolated from Chickens.

Microorganisms, 10(10): pii:microorganisms10101975.

Bacteria of the genus Pseudomonas are pathogens in both humans and animals. The most prevalent nosocomial pathogen is P. aeruginosa, particularly strains with elevated antibiotic resistance. In this study, a total of eighteen previously identified Pseudomonas species strains, were isolated from chicken. These strains were screened for biofilm formation and antibiotic resistance. In addition, we evaluated clove oil's effectiveness against Pseudomonas isolates as an antibiofilm agent. The results showed that Pseudomonas species isolates were resistant to most antibiotics tested, particularly those from the β-lactamase family. A significant correlation (p < 0.05) between the development of multidrug-resistant isolates and biofilms is too informal. After amplifying the AmpC-plasmid-mediated genes (blaCMY, blaMIR, DHA, and FOX) and biofilm-related genes (psld, rhlA, and pelA) in most of our isolates, PCR confirmed this relationship. Clove oil has a potent antibiofilm effect against Pseudomonas isolates, and may provide a treatment for bacteria that form biofilms and are resistant to antimicrobials.

RevDate: 2022-10-27

Sekoai PT, Chunilall V, Sithole B, et al (2022)

Elucidating the Role of Biofilm-Forming Microbial Communities in Fermentative Biohydrogen Process: An Overview.

Microorganisms, 10(10): pii:microorganisms10101924.

Amongst the biofuels described in the literature, biohydrogen has gained heightened attention over the past decade due to its remarkable properties. Biohydrogen is a renewable form of H2 that can be produced under ambient conditions and at a low cost from biomass residues. Innovative approaches are continuously being applied to overcome the low process yields and pave the way for its scalability. Since the process primarily depends on the biohydrogen-producing bacteria, there is a need to acquire in-depth knowledge about the ecology of the various assemblages participating in the process, establishing effective bioaugmentation methods. This work provides an overview of the biofilm-forming communities during H2 production by mixed cultures and the synergistic associations established by certain species during H2 production. The strategies that enhance the growth of biofilms within the H2 reactors are also discussed. A short section is also included, explaining techniques used for examining and studying these biofilm structures. The work concludes with some suggestions that could lead to breakthroughs in this area of research.

RevDate: 2022-10-27

Gaviria-Cantin T, Vargas AF, Mouali YE, et al (2022)

Gre Factors Are Required for Biofilm Formation in Salmonella enterica Serovar Typhimurium by Targeting Transcription of the csgD Gene.

Microorganisms, 10(10): pii:microorganisms10101921.

Rdar biofilm formation of Salmonella typhimurium and Escherichia coli is a common ancient multicellular behavior relevant in cell-cell and inter-organism interactions equally, as in interaction with biotic and abiotic surfaces. With the expression of the characteristic extracellular matrix components amyloid curli fimbriae and the exopolysaccharide cellulose, the central hub for the delicate regulation of rdar morphotype expression is the orphan transcriptional regulator CsgD. Gre factors are ubiquitously interacting with RNA polymerase to selectively overcome transcriptional pausing. In this work, we found that GreA/GreB are required for expression of the csgD operon and consequently the rdar morphotype. The ability of the Gre factors to suppress transcriptional pausing and the 147 bp 5'-UTR of csgD are required for the stimulatory effect of the Gre factors on csgD expression. These novel mechanism(s) of regulation for the csgD operon might be relevant under specific stress conditions.

RevDate: 2022-10-27

Lu Y, Cai WJ, Ren Z, et al (2022)

The Role of Staphylococcal Biofilm on the Surface of Implants in Orthopedic Infection.

Microorganisms, 10(10): pii:microorganisms10101909.

Despite advanced implant sterilization and aseptic surgical techniques, implant-associated infection remains a major challenge for orthopedic surgeries. The subject of bacterial biofilms is receiving increasing attention, probably as a result of the wide acknowledgement of the ubiquity of biofilms in the clinical environment, as well as the extreme difficulty in eradicating them. Biofilm can be defined as a structured microbial community of cells that are attached to a substratum and embedded in a matrix of extracellular polymeric substances (EPS) that they have produced. Biofilm development has been proposed as occurring in a multi-step process: (i) attachment and adherence, (ii) accumulation/maturation due to cellular aggregation and EPS production, and (iii) biofilm detachment (also called dispersal) of bacterial cells. In all these stages, characteristic proteinaceous and non-proteinaceous compounds are expressed, and their expression is strictly controlled. Bacterial biofilm formation around implants shelters the bacteria and encourages the persistence of infection, which could lead to implant failure and osteomyelitis. These complications need to be treated by major revision surgeries and extended antibiotic therapies, which could lead to high treatment costs and even increase mortality. Effective preventive and therapeutic measures to reduce risks for implant-associated infections are thus in urgent need.

RevDate: 2022-10-27

Roy PK, Song MG, Jeon EB, et al (2022)

Antibiofilm Efficacy of Quercetin against Vibrio parahaemolyticus Biofilm on Food-Contact Surfaces in the Food Industry.

Microorganisms, 10(10): pii:microorganisms10101902.

Vibrio parahaemolyticus, one of the most common foodborne pathogenic bacteria that forms biofilms, is a persistent source of concern for the food industry. The food production chain employs a variety of methods to control biofilms, although none are completely successful. This study aims to evaluate the effectiveness of quercetin as a food additive in reducing V. parahaemolyticus biofilm formation on stainless-steel coupons (SS) and hand gloves (HG) as well as testing its antimicrobial activities. With a minimum inhibitory concentration (MIC) of 220 µg/mL, the tested quercetin exhibited the lowest bactericidal action without visible growth. In contrast, during various experiments in this work, the inhibitory efficacy of quercetin at sub-MICs levels (1/2, 1/4, and 1/8 MIC) against V. parahaemolyticus was examined. Control group was not added with quercetin. With increasing quercetin concentration, swarming and swimming motility, biofilm formation, and expression levels of target genes linked to flagellar motility (flaA, flgL), biofilm formation (vp0952, vp0962), virulence (VopQ, vp0450), and quorum-sensing (aphA, luxS) were all dramatically suppressed. Quercetin (0-110 μg/mL) was investigated on SS and HG surfaces, the inhibitory effect were 0.10-2.17 and 0.26-2.31 log CFU/cm2, respectively (p < 0.05). Field emission scanning electron microscopy (FE-SEM) corroborated the findings because quercetin prevented the development of biofilms by severing cell-to-cell contacts and inducing cell lysis, which resulted in the loss of normal cell shape. Additionally, there was a significant difference between the treated and control groups in terms of motility (swimming and swarming). According to our research, quercetin produced from plants should be employed as an antibiofilm agent in the food sector to prevent the growth of V. parahaemolyticus biofilms. These results indicate that throughout the entire food production chain, bacterial targets are of interest for biofilm reduction with alternative natural food agents in the seafood industry.

RevDate: 2022-10-27

Zahidullah , Siddiqui MF, Tabraiz S, et al (2022)

Targeting Microbial Biofouling by Controlling Biofilm Formation and Dispersal Using Rhamnolipids on RO Membrane.

Membranes, 12(10): pii:membranes12100928.

Finding new biological ways to control biofouling of the membrane in reverse osmosis (RO) is an important substitute for synthetic chemicals in the water industry. Here, the study was focused on the antimicrobial, biofilm formation, and biofilm dispersal potential of rhamnolipids (RLs) (biosurfactants). The MTT assay was also carried out to evaluate the effect of RLs on biofilm viability. Biofilm was qualitatively and quantitatively assessed by crystal violet assay, light microscopy, fluorescence microscopy (bacterial biomass (µm2), surface coverage (%)), and extracellular polymeric substances (EPSs). It was exhibited that RLs can reduce bacterial growth. The higher concentrations (≥100 mg/L) markedly reduced bacterial growth and biofilm formation, while RLs exhibited substantial dispersal effects (89.10% reduction) on preformed biofilms. Further, RLs exhibited 79.24% biomass reduction while polysaccharide was reduced to 60.55 µg/mL (p < 0.05) and protein to 4.67 µg/mL (p < 0.05). Light microscopy revealed biofilm reduction, which was confirmed using fluorescence microscopy. Microscopic images were processed with BioImageL software. It was revealed that biomass surface coverage was reduced to 1.1% at 1000 mg/L of RLs and that 43,245 µm2 of biomass was present for control, while biomass was reduced to 493 µm2 at 1000 mg/L of RLs. Thus, these data suggest that RLs have antimicrobial, biofilm control, and dispersal potential against membrane biofouling.

RevDate: 2022-10-27

Łysik D, Deptuła P, Chmielewska S, et al (2022)

Degradation of Polylactide and Polycaprolactone as a Result of Biofilm Formation Assessed under Experimental Conditions Simulating the Oral Cavity Environment.

Materials (Basel, Switzerland), 15(20): pii:ma15207061.

Polylactide (PLA) and polycaprolactone (PCL) are biodegradable and bioabsorbable thermoplastic polymers considered as promising materials for oral applications. However, any abiotic surface used, especially in areas naturally colonized by microorganisms, provides a favorable interface for microbial growth and biofilm development. In this study, we investigated the biofilm formation of C. krusei and S. mutans on the surface of PLA and PCL immersed in the artificial saliva. Using microscopic (AFM, CLSM) observations and spectrometric measurements, we assessed the mass and topography of biofilm that developed on PLA and PCL surfaces. Incubated up to 56 days in specially prepared saliva and microorganisms medium, solid polymer samples were examined for surface properties (wettability, roughness, elastic modulus of the surface layer), structure (molecular weight, crystallinity), and mechanical properties (hardness, tensile strength). It has been shown that biofilm, especially S. mutans, promotes polymer degradation. Our findings indicate the need for additional antimicrobial strategies for the effective oral applications of PLA and PCL.

RevDate: 2022-10-27

Pistoia ES, Cosio T, Campione E, et al (2022)

All-Trans Retinoic Acid Effect on Candida albicans Growth and Biofilm Formation.

Journal of fungi (Basel, Switzerland), 8(10): pii:jof8101049.

Candida albicans (C. albicans) is the most common fungal pathogen causing recurrent mucosal and life-threatening systemic infections. The ability to switch from yeast to hyphae and produce biofilm are the key virulence determinants of this fungus. In fact, Candida biofilms on medical devices represent the major risk factor for nosocomial bloodstream infections. Novel antifungal strategies are required given the severity of systemic candidiasis, especially in immunocompromised patients, and the lack of effective anti-biofilm treatments. Retinoids have gained attention recently due to their antifungal properties.

MATERIAL AND METHODS: The present study aimed at evaluating the in vitro effects of different concentrations (300 to 18.75 µg/mL) of All-trans Retinoic Acid (ATRA), a vitamin A metabolite, on Candida growth and biofilm formation.

RESULTS: ATRA completely inhibited the fungal growth, by acting as both fungicidal (at 300 µg/mL) and fungistatic (at 150 µg/mL) agent. Furthermore, ATRA was found to negatively affect Candida biofilm formation in terms of biomass, metabolic activity and morphology, in a dose-dependent manner, and intriguingly, its efficacy was as that of amphotericin B (AmB) (2-0.12 μg/mL). Additionally, transmission electron microscopy (TEM) analysis showed that at 300 μg/mL ATRA induced plasma membrane damage in Candida cells, confirming its direct toxic effect against the fungus.

CONCLUSION: Altogether, the results suggest that ATRA has a potential for novel antifungal strategies aimed at preventing and controlling biofilm-associated Candida infections.

RevDate: 2022-10-27

Pokhrel S, Boonmee N, Tulyaprawat O, et al (2022)

Assessment of Biofilm Formation by Candida albicans Strains Isolated from Hemocultures and Their Role in Pathogenesis in the Zebrafish Model.

Journal of fungi (Basel, Switzerland), 8(10): pii:jof8101014.

Candida albicans, an opportunistic pathogen, has the ability to form biofilms in the host or within medical devices in the body. Biofilms have been associated with disseminated/invasive disease with increased severity of infection by disrupting the host immune response and prolonging antifungal treatment. In this study, the in vivo virulence of three strains with different biofilm formation strengths, that is, non-, weak-, and strong biofilm formers, was evaluated using the zebrafish model. The survival assay and fungal tissue burden were measured. Biofilm-related gene expressions were also investigated. The survival of zebrafish, inoculated with strong biofilms forming C. albicans,, was significantly shorter than strains without biofilms forming C. albicans. However, there were no statistical differences in the burden of viable colonogenic cell number between the groups of the three strains tested. We observed that the stronger the biofilm formation, the higher up-regulation of biofilm-associated genes. The biofilm-forming strain (140 and 57), injected into zebrafish larvae, possessed a higher level of expression of genes associated with adhesion, attachment, filamentation, and cell proliferation, including eap1, als3, hwp1, bcr1, and mkc1 at 8 h. The results suggested that, despite the difference in genetic background, biofilm formation is an important virulence factor for the pathogenesis of C. albicans. However, the association between biofilm formation strength and in vivo virulence is controversial and needs to be further studied.

RevDate: 2022-10-27

Toure S, Millot M, Ory L, et al (2022)

Access to Anti-Biofilm Compounds from Endolichenic Fungi Using a Bioguided Networking Screening.

Journal of fungi (Basel, Switzerland), 8(10): pii:jof8101012.

Endolichenic microorganisms represent a new source of bioactive natural compounds. Lichens, resulting from a symbiotic association between algae or cyanobacteria and fungi, constitute an original ecological niche for these microorganisms. Endolichenic fungi inhabiting inside the lichen thallus have been isolated and characterized. By cultivation on three different culture media, endolichenic fungi gave rise to a wide diversity of bioactive metabolites. A total of 38 extracts were screened for their anti-maturation effect on Candida albicans biofilms. The 10 most active ones, inducing at least 50% inhibition, were tested against 24 h preformed biofilms of C. albicans, using a reference strain and clinical isolates. The global molecular network was associated to bioactivity data in order to identify and priorize active natural product families. The MS-targeted isolation led to the identification of new oxygenated fatty acid in Preussia persica endowed with an interesting anti-biofilm activity against C. albicans yeasts.

RevDate: 2022-10-27

Shenkutie AM, Zhang J, Yao M, et al (2022)

Effects of Sub-Minimum Inhibitory Concentrations of Imipenem and Colistin on Expression of Biofilm-Specific Antibiotic Resistance and Virulence Genes in Acinetobacter baumannii Sequence Type 1894.

International journal of molecular sciences, 23(20): pii:ijms232012705.

Antibiotics at suboptimal doses promote biofilm formation and the development of antibiotic resistance. The underlying molecular mechanisms, however, were not investigated. Here, we report the effects of sub-minimum inhibitory concentrations (sub-MICs) of imipenem and colistin on genes associated with biofilm formation and biofilm-specific antibiotic resistance in a multidrug-tolerant clinical strain of Acinetobacter baumannii Sequence Type (ST) 1894. Comparative transcriptome analysis was performed in untreated biofilm and biofilm treated with sub-MIC doses of imipenem and colistin. RNA sequencing data showed that 78 and 285 genes were differentially expressed in imipenem and colistin-treated biofilm cells, respectively. Among the differentially expressed genes (DEGs), 48 and 197 genes were upregulated exclusively in imipenem and colistin-treated biofilm cells, respectively. The upregulated genes included those encoding matrix synthesis (pgaB), multidrug efflux pump (novel00738), fimbrial proteins, and homoserine lactone synthase (AbaI). Upregulation of biofilm-associated genes might enhance biofilm formation when treated with sub-MICs of antibiotics. The downregulated genes include those encoding DNA gyrase (novel00171), 30S ribosomal protein S20 (novel00584), and ribosome releasing factor (RRF) were downregulated when the biofilm cells were treated with imipenem and colistin. Downregulation of these genes affects protein synthesis, which in turn slows down cell metabolism and makes biofilm cells more tolerant to antibiotics. In this investigation, we also found that 5 of 138 small RNAs (sRNAs) were differentially expressed in biofilm regardless of antibiotic treatment or not. Of these, sRNA00203 showed the highest expression levels in biofilm. sRNAs regulate gene expression and are associated with biofilm formation, which may in turn affect the expression of biofilm-specific antibiotic resistance. In summary, when biofilm cells were exposed to sub-MIC doses of colistin and imipenem, coordinated gene responses result in increased biofilm production, multidrug efflux pump expression, and the slowdown of metabolism, which leads to drug tolerance in biofilm. Targeting antibiotic-induced or repressed biofilm-specific genes represents a new strategy for the development of innovative and effective treatments for biofilm-associated infections caused by A. baumannii.

RevDate: 2022-10-27

Rahman MA, Amirkhani A, Parvin F, et al (2022)

One Step Forward with Dry Surface Biofilm (DSB) of Staphylococcus aureus: TMT-Based Quantitative Proteomic Analysis Reveals Proteomic Shifts between DSB and Hydrated Biofilm.

International journal of molecular sciences, 23(20): pii:ijms232012238.

The Gram-positive bacterium Staphylococcus aureus is responsible for serious acute and chronic infections worldwide and is well-known for its biofilm formation ability. Recent findings of biofilms on dry hospital surfaces emphasise the failures in current cleaning practices and disinfection and the difficulty in removing these dry surface biofilms (DSBs). Many aspects of the formation of complex DSB biology on environmental surfaces in healthcare settings remains limited. In the present study, we aimed to determine how the protein component varied between DSBs and traditional hydrated biofilm. To do this, biofilms were grown in tryptic soy broth (TSB) on removable polycarbonate coupons in the CDC biofilm reactor over 12 days. Hydrated biofilm (50% TSB for 48 h, the media was then changed every 48 h with 20% TSB, at 37 °C with 130 rpm). DSB biofilm was produced in 5% TSB for 48 h at 35 °C followed by extended periods of dehydration (48, 66, 42 and 66 h at room temperature) interspersed with 6 h of 5% TSB at 35 °C. Then, we constructed a comprehensive reference map of 12-day DSB and 12-day hydrated biofilm associated proteins of S. aureus using a high-throughput tandem mass tag (TMT)-based mass spectrometry. Further pathway analysis of significantly differentially expressed identified proteins revealed that proteins significantly upregulated in 12-day DSB include PTS glucose transporter subunit IIBC (PtaA), UDP-N-acetylmuramate-L-alanine ligase (MurC) and UDP-N-acetylenolpyruvoylglucosamine (MurB) compared to 12-day hydrated biofilm. These three proteins are all linked with peptidoglycan biosynthesis pathway and are responsible for cell-wall formation and thicker EPS matrix deposition. Increased cell-wall formation may contribute to the persistence of DSB on dry surfaces. In contrast, proteins associated with energy metabolisms such as phosphoribosyl transferase (PyrR), glucosamine--fructose-6-phosphate aminotransferase (GlmS), galactose-6-phosphate isomerase (LacA), and argininosuccinate synthase (ArgG) were significantly upregulated whereas ribosomal and ABC transporters were significantly downregulated in the 12-day hydrated biofilm compared to DSB. However, validation by qPCR analysis showed that the levels of gene expression identified were only partially in line with our TMT-MS quantitation analysis. For the first time, a TMT-based proteomics study with DSB has shed novel insights and provided a basis for the identification and study of significant pathways vital for biofilm biology in this reference microorganism.

RevDate: 2022-10-27

Luo K, Guo X, Zhang H, et al (2022)

The Physiological Functions of AbrB on Sporulation, Biofilm Formation and Carbon Source Utilization in Clostridium tyrobutyricum.

Bioengineering (Basel, Switzerland), 9(10): pii:bioengineering9100575.

As a pleiotropic regulator, Antibiotic resistant protein B (AbrB) was reported to play important roles in various cellular processes in Bacilli and some Clostridia strains. In Clostridium tyrobutyricum, abrB (CTK_C 00640) was identified to encode AbrB by amino acid sequence alignment and functional domain prediction. The results of abrB deletion or overexpression in C. tyrobutyricum showed that AbrB not only exhibited the reported characteristics such as the negative regulation on sporulation, positive effects on biofilm formation and stress resistance but also exhibited new functions, especially the negative regulation of carbon metabolism. AbrB knockout strain (Ct/ΔabrB) could alleviate glucose-mediated carbon catabolite repression (CCR) and enhance the utilization of xylose compared with the parental strain, resulting in a higher butyrate titer (14.79 g/L vs. 7.91 g/L) and xylose utilization rate (0.19 g/L·h vs. 0.02 g/L·h) from the glucose and xylose mixture. This study confirmed the pleiotropic regulatory function of AbrB in C. tyrobutyricum, suggesting that Ct/ΔabrB was the potential candidate for butyrate production from abundant, renewable lignocellulosic biomass mainly composed of glucose and xylose.

RevDate: 2022-10-27

Vishnyakova A, Popova N, Artemiev G, et al (2022)

Effect of Mineral Carriers on Biofilm Formation and Nitrogen Removal Activity by an Indigenous Anammox Community from Cold Groundwater Ecosystem Alone and Bioaugmented with Biomass from a "Warm" Anammox Reactor.

Biology, 11(10): pii:biology11101421.

The complex pollution of aquifers by reduced and oxidized nitrogen compounds is currently considered one of the urgent environmental problems that require non-standard solutions. This work was a laboratory-scale trial to show the feasibility of using various mineral carriers to create a permeable in situ barrier in cold (10 °C) aquifers with extremely high nitrogen pollution and inhabited by the Candidatus Scalindua-dominated indigenous anammox community. It has been established that for the removal of ammonium and nitrite in situ due to the predominant contribution of the anammox process, quartz, kaolin clays of the Kantatsky and Kamalinsky deposits, bentonite clay of the Berezovsky deposit, and zeolite of the Kholinsky deposit can be used as components of the permeable barrier. Biofouling of natural loams from a contaminated aquifer can also occur under favorable conditions. It has been suggested that the anammox activity is determined by a number of factors, including the presence of the essential trace elements in the carrier and the surface morphology. However, one of the most important factors is competition with other microbial groups that can develop on the surface of the carrier at a faster rate. For this reason, carriers with a high specific surface area and containing the necessary microelements were overgrown with the most rapidly growing microorganisms. Bioaugmentation with a "warm" anammox community from a laboratory reactor dominated by Ca. Kuenenia improved nitrogen removal rates and biofilm formation on most of the mineral carriers, including bentonite clay of the Dinozavrovoye deposit, as well as loamy rock and zeolite-containing tripoli, in addition to carriers that perform best with the indigenous anammox community. The feasibility of coupled partial denitrification-anammox and the adaptation of a "warm" anammox community to low temperatures and hazardous components contained in polluted groundwater prior to bioaugmentation should be the scope of future research to enhance the anammox process in cold, nitrate-rich aquifers.

RevDate: 2022-10-27

Zheng M, Zhu K, Peng H, et al (2022)

CcpA Regulates Staphylococcus aureus Biofilm Formation through Direct Repression of Staphylokinase Expression.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101426.

Staphylococcus aureus represents a notorious opportunistic pathogen causing various infections in biofilm nature, imposing remarkable therapeutic challenges worldwide. The catabolite control protein A (CcpA), a major regulator of carbon catabolite repression (CCR), has been recognized to modulate S. aureus biofilm formation, while the underlying mechanism remains to be fully elucidated. In this study, the reduced biofilm was firstly determined in the ccpA deletion mutant of S. aureus clinical isolate XN108 using both crystal violet staining and confocal laser scanning microscopy. RNA-seq analysis suggested that sak-encoding staphylokinase (Sak) was significantly upregulated in the mutant ∆ccpA, which was further confirmed by RT-qPCR. Consistently, the induced Sak production correlated the elevated promoter activity of sak and increased secretion in the supernatants, as demonstrated by Psak-lacZ reporter fusion expression and chromogenic detection, respectively. Notably, electrophoretic mobility shift assays showed that purified recombinant protein CcpA binds directly to the promoter region of sak, suggesting the direct negative control of sak expression by CcpA. Double isogenic deletion of ccpA and sak restored biofilm formation for mutant ∆ccpA, which could be diminished by trans-complemented sak. Furthermore, the exogenous addition of recombinant Sak inhibited biofilm formation for XN108 in a dose-dependent manner. Together, this study delineates a novel model of CcpA-controlled S. aureus biofilm through direct inhibition of sak expression, highlighting the multifaceted roles and multiple networks regulated by CcpA.

RevDate: 2022-10-27

Früh R, Anderson A, Cieplik F, et al (2022)

Antibiotic Resistance of Selected Bacteria after Treatment of the Supragingival Biofilm with Subinhibitory Chlorhexidine Concentrations.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101420.

Due to increasing rates of antibiotic resistance and very few novel developments of antibiotics, it is crucial to understand the mechanisms of resistance development. The aim of the present study was to investigate the adaptation of oral bacteria to the frequently used oral antiseptic chlorhexidine digluconate (CHX) and potential cross-adaptation to antibiotics after repeated exposure of supragingival plaque samples to subinhibitory concentrations of CHX. Plaque samples from six healthy donors were passaged for 10 days in subinhibitory concentrations of CHX, while passaging of plaque samples without CHX served as control. The surviving bacteria were cultured on agar plates and identified with Matrix-assisted Laser Desorption/Ionization-Time of Flight-Mass spectrometry (MALDI-TOF). Subsequently, the minimum inhibitory concentrations (MIC) of these isolates toward CHX were determined using a broth-microdilution method, and phenotypic antibiotic resistance was evaluated using the epsilometertest. Furthermore, biofilm-forming capacities were determined. Repeated exposure of supragingival plaque samples to subinhibitory concentrations of CHX led to the selection of oral bacteria with 2-fold up to 4-fold increased MICs toward CHX. Furthermore, these isolates showed up to 12-fold increased MICs towards some antibiotics such as erythromycin and clindamycin. Conversely, biofilm-forming capacity was decreased. In summary, this study shows that oral bacteria are able to adapt to CHX, while also decreasing their susceptibility to antibiotics.

RevDate: 2022-10-27

Haasbroek K, Yagi M, Y Yonei (2022)

Staphylococcus aureus Biofilm Inhibiting Activity of Advanced Glycation Endproduct Crosslink Breaking and Glycation Inhibiting Compounds.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101412.

Staphylococcus aureus is a Gram-positive bacterium that plays a role in the pathogenesis of skin lesions in diabetes mellitus, atopic dermatitis, and psoriasis, all of which are associated with elevated non-enzymatic glycation biomarkers. The production of biofilm protects resident bacteria from host immune defenses and antibiotic interventions, prolonging pathogen survival, and risking recurrence after treatment. Glycated proteins formed from keratin and glucose induce biofilm formation in S. aureus, promoting dysbiosis and increasing pathogenicity. In this study, several glycation-inhibiting and advanced glycation endproduct (AGE) crosslink-breaking compounds were assayed for their ability to inhibit glycated keratin-induced biofilm formation as preliminary screening for clinical testing candidates. Ascorbic acid, astaxanthin, clove extract, n-phenacylthiazolium bromide, and rosemary extract were examined in an in vitro static biofilm model with S. aureus strain ATCC 12600. Near complete biofilm inhibition was achieved with astaxanthin (ED50 = 0.060 mg/mL), clove extract (ED50 = 0.0087 mg/mL), n-phenacylthiazolium bromide (ED50 = 5.3 mg/mL), and rosemary extract (ED50 = 1.5 mg/mL). The dosage necessary for biofilm inhibition was not significantly correlated with growth inhibition (R2 = 0.055. p = 0.49). Anti-glycation and AGE breaking compounds with biofilm inhibitory activity are ideal candidates for treatment of S. aureus dysbiosis and skin infection that is associated with elevated skin glycation.

RevDate: 2022-10-27

Xu J, Lin Q, Sheng M, et al (2022)

Antibiofilm Effect of Cinnamaldehyde-Chitosan Nanoparticles against the Biofilm of Staphylococcus aureus.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101403.

Food contamination caused by food-spoilage bacteria and pathogenic bacteria seriously affects public health. Staphylococcus aureus is a typical foodborne pathogen which easily forms biofilm. Once biofilm is formed, it is difficult to remove. The use of nanotechnology for antibiofilm purposes is becoming more widespread because of its ability to increase the bioavailability and biosorption of many drugs. In this work, chitosan nanoparticles (CSNPs) were prepared by the ion-gel method with polyanionic sodium triphosphate (TPP). Cinnamaldehyde (CA) was loaded onto the CSNPs. The particle size, potential, morphology, encapsulation efficiency and in vitro release behavior of cinnamaldehyde-chitosan nanoparticles (CSNP-CAs) were studied, and the activity of CA against S. aureus biofilms was evaluated. The biofilm structure on the silicone surface was investigated by scanning electron microscopy (SEM). Confocal laser scanning microscopy (CLSM) was used to detect live/dead organisms within biofilms. The results showed that CSNP-CAs were dispersed in a circle with an average diameter of 298.1 nm and a zeta potential of +38.73 mV. The encapsulation efficiency of cinnamaldehyde (CA) reached 39.7%. In vitro release studies have shown that CA can be continuously released from the CSNPs. Compared with free drugs, CSNP-CAs have a higher efficacy in removing S. aureus biofilm, and the eradication rate of biofilm can reach 61%. The antibiofilm effects of CSNP-CAs are determined by their antibacterial properties. The minimum inhibitory concentration (MIC) of CA is 1.25 mg/mL; at this concentration the bacterial cell wall ruptures and the permeability of the cell membrane increases, which leads to leakage of the contents. At the same time, we verified that the MIC of CSNP-CAs is 2.5 mg/mL (drug concentration). The synergy between CA and CSNPs demonstrates the combinatorial application of a composite as an efficient novel therapeutic agent against antibiofilm. We can apply it in food preservation and other contexts, providing new ideas for food preservation.

RevDate: 2022-10-27

Kukushkina EA, Mateos H, Altun N, et al (2022)

Highly Stable Core-Shell Nanocolloids: Synergy between Nano-Silver and Natural Polymers to Prevent Biofilm Formation.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101396.

Active investment in research time in the development and study of novel unconventional antimicrobials is trending for several reasons. First, it is one of the ways which might help to fight antimicrobial resistance and bacterial contamination due to uncontrolled biofilm growth. Second, minimizing harmful environmental outcomes due to the overuse of toxic chemicals is one of the highest priorities nowadays. We propose the application of two common natural compounds, chitosan and tannic acid, for the creation of a highly crosslinked polymer blend with not only intrinsic antimicrobial properties but also reducing and stabilizing powers. Thus, the fast and green synthesis of fine spherically shaped Ag nanoparticles and further study of the composition and properties of the colloids took place. A positively charged core-shell nanocomposition, with an average size in terms of the metal core of 17 ± 4 nm, was developed. Nanoantimicrobials were characterized by several spectroscopic (UV-vis and FTIR) and microscopic (transmission and scanning electron microscopies) techniques. The use of AgNPs as a core and an organic polymer blend as a shell potentially enable a synergistic long-lasting antipathogen effect. The antibiofilm potential was studied against the food-borne pathogens Salmonella enterica and Listeria monocytogenes. The antibiofilm protocol efficiency was evaluated by performing crystal violet assay and optical density measurements, direct visualization by confocal laser scanning microscopy and morphological studies by SEM. It was found that the complex nanocomposite has the ability to prevent the growth of biofilm. Further investigation for the potential application of this stable composition in food packaging will be carried out.

RevDate: 2022-10-27

Carradori S, Ammazzalorso A, De Filippis B, et al (2022)

Azole-Based Compounds That Are Active against Candida Biofilm: In Vitro, In Vivo and In Silico Studies.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101375.

Fungal pathogens, including Candida spp., Aspergillus spp. and dermatophytes, cause more than a billion human infections every year. A large library of imidazole- and triazole-based compounds were in vitro screened for their antifungal activity against C. albicans, C. glabrata, C. krusei, A. fumigatus and dermatophytes, such as Microsporum gypseum, Trichophyton rubrum and Trichophyton mentagrophytes. The imidazole carbamate 12 emerged as the most active compound, showing a valuable antifungal activity against C. glabrata (MIC 1-16 μg/mL) and C. krusei (MIC 4-24 μg/mL). No activity against A. fumigatus or the dermatophytes was observed among all the tested compounds. The compound 12 inhibited the formation of C.&nbsp;albicans, C.&nbsp;glabrata and C.&nbsp;krusei biofilms and reduced the mature Candida biofilm. In the Galleria mellonella larvae, 12 showed a significant reduction in the Candida infection, together with a lack of toxicity at the concentration used to activate its antifungal activity. Moreover, the in silico prediction of the putative targets revealed that the concurrent presence of the imidazole core, the carbamate and the p-chlorophenyl is important for providing a strong affinity for lanosterol 14α-demethylase (CgCYP51a1) and the fungal carbonic anhydrase (CgNce103), the S-enantiomer being more productive in these interactions.

RevDate: 2022-10-27

Andrade M, Oliveira K, Morais C, et al (2022)

Virulence Potential of Biofilm-Producing Staphylococcus pseudintermedius, Staphylococcus aureus and Staphylococcus coagulans Causing Skin Infections in Companion Animals.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101339.

Coagulase-positive staphylococci (CoPS) account for most bacteria-related pyoderma in companion animals. Emergence of methicillin-resistant strains of Staphylococcus pseudintermedius (MRSP), Staphylococcus aureus (MRSA) or Staphylococcus coagulans (MRSC), often with multidrug-resistant (MDR) phenotypes, is a public health concern. The study collection comprised 237 staphylococci (S. pseudintermedius (n = 155), S. aureus (n = 55) and S. coagulans (n = 27)) collected from companion animals, previously characterized regarding resistance patterns and clonal lineages. Biofilm production was detected for 51.0% (79/155), 94.6% (52/55) and 88.9% (24/27) of the S. pseudintermedius, S. aureus and S. coagulans, respectively, and was a frequent trait of the predominant S. pseudintermedius and S. aureus clonal lineages. The production of biofilm varied with NaCl supplementation of the growth media. All S. pseudintermedius and S. aureus strains carried icaADB. Kaplan-Meier survival analysis of Galleria mellonella infected with different CoPS revealed a higher virulence potential of S. aureus when compared with other CoPS. Our study highlights a high frequency of biofilm production by prevalent antimicrobial-resistant clonal lineages of CoPS associated with animal pyoderma, potentially related with a higher virulence potential and persistent or recurrent infections.

RevDate: 2022-10-27

Sánchez-Somolinos M, Díaz-Navarro M, Benjumea A, et al (2022)

Determination of the Elution Capacity of Dalbavancin in Bone Cements: New Alternative for the Treatment of Biofilm-Related Peri-Prosthetic Joint Infections Based on an In Vitro Study.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101300.

Antibiotic-loaded bone cement is the most widely used approach for the treatment of biofilm-induced septic sequelae in orthopedic surgery. Dalbavancin is a lipoglycopeptide that acts against Gram-positive bacteria and has a long half-life, so we aimed to assess whether it could be a new alternative drug in antibiotic-loaded bone cement for the treatment of periprosthetic joint infections. We assessed the elution capacity of dalbavancin and compared it with that of vancomycin in bone cement. Palacos®R (Heraeus Medical GmbH, Wehrheim, Germany) bone cement was manually mixed with each of the antibiotics studied at 2.5% and 5%. Three cylinders were obtained from each of the mixtures; these were weighed and incubated in 5 mL phosphate-buffered saline at 37°C under shaking for 1 h, 2 h, 4 h, 8 h, 24 h, 48 h, 168 h, and 336 h. PBS was replenished at each time point. The samples were analyzed using high-performance liquid chromatography (vancomycin) and mass cytometry (dalbavancin). Elution was higher than the minimum inhibitory concentration (MIC)90 for both antibiotics after 14 days of study. The release of vancomycin at 14 days was higher than of dalbavancin at each concentration tested (p = 0.05, both). However, the cumulative release of 5% dalbavancin was similar to that of 2.5% vancomycin (p = 0.513). The elution capacity of dalbavancin reached a cumulative concentration similar to that of vancomycin. Moreover, considering that the MIC90 of dalbavancin is one third that of vancomycin (0.06 mg/L and 2 mg/L, respectively) and given the long half-life of dalbavancin, it may be a new alternative for the treatment of biofilm-related periprosthetic infections when loaded in bone cement.

RevDate: 2022-10-27

Zúñiga I, Iniesta M, Virto L, et al (2022)

Dental Biofilm Removal and Bacterial Contamination of a New Doubled-Side Thermoplastic Polyurethane-Based Toothbrush: A Crossover Study in Healthy Volunteers.

Antibiotics (Basel, Switzerland), 11(10): pii:antibiotics11101296.

Multiple toothbrush designs have been developed to enhance dental biofilm removal and decrease bacterial contamination and retention over time. Therefore, the aim of this clinical study was to compare the efficacy of a prototype of a new double-sided thermoplastic polyurethane-based toothbrush with that of a conventional nylon-bristle toothbrush. A crossover study was conducted in systemically healthy volunteers (n = 24) for two one-week periods plus one washout week. As outcome variables, plaque and gingival indices, total bacterial contamination of the toothbrushes by quantitative polymerase chain reaction (qPCR), and patient-reported outcomes were measured. Clinical and microbiological variables were analysed using a general linear model and Friedman and Wilcoxon signed-rank tests. No statistically significant differences between toothbrushes were detected neither for full-mouth PlI (p > 0.05) nor for GI (p > 0.05). Similarly, no statistically significant differences were detected for bacterial contamination after 40 seconds or 1 week of use, with results expressed either in CFU/mL or in CFU/mm2 (p > 0.05). In conclusion, the tested prototype toothbrush was as effective and safe as the control toothbrush, and the participating subjects did not experience any adverse effects from its use and rated its efficiency and effectiveness in cleaning their teeth as satisfactory.


RJR Experience and Expertise


Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.


Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.


Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.


Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.


While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.


Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.


Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.


Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

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An examination of the research and translational application to prevent and treat biofilm-associated diseases In the decade since the first edition of Microbial Biofilms was published, the interest in this field has expanded, spurring breakthrough research that has advanced the treatment of biofilm-associated diseases. This second edition takes the reader on an exciting, extensive review of bacterial and fungal biofilms, ranging from basic molecular interactions to innovative therapies, with particular emphasis on the division of labor in biofilms, new approaches to combat the threat of microbial biofilms, and how biofilms evade the host defense.

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Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

short personal version

Curriculum Vitae for R J Robbins

long standard version

RJR Picks from Around the Web (updated 11 MAY 2018 )