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12 Jul 2020 at 01:33
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Bibliography on: Biofilm


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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: 2020-07-11

Morghad T, Hassaine H, Boutarfi Z, et al (2020)

Bacteriological water quality and biofilm formation in the treatment system of the hemodialysis unit in Tlemcen, Algeria.

Seminars in dialysis [Epub ahead of print].

OBJECTIVE: To evaluate and compare the microbiological quality of osmosis water at the distribution loop, at the dialysis generator inlet and to study the prevalence of biofilm in the tubing.

METHODS: Microbiological analysis of 20 water loop samples, 10 water samples were taken at the machine entry and 10 pipe segments from tubing connecting the machines to the loop was done.

RESULTS: The bacterial enumeration results of the loop water vary from 90 to 150 CFU/mL, while the average number of bacteria at the entry of the machines was 182 CFU/mL. The counts of the adhered bacteria in the tubing were worrying with rates ranging from 4.30 to 6.74 Log CFU/ cm2 . Fifty percentage of the strains isolated were Bacillus, followed by Enterobacter cloacae 23.52%, Staphylococcus, and others such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumanii. More than half of the tubing strains were highly formative of biofilm, 13 strains with medium capacity and 10 were weakly.

CONCLUSION: This study indicates bacterial water contamination. The formation of a biofilm will certainly harm the effectiveness of the various disinfection methods in this unit. Water quality is influenced not only by the high rate of bacterial colonization, but also differences in standards for dialysis water.

RevDate: 2020-07-11

Yu Z, Pei H, Li Y, et al (2020)

Inclined algal biofilm photobioreactor (IABPBR) for cost-effective cultivation of lipid-rich microalgae and treatment of seawater-diluted anaerobically digested effluent from kitchen waste with the aid of phytohormones.

Bioresource technology, 315:123761 pii:S0960-8524(20)31033-6 [Epub ahead of print].

Previous study has demonstrated that freshwater can be replaced with seawater for dilution of feed to algal production and wastewater treatment, but high harvest cost in suspended-growth systems is still a troublesome limitation for large-scale production. Therefore, a novel inclined algal biofilm photobioreactor (IABPBR) was constructed for algal bioproduct production and treatment of seawater-diluted anaerobically digested effluent (SA) in this study. Fluffy polyester was selected as the best carrier for the algal biofilm among ten discarded materials. With the help of phytohormones, the viability of SDEC-18 was clearly enhanced and an algal biomass productivity of 5.66 g/m2/d was achieved. The SDEC-18 biofilm provided removal capacities of 0.65, 0.25 and 3.31 g/m2/d for TN, TP and COD. Phytohormones clearly enhanced the lipid biosynthesis, with an extraordinary lipid productivity of 3.98 g/m2/d being achieved. Moreover, an automatic harvesting system was designed for the efficient harvesting process during large-scale production.

RevDate: 2020-07-11

Novotny LA, Goodman SD, LO Bakaletz (2020)

Targeting a bacterial DNABII protein with a chimeric peptide immunogen or humanised monoclonal antibody to prevent or treat recalcitrant biofilm-mediated infections.

EBioMedicine pii:S2352-3964(20)30242-5 [Epub ahead of print].

BACKGROUND: Chronic and recurrent bacterial diseases are recalcitrant to treatment due to the ability of the causative agents to establish biofilms, thus development of means to prevent or resolve these structures are greatly needed. Our approach targets the DNABII family of bacterial DNA-binding proteins, which serve as critical structural components within the extracellular DNA scaffold of biofilms formed by all bacterial species tested to date. DNABII-directed antibodies rapidly disrupt biofilms and release the resident bacteria which promote their subsequent clearance by either host immune effectors or antibiotics that are now effective at a notably reduced concentration.

METHODS: First, as a therapeutic approach, we used intact IgG or Fab fragments against a chimeric peptide immunogen designed to target protective epitopes within the DNA-binding tip domains of integration host factor to disrupt established biofilms in vitro and to mediate resolution of existing disease in vivo. Second, we performed preventative active immunisation with the chimeric peptide to induce the formation of antibody that blocks biofilm formation and disease development in a model of viral-bacterial superinfection. Further, toward the path for clinical use, we humanised a monoclonal antibody against the chimeric peptide immunogen, then characterised and validated that it maintained therapeutic efficacy.

FINDINGS: We demonstrated efficacy of each approach in two well-established pre-clinical models of otitis media induced by the prevalent respiratory tract pathogen nontypeable Haemophilus influenzae, a common biofilm disease.

INTERPRETATION: Collectively, our data revealed two approaches with substantive efficacy and potential for broad application to combat diseases with a biofilm component.

FUNDING: Supported by R01 DC011818 to LOB and SDG.

RevDate: 2020-07-11

Roscetto E, Masi M, Esposito M, et al (2020)

Anti-Biofilm Activity of the Fungal Phytotoxin Sphaeropsidin A Against Clinical Isolates of Antibiotic-Resistant Bacteria.

Toxins, 12(7): pii:toxins12070444.

Many pathogens involved in human infection have rapidly increased their antibiotic resistance, reducing the effectiveness of therapies in recent decades. Most of them can form biofilms and effective drugs are not available to treat these formations. Natural products could represent an efficient solution in discovering and developing new drugs to overcome antimicrobial resistance and treat biofilm-related infections. In this study, 20 secondary metabolites produced by pathogenic fungi of forest plants and belonging to diverse classes of naturally occurring compounds were evaluated for the first time against clinical isolates of antibiotic-resistant Gram-negative and Gram-positive bacteria. epi-Epoformin, sphaeropsidone, and sphaeropsidin A showed antimicrobial activity on all test strains. In particular, sphaeropsidin A was effective at low concentrations with Minimum Inhibitory Concentration (MIC) values ranging from 6.25 μg/mL to 12.5 μg/mL against all reference and clinical test strains. Furthermore, sphaeropsidin A at sub-inhibitory concentrations decreased methicillin-resistant S. aureus (MRSA) and P. aeruginosa biofilm formation, as quantified by crystal violet staining. Interestingly, mixtures of sphaeropsidin A and epi-epoformin have shown antimicrobial synergistic effects with a concomitant reduction of cytotoxicity against human immortalized keratinocytes. Our data show that sphaeropsidin A and epi-epoformin possess promising antimicrobial properties.

RevDate: 2020-07-10

Ogasawara H, Ishizuka T, Hotta S, et al (2020)

Novel regulators of the csgD gene encoding the master regulator of biofilm formation in Escherichia coli K-12.

Microbiology (Reading, England) [Epub ahead of print].

Under stressful conditions, Escherichia coli forms biofilm for survival by sensing a variety of environmental conditions. CsgD, the master regulator of biofilm formation, controls cell aggregation by directly regulating the synthesis of Curli fimbriae. In agreement of its regulatory role, as many as 14 transcription factors (TFs) have so far been identified to participate in regulation of the csgD promoter, each monitoring a specific environmental condition or factor. In order to identify the whole set of TFs involved in this typical multi-factor promoter, we performed in this study 'promoter-specific transcription-factor' (PS-TF) screening in vitro using a set of 198 purified TFs (145 TFs with known functions and 53 hitherto uncharacterized TFs). A total of 48 TFs with strong binding to the csgD promoter probe were identified, including 35 known TFs and 13 uncharacterized TFs, referred to as Y-TFs. As an attempt to search for novel regulators, in this study we first analysed a total of seven Y-TFs, including YbiH, YdcI, YhjC, YiaJ, YiaU, YjgJ and YjiR. After analysis of curli fimbriae formation, LacZ-reporter assay, Northern-blot analysis and biofilm formation assay, we identified at least two novel regulators, repressor YiaJ (renamed PlaR) and activator YhjC (renamed RcdB), of the csgD promoter.

RevDate: 2020-07-10

Cavalcanti GS, Wasserscheid J, Dewar K, et al (2020)

Complete Genome Sequences of Two Marine Biofilm Isolates, Leisingera sp. nov. Strains 201A and 204H, Novel Representatives of the Roseobacter Group.

Microbiology resource announcements, 9(28): pii:9/28/e00505-20.

Here, we report the complete-genome assemblies of biofilm isolates 201A and 204H. They possess six and seven plasmids, respectively, with a size ranging from 44 kb to 159 kb. Genomic comparisons place the two strains into one new species belonging to the genus Leisingera as novel representatives of the Roseobacter group.

RevDate: 2020-07-09

Schraa O, Rosenthal A, Wade MJ, et al (2020)

Assessment of aeration control strategies for biofilm-based partial nitritation/anammox systems.

Water science and technology : a journal of the International Association on Water Pollution Research, 81(8):1757-1765.

The objective of this work was to compare the nitrogen removal in mainstream, biofilm-based partial nitritation anammox (PN/A) systems employing (1) constant setpoint dissolved oxygen (DO) control, (2) intermittent aeration, and (3) ammonia-based aeration control (ABAC). A detailed water resource recovery facility (WRRF) model was used to study the dynamic performance of these aeration control strategies with respect to treatment performance and energy consumption. The results show that constant setpoint DO control cannot meet typical regulatory limits for total ammonia nitrogen (NHx-N). Intermittent aeration shows improvement but requires optimisation of the aeration cycle. ABAC shows the best treatment performance with the advantages of continuous operation and over 20% lower average energy consumption as compared to intermittent aeration.

RevDate: 2020-07-09

Minami M, Takase H, Taira M, et al (2020)

Suppressive Effects of Hainosan (Painongsan) against Biofilm Production by Streptococcus mutans.

Dentistry journal, 8(3): pii:dj8030071.

Streptococcus mutans, a bacterium that causes dental plaques, forms a biofilm on tooth surfaces. This biofilm can cause gingivitis by stimulating the gingival margin. However, there is no established treatment for biofilm removal. Hainosan (Painongsan), a traditional Japanese Kampo formula, has been used to treat gingivitis. Therefore, we investigated the biofilm suppressive effects of the hainosan extract (HNS) and its components on S. mutans. We conducted scanning electron microscopy and confocal laser microscopy analyses to clarify the anti-biofilm activities of HNS and its crude drugs. We also performed a quantitative RT-PCR assay to assess the biofilm-related gene expression. HNS showed a significant dose-dependent suppressive effect on biofilm formation. Both the scanning electron microscopy and confocal laser microscopy analyses also revealed the significant inhibitory effects of the extract on biofilm formation. Transmission electron microscopy analysis showed that HNS disrupted the surface of the bacterial wall. Furthermore, HNS reduced the hydrophobicity of the bacteria, and suppressed the mRNA expression of β-glucosyltransferase (gtfB), glucosyltransferase-SI (gtfC), and fructosyltransferase (ftf). Among the constituents of hainosan, the extract of the root of Platycodon grandiflorum (PG) showed the strongest biofilm suppression effect. Platycodin D, one of the constituent natural compounds of PG, inhibited S. mutans-associated biofilm. These findings indicate that hainosan eliminates dental plaques by suppressing biofilm formation by S. mutans.

RevDate: 2020-07-08

Gonzalez T, Stevens ML, Baatrebek Kyzy A, et al (2020)

Biofilm propensity of Staphylococcus aureus skin isolates is associated with increased atopic dermatitis severity and barrier dysfunction in the MPAACH pediatric cohort.

Allergy [Epub ahead of print].

BACKGROUND: Atopic dermatitis (AD) patients are often colonized with Staphylococcus aureus and staphylococcal biofilms have been reported on adult AD skin lesions. The commensal Staphylococcus epidermidis can antagonize S. aureus, although its role in AD is unclear. We sought to characterize S. aureus and S. epidermidis colonization and biofilm propensity and determine their associations with AD severity, barrier function, and epidermal gene expression in the first US early-life cohort of children with AD, the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children (MPAACH).

METHODS: The biofilm propensity of staphylococcal isolates was assessed by crystal violet assays. Gene expression of filaggrin and anti-microbial alarmins S100A8 and S100A9 was measured in keratinocyte RNA extracted from skin tape strips. Staphylococcal biofilms sampled from MPAACH skin were visualized using scanning electron microscopy.

RESULTS: Sixty-two percent of staphylococcal isolates (sampled from 400 subjects) formed moderate/strong biofilms. Sixty-eight percent of subjects co-colonized with both staphylococcal species exhibited strains that formed cooperative mixed-species biofilms. Scanning electron microscopy verified the presence of staphylococcal biofilms on the skin of MPAACH children. S. aureus strains showing higher relative biofilm propensity compared to S. epidermidis were associated with increased AD severity (p=0.03) and increased lesional and non-lesional transepidermal water loss (p=0.01, p=0.03).

CONCLUSIONS: Our data suggest a pathogenic role for S. aureus biofilms in AD. We found that strain-level variation in staphylococcal isolates governs the interactions between S. epidermidis and S. aureus, and that the balance between these two species, and their biofilm propensity, has important implications for AD.

RevDate: 2020-07-08

Han W, Zhou B, Yang K, et al (2020)

Biofilm-inspired adhesive and antibacterial hydrogel with tough tissue integration performance for sealing hemostasis and wound healing.

Bioactive materials, 5(4):768-778 pii:S2452-199X(20)30089-X.

Uncontrolled bleeding and infection can cause significant increases in mortalities. Hydrogel sealants have attracted extensive attention for their ability to control bleeding. However, because interfacial water is a formidable barrier to strong surface bonding, a challenge remains in finding a product that offers robust tissue adhesion combined with anti-infection properties. Inspired by the strong adhesive mechanism of biofilm and mussels, we report a novel dual bionic adhesive hydrogel (DBAH) based on chitosan grafted with methacrylate (CS-MA), dopamine (DA), and N-hydroxymethyl acrylamide (NMA) via a facile radical polymerization process. CS-MA and DA were simultaneously included in the adhesive polymer for imitating the two key adhesive components: polysaccharide intercellular adhesin (PIA) of staphylococci biofilm and 3,4-dihydroxy-l-phenylalanine (Dopa) of mussel foot protein, respectively. DBAH presented strong adhesion at 34 kPa even upon three cycles of full immersion in water and was able to withstand up to 168 mm Hg blood pressure, which is significantly higher than the 60-160 mm Hg measured in most clinical settings. Most importantly, these hydrogels presented outstanding hemostatic capability under wet and dynamic in vivo movements while displaying excellent antibacterial properties and biocompatibility. Therefore, DBAH represents a promising class of biomaterials for high-efficiency hemostasis and wound healing.

RevDate: 2020-07-08

Elamary RB, Albarakaty FM, WM Salem (2020)

Efficacy of Acacia nilotica aqueous extract in treating biofilm-forming and multidrug resistant uropathogens isolated from patients with UTI syndrome.

Scientific reports, 10(1):11125 pii:10.1038/s41598-020-67732-w.

Escherichia coli is the dominant bacterial cause of UTI among the uropathogens in both developed and developing countries. This study is to investigate the effect of Acacia nilotica aqueous extract on the survival and biofilm of isolated pathogens to reduce UTIs diseases. A total of 170 urine samples were collected from Luxor general hospital and private medical analysis laboratories in Luxor providence, Egypt. Samples were screened for the incidence of uropathogens by biochemical tests, antibiotics susceptibility, detection of virulence, and antibiotic-resistant genes by multiplex PCR, biofilm formation, and time-killing assay. Escherichia coli is by far the most prevalent causative agent with the percentage of 73.7% followed by Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeuroginosa, and Acinetobacter baumanii. Isolates were multidrug-resistant containing blaTEM, blaSHV, blaCTX, qnrs, and aac(3)-Ia resistant genes. All isolates were sensitive to 15-16.7 mg ml-1 of Acacia nilotica aqueous extract. Time killing assay confirmed the bactericidal effect of the extract over time (20-24 h). A high percentage of 3-Cyclohexane-1-Carboxaldehyde, 2,6,6-trimethyl (23.5%); á-Selinene (15.12%); Oleic Acid (14.52%); Globulol (11.35%) were detected among 19 bioactive phytochemical compounds in the aqueous extract of A. nilotica over the GC-mass spectra analysis. The plant extract reduced significantly the biofilm activity of E. coli, K. pneumoniae, P. mirabilis, and P. aeuroginosa by 62.6, 59. 03, 48.9 and 39.2%, respectively. The challenge to improve the production of A. nilotica phytochemicals is considered a very low price for the return.

RevDate: 2020-07-08

Freiberg JA, Le Breton Y, Harro JM, et al (2020)

The Arginine Deiminase Pathway Impacts Antibiotic Tolerance during Biofilm-Mediated Streptococcus pyogenes Infections.

mBio, 11(4): pii:mBio.00919-20.

Bacterial biofilms are responsible for a variety of serious human infections and are notoriously difficult to treat due to their recalcitrance to antibiotics. Further work is necessary to elicit a full understanding of the mechanism of this antibiotic tolerance. The arginine deiminase (ADI) pathway is responsible for bacterial pH maintenance and is highly expressed during biofilm growth in multiple bacterial species. Using the group A Streptococcus (GAS) as a model human pathogen, the ADI pathway was demonstrated to contribute to biofilm growth. The inability of antibiotics to reduce GAS populations when in a biofilm was demonstrated by in vitro studies and a novel animal model of nasopharyngeal infection. However, disruption of the ADI pathway returned GAS biofilms to planktonic levels of antibiotic sensitivity, suggesting the ADI pathway is influential in biofilm-related antibiotic treatment failure and provides a new strategic target for the treatment of biofilm infections in GAS and potentially numerous other bacterial species.IMPORTANCE Biofilm-mediated bacterial infections are a major threat to human health because of their recalcitrance to antibiotic treatment. Through the study of Streptococcus pyogenes, a significant human pathogen that is known to form antibiotic-tolerant biofilms, we demonstrated the role that a bacterial pathway known for responding to acid stress plays in biofilm growth and antibiotic tolerance. This not only provides some insight into antibiotic treatment failure in S. pyogenes infections but also, given the widespread nature of this pathway, provides a potentially broad target for antibiofilm therapies. This discovery has the potential to impact the treatment of many different types of recalcitrant biofilm infections.

RevDate: 2020-07-08

Park JS, Choi HY, WG Kim (2020)

The Nitrite Transporter Facilitates Biofilm Formation via Suppression of Nitrite Reductase and Is a New Antibiofilm Target in Pseudomonas aeruginosa.

mBio, 11(4): pii:mBio.00878-20.

Biofilm-forming bacteria, including the Gram-negative Pseudomonas aeruginosa, cause multiple types of chronic infections and are responsible for serious health burdens in humans, animals, and plants. Nitric oxide (NO) has been shown to induce biofilm dispersal via triggering a reduction in cyclic-di-GMP levels in a variety of bacteria. However, how NO, at homeostatic levels, also facilitates biofilm formation is unknown. Here, we found that complestatin, a structural analog of vancomycin isolated from Streptomyces, inhibits P. aeruginosa biofilm formation by upregulating NO production via nitrite reductase (NIR) induction and c-di-GMP degradation via phosphodiesterase (PDE) stimulation. The complestatin protein target was identified as a nitrite transporter from a genome-wide screen using the Keio Escherichia coli knockout library and confirmed using nitrite transporter knockout and overexpression strains. We demonstrated that the nitrite transporter stimulated biofilm formation by controlled NO production via appropriate NIR suppression and subsequent diguanylate cyclase (DGC) activation, not PDE activity, and c-di-GMP production in E. coli and P. aeruginosa Thus, this study provides a mechanism for NO-mediated biofilm formation, which was previously not understood.IMPORTANCE Bacterial biofilms play roles in infections and avoidance of host defense mechanisms of medically important pathogens and increase the antibiotic resistance of the bacteria. Nitric oxide (NO) is reported to be involved in both biofilm formation and dispersal, which are conflicting processes. The mechanism by which NO regulates biofilm dispersal is relatively understood, but there are no reports about how NO is involved in biofilm formation. Here, by investigating the mechanism by which complestatin inhibits biofilm formation, we describe a novel mechanism for governing biofilm formation in Escherichia coli and Pseudomonas aeruginosa Nitrite transporter is required for biofilm formation via regulation of NO levels and subsequent c-di-GMP production. Additionally, the nitrite transporter contributes more to P. aeruginosa virulence than quorum sensing. Thus, this study identifies nitrite transporters as new antibiofilm targets for future practical and therapeutic agent development.

RevDate: 2020-07-07

Lai CY, Song Y, Wu M, et al (2020)

Microbial selenate reduction in membrane biofilm reactors using ethane and propane as electron donors.

Water research, 183:116008 pii:S0043-1354(20)30545-5 [Epub ahead of print].

Selenate (Se(VI)) contamination in groundwater is one of major concerns for human health, in particular in shale gas extraction sites. Microbial selenate reduction coupled to methane (CH4) oxidation has been demonstrated very recently. Little is known whether ethane (C2H6) and butane (C3H8) are able to drive selenate reduction, although they are also important components in shale gas. In this study, we demonstrated Se(VI) bio-reduction could be achieved using C2H6 and C3H8 as electron donors and carbon sources. Scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX) confirmed elemental Se (Se0) was the major final product formed from Se(VI) bio-reduction. Polyhydroxyalkanoates (PHAs) were generated in the biofilms as the internal electron-storage materials, which were consumed for sustaining Se(VI) bio-reduction in absence of C2H6 and C3H8. Microbial community analysis showed that two genera capable of oxidizing gaseous alkanes dominated in the biofilms, including Mycobacterium (in both C2H6 and C3H8-fed biofilms) and Rhodococcus (in C3H8-fed biofilm). In addition, several potential Se(VI) reducers (e.g., Variovorax) were detected in the biofilms. Investigation of Communities by Reconstruction of Unobserved States analysis supported that predictive genes associated with alkanes oxidation, denitrification and PHAs cycle were enriched in the biofilms. These findings offer insights into the process of selenate reduction driven by C2H6 and C3H8, which ultimately may help to develop a solution to use shale gas for groundwater remediation, especially near shale gas exploitation sites.

RevDate: 2020-07-07

Lin Z, Huang W, Zhou J, et al (2020)

The variation on nitrogen removal mechanisms and the succession of ammonia oxidizing archaea and ammonia oxidizing bacteria with temperature in biofilm reactors treating saline wastewater.

Bioresource technology, 314:123760 pii:S0960-8524(20)31032-4 [Epub ahead of print].

To reveal nitrogen removal mechanisms under environmental stresses, biofilm reactors were operated at different temperatures (10 °C-35 °C) treating saline wastewater (salinity 3%). The results showed nitrogen removal efficiency was 98.46% at 30 °C and 60.85% at 10 °C, respectively. Both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) participated in nitrification. 94.9% of the overall ammonia oxidation was attributed to AOA at 10 °C, but only 48.2% of that was undertaken by AOA at 35 °C. AOA had a greater contribution at low temperature, which demonstrated that nitrogen removal pathway varied with temperature. Aerobic denitrification was more stable than anoxic denitrification. High-throughput sequencing showed Crenarchaeota was the dominant AOA (97.02-34.47%), cooperating with various heterotrophic AOB. Real-time PCR indicated that AOA was three orders of magnitude more abundant than AOB. AOA was more resistant to low temperature and high-saline stresses. Ammonia oxidizers had distinct responses to temperature change and showed diverse relationships at different temperatures.

RevDate: 2020-07-07

de Sá Almeida JS, de Oliveira Marre AT, Teixeira FL, et al (2020)

Lactoferrin and lactoferricin B reduce adhesion and biofilm formation in the intestinal symbionts Bacteroides fragilis and Bacteroides thetaiotaomicron.

Anaerobe pii:S1075-9964(20)30088-3 [Epub ahead of print].

Several factors affect the composition of species that inhabit our intestinal tract, including mode of delivery, genetics and nutrition. Antimicrobial peptides and proteins secreted in the gastrointestinal tract are powerful tools against bacteria. Lactoferrin (LF) inhibits the growth of several bacterial species, such as Enterobacteriaceae, but may stimulate probiotic bacteria. Activity of LF against gut symbiotic species of the Bacteroides genus could give us insights on how these species colonize the gut. We investigated the effects of the antimicrobial protein lactoferrin and its derived peptide, lactoferricin B on two species of strict anaerobes, opportunistic pathogens that cause diseases in both adults and children, commonly found in the microbiota of the human gastrointestinal tract, Bacteroides fragilis and B. thetaiotaomicron., In vitro biofilm formation and binding to laminin were strongly inhibited by a low concentration of lactoferrin (12.5 μg/ml). Conversely, the growth of the strains in a micro-dilution assay in minimal media with different iron sources was not affected by physiological concentrations (2 mg/ml) of apo-lactoferrin or holo-lactoferrin. The combination of lactoferrin with antibiotics in synergism assays was also negative. The lactoferricin B fragment was also unable to inhibit growth in a similar test with concentrations of up to 32 μg/ml. Resistance to lactoferrin could confer an advantage to these species, even when high amount of this protein is present in the gastrointestinal tract. However, colonization is hampered by the binding and biofilm inhibitiory effect of lactoferrin, which may explain the low prevalence of Bacteroides in healthy babies. Resistance to this antimicrobial protein may help understand the success of these opportunistic pathogens during infection in the peritoneum.

RevDate: 2020-07-07

Yin L, Zhu W, Chen D, et al (2020)

Small noncoding RNA sRNA0426 is involved in regulating biofilm formation in Streptococcus mutans.

MicrobiologyOpen [Epub ahead of print].

Evidence suggests that small noncoding RNAs (sRNAs) are involved in the complex regulatory networks governing biofilm formation. Few studies have investigated the role of sRNAs in Streptococcus mutans (S. mutans). In the present study, the association between sRNA and biofilm formation in S. mutans was explored. sRNAs that are differentially expressed in the biofilm and planktonic states of this bacterium were identified by quantitative real-time PCR (qRT-PCR). Confocal laser scanning microscopy was used to investigate the characteristics of biofilm formation in a standard strain of S. mutans (UA159, ATCC 700610) and ten clinical strains. Bioinformatics analyses were employed to predict and examine potential sRNA regulatory pathways. The results showed that sRNA0426 has a strong positive relationship with dynamic biofilm formation. Moreover, sRNA0426 expression was positively correlated with exopolysaccharide (EPS) production. Bioinformatics analyses showed that sRNA0426 is involved in biofilm formation such as metabolic pathways, especially carbon metabolism. Five target mRNAs (GtfB, GtfC, GtfD, ComE, and CcpA) involved in the synthesis of EPS were selected for further evaluation; the expression levels of three of these mRNAs (GtfB, GtfC, and CcpA) were positively correlated with sRNA0426 expression levels, and the expression level of one (ComE) was negatively correlated. In conclusion, the results suggested that sRNA0426 may play an important and positive role in the biofilm formation of S. mutans and provide novel insight into the S. mutans biofilm regulatory network.

RevDate: 2020-07-07

Thibeaux R, Kainiu M, C Goarant (2020)

Biofilm Formation and Quantification Using the 96-Microtiter Plate.

Methods in molecular biology (Clifton, N.J.), 2134:207-214.

Biofilm formation in microtiter plates is certainly the most commonly used method to grow and study biofilm. This simple design is very popular due to its high-throughput screening capacities, low cost, and easy handling. In the protocol described here, we focus on the use of 96-well optically clear, polystyrene flat-bottom plate to study biofilm formation by Leptospira spp. and quantify the biofilm formation by crystal violet (CV) staining. We also describe an alternative method, based on phase contrast image analysis that we believe is more suitable for accurately quantifying biofilm growth by reducing handling of this fragile structure.

RevDate: 2020-07-07

Collins AJ, Pastora AB, Smith TJ, et al (2020)

MapA, a second large RTX adhesin conserved across the Pseudomonads, contributes to biofilm formation by Pseudomonas fluorescens.

Journal of bacteriology pii:JB.00277-20 [Epub ahead of print].

Mechanisms by which cells attach to a surface and form a biofilm are diverse and differ greatly among organisms. The Gram-negative, Gammaproteobacterium Pseudomonas fluorescens attaches to a surface through the localization of the large type 1-secreted RTX adhesin LapA to the outer surface of the cell. LapA localization to the cell surface is controlled by the activities of a periplasmic protease, LapG and an inner-membrane spanning cyclic di-GMP responsive effector protein, LapD. A previous study identified a second, LapA-like protein encoded in the P. fluorescens Pf0-1 genome: Pfl01_1463. Here, we identified specific growth conditions wherein, Pfl01_1463, hereafter called MapA (Medium Adhesion Protein A) is a functional adhesin contributing to biofilm formation. This adhesin, like LapA, appears to be secreted through a Lap-related type 1 secretion machinery and its localization is controlled by LapD and LapG. However, differing roles of LapA and MapA in biofilm formation are achieved, at least in part, through the differences in the sequences of the two adhesins and different distributions of the expression of the lapA and mapA genes within a biofilm. LapA-like proteins are broadly distributed throughout the Proteobacteria, and furthermore, LapA and MapA are well conserved among other Pseudomonas species. Together, our data indicate that the mechanisms by which a cell forms a biofilm and the components of a biofilm matrix can differ depending on growth conditions and the matrix protein(s) expressed.Importance Adhesins are critical for the formation and maturation of bacterial biofilms. We identify a second adhesin in P. fluorescens, called MapA, which appears to play a role in biofilm maturation and whose regulation is distinct from the previously reported LapA adhesin, which is critical for biofilm initiation. Analysis of bacterial adhesins show that LapA-like and MapA-like adhesins are found broadly in Pseudomonads and related organisms, indicating that the utilization of different suites of adhesins may be broadly important in the Gammaproteobacteria.

RevDate: 2020-07-07

Dal Co A, MP Brenner (2020)

Tracing cell trajectories in a biofilm.

Science (New York, N.Y.), 369(6499):30-31.

RevDate: 2020-07-07

Mulansky S, Saballus M, Friedrichs J, et al (2017)

A novel protocol to prepare cell probes for the quantification of microbial adhesion and biofilm initiation on structured bioinspired surfaces using AFM for single-cell force spectroscopy: Dedicated to Prof. em. Dr. Dr. H.C. Karl Schügerl on the occasion of his 90th birthday.

Engineering in life sciences, 17(8):833-840.

We present a novel protocol that uses single-cell force spectroscopy to characterize the bacteria-to-surface interactions involved in early steps of biofilm formation. Bacteria are immobilized as a monolayer by electrostatic interactions on a polyethylenimine-coated silica bead, and the Escherichia coli-bead complex is then glued on a tipless cantilever. We validated our new protocol by comparing to earlier published methods using single bacteria, but in contrast to these, which carry out bacterial attachment to the bead after fixation to the cantilever, our protocol results in more reliable production of usable cell probes. Measurements of interactions of E. coli with bio-inspired surfaces by single-cell force spectroscopy yielded comparable detachment forces to those found with the previous methods.

RevDate: 2020-07-06

Mahdi LH, Ghufran Nazem AH, IG Auda (2020)

Evidence of anti- K. pneumoniae biofilm activity of novel Entrococcus faecalis enterocin GLHM.

Microbial pathogenesis pii:S0882-4010(20)30732-4 [Epub ahead of print].

Many enterocins were produced from the lactic acid bacteria, Enterococcus faecalis, they belonged to different types of bacteriocins and have different characteristics. The present study aimed to search for another enterocin and test its ability to inhibit Klebsiella pneumoniae biofilm as compared with the most effective antibacterial agent. E. faecalis isolates were isolated from stools of breastfeeding babies. Klebsiella pneumoniae isolates were from urinary tract infections and urinary catheters. K. pneumoniae isolates showed biofilm formation potential and multidrug resistance phenotype but amikacin was the most effective one. Enterocin production by gene harboring E. faecalis was screened, then enterocin was purified, characterized, and antibacterial activity and MIC of enterocin were determined. Produced enterocin has characteristics differ from other discovered enterocins. Furthermore, the crude and purified enterocin of E. faecalis possess significant antibacterial activity against K. pneumoniae isolates as compare with control (p < 0.05), and antibiofilm activity of enterocin was stronger than the antibiofilm activity of amikacin (P < 0.05), as well as the enterocin, was potent than the amikacin in preventing the formation of biofilm on the catheter. In conclusion, a novel enterocin was produced from Enterococcus faecalis (enterocin GLHM) is proteinous bacteriocin, relatively heat-stable and have full activity at neutral pH and was belong to type II bacteriocin. Enterocin GLHM have anti-K. pneumoniae and anti-K. pneumoniae biofilm significantly better than amikacin.

RevDate: 2020-07-05

Donmez HG, Sahal G, Akgor U, et al (2020)

The relationship between the presence of HPV infection and biofilm formation in cervicovaginal smears.

Infection pii:10.1007/s15010-020-01478-5 [Epub ahead of print].

PURPOSE: To demonstrate and understand the association of HPV infection and biofilm formation.

METHODS: The study consisted of cervicovaginal samples of 72 women who were evaluated at the colposcopy unit. Papanicolaou staining was used for cytological examination while "Crystal Violet Binding" assay was performed to detect biofilm formation.

RESULTS: HPV-DNA was positive in 55.5% (n = 40) of the patients. The biofilm formation rate was statistically significantly higher in the HPV-positive women (45%) compared to HPV-negative women (21.9%) (P < 0.05). There was a statistically significant relationship between the presence of single HPV and "high-risk HPV" types and biofilm formation (P < 0.05). Biofilm formation was found in 80% of women with abnormal smear demonstrating atypical epithelial cells (P < 0.05).

CONCLUSION: Biofilm formation is more frequent at the cervicovaginal microbiota of patients with HPV infection. This finding is especially important in cases with atypical epithelial cells at their cervicovaginal smears.

RevDate: 2020-07-05

Kunrath MF, Monteiro MSG, Gupta S, et al (2020)

Influence of titanium and zirconia modified surfaces for rapid healing on adhesion and biofilm formation of Staphylococcus epidermidis.

Archives of oral biology, 117:104824 pii:S0003-9969(20)30202-8 [Epub ahead of print].

OBJECTIVE: Surface alterations have been employed to enhance the osseointegration process in biomedical implants. However, these modifications may influence bacterial adhesion in different ways. Therefore, this study developed five different surfaces and evaluated the Staphylococcus epidermidis growth in early (1 h) and late (24 h) contact.

DESIGN: The Titanium (Ti) and Zirconia (Zr) surfaces were divided in five groups and characterized concerning your morphology, roughness, wettability and chemical surface composition. Then, were evaluated regarding bacterial adhesion and biofilm formation/thickness, viability and morphology.

RESULTS: Different topographies were manufactured resulting in a variety of combinations of surface properties. High roughness showed significantly higher bacterial adhesion in 1 h, while high hydrophilicity revealed greater bacterial proliferation in 24 h. Morphological changes were not found visually, however the viability test showed some cell membrane damage in the Ti micro and nano groups.

CONCLUSIONS: Finally, surface distinct properties influence the growth of S. epidermidis independent of the based-material. Furthermore, some surface properties require precautions for use in contaminated sites according to the increased adhesion of S. epidermidis presented when in contact.

RevDate: 2020-07-04

Ayoub HM, Gregory RL, Tang Q, et al (2020)

The anti-caries efficacy of three fluoride compounds at increasing maturation of a microcosm biofilm.

Archives of oral biology, 117:104781 pii:S0003-9969(20)30159-X [Epub ahead of print].

OBJECTIVE: To explore the anti-caries efficacy of three fluoride compounds at increasing maturation of a microcosm biofilm.

DESIGN: Microcosm biofilm, obtained from saliva collected from three donors (IRB #1406440799), was grown on enamel samples (n = 18/group) for 24-h (Brain Heart Infusion; 0.2 % sucrose). Then, pH cycling model started. Three maturations were explored (4d, 8d, and 12d). The pH cycling consisted of daily 2 × 5 min treatments (NaF, SnF2, AmF: 287.5 ppm F, and de-ionized water [DIW]), 4 × 10 min remineralization (BHI, no sucrose, pH 7.0), and 3 × 2:15 h demineralization (BHI, 1% sucrose, pH 4.5). We analyzed the enamel (surface microhardness [VHNchange], integrated mineral loss [ΔZ], lesion depth [L]), and the biofilm (viability [log10 CFU/mL], lactic acid production [LDH], and exopolysaccharide [EPS] amount). Data were analyzed using two-way ANOVA (p = 0.05).

RESULTS: The interaction between tested variables was significant for VHNchange, viability, LDH, EPS (p = 0.0354, p = 0.0001, p < 0.0001, p < 0.0001), but not for L (p = 0.2412) or ΔZ (p = 0.6811). LDH and EPS analyses exhibited more tolerance of mature biofilm against NaF (LDH and EPS p < 0.0001); NaF-treated groups demonstrated significantly lower results than the control in the 12d group. The effect of SnF2 and AmF continued over time. VHNchange, L, and ΔZ: The effect of SnF2 and AmF was higher than NaF and DIW. L and ΔZ did not result in significant differences over time (all treatments). Within each maturation, fluoride compounds demonstrated statistically significantly lower L and ΔZ values than DIW.

CONCLUSIONS: Biofilm's maturation may influence the selection of fluoride compounds to achieve an optimum cariostatic effect.

RevDate: 2020-07-04

Hou YN, Ma JF, Yang ZN, et al (2020)

Insight into the electrocatalytic performance of in-situ fabricated electroactive biofilm-Pd: The role of biofilm thickness, initial Pd(II) concentration and the exposure time to Pd precursor.

The Science of the total environment, 742:140536 pii:S0048-9697(20)34058-4 [Epub ahead of print].

Biogenic palladium (bio-Pd) nanoparticles have been considered as promising biocatalyst for energy generation and contaminants remediation in water and sediment. Recently, an electroactive biofilm-Pd (EAB-Pd) network, which can be used directly as electrocatalyst and show enhanced electrocatalytic performance, has exhibited tremendous application potential. However, the information regarding to the controllable biosynthetic process and corresponding catalytic properties is scarce. This study demonstrated that the catalytic performance of EAB-Pd could be influenced by Pd loading on bacteria cells (Pd/cells), which was crucial to determine the final distribution characteristic of Pd nanocrystal on EAB skeleton. For instance, the high Pd/cells (over 0.18 pg cell-1) exhibited almost 6-fold and 1.5-fold enhancement over EAB-Pds with Pd/cells below 0.03 in catalytic current toward hydrogen evolution reaction and nitrobenzene reduction, respectively. In addition, the Pd/cells was found to be affected by the synthesis factors, such as the ratio of biomass to initial Pd(II) concentration (cells/PdII) and the exposure time of EAB to Pd(II) precursor solution. The Pd/cells increased significantly as the cell/PdII ratio decreased from ~5.5 × 107 to ~1.3 × 107 cells L mg-1 or the prolongation of exposure time from 3 h to 24 h. The findings developed in this work extensively expand our knowledge for the in-situ designing biogenic electrocatalyst and provide important information for the development of its catalytic property.

RevDate: 2020-07-04

Skariyachan S, Ravishankar R, Gopal D, et al (2020)

Response regulator GacA and transcriptional activator RhlR proteins involved in biofilm formation of Pseudomonas aeruginosa are prospective targets for natural lead molecules: Computational modelling, molecular docking and dynamic simulation studies.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(20)30279-3 [Epub ahead of print].

Pseudomonas aeruginosa has become a global concern due to its extreme resistance to most of the last resort antibiotics. Present study focuses on the screening of potential molecular targets involved in regulation of biofilm formation in P. aeruginosa and identification of potential natural lead molecules against these targets by molecular modelling, docking and simulation studies. Response regulator (GacA) and transcriptional activator (RhlR) involved in biofilm formation in P. aeruginosa were identified as molecular targets by metabolic pathway analysis and the three dimensional structures of these proteins were predicted by homology modelling and validated. By thorough literature survey, 78 lead molecules were screened and their pharmacokinetic profiles were determined and best two of them selected. The binding potential of selected lead molecules against GacA and RhlR were predicted by molecular docking and their binding energy was compared with the interaction of meropenem and its usual target penicillin binding protein-3. The stabilities of best docked complex were studied by molecular dynamic (MD) simulation. This study showed that Celastrol present in Celastrus paniculatus and Rotiorinol present in Chaetomium cupreum showed better binding affinities with GacA (binding energy -7.2 kcal/mol) and RhlR (binding energy -8.0 kcal/mol) respectively in comparison with the binding of Meropenem and its target (binding energy -6.2 kcal/mol). MD simulation studies showed that GacA-Celastrol and RhlR-Rotiorinol complexes demonstrated conformational stability throughout the simulation. This study highlights the application of GacA and RhlR as prospective targets and Celastrol and Rotiorinol are the potential lead molecules towards biofilm producing drug resistant P. aeruginosa.

RevDate: 2020-07-04

Nagaram P, Pasupuleti M, J Arockiaraj (2020)

CxxC Zinc Finger Protein Derived Peptide, MF18 Functions Against Biofilm Formation.

The protein journal pii:10.1007/s10930-020-09904-1 [Epub ahead of print].

The major threat in modern medicine was biofilm forming bacterial related infections and they were highly tolerant to conventional antibiotics and a boundless demand for new drugs. In this regard, antimicrobial peptide (AMP) have been considered as potential alternative agents to conventional antibiotics. In this study, we have reported a CxxC zinc finger protein derived peptide, MF18 and its various biological role including activity against biofilm forming bacteria. Zinc finger protein are important in regulation of several cellular processes and wide range of molecular functions. The CxxC zinc finger protein identified from the cDNA library of a teleost fish; further it was characterised using various online bioinformatics programs. During the in-silico analysis, an AMP named MF18 was identified from the CxxC zinc finger protein, then it was synthesised for further biological activity studies. The antimicrobial activity of MF18 was confirmed against the biofilm clinical isolates such as Staphylococcus aureus and Escherichia coli. The MIC of the antimicrobial peptide at the concentration of 320 µM was observed against these two biofilm bacteria. The mechanism of the peptides was determined using bacteria on its membrane permeabilization ability by scanning electron microscopy. It is exhibited that the MF18 potentially influenced in damaging the morphology of the bacteria. The toxicity of MF18 against the continuous cell line (RAW 264.7) was demonstrated by MTT assay and also using peripheral red blood cells by haemolytic assay; both assays showed that the peptide have no toxicity on the cells at lower concentration. Overall, the study showed the potential therapeutic application of the peptide in pharma industry.

RevDate: 2020-07-04

Xiong Q, Liu D, Zhang H, et al (2020)

Quorum sensing signal autoinducer-2 promotes root colonization of Bacillus velezensis SQR9 by affecting biofilm formation and motility.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10713-w [Epub ahead of print].

Root colonization of beneficial rhizobacteria is critical for their beneficial effects. Quorum sensing (QS) has been reported to affect the colonization of many plant pathogens. However, how QS signals regulate root colonization of beneficial rhizobacteria is unclear. In this study, the QS signal AI-2 synthetase-encoding gene luxS was completely deleted from the genome of the plant beneficial rhizobacterium Bacillus velezensis SQR9, and bioluminescence experiments showed that AI-2 production was blocked. Deletion of luxS reduced biofilm formation, motility, and root colonization of B. velezensis SQR9, while addition of exogenous AI-2 to the mutant restored this phenomenon. These results indicated that AI-2 positively affects the root colonization of B. velezensis SQR9. This study provided new insights for enhancing the colonization of beneficial rhizobacteria. KEY POINTS: • LuxS participated in the synthesis of the quorum sensing signal AI-2 in B. velezensis. • AI-2 enhanced motility, biofilm formation, and root colonization of B. velezensis. • AI-2 stimulated the production of γ-polyglutamic acid by B. velezensis.

RevDate: 2020-07-04

Daood U, Matinlinna JP, Pichika MR, et al (2020)

A quaternary ammonium silane antimicrobial triggers bacterial membrane and biofilm destruction.

Scientific reports, 10(1):10970 pii:10.1038/s41598-020-67616-z.

To study the antimicrobial effects of quaternary ammonium silane (QAS) exposure on Streptococcus mutans and Lactobacillus acidophilus bacterial biofilms at different concentrations. Streptococcus mutans and Lactobacillus acidophilus biofilms were cultured on dentine disks, and incubated for bacterial adhesion for 3-days. Disks were treated with disinfectant (experimental QAS or control) and returned to culture for four days. Small-molecule drug discovery-suite was used to analyze QAS/Sortase-A active site. Cleavage of a synthetic fluorescent peptide substrate, was used to analyze inhibition of Sortase-A. Raman spectroscopy was performed and biofilms stained for confocal laser scanning microscopy (CLSM). Dentine disks that contained treated dual-species biofilms were examined using scanning electron microscopy (SEM). Analysis of DAPI within biofilms was performed using CLSM. Fatty acids in bacterial membranes were assessed with succinic-dehydrogenase assay along with time-kill assay. Sortase-A protein underwent conformational change due to QAS molecule during simulation, showing fluctuating alpha and beta strands. Spectroscopy revealed low carbohydrate intensities in 1% and 2% QAS. SEM images demonstrated absence of bacterial colonies after treatment. DAPI staining decreased with 1% QAS (p < 0.05). Fatty acid compositions of dual specie biofilm increased in both 1% and 2% QAS specimens (p < 0.05). Quaternary ammonium silane demonstrated to be a potent antibacterial cavity disinfectant and a plaque inhibitor and can be of potential significance in eliminating caries-forming bacteria.

RevDate: 2020-07-04

Kelten OS, Hepdeniz OK, Tuncer Y, et al (2020)

Effect of surface characteristic of different restorative materials containing glass ionomer on Streptococcus mutans biofilm.

Nigerian journal of clinical practice, 23(7):957-964.

Aim: The aims of this study were to evaluate the surface morphology and surface roughness of restorative materials containing glass ionomer, analyze Streptococcus mutans biofilm formation on the surface of materials, and determine the correlation between surface roughness and biofilm.

Materials and Methods: Four restorative materials: resin-modified glass ionomer; giomer; amalgomer; and glass carbomer were used and for each material, 6 mm in diameter and 2 mm in thickness disc-shaped specimens were prepared to evaluate the surface morphology (n = 3), surface roughness (n = 16), and biofilm (n = 20). Surface morphology was analyzed with a scanning electron microscope. Surface roughness was evaluated via an atomic force microscope. The biofilm was evaluated by counting the colony-forming units. Surface roughness measurements were evaluated using a one-way analysis of variance and Tukey HSD test. Biofilm parameters were analyzed using the Kruskal-Wallis H and Mann-Whitney U test. Pearson's correlation test was used to determine the correlation between surface roughness and biofilm.

Results: While the highest roughness values were obtained for amalgomer and glass carbomer, the lowest roughness values belonged to giomer and resin-modified glass ionomer. Statistically significant differences in the number of adherent bacteria were observed between the materials only on day 1. No statistically significant correlation was determined between surface roughness and biofilm.

Conclusions: The resin content and small filler particle size of material positively affect surface roughness. However, there is no direct relationship between surface roughness and biofilm.

RevDate: 2020-07-03

Zhang P, Ding XS, Zhao B, et al (2020)

Acceleration of biofilm formation in start-up of sequencing batch biofilm reactor using carriers immobilized with Pseudomonas stutzeri strain XL-2.

Bioresource technology, 314:123736 pii:S0960-8524(20)31008-7 [Epub ahead of print].

P. stutzeri strain XL-2 initially immobilized on polypropylene carriers accelerated the biofilm formation in start-up of sequencing batch biofilm reactor (SBBR) (denoted R1). The biofilm formation in R1 was approximately completed in 36 days, which was shorter than that of 48 days in an identical SBBR (denoted R2) without strain XL-2. Meanwhile, R1 presented a rapid stabilization of NH4+-N and TN removal to 81.7% and 72.4% respectively. Surface plasmon resonance demonstrated that strain XL-2 enhanced the initial adhesion of carrier surface due to the production of extracellular polymeric substances (EPS), which made it easier for other EPS-producing strains, such as Thauera and Flavobacterium, to adhere to the carriers. PICRUSt revealed that biofilm in R1 presented relatively higher activity of EPS biosynthesis enzymes (glycosyltransferase and asparagine synthase). Thus, high EPS content was obtained due to the application of carriers immobilized with strain XL-2 and finally promoted the biofilm formation.

RevDate: 2020-07-03

Cordeiro RA, de Andrade ARC, Portela FVM, et al (2020)

Proposal for a microcosm biofilm model for the study of vulvovaginal candidiasis.

Biofouling [Epub ahead of print].

This study proposes a microcosm biofilm (MiB) model for the study of vulvovaginal candidiasis (VVC). Different conditions that mimic the vaginal environment were tested for MiB formation. The best growth conditions were obtained with samples incubated in vaginal fluid simulator medium pH 4.5 at 35 °C under a microaerophilic atmosphere. MiBs were evaluated for growth kinetics, fluconazole susceptibility and morphology. Samples containing high numbers of bacteria were analyzed for metagenomics. At 48 h, MiBs presented a higher cell density (CFU ml-1), a higher biomass and tolerance to fluconazole than their corresponding monospecies biofilms. Morphological analysis of MiBs revealed blastoconidia preferentially adhered to epithelial cells. Abundant Lactobacillus spp. were detected in two clinical samples; their MiBs showed a lower biomass and a higher fluconazole susceptibility. The proposed model proved to be a useful tool for the study of the complex microbial relationship in the vaginal environment, and may help to find new strategies for VVC control.

RevDate: 2020-07-03

Wu Z, Zheng R, Zhang J, et al (2020)

Transcriptional profiling of Pseudomonas aeruginosa PAO1 in response to anti-biofilm and anti-infection agent exopolysaccharide EPS273.

Journal of applied microbiology [Epub ahead of print].

AIMS: Relative few anti-biofilm polysaccharides against Pseudomonas aeruginosa were done to investigate the underlying molecular mechanism. Exopolysaccharide EPS273 can clearly reduce biofilm formation and infection of P. aeruginosa. This study aims to investigate its anti-biofilm and anti-infection mechanism on transcriptional level.

METHODS AND RESULTS: Herein we used an RNA-Seq transcriptomic approach to investigate the underlying anti-biofilm and anti-infection mechanism of EPS273. The expression levels of a large number of genes were changed after P. aeruginosa PAO1 was treated with EPS273. Especially, the genes related to biofilm formation, such as gene involved in production of extracellular matrix and virulence factor, genes involved in flagella and cell motility and genes involved in iron acquisition. Notably, the expression levels of genes involved in regulatory and signal transduction were markedly downregulated, such as two-component system PhoP-PhoQ and quorum sensing (QS) system LasI/ LasR and RhlI/ RhlR. Furthermore, when gene phoP and phoQ was disrupted respectively, the reduction of biofilm formation and cell motility in mutant △phoP or △phoQ was also detected.

CONCLUSION: EPS273 may exert its anti-biofilm and anti-infection function by downregulating gene expression of two-component system PhoP-PhoQ and QS systems LasI/ LasR and RhlI/ RhlR of P. aeruginosa, which further regulated expression of genes involved in biofilm formation.

Our data will expand understanding of anti-biofilm mechanisms of polysaccharides on transcriptomic level.

RevDate: 2020-07-03

da Silva ACB, Sardi JCO, de Oliveira DGL, et al (2020)

Development of a novel anti-biofilm peptide derived from profilin of Spodoptera frugiperda.

Biofouling [Epub ahead of print].

Candida yeast infections are the fourth leading cause of death worldwide. Peptides with antimicrobial activity are a promising alternative treatment for such infections. Here, the antifungal activity of a new antimicrobial peptide-PEP-IA18-was evaluated against Candida species. PEP-IA18 was designed from the primary sequence of profilin, a protein from Spodoptera frugiperda, and displayed potent activity against Candida albicans and Candida tropicalis, showing a minimum inhibitory concentration (MIC) of 2.5 µM. Furthermore, the mechanism of action of PEP-IA18 involved interaction with the cell membrane (ergosterol complexation). Treatment at MIC and/or 10 × MIC significantly reduced biofilm formation and viability. PEP-IA18 showed low toxicity toward human fibroblasts and only revealed hemolytic activity at high concentrations. Thus, PEP-IA18 exhibited antifungal and anti-biofilm properties with potential applicability in the treatment of infections caused by Candida species.

RevDate: 2020-07-03

Liu Y, Zeng R, Duan Z, et al (2020)

[Effect of 5-aminolevulinic Acid Photodynamics Therapy on Biofilm of Propionibacterium Acnes].

Zhongguo yi xue ke xue yuan xue bao. Acta Academiae Medicinae Sinicae, 42(3):283-288.

Objective To investigate the effect of 5-aminolevulinic acid photodynamic therapy (ALA-PDT) on Propionibacterium acnes (P.acnes) biofilm. MethodsP.acnes biofilms were constructed on a cell slide and treated with ALA-PDT.According to different light doses,the biofilms were divided into six groups:ALA-PDT group [ALA-PDT1 (50 J/cm2),ALA-PDT2 group (100 J/cm2),ALA-PDT3 group (200 J/cm2)],ALA-only group (ALA group),light-only group (LED),and a negative control group (ALA-PDT-group).The biofilm structure and the ratio of the dead bacteria/live bacteria were observed using a laser confocal microscope (CLSM).Biofilm viability was measured using the XTT assay. Results CLSM showed that the biofilm structures of ALA group and LED group were not significantly different from that of ALA-PDT-group,whereas the biofilm structure was more seriously damaged in ALA-PDT1 group,ALA-PDT2 group,and ALA-PDT3 group than in the ALA-PDT-group.The ratios of the dead/live bacteria in ALA-PDT-group,ALA group,LED group,ALA-PDT1 group,ALA-PDT2 group,and ALA-PDT3 group were 0.350±0.033, 0.305±0.046, 0.330±0.032, 1.525±0.439, 2.293±0.148 and 3.092±0.189,respectively.ALA group(md=0.003, P=1.000)and LED group(md=-0.025, P=1.000)did not significantly differ from the ALA-PDT-group.However,the ratio of dead/live bacteria in ALA-PDT-group was significantly lower than those in ALA-PDT1 group (md=-0.162, P<0.001),ALA-PDT2 group (md=-0.254, P<0.001),and ALA-PDT3 group (md=-0.352, P<0.001).The values of the XTT assay were were 0.462±0.028,0.465±0.044,0.437±0.047,0.301±0.040,0.207±0.001,and 0.110±0.007,respectively,in ALA-PDT-group,ALA group,LED group,ALA-PDT1 group,ALA-PDT2 group,and ALA-PDT3 group.Although the values of XTT assay in ALA(md=-0.044, P=1.000)and LED groups (md=-0.020, P=1.000)did not significantly differ from that in ALA-PDT-group,it was significantly higher in ALA-PDT-group than in ALA-PDT1 group (md=1.175, P<0.001),ALA-PDT2 group (md=1.942, P<0.001),and ALA-PDT3 group (md=-0.352, md=2.742, P<0.001). Conclusions ALA-PDT has an inhibitory effect on P.acnes biofilm.ALA-PDT destroys biofilm structure and inhibits biofilm viability.

RevDate: 2020-07-02

Chaves S, Longo M, Gómez López A, et al (2020)

Control of microbial biofilm formation as an approach for biomaterials synthesis.

Colloids and surfaces. B, Biointerfaces, 194:111201 pii:S0927-7765(20)30557-9 [Epub ahead of print].

The search for new biomaterials with superior mechanical properties is the focus in the area of materials science. A promising pathway is drawing inspiration from nature to design and develop materials with enhanced properties. In this work, a novel strategy to produce functionalized supramolecular bionanomaterials from the microbial biofilm is reported. Tuneable biofilms with specific characteristics were obtained by controlling the culture condition of the microorganism. When the exopolysaccharide (EPS) production was desired the tryptone was the best nutritional component for the EPS production into the biofilm. However, for the expression of a high amount of amyloid protein the combination of peptone and glucose was the best nutritional choice. Each biofilm obtained showed its owner rheology properties. These properties were altered by the addition of extracellular DNA, which increased the viscosity of the biofilm and induced a viscoelastic hydrogel behavior. Besides, as a proof of concept of bionanomaterial, a novel supramolecular polymeric hybrid EPS-Amyloid protein (EPAP) was obtained from the biofilm and it was tested as a new natural functionalized support for enzyme immobilization. The results suggest that this technology could be used as a new concept to obtain biomaterials from biofilms by controlling the nutritional conditions of a microorganism. Understanding environmental factors affecting biofilm formation will help the development of methods for controlling biofilm production and therefore obtaining new biomaterials.

RevDate: 2020-07-02

Moussa DG, C Aparicio (2020)

Targeting the oral plaque microbiome with immobilized anti-biofilm peptides at tooth-restoration interfaces.

PloS one, 15(7):e0235283 pii:PONE-D-20-11697.

Recurrent caries, the development of carious lesions at the interface between the restorative material and the tooth structure, is highly prevalent and represents the primary cause for failure of dental restorations. Correspondingly, we exploited the self-assembly and strong antibiofilm activity of amphipathic antimicrobial peptides (AAMPs) to form novel coatings on dentin that aimed to prevent recurrent caries at susceptible cavosurface margins. AAMPs are alternative to traditional antimicrobial agents and antibiotics with the ability to target the complex and heterogeneous organization of microbial communities. Unlike approaches that have focused on using these AAMPs in aqueous solutions for a transient activity, here we assess the effects on microcosm biofilms of a long-acting AAMPs-based antibiofilm coating to protect the tooth-composite interface. Genomewise, we studied the impact of AAMPs coatings on the dental plaque microbial community. We found that non-native all D-amino acids AAMPs coatings induced a marked shift in the plaque community and selectively targeted three primary acidogenic colonizers, including the most common taxa around Class II composite restorations. Accordingly, we investigated the translational potential of our antibiofilm dentin using multiphoton pulsed near infra-red laser for deep bioimaging to assess the impact of AAMPs-coated dentin on plaque biofilms along dentin-composite interfaces. Multiphoton enabled us to record the antibiofilm potency of AAMPs-coated dentin on plaque biofilms throughout exaggeratedly failed interfaces. In conclusion, AAMPs-coatings on dentin showed selective and long-acting antibiofilm activity against three dominant acidogenic colonizers and potential to resist recurrent caries to promote and sustain the interfacial integrity of adhesive-based interfaces.

RevDate: 2020-07-03

Dosler S, Hacioglu M, Yilmaz FN, et al (2020)

Biofilm modelling on the contact lenses and comparison of the in vitro activities of multipurpose lens solutions and antibiotics.

PeerJ, 8:e9419.

During the contact lens (CL) usage, microbial adhesion and biofilm formation are crucial threats for eye health due to the development of mature biofilms on CL surfaces associated with serious eye infections such as keratitis. For CL related eye infections, multi drug resistant Pseudomonas aeruginosa or Staphylococcus aureus (especially MRSA) and Candida albicans are the most common infectious bacteria and yeast, respectively. In this study, CL biofilm models were created by comparing them to reveal the differences on specific conditions. Then the anti-biofilm activities of some commercially available multipurpose CL solutions (MPSs) and antibiotic eye drops against mature biofilms of S. aureus, P. aeruginosa, and C. albicans standard and clinical strains were determined by the time killing curve (TKC) method at 6, 24 and 48 h. According to the biofilm formation models, the optimal biofilms occurred in a mixture of bovine serum albumin (20% v/v) and lysozyme (2 g/L) diluted in PBS at 37 °C for 24 h, without shaking. When we compared the CL types under the same conditions, the strongest biofilms according to their cell density, were formed on Pure Vision ≥ Softens 38 > Acuve 2 ∼ Softens Toric CLs. When we compared the used CLs with the new ones, a significant increase at the density of biofilms on the used CLs was observed. The most active MPS against P. aeruginosa and S. aureus biofilms at 24 h was Opti-Free followed by Bio-True and Renu according to the TKC analyses. In addition, the most active MPS against C. albicans was Renu followed by Opti-Free and Bio-True at 48 h. None of the MPSs showed 3 Log bactericidal/fungicidal activity, except for Opti-Free against S. aureus and P. aeruginosa biofilms during 6 h contact time. Moreover, all studied antibiotic eye drops were active against S. aureus and P. aeruginosa biofilms on CLs at 6 h and 24 h either directly or as 1/10 concentration, respectively. According to the results of the study, anti-biofilm activities of MPSs have changed depending on the chemical ingredients and contact times of MPSs, the type of infectious agent, and especially the CL type and usage time.

RevDate: 2020-07-03

Li T, Zhang Z, Wang F, et al (2020)

Antimicrobial Susceptibility Testing of Metronidazole and Clindamycin against Gardnerella vaginalis in Planktonic and Biofilm Formation.

The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale, 2020:1361825.

Background: Bacterial vaginosis (BV), one of the most common vaginal ecosystem-related microbiologic syndromes, is the most common disorder in women of reproductive age. Gardnerella (G.) vaginalis is the predominant species causing this infection. Our aim was to compare the antimicrobial susceptibilities of metronidazole and clindamycin against G. vaginalis at planktonic and biofilm levels.

Methods: From September 2019 to October 2019, we recruited a total of 10 patients with BV who underwent gynecological examinations at Beijing Obstetrics and Gynecology Hospital. G. vaginalis isolates were obtained from the vagina and identified using their characteristic colony morphology. Sequence data of clinical G. vaginalis isolates were confirmed by comparing 16S rDNA sequences. Subsequently, clinical isolates were evaluated for antimicrobial susceptibilities in vitro to metronidazole and clindamycin at planktonic and biofilm levels. The minimum inhibitory concentration (MIC) for metronidazole and clindamycin was evaluated by antimicrobial susceptibility testing. The minimum biofilm eradication concentration (MBEC) was evaluated by the biofilm inhibition assay.

Results: Planktonic clinical isolates showed a significantly higher susceptibility rate (76.67%) and lower resistance rate (23.33%) to clindamycin than to metronidazole (susceptibility rate: 38.24%; resistance rate: 58.82%; P < 0.05 for both). Furthermore, in comparison to planktonic isolates, the minimum inhibitory concentration (MIC) of metronidazole was significantly higher for biofilm-forming isolates (7.3 ± 2.6 μg/mL vs. 72.4 ± 18.3 μg/mL; P=0.005); the resistance rate was 27.3%, and the minimum biofilm eradication concentration (MBEC) was >128 μg/mL. Moreover, the MIC of clindamycin was higher too for biofilm-forming isolates (0.099 ± 0.041 μg/mL vs. 23.7 ± 9.49 μg/mL; P=0.034); the resistance rate was 27.3%, and the MBEC of clindamycin was 28.4 ± 6.50 μg/mL.

Conclusion: Our results indicate that in comparison to metronidazole, clindamycin seems to be a better choice to tackle G. vaginalis as it exhibits a relatively higher susceptibility rate and lower resistance rate.

RevDate: 2020-07-03

Zhuang Z, Yang G, Mai Q, et al (2020)

Physiological potential of extracellular polysaccharide in promoting Geobacter biofilm formation and extracellular electron transfer.

The Science of the total environment, 741:140365 pii:S0048-9697(20)33887-0 [Epub ahead of print].

Geobacter sulfurreducens biofilms have promising applications in renewable energy, pollutant bioremediation, and bioelectronic applications. Genetically manipulating G. sulfurreducens biofilms is an effective strategy to improve the capacity of extracellular electron transfer (EET). Extracellular polysaccharide, a sticky component surrounding microbes, plays an important role in EET. Herein, we constructed a mutant of G. sulfurreducens strain PCA overexpressing the gene GSU1501 (part of the ATP-dependent exporter of the polysaccharide biosynthesis gene operon), designated strain PCA-1501, to increase EET capacity. Experimental results showed that the overexpression of GSU1501 increased extracellular polysaccharide secretion by 25.5%, which promoted the formation of biofilm with higher thickness and viability, as well as the content of extracellular c-type cytochromes. Compared with the control strain, the mutant showed a higher capacity of Fe(III) oxide reduction and current generation (increased by 20.4% and 22.2%, respectively). Interestingly, the overexpression of GSU1501 hindered the pili formation by reducing the transcription level of pilA; a compensatory relationship between extracellular polysaccharide and pili in promoting biofilm formation deserves further investigation. This study provides a feasible method to promote the EET capacity of G. sulfurreducens biofilms, which benefit their bioelectrochemical applications.

RevDate: 2020-07-02

Jain A, Armstrong SR, Banas JA, et al (2020)

Dental adhesive microtensile bond strength following a biofilm-based in vitro aging model.

Journal of applied oral science : revista FOB, 28:e20190737 pii:S1678-77572020000100451.

OBJECTIVE: Laboratory tests are routinely used to test bonding properties of dental adhesives. Various aging methods that simulate the oral environment are used to complement these tests for assessment of adhesive bond durability. However, most of these methods challenge hydrolytic and mechanical stability of the adhesive- enamel/dentin interface, and not the biostability of dental adhesives. To compare resin-dentin microtensile bond strength (μTBS) after a 15-day Streptococcus mutans (SM) or Streptococcus sobrinus (SS) bacterial exposure to the 6-month water storage (WS) ISO 11405 type 3 test.

METHODOLOGY: A total of 31 molars were flattened and their exposed dentin was restored with Optibond-FL adhesive system and Z-100 dental composite. Each restored molar was sectioned and trimmed into four dumbbell-shaped specimens, and randomly distributed based on the following aging conditions: A) 6 months of WS (n=31), B) 5.5 months of WS + 15 days of a SM-biofilm challenge (n=31), C) 15 days of a SM-biofilm challenge (n=31) and D) 15 days of a SS-biofilm challenge (n=31). μTBS were determined and the failure modes were classified using light microscopy.

RESULTS: Statistical analyses showed that each type of aging condition affected μTBS (p<0.0001). For Group A (49.7±15.5MPa), the mean μTBS was significantly greater than in Groups B (19.3±6.3MPa), C (19.9±5.9MPa) and D (23.6±7.9MPa). For Group D, the mean μTBS was also significantly greater than for Groups B and C, but no difference was observed between Groups B and C.

CONCLUSION: A Streptococcus mutans- or Streptococcus sobrinus-based biofilm challenge for 15 days resulted in a significantly lower μTBS than did the ISO 11405 recommended 6 months of water storage. This type of biofilm-based aging model seems to be a practical method for testing biostability of resin-dentin bonding.

RevDate: 2020-07-01

Qin JW, Xin X, Lu H, et al (2020)

[Bacterial Community Shifts and Nitrogen Removal Characteristics for a SNAD Process Treating Anaerobic Digester Liquor of Swine Wastewater (ADLSW) in a Continuous-Flow Biofilm Reactor (CFBR)].

Huan jing ke xue= Huanjing kexue, 41(5):2349-2357.

To realize a simultaneous partial nitrification, ANAMMOX (anaerobic ammonium oxidation), and denitrification (SNAD) process treating anaerobic digester liquor of swine wastewater (ADLSW) in a continuous-flow biofilm reactor (CFBR), we first gradually increased the influent ammonium (NH4+-N) concentration, and then enhanced the ADLSW ratio in the influent during operation; dissolved oxygen (DO) was controlled at (0.4±0.1) mg·L-1 by adjusting the air flow rate, and the temperature was kept at (30±1)℃. Meanwhile, high-throughput sequencing and quantitative PCR (polymerase chain reaction) techniques were used to analyze the bacterial community shifts and the amount of dominant nitrogen removal bacteria. The results demonstrated that a successful start-up of the SNAD process was accomplished in 150 d, and replacement of the actual biogas slurry was completed in 298 d. The effluent (NO3--N+NO2--N)/ΔNH4+-N value was less than 0.11, and the average removal rates of NH4+-N and TN (total nitrogen) increased to 63.26% and 55.71%, respectively. Moreover, high-throughput sequencing results demonstrated that the dominant microbial populations at phylum level were Chloroflexi (with a relative abundance of 50.78%), Proteobacteria (13.34%), and Planctomycetes (9.26%). The relative abundance of Nitrosomonas increased from 1.55% to 1.98%. In addition, the relative abundance of Candidatus_Brocadia and Candidatus_Kuenenia increased from 0.01% and (<0.01%) to 4.66% and 4.18%, respectively, and the relative abundance of Denitratisoma increased from (<0.01%) to 2.06%. Meanwhile, qPCR analysis showed that the amounts of ammonia-oxidizing bacteria, ANAMMOX, and denitrifying bacteria increased significantly compared with the inoculated sludge. An efficient and stable nitrogen removal rate can be achieved, and the follow-up processing cost can be reduced, by application of the SNAD treatment process for ADLSW.

RevDate: 2020-07-01

Zhao ZR, Zhang JY, Li D, et al (2020)

[Purification Characteristics of Urban Tail Water from Sewage Treatment Plant by Biofilm Ecological Floating Bed].

Huan jing ke xue= Huanjing kexue, 41(2):809-814.

The purification characteristics of nitrogenous tail water were investigated using a biofilm ecological floating bed technology to study biofilm length, hydraulic retention time (HRT), and biofilm coverage area with the aim to explore the purification characteristics of biofilm on urban tail water. Results show that the removal rates of NH4+-N, NO3--N, and TN were 90.82%, 62.7%, and 81.96%, respectively, at the half water depth to the suspended biofilm. The removal rate of NH4+-N was only 22.07%, and the concentration changes of NO3--N and TN were not obvious throughout the whole water depth to the suspended biofilm. When the HRT was 6 days, the removal rates of NH4+-N and TN could reach 82.01% and 62.88%, respectively, whereas the lowest rates were 55.24% and 46.82%, respectively. When the HRT was 12 days, the removal rates of NH4+-N and TN reached up to 81.4% and 79.93%, respectively, whereas the lowest rates were 8.73% and 17.23%, respectively. In contrast, the nitrogen removal efficiency was high and stable when the HRT was 6 days. When the coverage area was 10%, the removal rate was decreased in one operation cycle. When the coverage area was 20%, the removal rate showed an upward trend. Under the conditions of 10% and 20% biofilm coverage area, the removal rates of TN were 62.88% and 71.09%, respectively.

RevDate: 2020-07-01

Ho MH, Hasturk H, Young DF, et al (2020)

In vivo and ex vivo actions of a novel P. gingivalis inhibitor on multi-species biofilm, inflammatory response and periodontal bone loss.

Molecular oral microbiology [Epub ahead of print].

Chronic periodontitis is one of the most common infectious inflammatory diseases worldwide. Current therapeutic options for the disease are only partially and temporarily successful due to periodontal re-emergence of pathogens such as Porphyromonas gingivalis, a keystone bacterium in the oral microbial communities, which elicits a dysbiosis between the microbiota and the host. Previously, we reported a peptide inhibitor of P. gingivalis (SAPP) that specifically targets P. gingivalis and reduces its virulence potential in vitro. Here, we show that SAPP can modulate the ability of P. gingivalis to suppress the host innate immune system. Using a cytokine array analysis, we found that the levels of several cytokines including IL-6, IL-8, and MCP-1 in the culture media of human oral keratinocytes (HOKs) were significantly diminished in the presence of P. gingivalis. Whereas the levels of these cytokines were restored, at least partially, in the culture media of HOKs by SAPP treatment. Furthermore, we also observed in an ex-vivo assay that SAPP efficiently inhibited biofilm primed formation by mixed species oral bacteria, and significantly dampened the abnormally innate immune responses induced by these bacteria. We also demonstrated, using a mouse model, that SAPP could prevent alveolar bone loss induced by P. gingivalis. Our results suggest that SAPP specifically targets P. gingivalis and its associated bacterial communities and could be envisioned as an emerging therapy for periodontitis.

RevDate: 2020-07-01

Ueda A, Ogasawara S, K Horiuchi (2020)

Identification of the genes controlling biofilm formation in the plant commensal Pseudomonas protegens Pf-5.

Archives of microbiology pii:10.1007/s00203-020-01966-0 [Epub ahead of print].

Determinant genes controlling biofilm formation in a plant commensal bacterium, Pseudomonas protegens Pf-5, were identified by transposon mutagenesis. Comprehensive screening of 7500 transposon-inserted mutants led to the isolation of four mutants exhibiting decreased and five mutants exhibiting increased biofilm formation. Mutations in the genes encoding MFS drug resistance transporter, LapA adhesive protein, RetS sensor histidine kinase/response regulator, and HecA adhesin/hemagglutinin led to decreased biofilm formation, indicating that these genes are necessary for biofilm formation in Pf-5. The mutants exhibiting increased biofilm formation had transposon insertions in the genes coding for an outer membrane protein, a GGDEF domain-containing protein, AraC transcriptional regulator, non-ribosomal peptide synthetase OfaB, and the intergenic region of a DNA-binding protein and the Aer aerotaxis receptor, suggesting that these genes are negative regulators of biofilm formation. Some of these mutants also showed altered swimming and swarming motilities, and a negative correlation between biofilm formation and swarming motility was observed. Thus, sessile-motile lifestyle is regulated by divergent regulatory genes in Pf-5.

RevDate: 2020-07-02

Lamichhane K, Adhikari N, Bastola A, et al (2020)

Biofilm-Producing Candida Species Causing Oropharyngeal Candidiasis in HIV Patients Attending Sukraraj Tropical and Infectious Diseases Hospital in Kathmandu, Nepal.

HIV/AIDS (Auckland, N.Z.), 12:211-220.

Introduction: Oropharyngeal candidiasis are the commonest fungal infections among HIV-positive patients. The main objective of this study was to explore biofilm-producing Candida species causing oropharyngeal infections among HIV patients attending Sukraraj Tropical and Infectious Diseases Hospital (STIDH) in Kathmandu, Nepal.

Methods: Oropharyngeal swabs were collected from the HIV-positive patients between July and December 2019. A total of 174 oropharyngeal swabs were cultured on Sabouraud Dextrose Agar (SDA). All samples were inoculated on SDA slants supplemented with chloramphenicol and underwent incubation at 37°C for 24-48 hours. Any visible growth reported was processed for the identification of the species. Candida species were differentiated based on the growth and colour of the isolates on CHROM agar candida. Biofilm production in Candida species was determined by the microtiter plate method (MPM). Antifungal susceptibility testing was performed using the disc diffusion method.

Results: Among 174 oropharyngeal samples, 23.6% (n=41/174) of them had oropharyngeal infections and 36.6% of the oropharyngeal infections (15/41) had CD4 T-lymphocytes count below 200 cells/mm3 who were also active tobacco users (p<0.05). Among Candidial growth, 61% (25/41) were Candida albicans and 39% (16/41) were non-albicans. Of 41 Candida spp., 65% (27/41) were biofilm producers. An equal proportion of Candida albicans (4 isolates) and non-albicans (4 isolates) were strong biofilm producers. C. albicans isolates were sensitive towards clotrimazole (96%; 24/25) and fluconazole (92%; 23/25), whereas sensitivity towards ketoconazole was only 48% (12/25). Non-albicans Candida was highly sensitive to amphotericin-B (62.5%; 10/16) followed by clotrimazole (56.2%; 9/16). The biofilm-producing Candida isolates showed the highest resistivity (51.9%; 14/27) to ketoconazole and lowest (22.2%; 6/27) to clotrimazole.

Conclusion: Oropharyngeal candidiasis is a common opportunistic infection among HIV-infected individuals. The majority of cases of oropharyngeal candidiasis are caused by biofilm producers Candida albicans and non-albicans Candida. Biofilm producers Candida were more resistant towards commonly used antifungal drugs.

RevDate: 2020-07-02

Kashef MT, Saleh NM, Assar NH, et al (2020)

The Antimicrobial Activity of Ciprofloxacin-Loaded Niosomes against Ciprofloxacin-Resistant and Biofilm-Forming Staphylococcus aureus.

Infection and drug resistance, 13:1619-1629.

Purpose: The threat of Staphylococcus aureus antimicrobial resistance is increasing worldwide. Niosomes are a new drug delivery system that enhances the antimicrobial potential of antibiotics. We hereby aim to evaluate the antimicrobial and antibiofilm activity of ciprofloxacin-loaded niosomes.

Methods: The antimicrobial susceptibility of clinical S. aureus isolates (n=59) was determined by Kirby-Bauer disk diffusion method. Their biofilm formation activity was tested by Christensen's method. Two ciprofloxacin-loaded niosomal formulations were prepared by thin-film hydration method, and their minimum inhibitory concentrations (MIC) were determined by agar dilution method, against ciprofloxacin-resistant and biofilm-forming isolates (n=24). Their ability to inhibit biofilm formation and eradicate already formed biofilms was evaluated and further confirmed by scanning electron microscope images. Non-synonymous mutations, in a quinolone resistance-determining regions of S. aureus isolates, were detected by polymerase chain reaction.

Results: Most of the isolates were methicillin- (47/59) and ciprofloxacin-resistant (45/59). All except two isolates were capable of biofilm production. Niosomal preparation I reduced ciprofloxacin MIC by twofold in four isolates, whereas preparation II reduced ciprofloxacin MIC of most isolates by 8- to 32-fold, with three isolates that became ciprofloxacin-susceptible. Non-synonymous mutations were detected in isolates that maintained phenotypic ciprofloxacin resistance against ciprofloxacin-loaded niosomal preparation II. Ciprofloxacin-loaded niosomes reduced the minimum biofilm inhibitory concentration and the minimum biofilm eradication concentration in 58% and 62% of the tested isolates, respectively.

Conclusion: Ciprofloxacin-loaded niosomes can restore ciprofloxacin activity against resistant S. aureus isolates. To our knowledge, this is the first report on the inhibition of biofilm formation and eradication of formed biofilms by ciprofloxacin-loaded niosomes.

RevDate: 2020-07-01

De Gregorio E, Esposito A, Vollaro A, et al (2020)

N-Nonyloxypentyl-l-Deoxynojirimycin Inhibits Growth, Biofilm Formation and Virulence Factors Expression of Staphylococcus aureus.

Antibiotics (Basel, Switzerland), 9(6): pii:antibiotics9060362.

Staphylococcus aureus is one of the major causes of hospital- and community-associated bacterial infections throughout the world, which are difficult to treat due to the rising number of drug-resistant strains. New molecules displaying potent activity against this bacterium are urgently needed. In this study, d- and l-deoxynojirimycin (DNJ) and a small library of their N-alkyl derivatives were screened against S. aureus ATCC 29213, with the aim to identify novel candidates with inhibitory potential. Among them, N-nonyloxypentyl-l-DNJ (l-NPDNJ) proved to be the most active compound against S. aureus ATCC 29213 and its clinical isolates, with the minimum inhibitory concentration (MIC) value of 128 μg/mL. l-NPDNJ also displayed an additive effect with gentamicin and oxacillin against the gentamicin- and methicillin-resistant S. aureus isolate 00717. Sub-MIC values of l-NPDNJ affected S. aureus biofilm development in a dose-dependent manner, inducing a strong reduction in biofilm biomass. Moreover, real-time reverse transcriptase PCR analysis revealed that l-NPDNJ effectively inhibited at sub-MIC values the transcription of the spa, hla, hlb and sea virulence genes, as well as the agrA and saeR response regulator genes.

RevDate: 2020-06-30

Locke L, Shankaran K, Gong L, et al (2020)

Evaluation of peptide-based probes towards in vivo diagnostic imaging of bacterial biofilm-associated infections.

ACS infectious diseases [Epub ahead of print].

The clinical management of bacterial biofilm infections represents an enormous challenge in today's healthcare setting. The NIH estimates that 65% of bacterial infections are biofilm related and therapeutic outcomes are positively correlated with early intervention. Currently, there is no reliable imaging technique to detect biofilm infections in vivo and current clinical protocols for accurate and direct biofilm identification are non-existent. In orthopedic implant-associated biofilm infections, for example, current detection methods are based on non-specific X-ray or radiolabeled white blood cell imaging, coupled with peri-prosthetic tissue or fluid samples taken invasively and must be cultured. This approach is time consuming and often fails to detect biofilm bacteria due to sampling errors and lack of sensitivity. The ability to quantify bacterial biofilms by real-time, non-invasive imaging is an urgent, unmet clinical need that would revolutionize the management and treatment of these devastating types of infections. In the present study, we assembled a collection of fluorescently labeled peptide candidates to specifically explore their biofilm targeting properties. We evaluated these fluorescently labeled peptides using various in vitro assays for their ability to specifically and non-destructively target biofilms produced by the model bacterial pathogen Pseudomonas aeruginosa. The lead candidate that emerged, 4Iphf-HN17, demonstrated rapid biofilm labeling kinetics, a lack of bactericidal activity, and biofilm targeting specificity in human cell infection models. In vivo, fluorescently labeled 4Iphf-HN17 showed enhanced accumulation in biofilm-infected wounds, thus warranting further study.

RevDate: 2020-06-30

Ohn HM, Mizuno T, Sudo Y, et al (2020)

Interaction of Escherichia coli and its culture supernatant with Vibrio vulnificus during biofilm formation.

Microbiology and immunology [Epub ahead of print].

Vibrio vulnificus is a foodborne pathogen causing septicemia with high mortality rate. In this study, we explored how Escherichia coli, one of the commensal bacteria in human gastrointestinal tract, can interact with V. vulnificus. Our study showed that, the amount of biofilm produced by V. vulnificus was reduced in the presence of E. coli ATCC 35218, although the growth of V. vulnificus L-180 remains unaffected. We also detected antibiofilm effect of E. coli culture supernatant against V. vulnificus. But this effect could not be reduced even after heat treatment. These findings indicate that E. coli and its culture supernatant may be suitable to prevent the biofilm formation by V. vulnificus. On the other hand, V. vulnificus living cells could reduce the amount of preformed E. coli biofilm, however, its culture supernatant could not. This suggests that the cell-associated factors contribute towards reduction in the E. coli biofilm. Therefore, we speculate that ingestion of infectious dose of V. vulnificus might induce dislodging of the commensal bacteria from the intestinal epithelia and thus can colonize to initiate the infection. This article is protected by copyright. All rights reserved.

RevDate: 2020-06-30

Marmont LS, Whitfield GB, Pfoh R, et al (2020)

PelX is a UDP-N-acetylglucosamine C4-epimerase involved in Pel polysaccharide-dependent biofilm formation.

The Journal of biological chemistry pii:RA120.014555 [Epub ahead of print].

Pel is an N-acetylgalactosamine-rich bacterial polysaccharide that contributes to the structure and function of Pseudomonas aeruginosa biofilms. The pelABCDEFG operon is highly conserved among diverse bacterial species, and Pel may therefore be a widespread biofilm determinant. Previous annotation of pel gene clusters has helped us identify an additional gene, pelX, that is present adjacent to pelABCDEFG in >100 different bacterial species. The pelX gene is predicted to encode a member of the short-chain dehydrogenase/reductase (SDR) superfamily, but its potential role in Pel-dependent biofilm formation is unknown. Herein, we have used Pseudomonas protegens Pf-5 as a model to elucidate PelX function as P. aeruginosa lacks a pelX homologue in its pel gene cluster. We found that P. protegens forms Pel-dependent biofilms; however, despite expression of pelX under these conditions, biofilm formation was unaffected in a ΔpelX strain. This observation led us to identify a pelX paralog, PFL_5533, which we designate here PgnE, that appears to be functionally redundant to pelX In line with this, a ΔpelX ΔpgnE double mutant was substantially impaired in its ability to form Pel-dependent biofilms. To understand the molecular basis for this observation, we determined the structure of PelX to 2.1 Å resolution. The structure revealed that PelX resembles UDP-N-acetylglucosamine (UDP-GlcNAc) C4-epimerases. Using 1H NMR analysis, we show that PelX catalyzes the epimerization between UDP-GlcNAc and UDP-GalNAc. Our results indicate that Pel-dependent biofilm formation requires a UDP-GlcNAc C4-epimerase that generates the UDP-GalNAc precursors required by the Pel synthase machinery for polymer production.

RevDate: 2020-07-02

Thorarinsdottir HR, Kander T, Holmberg A, et al (2020)

Biofilm formation on three different endotracheal tubes: a prospective clinical trial.

Critical care (London, England), 24(1):382.

BACKGROUND: Biofilm formation on endotracheal tubes (ETTs) is an early and frequent event in mechanically ventilated patients. The biofilm is believed to act as a reservoir for infecting microorganisms and thereby contribute to development and relapses of ventilator-associated pneumonia (VAP). Once a biofilm has formed on an ETT surface, it is difficult to eradicate. This clinical study aimed to compare biofilm formation on three widely used ETTs with different surface properties and to explore factors potentially predictive of biofilm formation.

METHODS: We compared the grade of biofilm formation on ETTs made of uncoated polyvinyl chloride (PVC), silicone-coated PVC, and PVC coated with noble metals after > 24 h of mechanical ventilation in critically ill patients. The comparison was based on scanning electron microscopy of ETT surfaces, biofilm grading, surveillance and biofilm cultures, and occurrence of VAP.

RESULTS: High-grade (score ≥ 7) biofilm formation on the ETTs was associated with development of VAP (OR 4.17 [95% CI 1.14-15.3], p = 0.031). Compared to uncoated PVC ETTs, the silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation (OR 0.18 [95% CI 0.06-0.59], p = 0.005, and OR 0.34 [95% CI 0.13-0.93], p = 0.036, respectively). No significant difference was observed between silicon-coated ETTs and noble-metal-coated ETTs (OR 0.54 [95% CI 0.17-1.65], p = 0.278). In 60% of the oropharyngeal cultures and 58% of the endotracheal cultures collected at intubation, the same microorganism was found in the ETT biofilm at extubation. In patients who developed VAP, the causative microbe remained in the biofilm in 56% of cases, despite appropriate antibiotic therapy. High-grade biofilm formation on ETTs was not predicted by either colonization with common VAP pathogens in surveillance cultures or duration of invasive ventilation.

CONCLUSION: High-grade biofilm formation on ETTs was associated with development of VAP. Compared to the uncoated PVC ETTs, the silicone-coated and noble-metal-coated PVC ETTs were independently associated with reduced high-grade biofilm formation. Further research on methods to prevent, monitor, and manage biofilm occurrence is needed.

TRIAL REGISTRATION: ClinicalTrials.gov NCT02284438 . Retrospectively registered on 21 October 2014.

RevDate: 2020-07-02

Loimaranta V, Mazurel D, Deng D, et al (2020)

Xylitol and erythritol inhibit real-time biofilm formation of Streptococcus mutans.

BMC microbiology, 20(1):184.

BACKGROUND: Regular consumption of xylitol decreases the number of cariogenic streptococci in dental plaque. In vitro biofilm models to study the mechanism of xylitol action have been set-up, but the obtained results are contradictory. Biofilm growth is a dynamic process with time-specific characteristics that may remain undetected in conventional end-point biofilm tests. In this study we used an impedance spectroscopy instrument, xCELLigence Real Time Cell Analyzer (RTCA), that allows label-free, non-invasive real-time monitoring of biofilm formation, to explore effects of xylitol on biofilm formation by Streptococcus mutans. Based on the obtained information of biofilm dynamics, we assessed the number of viable bacteria, the polysaccharide content, and the expression levels of selected genes involved in glucan-mediated biofilm formation in different biofilm stages. Xylitol inhibition was compared with that of erythritol; another polyol suggested to have a positive impact on oral health.

RESULTS: Our results showed that real-time monitoring provided new information of polyol-induced changes in S. mutans biofilm formation dynamics. The inhibitory effect of polyols was more pronounced in the early stages of biofilm formation but affected also the measured total amount of formed biofilm. Effects seen in the real-time biofilm assay were only partially explained by changes in CFU values and polysaccharide amounts in the biofilms. Both xylitol and erythritol inhibited real-time biofilm formation by all the nine tested S. mutans strains. Sensitivity of the strains to inhibition varied: some were more sensitive to xylitol and some to erythritol. Xylitol also modified the expression levels of gbpB, gtfB, gtfC and gtfD genes that are important in polysaccharide-mediated adherence of S. mutans.

CONCLUSION: The erythritol- and xylitol- induced inhibition of biofilm formation was only partly explained by decrease in the number of viable S. mutans cells or the amount of polysaccharides in the biofilm matrix, suggesting that in addition to reduced proliferation also the matrix composition and thereby the surface attachment quality of biofilm matrix may be altered by the polyols.

RevDate: 2020-07-02

Katongole P, Nalubega F, Florence NC, et al (2020)

Biofilm formation, antimicrobial susceptibility and virulence genes of Uropathogenic Escherichia coli isolated from clinical isolates in Uganda.

BMC infectious diseases, 20(1):453.

INTRODUCTION: Uropathogenic E. coli is the leading cause of Urinary tract infections (UTIs), contributing to 80-90% of all community-acquired and 30-50% of all hospital-acquired UTIs. Biofilm forming Uropathogenic E. coli are associated with persistent and chronic inflammation leading to complicated and or recurrent UTIs. Biofilms provide an environment for poor antibiotic penetration and horizontal transfer of virulence genes which favors the development of Multidrug-resistant organisms (MDRO). Understanding biofilm formation and antimicrobial resistance determinants of Uropathogenic E. coli strains will provide insight into the development of treatment options for biofilm-associated UTIs. The aim of this study was to determine the biofilm forming capability, presence of virulence genes and antimicrobial susceptibility pattern of Uropathogenic E. coli isolates in Uganda.

METHODS: This was a cross-sectional study carried in the Clinical Microbiology and Molecular biology laboratories at the Department of Medical Microbiology, Makerere University College of Health Sciences. We randomly selected 200 Uropathogenic E. coli clinical isolates among the stored isolates collected between January 2018 and December 2018 that had significant bacteriuria (> 105 CFU). All isolates were subjected to biofilm detection using the Congo Red Agar method and Antimicrobial susceptibility testing was performed using the Kirby disk diffusion method. The isolates were later subjected PCR for the detection of Urovirulence genes namely; Pap, Fim, Sfa, Afa, Hly and Cnf, using commercially designed primers.

RESULTS: In this study, 62.5% (125/200) were positive biofilm formers and 78% (156/200) of these were multi-drug resistant (MDR). The isolates were most resistant to Trimethoprim sulphamethoxazole and Amoxicillin (93%) followed by gentamycin (87%) and the least was imipenem (0.5%). Fim was the most prevalent Urovirulence gene (53.5%) followed by Pap (21%), Sfa (13%), Afa (8%), Cnf (5.5%) and Hyl (0%).

CONCLUSIONS: We demonstrate a high prevalence of biofilm-forming Uropathogenic E. coli strains that are highly associated with the MDR phenotype. We recommend routine surveillance of antimicrobial resistance and biofilm formation to understand the antibiotics suitable in the management of biofilm-associated UTIs.

RevDate: 2020-06-30

Balaure PC, AM Grumezescu (2020)

Recent Advances in Surface Nanoengineering for Biofilm Prevention and Control. Part I: Molecular Basis of Biofilm Recalcitrance. Passive Anti-Biofouling Nanocoatings.

Nanomaterials (Basel, Switzerland), 10(6): pii:nano10061230.

Medical device-associated infections are becoming a leading cause of morbidity and mortality worldwide, prompting researchers to find new, more effective ways to control the bacterial colonisation of surfaces and biofilm development. Bacteria in biofilms exhibit a set of "emergent properties", meaning those properties that are not predictable from the study of free-living bacterial cells. The social coordinated behaviour in the biofilm lifestyle involves intricate signaling pathways and molecular mechanisms underlying the gain in resistance and tolerance (recalcitrance) towards antimicrobial agents as compared to free-floating bacteria. Nanotechnology provides powerful tools to disrupt the processes responsible for recalcitrance development in all stages of the biofilm life cycle. The present paper is a state-of-the-art review of the surface nanoengineering strategies currently used to design antibiofilm coatings. The review is structurally organised in two parts according to the targeted biofilm life cycle stages and molecular mechanisms intervening in recalcitrance development. Therefore, in the present first part, we begin with a presentation of the current knowledge of the molecular mechanisms responsible for increased recalcitrance that have to be disrupted. Further, we deal with passive surface nanoengineering strategies that aim to prevent bacterial cells from settling onto a biotic or abiotic surface. Both "fouling-resistant" and "fouling release" strategies are addressed as well as their synergic combination in a single unique nanoplatform.

RevDate: 2020-06-30

Hathroubi S, Zerebinski J, Clarke A, et al (2020)

Helicobacter pylori Biofilm Confers Antibiotic Tolerance in Part via A Protein-Dependent Mechanism.

Antibiotics (Basel, Switzerland), 9(6): pii:antibiotics9060355.

Helicobacter pylori, a WHO class I carcinogen, is one of the most successful human pathogens colonizing the stomach of over 4.4 billion of the world's population. Antibiotic therapy represents the best solution but poor response rates have hampered the elimination of H. pylori. A growing body of evidence suggests that H. pylori forms biofilms, but the role of this growth mode in infection remains elusive. Here, we demonstrate that H. pylori cells within a biofilm are tolerant to multiple antibiotics in a manner that depends partially on extracellular proteins. Biofilm-forming cells were tolerant to multiple antibiotics that target distinct pathways, including amoxicillin, clarithromycin, and tetracycline. Furthermore, this tolerance was significantly dampened following proteinase K treatment. These data suggest that H. pylori adapts its phenotype during biofilm growth resulting in decreased antibiotic susceptibility but this tolerance can be partially ameliorated by extracellular protease treatment.

RevDate: 2020-07-03

Li C, Gu Z, Zhu S, et al (2020)

17β-Estradiol removal routes by moving bed biofilm reactors (MBBRs) under various C/N ratios.

The Science of the total environment, 741:140381 pii:S0048-9697(20)33903-6 [Epub ahead of print].

This study evaluated the contribution of biotic and abiotic routes to the 17β-estradiol (E2) removal in moving bed biofilm reactors (MBBRs), and uncovered the interrelation between the E2 removal routes and biofilm characteristics, which was not researched in previous literature. Three MBBRs with different C/N ratios (0 for C/N0; 2 for C/N2; and 5 for C/N5) were operated in continuous mode. A 65-day degradation demonstrated that the MBBRs had high potential to remove E2 regardless of the C/N (E2 removal greater than 99% for all MBBRs; P > 0.05). Further batch tests showed that the E2 removal mainly resulted from heterotrophic activities for all MBBRs, accounting for approximately 85% for all MBBRs (P > 0.05), followed by nitrification (10-11%) and adsorption (4-5%). Importantly, lower adhesive force likely led to higher E2 adsorption onto biofilms. Besides, enhanced ammonia oxidizing rate (AOR) was consistent with the high contribution of nitrification to the E2 attenuation. Importantly, heterotrophic activity was positively correlated with its contribution to E2 removal (r = 0.99, P < 0.05). To sum, the results obtained in this study helped to understand the E2 removal routes in nitrifying biofilm systems.

RevDate: 2020-07-03

Tang K, Ooi GTH, Torresi E, et al (2020)

Municipal wastewater treatment targeting pharmaceuticals by a pilot-scale hybrid attached biofilm and activated sludge system (Hybas™).

Chemosphere, 259:127397 pii:S0045-6535(20)31591-5 [Epub ahead of print].

A hybrid wastewater treatment process with combined attached biofilm (moving bed biofilm reactor) and activated sludge, named as Hybas™, was implemented for the treatment of municipal wastewater. The system consisted of six staged reactors in series including pre-denitrification and nitrification in the Hybas™ line and post-denitrification in a pure MBBR. In addition to the significant removal of nutrients and organic matter from municipal wastewater, Hybas™ also showed removal capacity for pharmaceuticals. Of particular interest was the enhanced removal for pharmaceuticals (i.e. X-ray contrast media) compared to other biological systems. Spiking experiments showed that the maximum removal rate constants (k, h-1) for 10 out of the 21 investigated pharmaceuticals (including diclofenac) were observed to occur within the two aerobic Hybas ™ reactors, operated in a flow-shifting mode that allows even biofilm growth of nitrifying bacteria. In total, 14 out of the 21 pharmaceuticals were removed by more than 50% during continuous flow operation in the all Hybas™ line and post-denitrification MBBR. The calculated and estimated removal contributions of pharmaceuticals by each individual reactor were also assessed.

RevDate: 2020-06-29

Ismail NS, Subbiah SK, NM Taib (2020)

Application of Phenotype Microarray for Profiling Carbon Sources Utilization between Biofilm and Non-Biofilm of Clinical Isolates Pseudomonas aeruginosa.

Current pharmaceutical biotechnology pii:CPB-EPUB-107768 [Epub ahead of print].

Pseudomonas aeruginosa a gram-negative bacterium with high versatility that can undergo aerobic and anaerobic respiration. Capabilities in deploying different carbon sources, energy metabolism, and regulatory system, ensure the survival of this microorganism in the diverse environmental conditions. Determination of differences in carbon sources utilization among biofilm and non-biofilm of P. aeruginosa provides a platform in understanding the metabolic activities of the microorganism. Three archived clinical isolates of strong, moderate, and non-biofilm producers were identified. ATCC 27853 P. aeruginosa was used as a negative control or non-biofilm producing microorganism. Biofilm formation of ATCC 27853 P. aeruginosa was confirmed by crystal violet assay (CVA) and Congo red agar (CRA). Metabolic profiles of the biofilm and non-biofilms isolates were determined by phenotype microarrays (Biolog Omnilog). In this study, the biofilm isolates utilized uridine, threonine, and serine while non-biofilm isolates utilized adenosine, inosine, monomethyl, sorbic acid, and succinamic acid. Sugar utilization was seen between the isolates adhering that biofilm P. aeruginosa preferred glucoside, galactoside, glucuronide, glucosaminide, mannoside, and galactosaminide, but it was not utilized by the non-biofilm. The outcome of this result can be used for future studies to improve detection or inhibition of the growth of clinical P. aeruginosa biofilm and non-biofilm, respectively.

RevDate: 2020-06-30

Pettersson S, Ahnoff M, Edin F, et al (2020)

A Hydrogel Drink With High Fructose Content Generates Higher Exogenous Carbohydrate Oxidation and Lower Dental Biofilm pH Compared to Two Other, Commercially Available, Carbohydrate Sports Drinks.

Frontiers in nutrition, 7:88.

The purpose of this study was to evaluate the substrate oxidation of three commercially available, 14%-carbohydrate sports drinks with different compositions, osmolality, and pH for their impact on dental exposure to low pH. In a cross-over, randomized double-blinded design, 12 endurance athletes (age 31. 2 ± 7.7 years, V ˙ O2max 65.6 ± 5.0 mL·kg-1) completed 180 min of cycling at 55% Wmax. During the first 100 min of cycling, athletes consumed amylopectin starch (AP), maltodextrin+sucrose (MD+SUC), or maltodextrin+fructose hydrogel (MD+FRU) drinks providing 95 g carbohydrate·h-1, followed by water intake only at 120 and 160 min. Fuel use was determined using indirect calorimetry and stable-isotope techniques. Additionally, dental biofilm pH was measured using the microtouch method in a subsample of participants (n = 6) during resting conditions before, and at different time intervals up to 45 min following a single bolus of drink. Exogenous carbohydrate oxidation (CHOEXO) during the 2nd hour of exercise was significantly (P < 0.05) different between all three drinks: MD+FRU (1.17 ± 0.17 g·min-1), MD+SUC (1.01 ± 0.13 g·min-1), and AP (0.84 ± 0.11 g·min-1). At the end of exercise, CHOEXO and blood glucose concentrations (3.54 ± 0.50, 4.07 ± 0.67, and 4.28 ± 0.47 mmol·L-1, respectively) were significantly lower post MD+FRU consumption than post MD+SUC and AP consumption (P < 0.05). Biofilm acidogenicity at rest demonstrated a less pronounced pH fall for MD+FRU compared to the acidulant-containing MD+SUC and AP (P < 0.05). In conclusion, while total intake of MD+FRU showed signs of completed uptake before end of monitoring, this was less so for MD+SUC, and not at all the case for AP. Thus, this study showed that despite carbohydrates being encapsulated in a hydrogel, a higher CHOEXO was observed following MD+FRU drink ingestion compared to AP and MD+SUC consumption upon exposure to the acidic environment of the stomach. This finding may be related to the higher fructose content of the MD+FRU drink compared with the MD+SUC and AP drinks. Furthermore, a carbohydrate solution without added acidulants, which are commonly included in commercial sport drinks, may have less deleterious effects on oral health.

RevDate: 2020-06-30

Hu D, Zou L, Yu W, et al (2020)

Relief of Biofilm Hypoxia Using an Oxygen Nanocarrier: A New Paradigm for Enhanced Antibiotic Therapy.

Advanced science (Weinheim, Baden-Wurttemberg, Germany), 7(12):2000398.

Biofilms are chief culprits of most intractable infections and pose great threats to human health. Conventional antibiotic therapies are hypodynamic to biofilms due to their strong drug resistance, closely related with biofilm hypoxia. A new strategy for enhanced antibiotic therapy by relieving biofilm hypoxia is reported here. A two-step sequential delivery strategy is fabricated using perfluorohexane (PFH)-loaded liposomes (lip) as oxygen (O2) carriers (denoted as lip@PFH@O2) and commercial antibiotics. The results indicate that the two-step sequential treatment exhibits much lower minimum bactericidal concentrations than the antibiotic treatment alone. In this design, the lip@PFH@O2 holds positively charged surface for better biofilm penetration. After penetrating into biofilm, oxygen can be released from lip@PFH@O2 by inches, which greatly relieves biofilm hypoxia. With the relief of hypoxia, the quorum sensing and the drug efflux pumps of bacteria are suppressed by restraining related gene expression, leading to the reduced antibiotic resistance. Furthermore, the in vivo experimental results also demonstrate that lip@PFH@O2 can effectively relieve biofilm hypoxia and enhance therapeutic efficacy of antibiotics. As a proof-of-concept, this research provides an innovative strategy for enhanced antibiotic therapy by relieving hypoxia, which may hold a bright future in combating biofilm-associated infections.

RevDate: 2020-06-30

Hakimi Alni R, Ghorban K, M Dadmanesh (2020)

Combined effects of Allium sativum and Cuminum cyminum essential oils on planktonic and biofilm forms of Salmonella typhimurium isolates.

3 Biotech, 10(7):315.

Salmonella typhimurium (S. typhimurium) represents an important global public health problem and has the ability to survive under desiccation conditions in foods and food processing facilities for years. The aim of this study was to investigate the effects of Allium sativum (A. sativum) and Cuminum cyminum (C. cyminum) essential oils (EOs) against planktonic growth, biofilm formation and quorum sensing (QS) of S. Typhimurium isolates, the strong biofilm producers. The major components of EOs were determined by gas chromatography-mass spectrometry (GC-MS). Biofilm formation of S. Typhimurium isolates was measured by crystal violet staining. Then, the effects of the EOs on the planktonic cell growth (using determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)), measurement of the synergistic effects of EOs (using checkerboard method), biofilm formation (using microtiter-plate test and scanning electron microscope (SEM)), and expression of QS and cellulose synthesis genes (using quantitative real-time PCR) were assessed. Finally, tetrazolium-based colorimetric (MTT) assay was used to examine EOs cytotoxicity on the Vero cell line. GC-MS analysis showed that terpineol, carene and pinene in C. cyminum EO and sulfur compounds in A. sativum EO were the major components of the plant extract. The Geometric mean of MIC values of the A. sativum and C. cyminum were 0.66 and 2.62 μL mL-1, respectively. The geometric means of the fractional inhibitory concentration index (FICi) for both EOs were calculated as 1.05. The qPCR results showed that MIC/2 concentrations of both EOs significantly down-regulated of QS (sdiA and luxS) and cellulose synthesis (csgD and adrA) genes. Scanning electron microscopy showed the EOs reduced the amount of S. Typhimurium mature biofilm. In general, we showed that C. cyminum and A. sativum EOs can be considered as the potential agents against planktonic and biofilm form of S. Typhimurium without any concern of cytotoxic effect at 4 MIC concentrations on the eukaryotic Vero cells.

RevDate: 2020-06-30

Cui P, Feng L, Zhang L, et al (2020)

Antimicrobial Resistance, Virulence Genes, and Biofilm Formation Capacity Among Enterococcus species From Yaks in Aba Tibetan Autonomous Prefecture, China.

Frontiers in microbiology, 11:1250.

Yaks provide necessities such as meat and milk for Tibetans living at high altitudes on and around the Qinghai-Tibetan Plateau. Enterococci are ubiquitous members of the animal gut microbiota that can cause biofilm-associated opportunistic infections. Meanwhile, multidrug-resistant Enterococcus also poses a serious threat to public health. This study aims to characterize antibiotic resistance, virulence genes, and biofilm formation of enterococci from yaks. From April 2018 to July 2019, we collected 395 fecal samples of yaks in Aba Tibetan Autonomous Prefecture, China. Enterococci isolated from the samples were identified and classified according to the 16S rDNA sequence. The antibiotic resistance of each isolate was detected according to the Kirby-Bauer disk diffusion method, and antibiotic resistance genes were detected by polymerase chain reaction (PCR) and sequencing. Enterococcal biofilms were assessed using standard procedures. Different virulence genes were detected by PCR and sequencing. In total, 381 enterococci strains were recovered, with Enterococcus faecalis (41.99%) and Enterococcus faecium (37.80%) being the predominant species. Many isolates were multidrug- resistant (60.37%) and showed a high resistance rate to rifampicin (64.30%) and tetracycline (61.54%). We also detected various antimicrobial resistance (AMR) genes in the tested strains. The E. faecalis strains had higher frequency of biofilm formation and virulence genes than other enterococcal species. This is the first report that shows yaks are repositories for drug-resistant enterococci with virulent determinants and biofilms that may spread into humans and to environment. This study also provides useful data suggesting that enterococci may pose a potential health risk to yaks. Therefore, active surveillance of AMR and pathogenesis in enterococci from yaks is urgently warranted.

RevDate: 2020-06-29

Cherdvorapong V, Panti N, Suyotha W, et al (2020)

Prevention of oral biofilm formation and degradation of biofilm by recombinant α-1,3-glucanases from Streptomyces thermodiastaticus HF3-3.

The Journal of general and applied microbiology [Epub ahead of print].

The genes encoding α-1,3-glucanases (Agls; AglST1 and AglST2) from Streptomyces thermodiastaticus HF3-3 were cloned and were then expressed in Escherichia coli Rosetta-gami B (DE3). We purified the resultant histidine (His)-tagged α-1,3-glucanases (recombinant enzymes, rAglST1 and rAglST2). Both the recombinant enzymes were similar to the wild-type enzymes. We examined the effects of rAglST1 and rAglST2 on the formation and degradation of biofilms on glass plates with Streptococcus mutans NRBC 13955 by evaluating the biofilm content (%), release of reducing sugar (mM), release of S. mutans (log CFU/mL), and the biofilm structure using laser scanning microscopy (LSM). The results showed that after incubation for 16 h, rAglST1 and rAglST2 reduced the formation of biofilm to 52% and 49% of the control, respectively. The result may reflect the fact that the concentration of the reducing sugar and the number of S. mutans cells in the rAglATs-added medium were higher than in the control medium. After an 8-h treatment with rAglST1 and rAglST2, biofilms decreased to less than 60% of the control. The number of S. mutans cells in the reaction mixture gradually increased during the incubation period. The enzymes can degrade the biofilms that were pre-formed on the glass plate by more than 50% after a 30-min incubation in the presence of toothpaste ingredients (1% w/v of sodium fluoride, benzethonium chloride, and sodium dodecyl sulfate) at 50°C. Our study showed that rAglST1 and rAglST2 have advantageous properties for dental care applications.

RevDate: 2020-06-29

Huang C, Liu LZ, Kong HK, et al (2020)

A novel incompatibility group X3 plasmid carrying blaNDM-1 encodes a small RNA that regulates host fucose metabolism and biofilm formation.

RNA biology [Epub ahead of print].

The emergence of New Delhi metallo-beta-lactamase (NDM-1) has become a major health threat to clinical managements of gram-negative bacteria infections. A novel incompatibility group X3 plasmid (IncX3) pNDM-HN380 carrying blaNDM-1 has recently been found to epidemiologically link with multiple geographical areas in China. In this paper, we studied the metabolic responses of host bacteria E. coli J53 upon introduction of pNDM-HN380. A reduction of bacterial motility was observed in J53/pNDM-HN380. We profiled the RNA repertoires of the transconjugants and found a downregulation of genes involved in flagella and chemotaxis metabolic pathways at logarithmic (log) phase. We also identified a novel intragenic region (IGR) small RNA plas2. The plasmid-transcribed sRNA IGR plas2 was further characterized as a regulator of fucRwhich controls the fucose metabolism. By knockdown of IGR plas2 using an antisense decoy, we managed to inhibit the formation of bacterial biofilm of the host. Our study demonstrated a potential way of utilizing plasmid-transcribed sRNA against infectious bacteria.

RevDate: 2020-06-28

Zeng M, Yang J, Wu Z, et al (2020)

Achieving single-stage autotrophic nitrogen removal by composite membrane aerated biofilm with gel under two microbial entrapping patterns: experimental and modeling aspects.

Environmental science and pollution research international pii:10.1007/s11356-020-09660-w [Epub ahead of print].

Single-stage autotrophic nitrogen removal offers advantages of low energy and carbon consumptions. Based on previous work about a novel composite membrane aerated biofilm (CMAB), two microbial entrapping patterns (mixed and stratified patterns) were evaluated for their applicability to artificially regulate the spatial distribution of distinct microbial aggregates for single-stage autotrophic nitrogen removal. Experimental results showed that the stratified pattern caused little accumulation of NO2- and NO3-, which leads to a superior nitrogen removal performance compared with the mixed pattern. Candidatus Kuenenia was found to be the major anammox bacterium in the gel film of the mixed pattern and the outer film of the stratified pattern. In contrast, Nitrosomonas, as a representative genus of ammonia-oxidizing bacteria, was substantially enriched in the inner film of the stratified pattern and the gel film of the mixed pattern. Finally, modeling results further confirmed the advantages of the stratified pattern with respect to the formation of rational microbial and nutrient profiles in gel films. The ratio of partial nitrification and anammox film thicknesses should remain below 3:2 to obtain a high fraction of anammox bacteria and to avoid NO2- accumulation. Increasing O2 surface loading does not affect microbial profiles, but can greatly promote the TN removal performance only in the stratified pattern. Overall, the stratified pattern should be employed to achieve optimal microbial profiles and nitrogen removal efficiency.

RevDate: 2020-07-03

Gao L, Han F, Zhang X, et al (2020)

Simultaneous nitrate and dissolved organic matter removal from wastewater treatment plant effluent in a solid-phase denitrification biofilm reactor.

Bioresource technology, 314:123714 pii:S0960-8524(20)30986-X [Epub ahead of print].

In the present study, an up-flow solid-phase denitrification biofilm reactor (US-DBR) was established for simultaneous nitrate and dissolved organic matter (DOM) removal from wastewater treatment plant effluent. After 100 days operation, the nitrate and COD removal efficiencies were high of 97% and 80%, respectively. According to EEM-FRI analysis, aromatic and tryptophan protein-like, humic-like and fulvic acid-like substances were identified in DOM. Additionally, protein-like substances in DOM components were much easier transformed as carbon source for denitrification. Moreover, protein secondary structure of DOM changed significantly due to the biodegradation and microorganisms metabolic process. High-throughput sequencing analysis implied that Simplicispira, Diaphorobacter, Hydrogenophaga, Pseudoxanthmonas and Stenotrophomonas were the dominate genera in the whole of US-DBR, that were responsible for the removal of nitrate, organics and degradation of solid carbon source, respectively. This study provided a further biological basis about practical application of solid-phase denitrification for simultaneously remove nitrate and organic matter.

RevDate: 2020-06-28

Sorkhdini P, Gregory RL, Crystal YO, et al (2020)

Effectiveness of In Vitro Primary Coronal Caries Prevention with Silver Diamine Fluoride - chemical vs biofilm models.

Journal of dentistry pii:S0300-5712(20)30164-0 [Epub ahead of print].

OBJECTIVES: The main goal of this study was to investigate the effectiveness of SDF and its individual components, silver (Ag+) and fluoride (F-) ions, in preventing enamel demineralization using biofilm and chemical models.

METHODES: Polished human enamel specimens were assigned to five treatment groups (n = 18 per group): SDF (38%); SDF followed by application of a saturated solution of potassium iodide (SDF + KI); silver nitrate (AgNO3; silver control, 253,900 ppm Ag+); potassium fluoride (KF; fluoride control, 44,800 ppm F); deionized water (DIW). Treatments were applied once to sound enamel. In the biofilm model, specimens were demineralized by aerobic overnight incubation using cariogenic bacteria isolated from human saliva in brain heart infusion supplemented with 0.2% sucrose for three days. In the chemical model, enamel specimens were immersed in a demineralizing solution containing 0.1 M lactic acid, 4.1 mM CaCl2, 8.0 mM KH2PO4, 0.2% Carbopol 907, pH adjusted to 5.0 for five days. Vickers surface microhardness was used to determine the extent of enamel demineralization. Data were analyzed using one-way ANOVA.

RESULTS: In the chemical model, there was no statistically significant difference between SDF and SDF + KI in preventing coronal caries (p < 0.0001). In the biofilm model, SDF + KI was significantly less effective in preventing demineralization than SDF (p < 0.0001). In both models, SDF and SDF + KI were superior in their ability to prevent caries lesion formation than AgNO3 and DIW.

CONCLUSION: KI application after SDF treatment appears to impair SDF's ability to prevent biofilm-mediated but not chemically induced demineralization.

CLINICAL SIGNIFICANCE: SDF may be a viable option in preventing primary coronal caries.

RevDate: 2020-07-03

Xiang Y, Shao Z, Chai H, et al (2020)

Functional microorganisms and enzymes related nitrogen cycle in the biofilm performing simultaneous nitrification and denitrification.

Bioresource technology, 314:123697 pii:S0960-8524(20)30969-X [Epub ahead of print].

Simultaneous nitrification and denitrification (SND) is a potential energy-saving process in wastewater treatment while the nitrogen removal mechanism is still unclear due to the lack of information about the functional microbes and enzymes. Sequencing batch biofilm reactors were implemented to achieve efficient SND. Eight nitrogen removal related microorganisms out of the top abundant 20 microbial community and reference species were used to construct a phylogenetic tree. Functional enzymes and modules analysis were investigated to reveal the SND pathway: in the aerobic part of the biofilm, ammonia oxidation was catalyzed by complete ammonia oxidizers while in the inner anoxic part, denitrification, dissimilatory nitrate reduction (DNRA) and nitrogen fixation (NF) cooperated to stimulate nitrate removal. These results provide a practical aeration control strategy to achieve SND and indicate that DNRA and NF are important nitrogen removal pathways that should not be ignored in the SND mechanism.

RevDate: 2020-07-01

Kato K, Tamura K, Y Shimazaki (2020)

Oral biofilm uptake of mineral ions released from experimental toothpaste containing surface pre-reacted glass-ionomer (S-PRG) filler.

Archives of oral biology, 117:104777 pii:S0003-9969(20)30155-2 [Epub ahead of print].

OBJECTIVE: To clarify the fluoride/mineral kinetics in an oral biofilm following concurrent application of fluoride and other mineral ions released from experimental toothpaste containing S-PRG filler using depth-specific analysis.

STUDY DESIGN: Twenty subjects wore in situ plaque-generating devices, comprised of a pair of enamel slabs, and a biofilm was allowed to form. The devices were removed after three days, immersed in the toothpaste filtrate containing Al, B, Sr and F ions for 1 min, and then reinserted at the same location. After 30 min, the devices were removed and samples were obtained by sectioning into outer, middle and inner biofilm layers (300-μm thick). Samples treated with filtrate containing F without S-PRG filler extract served as the control. Fluoride and the three other mineral ions extracted from 4-μm sections were quantified using a fluoride electrode and ICP-AES, respectively. The results were corrected for biomass volume, estimated by the area measurement of stained 2-μm sections.

RESULTS: The mean uptake ratios (S-PRG/control, ng/mm3) of Al, B, Sr and F were 186.6/53.7, 58.4/25.0, 456.9/125.7 and 43.6/12.0, respectively, in the outer layer, indicating that the mineral ions could easily diffuse into the biofilm. F concentrations in the outer biofilm treated using filtrate with S-PRG filler extract were significantly higher than those in controls, although both biofilms were exposed to filtrates containing the same level of F.

CONCLUSIONS: The results suggest that toothpaste containing S-PRG filler promotes fluoride retention in oral biofilms via the uptake of other mineral ions.

RevDate: 2020-06-27

Braga AS, de Melo Simas LL, Pires JG, et al (2020)

Antibiofilm and anti-caries effects of an experimental mouth rinse containing Matricaria chamomilla L. extract under microcosm biofilm on enamel.

Journal of dentistry pii:S0300-5712(20)30161-5 [Epub ahead of print].

OBJECTIVE: This study evaluated the antibiofilm and anti-caries effects of an experimental mouth rinse containing aqueous extract of Matricaria chamomilla L.

METHODS: Microcosm biofilm was produced on bovine enamel, from pooled human saliva mixed with McBain saliva, under 0.2 % sucrose exposure, for 5 days. The biofilm was daily treated using (1 mL/1 min): Vochysia tucanorum Mart. (2.5 mg/mL); Myrcia bella Cambess. (1.25 mg/mL); Matricaria chamomilla L. (20 mg/mL); Malva sylvestris (Malvatricin® Plus-Daudt); 0.12 % Chlorhexidine (PerioGard®-Palmolive, Positive control) and PBS (Negative control). The % dead bacteria, biofilm thickness, EPS biovolume, lactic acid concentration, the CFU counting (total microorganisms, Lactobacillus sp., total streptococci and Streptococcus mutans/S. sobrinus) were determined. Enamel demineralization was measured by TMR.

RESULTS: All mouth rinses induced bacterial death compared to PBS (p < 0.0001). The biofilm thickness varied from 12 ± 2 µm (chlorhexidine) to 18 ± 2 µm (V. tucanorum) (ANOVA/Tukey, p < 0.0001). The EPS biovolume varied from 7(4)% (chlorhexidine) to 30(20)% (PBS) (Kruskal-Wallis/Dunn, p < 0.0001). The lactic acid production was reduced by M. sylvestris (1.1 ± 0.2 g/L) and chlorhexidine (0.6 ± 0.2 g/L) compared to PBS (2.6 ± 1.3 g/L) (ANOVA, p < 0.0001). Malva sylvestris and chlorhexidine showed significant low CFU for total microorganisms, Lactobacillus sp. and total streptococci. Only chlorhexidine significantly reduced S. mutans/S. sobrinus. CFUs for total streptococci and Lactobacillus sp, were also significantly reduced by M. chamomilla L. Malva sylvestris (63.4 % of mineral loss reduction), chlorhexidine (47.4 %) and M. chamomilla L. (39.4 %) significantly reduced enamel demineralization compared to PBS (ANOVA/Tukey, p < 0.0001).

CONCLUSION: M. chamomilla L. has lower antibiofilm action, but comparable anti-caries effect to those found for chlorhexidine, under this model.

CLINICAL RELEVANCE: This study shows that the antibiofilm and anti-caries potential may vary between the commercial and experimental mouth rinses containing natural agents, with promising results for those containing Matricaria chamomilla L. and Malva Sylvestris.

RevDate: 2020-06-29

Koşarsoy Ağçeli G, N Cihangir (2020)

Nano-sized biopolymer levan: Its antimicrobial, anti-biofilm and anti-cancer effects.

Carbohydrate research, 494:108068 pii:S0008-6215(20)30214-7 [Epub ahead of print].

Among other polysaccharides, levan is a fructan with great potential in biotechnological applications due to its functional properties. The levan has only been available in small quantities because of its high cost. Here, a levan-producing microorganism was isolated from soil and identified as Pseudomonas mandelii. TGA, SEM, FTIR, 1H NMR, 13C NMR and Zetasizer analyses were used to characterize thermal properties and the morphology of the levan. It is the first time, the levan synthesized from P. mandelii is reported as nano sized. The culture conditions were optimized. It is the most comprehensive optimization study regarding levan production of P. mandelii up to the present. The optimum conditions found for levan production were 37 °C, at pH 8, under static conditions, with 15% sucrose and 1.5% mannitol as the C sources and yeast extract as the N source. In addition, the levan production yield was calculated at optimum conditions. Antibacterial activity of levan was evaluated against bacteria and the largest zone of inhibition was observed against E. coli at a concentration of 1000 μg/mL. Antibiofilm activity of levan was evaluated, and we found that all levan concentrations inhibited biofilm formation of all microorganisms in the study. We have shown that the levan from Pseudomonas mandelii induce cytotoxicity breast (MCF-7) cells in a dose-dependent manner.

RevDate: 2020-06-26

Wang S, Breslawec AP, Li C, et al (2020)

A Colorimetric Assay to Enable High-Throughput Identification of Biofilm Exopolysaccharide-Hydrolyzing Enzymes.

Chemistry (Weinheim an der Bergstrasse, Germany) [Epub ahead of print].

Glycosidase enzymes that hydrolyze the biofilm exopolysaccharide poly-ß-(1,6)-N-acetylglucosamine (PNAG) are critical tools to study biofilm and potential therapeutic biofilm dispersal agents. Function-driven metagenomic screening is a powerful approach for discovery of new glycosidase but requires sensitive assays capable of distinguishing between the desired enzyme and functionally related enzymes. Here, we report the synthesis of a colorimetric PNAG disaccharide analog whose hydrolysis by PNAG glycosidases results in production of para-nitroaniline that can be continuously monitored at 410 nm. The assay is specific for enzymes capable of hydrolyzing PNAG and not related ß-hexosaminidase enzymes with alternative glycosidic linkage specificities. This analog enabled development of a continuous colorimetric assay for detection of PNAG hydrolyzing enzyme activity in crude E. coli cell lysates and suggest that this disaccharide probe will be critical for establishing the functional screening of metagenomic DNA libraries.

RevDate: 2020-06-26

Kang J, Liu L, Liu Y, et al (2020)

Ferulic Acid Inactivates Shigella flexneri through Cell Membrane Destructieon, Biofilm Retardation, and Altered Gene Expression.

Journal of agricultural and food chemistry [Epub ahead of print].

Antibiotic resistance and capacity for biofilm formation of Shigella flexneri render previous prevention and control strategies minimally effective. Ferulic acid (FA) has been demonstrated to be useful due to its application in foods as an alternative natural preservative. However, information regarding the S. flexneri phenotype and molecular responses to FA exposure is limited. The present study investigated the effects of FA on S. flexneri planktonic growth and biofilm formation. The results demonstrated that the cell membrane of S. flexneri in planktonic growth mode exhibited irreversible destruction after FA exposure, as characterized by decreased cell viability, leakage of cytoplasmic constituents, accelerated adenosine triphosphate (ATP) consumption, cell membrane depolarization, and cellular morphological changes. FA significantly inhibited S. flexneri adhesion and biofilm formation at a working concentration (1/8 MIC) that almost did not inhibit planktonic growth. Transcriptomics profiling showed that the exposure to a subinhibitory concentration of FA dramatically altered gene expression in the S. flexneri biofilm, as a total of 169 differentially expressed genes (DEGs) were upregulated and 533 DEGs were downregulated, compared to the intact biofilm. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the DEGs were mainly involved in pathways of ribosomes, ABC transporters, and the citrate cycle. Furthermore, we show that FA altered the transcription of S. flexneri genes associated with adhesion, transcriptional regulation, and the synthesis and transport of extracellular polymeric substances that contribute to biofilm formation. These data provide novel insights into S. flexneri behavioral responses to FA exposure and suggest that FA could effectively constrain S. flexneri and its biofilm formation.

RevDate: 2020-06-26

Parlak O, A Richter-Dahlfors (2020)

Bacterial Sensing and Biofilm Monitoring for Infection Diagnostics.

Macromolecular bioscience [Epub ahead of print].

Recent insights into the rapidly emerging field of bacterial sensing and biofilm monitoring for infection diagnostics are discussed as well as recent key developments and emerging technologies in the field. Electrochemical sensing of bacteria and bacterial biofilm via synthetic, natural, and engineered recognition, as well as direct redox-sensing approaches via algorithm-based optical sensing, and tailor-made optotracing technology are discussed. These technologies are highlighted to answer the very critical question: "how can fast and accurate bacterial sensing and biofilm monitoring be achieved? Following on from that: "how can these different sensing concepts be translated for use in infection diagnostics? A central obstacle to this transformation is the absence of direct and fast analysis methods that provide high-throughput results and bio-interfaces that can control and regulate the means of communication between biological and electronic systems. Here, the overall progress made to date in building such translational efforts at the level of an individual bacterial cell to a bacterial community is discussed.

RevDate: 2020-06-29

do Nascimento Dias J, de Souza Silva C, de Araújo AR, et al (2020)

Mechanisms of action of antimicrobial peptides ToAP2 and NDBP-5.7 against Candida albicans planktonic and biofilm cells.

Scientific reports, 10(1):10327.

Candida albicans is a major cause of human infections, ranging from relatively simple to treat skin and mucosal diseases to systemic life-threatening invasive candidiasis. Fungal infections treatment faces three major challenges: the limited number of therapeutic options, the toxicity of the available drugs, and the rise of antifungal resistance. In this study, we demonstrate the antifungal activity and mechanism of action of peptides ToAP2 and NDBP-5.7 against planktonic cells and biofilms of C. albicans. Both peptides were active against C. albicans cells; however, ToAP2 was more active and produced more pronounced effects on fungal cells. Both peptides affected C. albicans membrane permeability and produced changes in fungal cell morphology, such as deformations in the cell wall and disruption of ultracellular organization. Both peptides showed synergism with amphotericin B, while ToAP2 also presents a synergic effect with fluconazole. Besides, ToAP2 (6.25 µM.) was able to inhibit filamentation after 24 h of treatment and was active against both the early phase and mature biofilms of C. albicans. Finally, ToAP2 was protective in a Galleria mellonella model of infection. Altogether these results point to the therapeutic potential of ToAP2 and other antimicrobial peptides in the development of new therapies for C. albicans infections.

RevDate: 2020-06-26

Kannappan A, Durgadevi R, Srinivasan R, et al (2020)

2-Hydroxy-4-methoxybenzaldehyde from Hemidesmus indicus is antagonistic to Staphylococcus epidermidis biofilm formation.

Biofouling [Epub ahead of print].

Staphylococcus epidermidis (SE) is an opportunistic nosocomial pathogen that accounts for recalcitrant device-related infections worldwide. Owing to the growing interest in plants and their secondary metabolites targeting bacterial adhesion, this study was intended to uncover the anti-biofilm potential of Hemidesmus indicus and its major constituent 2-hydroxy-4-methoxybenzaldehyde (HMB) against SE. The minimum biofilm inhibitory concentration (MBIC) of H. indicus root extract and HMB were found to be 500 and 250 µg ml-1, respectively. The results of time-dependent biofilm inhibition and mature biofilm disruption assays confirmed that HMB targets initial cell adhesion. Furthermore, interference by HMB in the expression of adhesin genes (icaA, aap and bhp) and biofilm components was associated with an increased susceptibility of SE to oxidative stress and antibiotics. To conclude, this study reports for the first time HMB as a potential drug against SE biofilms.

RevDate: 2020-06-26

Szymczyk-Ziółkowska P, Hoppe V, Rusińska M, et al (2020)

The Impact of EBM-Manufactured Ti6Al4V ELI Alloy Surface Modifications on Cytotoxicity toward Eukaryotic Cells and Microbial Biofilm Formation.

Materials (Basel, Switzerland), 13(12): pii:ma13122822.

Electron beam melting (EBM) is an additive manufacturing technique, which allows forming customized implants that perfectly fit the loss of the anatomical structure of bone. Implantation efficiency depends not only on the implant's functional or mechanical properties but also on its surface properties, which are of great importance with regard to such biological processes as bone regeneration or microbial contamination. This work presents the impact of surface modifications (mechanical polishing, sandblasting, and acid-polishing) of EBM-produced Ti6Al4V ELI implants on essential biological parameters. These include wettability, cytotoxicity toward fibroblast and osteoblast cell line, and ability to form biofilm by Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Obtained results indicated that all prepared surfaces exhibited hydrophilic character and the highest changes of wettability were obtained by chemical modification. All implants displayed no cytotoxicity against osteoblast and fibroblast cell lines regardless of the modification type. In turn, the quantitative microbiological tests and visualization of microbial biofilm by means of electron microscopy showed that type of implant's modification correlated with the species-specific ability of microbes to form biofilm on it. Thus, the results of the presented study confirm the relationship between such technological aspects as surface modification and biological properties. The provided data are useful with regard to applications of the EBM technology and present a significant step towards personalized, customized implantology practice.

RevDate: 2020-07-01

Dornelas Figueira LM, Ricomini Filho AP, da Silva WJ, et al (2020)

Glucose effect on Candida albicans biofilm during tissue invasion.

Archives of oral biology, 117:104728 pii:S0003-9969(20)30106-0 [Epub ahead of print].

OBJECTIVE: To evaluate, in vitro, the effect of two glucose concentrations (0.1 mM and 1.0 mM, simulating glucose concentration in saliva of healthy and diabetic individuals) on Candida albicans biofilm grown on epithelial monolayer.

MATERIAL AND METHODS: C. albicans was inoculated on epithelial monolayers supplemented with 0.1 mM, 1.0 mM or no glucose. Control groups without C. albicans were also evaluated. Tissue response was assessed through the production of Interleukin-1α, Interleukin-8, Interleukin-6, Interleukin-10 and tumor necrosis factor-α. The complex of monolayer and biofilms were evaluated by quantitative reverse transcription polymerase chain reaction for expression of E-cadherin (CDH1), Caspase-3 (CASP3), β-defensin-1 (DEFB-1) and β-defensin-3 (DEFB-3). The biofilm architecture was visualized by confocal laser scanning microscopy.

RESULTS: The production of Interleukin-1α and Interleukin-8 were increased in the presence of C. albicans (p < 0.05). Glucose did not interfere in the release of any cytokine evaluated. C. albicans downregulated transcripts for CDH1 (p < 0.05). Glucose did not induce a significant change in CDH1, CASP3, DEFB-1 and DEFB-3 messenger RNA expression. The biofilms were more structured in the presence of glucose, but no difference in the diffusion of hyphae through the epithelial cells were observed.

CONCLUSIONS: The data suggest that glucose concentration does not affect the behavior of C. albicans during tissue invasion and other mechanisms must be related to the greater susceptibility of diabetic individuals to candidiasis.

RevDate: 2020-07-01

Li Y, Liu X, Li B, et al (2020)

Near-Infrared Light Triggered Phototherapy and Immunotherapy for Elimination of Methicillin-Resistant Staphylococcus aureus Biofilm Infection on Bone Implant.

ACS nano [Epub ahead of print].

Clinically, methicillin-resistant Staphylococcus aureus (MRSA) biofilm infection inevitably induces the failure of bone implants. Herein, a hydrophilic and viscous hydrogel of poly(vinyl alcohol) modified with chitosan, polydopamine, and NO release donor was formed on a red phosphorus nanofilm deposited on a titanium implant (Ti-RP/PCP/RSNO). Under the irradiation of near-infrared light (NIR), peroxynitrite (•ONOO-) was formed by the reaction between the released NO and superoxide (•O2-) produced by the RP nanofilm. Specifically, we revealed the antibacterial mechanism of the ONOO- against the MRSA biofilm. In addition, osteogenic differentiation was promoted and inflammatory polarization was regulated by the released NO without NIR irradiation through upregulating the expression of Opn and Ocn genes and TNF-α. The MRSA biofilm was synergistically eradicated by •ONOO-, hyperthermia, and •O2- under NIR irradiation as well as the immunoreaction of the M1 polarization. The in vivo results also confirmed the excellent osteogenesis and biofilm eradication by released NO from the RP/PCP/RSNO system under NIR irradiation, indicating the noninvasive tissue reconstruction of MRSA-infected tissues through phototherapy and immunotherapy.

RevDate: 2020-06-25

Costa ACBP, Back-Brito GN, Mayer FL, et al (2020)

Candida albicans Mrv8, is involved in epithelial damage and biofilm formation.

FEMS yeast research pii:5862582 [Epub ahead of print].

Candida albicans is the most common human fungal pathogen that can cause superficial and deep-seated infections in susceptible individuals. Despite its medical importance, the vast majority of C. albicans genes remain of unknown function. Here we report a role for the lineage-specific gene, MRV8, in host pathogen interactions, mycelial microcolony maturation and biofilm formation. In silico analysis indicated that MRV8 encodes a four-pass transmembrane protein unique to the closely related pathogens C. albicans and Candida dubliniensis. Deletion of MRV8 did not affect C. albicans adherence to, or initial invasion into human oral epithelia, but inhibited mycelial development and strongly reduced epithelial damage. mrv8Δ/Δ cells exhibited a media-dependent defect in biofilm formation and mutant biofilm metabolic activity was enhanced by cyclosporin A. mrv8Δ/Δ biofilms were more tolerant to treatment with caspofungin, but not to fluconazole or amphotericin B. Co-stimulation with calcium chloride and calcofluor white rescued biofilm growth in the presence of caspofungin, and this rescue-effect was Mrv8-dependent. Together, our data demonstrate an important role for a lineage-specific gene (MRV8) in C. albicans biofilm formation, drug tolerance and host-pathogen interactions.

RevDate: 2020-06-25

Desch A, Freifrau von Maltzahn N, Stumpp N, et al (2020)

Biofilm formation on zirconia and titanium over time - an in vivo model study.

Clinical oral implants research [Epub ahead of print].

OBJECTIVES: The aim of this study was to evaluate volume, vitality and diversity of biofilms on the abutment materials zirconia and titanium as a function of time using an in vivo model for the biofilm formation.

MATERIALS AND METHODS: The development of biofilms on zirconia and titanium grade 4 test specimens in the human oral cavity over time was analysed. After pretreatment, a total of 96 titanium and 96 zirconia discs were fixed on 12 composite splints, which were worn by 12 volunteers. After 6 hours, 24 hours, 3 days and 5 days, biofilms on 48 specimens of each material were analysed with confocal laser scanning microscopy (CLSM). The microbiota composition on the other 48 test specimens was examined using full-length 16S sequence analysis. Statistical analysis was performed by SPSS and R, level of significance was set at 0.05.

RESULTS: CLSM analysis of the biofilms revealed significant changes in volume over time on zirconia and titanium. The material did not significantly influence the volume or live/dead ratio at the individual time points. The composition of the microbiome was influenced by the age of the biofilm, but not by the material of the test specimen. The most frequently found bacteria were Streptococcus spp., followed by Neisseria spp., Rothia spp., Haemophilus spp., Gemella spp. and Abiotrophia spp..

CONCLUSIONS: On both materials, the quantity and diversity of the microbiome increased over time. Apart from a slight difference in Veillonella abundance at one time point, there were no significant differences between zirconia and titanium.

RevDate: 2020-06-25

Kallscheuer N, Wiegand S, Boedeker C, et al (2020)

Caulifigura coniformis gen. nov., sp. nov., a novel member of the family Planctomycetaceae isolated from a red biofilm sampled in a hydrothermal area.

Antonie van Leeuwenhoek pii:10.1007/s10482-020-01439-w [Epub ahead of print].

Pan44T, a novel strain belonging to the phylum Planctomycetes, was isolated from a red biofilm in a hydrothermal area close to the island Panarea in the Tyrrhenian Sea north of Sicily, Italy. The strain forms white colonies on solid medium and displays the following characteristics: cell division by budding, formation of rosettes, presence of matrix or fimbriae and long stalks. The cell surface has an interesting and characteristic texture made up of triangles and rectangles, which leads to a pine cone-like morphology of the strain. Strain Pan44T is mesophilic (temperature optimum 26 °C), slightly alkaliphilic (pH optimum 8.0), aerobic and heterotrophic. The strain has a genome size of 6.76 Mb with a G + C content of 63.2%. Phylogenetically, the strain is a member of the family Planctomycetaceae, order Planctomycetales, class Planctomycetia. Our analysis supports delineation of strain Pan44T from all known genera in this family, hence, we propose to assign it to a novel species within a novel genus, for which we propose the name Caulifigura coniformis gen. nov., sp. nov., represented by Pan44T (DSM 29405T = LMG 29788T) as the type strain.

RevDate: 2020-06-27

Kim JH, Ruegger PR, Lebig EG, et al (2020)

High Levels of Oxidative Stress Create a Microenvironment That Significantly Decreases the Diversity of the Microbiota in Diabetic Chronic Wounds and Promotes Biofilm Formation.

Frontiers in cellular and infection microbiology, 10:259.

Diabetics chronic wounds are characterized by high levels of oxidative stress (OS) and are often colonized by biofilm-forming bacteria that severely compromise healing and can result in amputation. However, little is known about the role of skin microbiota in wound healing and chronic wound development. We hypothesized that high OS levels lead to chronic wound development by promoting the colonization of biofilm-forming bacteria over commensal/beneficial bacteria. To test this hypothesis, we used our db/db-/- mouse model for chronic wounds where pathogenic biofilms develop naturally after induction of high OS immediately after wounding. We sequenced the bacterial rRNA internal transcribed spacer (ITS) gene of the wound microbiota from wound initiation to fully developed chronic wounds. Indicator species analysis, which considers a species' fidelity and specificity, was used to determine which bacterial species were strongly associated with healing wounds or chronic wounds. We found that healing wounds were colonized by a diverse and dynamic bacterial microbiome that never developed biofilms even though biofilm-forming bacteria were present. Several clinically relevant species that are present in human chronic wounds, such as Cutibacterium acnes, Achromobacter sp., Delftia sp., and Escherichia coli, were highly associated with healing wounds. These bacteria may serve as bioindicators of healing and may actively participate in the processes of wound healing and preventing pathogenic bacteria from colonizing the wound. In contrast, chronic wounds, which had high levels of OS, had low bacterial diversity and were colonized by several clinically relevant, biofilm-forming bacteria such as Pseudomonas aeruginosa, Enterobacter cloacae, Corynebacterium frankenforstense, and Acinetobacter sp. We observed unique population trends: for example, P. aeruginosa associated with aggressive biofilm development, whereas Staphylococcus xylosus was only present early after injury. These findings show that high levels of OS in the wound significantly altered the bacterial wound microbiome, decreasing diversity and promoting the colonization of bacteria from the skin microbiota to form biofilm. In conclusion, bacteria associated with non-chronic or chronic wounds could function as bioindicators of healing or non-healing (chronicity), respectively. Moreover, a better understanding of bacterial interactions between pathogenic and beneficial bacteria within an evolving chronic wound microbiota may lead to better solutions for chronic wound management.

RevDate: 2020-06-26

Yan J, J Xie (2020)

Comparative Proteome Analysis of Shewanella putrefaciens WS13 Mature Biofilm Under Cold Stress.

Frontiers in microbiology, 11:1225.

Worldwide, Shewanella putrefaciens is the predominant seafood spoilage microorganism during cold storage. This bacterium can attach to biotic/abiotic surfaces to form biofilms which contribute to seafood quality degradation and shelf-life reduction. The mechanism of S. putrefaciens biofilm formation is not yet described. Crystal violet staining in combination with confocal laser scanning microscopy (CLSM) was used to study the sequence of events leading to the establishment of a mature biofilm at 4, 15, and 30°C. In addition, the main chemical constituents of the mature biofilm were determined by Raman spectroscopy (RM), whereas, comparative proteomic analysis was used to quantify changes in metabolic pathways and to find out underlying protein determinants. The physical dimensions of the mature biofilm, i.e., biomass, biovolume, and mean thickness, were higher at 4°C when compared to 15 and 30°C. The variations of proteins measured by RM confirmed the importance of proteins during the formation of a mature biofilm. Comparative proteomic analysis showed that siderophore and iron chelate transport proteins were down-regulated during mature biofilm formation. The down-regulated aforementioned proteins are involved in promoting iron storage in response to a higher demand for metabolic energy, whereas, the upregulated proteins of the sulfur relay system, pyrimidine metabolism, and purine metabolism are related to bacterial adaptability. Synthesis of proteins related to cold stress was increased and proteins involved in aminoacyl-tRNA biosynthesis were up-regulated, whereas, proteins involved in aminopeptidase activity were down-regulated. Proteolysis to scavenge energy was reduced as proteins involved in pyrophosphatase activity were up-regulated. Also extracellular eDNA was found which may play an important role in maintaining the stability of mature S. putrefaciens biofilm structures under cold stress. This work provides a better understanding of the role of proteins in mature biofilms. In addition, the biofilm formation mechanism of a psychrotrophic spoilage bacterial species at low temperature is explored, which may contribute to generating biofilm controlling strategies during seafood preservation and processing.

RevDate: 2020-06-26

Trego AC, Galvin E, Sweeney C, et al (2020)

Growth and Break-Up of Methanogenic Granules Suggests Mechanisms for Biofilm and Community Development.

Frontiers in microbiology, 11:1126.

Methanogenic sludge granules are densely packed, small, spherical biofilms found in anaerobic digesters used to treat industrial wastewaters, where they underpin efficient organic waste conversion and biogas production. Each granule theoretically houses representative microorganisms from all of the trophic groups implicated in the successive and interdependent reactions of the anaerobic digestion (AD) process. Information on exactly how methanogenic granules develop, and their eventual fate will be important for precision management of environmental biotechnologies. Granules from a full-scale bioreactor were size-separated into small (0.6-1 mm), medium (1-1.4 mm), and large (1.4-1.8 mm) size fractions. Twelve laboratory-scale bioreactors were operated using either small, medium, or large granules, or unfractionated sludge. After >50 days of operation, the granule size distribution in each of the small, medium, and large bioreactor sets had diversified beyond-to both bigger and smaller than-the size fraction used for inoculation. Interestingly, extra-small (XS; <0.6 mm) granules were observed, and retained in all of the bioreactors, suggesting the continuous nature of granulation, and/or the breakage of larger granules into XS bits. Moreover, evidence suggested that even granules with small diameters could break. "New" granules from each emerging size were analyzed by studying community structure based on high-throughput 16S rRNA gene sequencing. Methanobacterium, Aminobacterium, Propionibacteriaceae, and Desulfovibrio represented the majority of the community in new granules. H2-using, and not acetoclastic, methanogens appeared more important, and were associated with abundant syntrophic bacteria. Multivariate integration (MINT) analyses identified distinct discriminant taxa responsible for shaping the microbial communities in different-sized granules.

RevDate: 2020-06-26

Wu X, Zhang S, Li H, et al (2020)

Biofilm Formation of Candida albicans Facilitates Fungal Infiltration and Persister Cell Formation in Vaginal Candidiasis.

Frontiers in microbiology, 11:1117.

Background: Vaginal candidiasis is an important medical condition awaiting more effective treatment. How Candida albicans causes this disease and survives antifungal treatment is not yet fully understood. This study aimed to establish a comprehensive understanding of biofilm-related defensive strategies that C. albicans uses to establish vaginal candidiasis and to survive antifungal treatment.

Methods: A mouse model of vaginal candidiasis was adopted to examine the formation of biotic biofilms on the vaginal epithelium and fungal infiltration by laboratory and clinical strains of C. albicans. Histopathological changes and local inflammation in the vaginal epithelium caused by C. albicans of different biofilm phenotypes were compared. Antifungal susceptibility testing was carried out for C. albicans grown as planktonic cells, microplate-based abiotic biofilms, and epithelium-based biotic biofilms. Formation of persister cells by C. albicans in different growth modes was also quantified and compared.

Results: C. albicans wild-type reference strains and clinical isolates, but not the biofilm-defective mutants, formed a significant number of biotic biofilms on the vaginal epithelium of mice and infiltrated the epithelium. Biofilm formation and epithelial invasion induced local inflammatory responses and histopathological changes in the vaginal epithelium including neutrophil infiltration and subcorneal microabscesses. Biofilm growth on the vaginal epithelium also led to high resistance to antifungal treatments and promoted the formation of antifungal-tolerant persister cells.

Conclusion: This study comprehensively assessed biofilm-related microbial strategies that C. albicans uses in vaginal candidiasis and provided experimental evidence to support the important role of biofilm formation in the histopathogenesis of vaginal candidiasis and the recalcitrance of the infection to antifungal treatment.

RevDate: 2020-06-24

Choo S, Borchert E, Wiese J, et al (2020)

Polaribacter septentrionalilitoris sp. nov., isolated from the biofilm of a stone from the North Sea.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

A new member of the family Flavobacteriaceae was isolated from the biofilm of a stone at Nordstrand, a peninsula at the German North Sea shore. Phylogenetic analysis of the 16S rRNA gene sequence showed that strain ANORD1T was most closely related to the validly described type strains Polaribacter porphyrae LNM-20T (97.0 %) and Polaribacter reichenbachii KMM 6386T (96.9 % 16S rRNA gene sequence similarity) and clustered with Polaribacter gangjinensis K17-16T (96.0 %). Strain ANORD1T was determined to be mesophilic, Gram-negative, non-motile and strictly aerobic. Optimal growth was observed at 20-30 °C, within a salinity range of 2-7 % sea salt and from pH 7-10. Like other type strains of the genus Polaribacter, ANORD1T was tested negative for flexirubin-type pigments, while carotenoid-type pigments were detected. The DNA G+C content of strain ANORD1T was 30.6 mol%. The sole respiratory quinone detected was menaquinone 6 (MK-6). The major fatty acids identified were C15 : 0, iso-C15 : 0, C15 : 1 ω6c and iso-C15 : 0 3-OH. Based on the polyphasic approach, strain ANORD1T represents a novel species in the genus Polaribacter, with the name Polaribacter septentrionalilitoris sp. nov. being proposed. The type strain is ANORD1T (=DSM 110039T=NCIMB 15081T=MTCC 12685T).

RevDate: 2020-06-29
CmpDate: 2020-06-29

Silva AM, Miranda LFB, AraÚjo ASM, et al (2020)

Electric toothbrush for biofilm control in individuals with Down syndrome: a crossover randomized clinical trial.

Brazilian oral research, 34:e057 pii:S1806-83242020000100244.

Poor oral hygiene seems to be the norm in children and teenagers with Down Syndrome (DS). Advances in design and types of toothbrushes may improve biofilm control. This randomized, single-blind, crossover clinical trial evaluated the effectiveness of electric toothbrushes regarding mechanical control of biofilm in children and teenagers with DS and their cooperation. Twenty-nine participants with DS, aged 6 to 14 years, used both types of toothbrushes: electric (ET) and manual (MT). The order of use of the different types of toothbrushes was randomly defined, including a 7-day period with each type with 7-day washout period in between. The Turesky-Quigley-Hein biofilm index was used before and after brushing to assess the effectiveness of the technique. Frankl's behavioral scale was used during toothbrushing to assess the participants' cooperation. Paired T-test, Mann Whitney, Chi-square, and Fisher's Exact tests were applied, with a significance level of 5%. The quantity of dental biofilm was significantly reduced after both brushing techniques (p < 0.001). However, no significant difference was found in total biofilm (ET: 0.73 ± 0.36; MT: 0.73 ± 0.34; p = 0.985) or % biofilm reduction (ET: 72.22%; MT: 70.96%; p = 0.762) after brushing between techniques or in % biofilm reduction between toothbrushes of age groups (6 -9 years, p = 0.919; 10-14 years, p = 0.671). Participants showed similar cooperation level with the two types of toothbrush (p = 1.000). The use of electric or manual toothbrush had no effect on the quantity of dental biofilm removed in children and teenagers with DS, nor did it influence their cooperation during the procedure.

RevDate: 2020-06-24

Bulut F, Cumbul A, AS Safak (2020)

An analysis of the histomorphometric and clinical significance of mucosal biofilm in tonsil tissue of the children with a history of recurrent/chronic tonsillitis in both the mother and father.

European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery pii:10.1007/s00405-020-06111-7 [Epub ahead of print].

PURPOSE: The aim of this study is to analyse the histomorphometric and clinical features of the mucosal biofilm in tonsil tissue of children with a history of recurrent/chronic tonsillitis in both the mother and father.

METHODS: This study enrolled 82 children (between 3 and 14 years of age). These children were divided into two main groups according to the present of recurrent/chronic tonsillitis. Patients in group 1 were divided into four subgroups (A, B, C, D) according to the history of recurrent/chronic tonsillitis in mother and/or father. 30 patients in group 1 were underwent tonsillectomy and the 52 patients in control group (2) have not had history of recurrent/chronic tonsillitis. To that end, among children with a history of recurrent/chronic tonsillitis certain changes in the volume and thickness of mucosal biofilm in tonsil tissue have been exhibited with respect to it is histomorphometric and clinical significance.

RESULTS: The children with a parental history of recurrent/chronic tonsillitis in group A, an increase in the thickness and volume of mucosal biofilm samples was detected according to the other subgroups (B, C, D). Parents history of group A patients statistically significant differences were detected with respect to halitosis symptoms, attack age of the first tonsillitis and resistant fever despite antibiotic treatment for children under the age of 3 years.

CONCLUSIONS: This study showed that children under the age of 3 years of age with a history of recurrent/chronic tonsillitis in both the mother and father, halitosis symptoms, attack age of the first tonsillitis and resistant fever despite antibiotic treatment are collectively linked.

RevDate: 2020-06-27

Walsh BJC, Wang J, Edmonds KA, et al (2020)

The Response of Acinetobacter baumannii to Hydrogen Sulfide Reveals Two Independent Persulfide-Sensing Systems and a Connection to Biofilm Regulation.

mBio, 11(3):.

Acinetobacter baumannii is an opportunistic nosocomial pathogen that is the causative agent of several serious infections in humans, including pneumonia, sepsis, and wound and burn infections. A. baumannii is also capable of forming proteinaceous biofilms on both abiotic and epithelial cell surfaces. Here, we investigate the response of A. baumannii toward sodium sulfide (Na2S), known to be associated with some biofilms at oxic/anoxic interfaces. The addition of exogenous inorganic sulfide reveals that A. baumannii encodes two persulfide-sensing transcriptional regulators, a primary σ54-dependent transcriptional activator (FisR), and a secondary system controlled by the persulfide-sensing biofilm growth-associated repressor (BigR), which is only induced by sulfide in a fisR deletion strain. FisR activates an operon encoding a sulfide oxidation/detoxification system similar to that characterized previously in Staphylococcus aureus, while BigR regulates a secondary persulfide dioxygenase (PDO2) as part of yeeE-yedE-pdo2 sulfur detoxification operon, found previously in Serratia spp. Global S-sulfuration (persulfidation) mapping of the soluble proteome reveals 513 persulfidation targets well beyond FisR-regulated genes and includes five transcriptional regulators, most notably the master biofilm regulator BfmR and a poorly characterized catabolite regulatory protein (Crp). Both BfmR and Crp are well known to impact biofilm formation in A. baumannii and other organisms, respectively, suggesting that persulfidation of these regulators may control their activities. The implications of these findings on bacterial sulfide homeostasis, persulfide signaling, and biofilm formation are discussed.IMPORTANCE Although hydrogen sulfide (H2S) has long been known as a respiratory poison, recent reports in numerous bacterial pathogens reveal that H2S and more downstream oxidized forms of sulfur collectedly termed reactive sulfur species (RSS) function as antioxidants to combat host efforts to clear the infection. Here, we present a comprehensive analysis of the transcriptional and proteomic response of A. baumannii to exogenous sulfide as a model for how this important human pathogen manages sulfide/RSS homeostasis. We show that A. baumannii is unique in that it encodes two independent persulfide sensing and detoxification pathways that govern the speciation of bioactive sulfur in cells. The secondary persulfide sensor, BigR, impacts the expression of biofilm-associated genes; in addition, we identify two other transcriptional regulators known or projected to regulate biofilm formation, BfmR and Crp, as highly persulfidated in sulfide-exposed cells. These findings significantly strengthen the connection between sulfide homeostasis and biofilm formation in an important human pathogen.

RevDate: 2020-06-26

Béchon N, Mihajlovic J, Vendrell-Fernández S, et al (2020)

Capsular Polysaccharide Cross-Regulation Modulates Bacteroides thetaiotaomicron Biofilm Formation.

mBio, 11(3):.

Bacteroides thetaiotaomicron is one of the most abundant gut symbiont species, whose contribution to host health through its ability to degrade dietary polysaccharides and mature the immune system is under intense scrutiny. In contrast, adhesion and biofilm formation, which are potentially involved in gut colonization and microbiota structure and stability, have hardly been investigated in this intestinal bacterium. To uncover B. thetaiotaomicron biofilm-related functions, we performed a transposon mutagenesis in the poorly biofilm-forming reference strain VPI-5482 and showed that capsule 4, one of the eight B. thetaiotaomicron capsules, hinders biofilm formation. We then showed that the production of capsules 1, 2, 3, 5, and 6 also inhibits biofilm formation and that decreased capsulation of the population correlated with increased biofilm formation, suggesting that capsules could be masking adhesive surface structures. In contrast, we showed that capsule 8 displayed intrinsic adhesive properties. Finally, we demonstrated that BT2934, the wzx homolog of the B. thetaiotaomicron glycosylation locus, competes with capsule production and impacts its adhesion capacity. This study therefore establishes B. thetaiotaomicron capsule regulation as a major determinant of B. thetaiotaomicron biofilm formation, providing new insights into how modulation of different B. thetaiotaomicron surface structures affects in vitro biofilm formation.IMPORTANCE The human gut harbors a complex bacterial community that plays important roles in host health and disease, including nutrient acquisition, maturation of the immune system, and resistance to infections. The capacity to adhere to surfaces and form communities called biofilms is believed to be important for niche colonization and maintenance of gut bacteria. However, little is known about the adhesion capacity of most gut bacteria. In this study, we investigated biofilm formation in Bacteroides thetaiotaomicron, one of the most abundant bacteria of the normal mammalian intestine. We identified that B. thetaiotaomicron capsules, a group of eight surface-exposed polysaccharidic layers mediating important interactions with the gut environment, are also major determinants of biofilm formation that mask or unmask adhesion factors. Studying how B. thetaiotaomicron regulates its adhesion properties will allow us to better understand the physiology and specific properties of this important gut symbiont within anaerobic biofilms.

RevDate: 2020-06-27

Simmons EL, Bond MC, Koskella B, et al (2020)

Biofilm Structure Promotes Coexistence of Phage-Resistant and Phage-Susceptible Bacteria.

mSystems, 5(3):.

Encounters among bacteria and their viral predators (bacteriophages) are among the most common ecological interactions on Earth. These encounters are likely to occur with regularity inside surface-bound communities that microbes most often occupy in natural environments. Such communities, termed biofilms, are spatially constrained: interactions become limited to near neighbors, diffusion of solutes and particulates can be reduced, and there is pronounced heterogeneity in nutrient access and physiological state. It is appreciated from prior theoretical work that phage-bacteria interactions are fundamentally different in spatially structured contexts, as opposed to well-mixed liquid culture. Spatially structured communities are predicted to promote the protection of susceptible host cells from phage exposure, and thus weaken selection for phage resistance. The details and generality of this prediction in realistic biofilm environments, however, are not known. Here, we explore phage-host interactions using experiments and simulations that are tuned to represent the essential elements of biofilm communities. Our simulations show that in biofilms, phage-resistant cells-as their relative abundance increases-can protect clusters of susceptible cells from phage exposure, promoting the coexistence of susceptible and phage-resistant bacteria under a large array of conditions. We characterize the population dynamics underlying this coexistence, and we show that coexistence is recapitulated in an experimental model of biofilm growth measured with confocal microscopy. Our results provide a clear view into the dynamics of phage resistance in biofilms with single-cell resolution of the underlying cell-virion interactions, linking the predictions of canonical theory to realistic models and in vitro experiments of biofilm growth.IMPORTANCE In the natural environment, bacteria most often live in communities bound to one another by secreted adhesives. These communities, or biofilms, play a central role in biogeochemical cycling, microbiome functioning, wastewater treatment, and disease. Wherever there are bacteria, there are also viruses that attack them, called phages. Interactions between bacteria and phages are likely to occur ubiquitously in biofilms. We show here, using simulations and experiments, that biofilms will in most conditions allow phage-susceptible bacteria to be protected from phage exposure, if they are growing alongside other cells that are phage resistant. This result has implications for the fundamental ecology of phage-bacteria interactions, as well as the development of phage-based antimicrobial therapeutics.

RevDate: 2020-06-24

Rodríguez López AL, Lee MR, Wang NB, et al (2020)

Correction for Rodríguez López et al., "Small-Molecule Morphogenesis Modulators Enhance the Ability of 14-Helical β-Peptides To Prevent Candida albicans Biofilm Formation".

Antimicrobial agents and chemotherapy, 64(7): pii:64/7/e00841-20.

RevDate: 2020-06-24

Singh R, AK Dubey (2020)

Isolation and Characterization of a New Endophytic Actinobacterium Streptomyces californicus Strain ADR1 as a Promising Source of Anti-Bacterial, Anti-Biofilm and Antioxidant Metabolites.

Microorganisms, 8(6): pii:microorganisms8060929.

In view of the fast depleting armamentarium of drugs against significant pathogens, like methicillin-resistant Staphylococcus aureus (MRSA) and others due to rapidly emerging drug-resistance, the discovery and development of new drugs need urgent action. In this endeavor, a new strain of endophytic actinobacterium was isolated from the plant Datura metesl, which produced secondary metabolites with potent anti-infective activities. The isolate was identified as Streptomyces californicus strain ADR1 based on 16S rRNA gene sequence analysis. Metabolites produced by the isolate had been investigated for their antibacterial attributes against important pathogens: S. aureus, MRSA, S. epidermis, Enterococcus faecium and E. faecalis. Minimum inhibitory concentration (MIC90) values against these pathogens varied from 0.23 ± 0.01 to 5.68 ± 0.20 μg/mL. The metabolites inhibited biofilm formation by the strains of S. aureus and MRSA (Biofilm inhibitory concentration [BIC90] values: 0.74 ± 0.08-4.92 ± 0.49 μg/mL). The BIC90 values increased in the case of pre-formed biofilms. Additionally, the metabolites possessed good antioxidant properties, with an inhibitory concentration (IC90) value of 217.24 ± 6.77 µg/mL for 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging. An insight into different classes of compounds produced by the strain ADR1 was obtained by chemical profiling and GC-MS analysis, wherein several therapeutic classes, for example, alkaloids, phenolics, terpenes, terpenoids and glycosides, were discovered.

RevDate: 2020-06-23

Ma Y, Zhang Z, Nitin N, et al (2020)

Integration of photo-induced biocidal and hydrophilic antifouling functions on nanofibrous membranes with demonstrated reduction of biofilm formation.

Journal of colloid and interface science, 578:779-787 pii:S0021-9797(20)30782-7 [Epub ahead of print].

Survival and pathogenic microbial adhesions on surfaces of materials followed by the formation of biofilms with robust resistance to antibiotics constitute the forefront of disease transmissions. Conventional strategies responding to this challenge are rather limited due to the biofouling effect of microorganisms or the irreversible consumption of antimicrobial agents embedded into the materials. Herein, we report an approach of combining photo-induced rechargeable biocidal properties with microbial resisting and releasing zwitterionic hydrophilic functions on surfaces of materials to improve antifouling performances. Poly(vinyl alcohol-co-ethylene) (EVOH) nanofibrous membranes (NFMs) were chemically incorporated with both 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BPTCD), a photoactive chemical, and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), a zwitterionic monomer. Both functional agents work independently and construct concerted microbial resisting, killing, and releasing functions to reduce microbial contamination and biofilm formation. The resulted SBMA@EVOH NFMs exhibited integrated features of large ROS production capacity, ease of photoactive rechargeability and controllability, long-term stability, high biocidal efficacy (>99.9999% via contact killing), and promising antifouling performance, which enable the SBMA@EVOH NFMs to serve as a biocidal material for food safety and medical applications.

RevDate: 2020-06-29

Yuan K, Li S, F Zhong (2020)

Treatment of coking wastewater in biofilm-based bioaugmentation process: Biofilm formation and microbial community analysis.

Journal of hazardous materials, 400:123117 pii:S0304-3894(20)31106-7 [Epub ahead of print].

Coking wastewater (CWW) containing complicated organic compositions and strong toxicity cause potential hazards to natural water bodies as well as human health. The aim of this study was integrating newly isolated Comamonas sp. ZF-3, biofilm-based bioaugmentation and fluidized bed reactor into an anoxic filter-fluidized bed reactor (AF-FBR) system to treat actual CWW. The results showed that 93 % of chemical oxygen demand (COD) and 97 % of ammonia nitrogen (NH4+-N) removal efficiency were achieved with hydraulic retention time of 70 h. The main pollutants including phenolic compounds, heterocyclic compounds and polycyclic aromatic hydrocarbons could be removed via biofilm-based process in AF-FBR. The formation of carrier biofilm was consistent with the system performance as well as the biofilm community evolution, during which the microbial community was gradually dominated by some functional genus (e.g., Comamonas, Thiobacillus, Pseudomonas and Thauera), meanwhile, ammonium-oxidizing bacteria Nitrosomonas, nitrite-oxidizing bacteria Nitrospira and denitrifiers (e.g., Pseudomonas, Thiobacillus and Bacillus) coexisted in biofilm to form a microbial community for biological nitrogen removal. Such microbial community structure explained the observed simultaneous removal of COD and NH4+-N in the AF-FBR.

RevDate: 2020-06-23

Díaz MA, González SN, Alberto MR, et al (2020)

Human probiotic bacteria attenuate Pseudomonas aeruginosa biofilm and virulence by quorum-sensing inhibition.

Biofouling [Epub ahead of print].

This work investigated chloroform extracts from culture supernatants of two human probiotic bacteria, Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730 for the production of virulence factors and quorum sensing (QS) interference against three Pseudomonas aeruginosa strains. Both extracts inhibited biofilm biomass (up to 50%), biofilm metabolic activity (up to 39%), the production of the enzyme elastase (up to 63%) and pyocyanin (up to 77%), and decreased QS, without presenting any antibacterial acgivity. In addition, the chloroform extracts of both strains disrupted preformed biofilms of the three strains of P. aeruginosa analyzed (up to 40%). GC-MS analysis revealed that the major compounds detected in the bioactive extracts were four diketopiperazines. This study suggests that the metabolites of L. casei and L. acidophilus could be a promising alternative to combat the pathogenicity of P. aeruginosa.

RevDate: 2020-06-25

Szerencsés B, Igaz N, Tóbiás Á, et al (2020)

Size-dependent activity of silver nanoparticles on the morphological switch and biofilm formation of opportunistic pathogenic yeasts.

BMC microbiology, 20(1):176.

BACKGROUND: Dimorphism and biofilm formation are important virulence factors of some opportunistic human pathogenic yeasts. Such species commensally colonize skin or mucosal surfaces generally in yeast form, but under particular circumstances, convert into virulent hyphae and disseminate internal organs or cause mucocutaneous infections. The yeast-to-hypha shape-conversion promotes the development of a biofilm, a thick extracellular matrix with sessile cells within. The biofilm is capable to prevent the penetration of antifungal drugs, rendering the surviving biofilm-resident cells intrinsic sources of recurrent infections. The aim of this study was to evaluate the ability of silver nanoparticles (AgNPs) to attenuate the morphological switch and biofilm formation of several opportunistic pathogenic yeasts and to determine whether this feature depends on the nanoparticle size.

RESULTS: AgNPs in three different sizes were prepared by chemical reduction approach and characterized by transmission electron microscopy, ultraviolet-visible spectroscopy and dynamic light scattering. The antifungal activity was evaluated by the microdilution method, the inhibitory capacity on biofilm formation and the biofilm degradation ability of differently sized AgNPs was assessed by viability assay. The morphological state of opportunistic pathogenic yeast cells in monoculture and in co-culture with human keratinocytes in the presence of AgNPs was examined by flow cytometry and scanning electron microscopy. All the three AgNPs inhibited the growth of the examined opportunistic pathogenic yeasts, nevertheless, AgNPs with the smallest diameter exhibited the most prominent toxic activities. AgNPs attenuated the biofilm formation in a nanoparticle size-dependent manner; however, their biofilm destruction capacity was negligible. AgNPs with the smallest size exerted the most significant effect on suppressing the morphological change of pathogens in monoculture as well as in a co-culture with keratinocytes.

CONCLUSIONS: Our results confirm that AgNPs are capable to hinder yeast-to-hypha morphological conversion and biofilm formation of opportunistic pathogens and this biological effect of AgNPs is size-dependent.


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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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

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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

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