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26 Mar 2019 at 01:34
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Bibliography on: Biofilm


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RJR: Recommended Bibliography 26 Mar 2019 at 01:34 Created: 


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

Created with PubMed® Query: biofilm[title] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-03-25

Méndez-Tovar M, García-Meza JV, I González (2019)

Electrochemical monitoring of Acidithiobacillus thiooxidans biofilm formation on graphite surface with elemental sulfur.

Bioelectrochemistry (Amsterdam, Netherlands), 128:30-38 pii:S1567-5394(19)30117-3 [Epub ahead of print].

Inorganic wastewaters and sediments from the mining industry and mineral bioleaching processes have not been fully explored in bioelectrochemical systems (BES). Knowledge of interfacial changes due to biofilm evolution under acidic conditions may improve applications in electrochemical processes, specifically those related to sulfur compounds. Biofilm evolution of Acidithiobacillus thiooxidans on a graphite plate was monitored by electrochemical techniques, using the graphite plate as biofilm support and elemental sulfur as the only energy source. Even though the elemental sulfur was in suspension, S0 particles adhered to the graphite surface favoring biofilm development. The biofilms grown at different incubation times (without electric perturbation) were characterized in a classical three electrode electrochemical cell (sulfur and bacteria free culture medium) by non-invasive electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The biofilm structure was confirmed by Environmental Scanning Electrode Microscopy, while the relative fractions of exopolysaccharides and extracellular hydrophobic compounds at different incubation times were evaluated by Confocal Laser Scanning Microscopy. The experimental conditions chosen in this work allowed the EIS monitoring of the biofilm growth as well as the modification of Extracellular Polymeric Substances (EPS) composition (hydrophobic/ exopolysaccharides EPS ratio). This strategy could be useful to control biofilms for BES operation under acidic conditions.

RevDate: 2019-03-25

Zheng Z, Huang S, Bian W, et al (2019)

Enhanced nitrogen removal of the simultaneous partial nitrification, anammox and denitrification (SNAD) biofilm reactor for treating mainstream wastewater under low dissolved oxygen (DO) concentration.

Bioresource technology, 283:213-220 pii:S0960-8524(19)30238-X [Epub ahead of print].

The simultaneous partial nitrification, anammox and denitrification (SNAD) process for treating mainstream wastewater was investigated under different intermittent aeration modes. By controlling the aeration time of 20, 60 and 180 min during the intermittent modes, the oxygen concentration remained 3.50, 1.45 and 0.70 mg·L-1. Correspondingly, the reactor achieved the nitrogen removal rate of 0.17, 0.29 and 0.30 kg N·m-3·d-1. Meanwhile, the average total inorganic nitrogen (TIN) removal efficiency reached 93.4%, 87.5% and 92.7%. The effluent NO3--N concentration was very low. High-throughput sequencing analysis indicated that the proportion of nitrite oxidization bacteria (NOB), anammox bacteria and denitrification bacteria was 0.15%, 0.33% and 8.78%. Candidatus Anammoxoglobus was the abundant anammox bacteria genus. Further study on the unclassified sequences revealed the possibility of the high relative abundance of Nitrosomonas-related genus and Candidatus Kuenenia-related genus on the SNAD biofilm.

RevDate: 2019-03-25

Alrabiah M, Alshagroud RS, Alsahhaf A, et al (2019)

Presence of Candida species in the subgingival oral biofilm of patients with peri-implantitis.

Clinical implant dentistry and related research [Epub ahead of print].

BACKGROUND: There are no studies that have investigated the presence of Candida species in the subgingival oral biofilm (OB) of patients with peri-implantitis.

PURPOSE: The aim was to assess the presence of Candida species in the subgingival OB of patients with peri-implantitis.

MATERIALS AND METHODS: Individuals with (group A) and without (group B) peri-implantitis were included. Life style related and demographic data were collected using a questionnaire. In both groups, peri-implant plaque-index (PI), bleeding-on-probing (BOP), and probing-depth (PD) were evaluated and crestal bone loss (CBL) were measured on digital bitewing radiographs. In both groups, subgingival OB samples were collected using sterile paper points. Identification of Candida species was performed using ChromAgar medium and colony forming units per milliliter (CFU/mL) were determined. Statistical analysis was performed, and level of significance was set at P < 0.05.

RESULTS: The mean age of individuals in groups A (n = 43) and B (n = 41) were 52.2 ± 4.4 and 55.1 ± 2.3 years, respectively. All participants were male. In groups A and B, implants were in function for 7.4 ± 1.3 and 6.8 ± 0.6 years, respectively. Scores of peri-implant PI (P < 0.001), BOP (P < 0.001), PD (P < 0.001), and CBL (P < 0.001) were significantly higher in group A than group B. Subgingival Candida was isolated from the OB of 33 (76.7%) patients in group A and 5 (12.2%) individuals in group B. The most common yeast species was Candida albicans, which was isolated from 67.4% to 60% individuals in groups A and B, respectively. The number of subgingival oral yeasts CFU/mL were significantly higher in group A (3147.54 ± 1052.6 CFU/mL) compared with group B (496.68 ± 100.2 CFU/mL; P < 0.01).

CONCLUSION: Candida species (predominantly C. albicans) are present in the subgingival OB of patients with peri-implantitis. Community-based efforts toward routine oral hygiene maintenance are needed to improve oral health and minimize the risks of peri-implant diseases in populations.

RevDate: 2019-03-25

Malhotra R, Dhawan B, Garg B, et al (2019)

A Comparison of Bacterial Adhesion and Biofilm Formation on Commonly Used Orthopaedic Metal Implant Materials: An In vitro Study.

Indian journal of orthopaedics, 53(1):148-153.

Background: Bacterial adherence and biofilm formation on the surface of biomaterials can often lead to implant-related infections, which may vary depending on the species of microorganisms, type of biomaterial used, and physical characteristics of implant surfaces. However, there are limited studies specifically comparing biofilm formation between commonly used metallic orthopaedic implant materials and different bacterial strains. This in vitro study is to evaluate the ability of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa to adhere to and to form biofilms on the surface of five orthopaedic biomaterials, viz., cobalt and chromium, highly cross-linked polyethylene, stainless steel, trabecular metal, and titanium alloy.

Materials and Methods: Bacterial adherence and bacterial biofilm-formation assays were performed by culturing S. aureus ATCC 29213, S. epidermidis ATCC 35984, E. coli ATCC 35218, K. pneumoniae ATCC 700603, and P. aeruginosa ATCC 27853 for 48 h on five different biomaterials. Quantitative bacterial adherence and biofilm formation were analyzed with a scanning electron microscope.

Results: The highest level of adherence was observed on highly cross-linked polyethylene, followed by titanium, stainless steel, and trabecular metal, with the lowest occurring on the cobalt-chromium alloy. Among the bacterial strains tested, the ability for high adherence was observed with S. epidermidis and K. pneumoniae followed by P. aeruginosa and E. coli, whereas S. aureus showed the least adherence.

Conclusion: Cobalt-chromium was observed to have the lowest proclivity towards bacterial adherence compared to the other biomaterials tested. However, bacterial adhesion occurred with all the materials. Hence, it is necessary to further evaluate newer biomaterials that are resistant to bacterial adherence.

RevDate: 2019-03-25

Hossain MI, Cheng L, R Cord-Ruwisch (2019)

Energy efficient COD and N-removal from high-strength wastewater by a passively aerated GAO dominated biofilm.

Bioresource technology, 283:148-158 pii:S0960-8524(19)30405-5 [Epub ahead of print].

Conventional aerobic treatment of high-strength wastewater is not economical due to excessively high energy requirement for compressed air supply. The use of passive aeration avoids the use of compressed air and enables energy efficient oxygen supply directly from the air. This study evaluates a passively aerated simultaneous nitrification and denitrification performing biofilm to treat concentrated wastewater. The biofilm reactor was operated > 5-months under alternating anaerobic/aerobic conditions. For 4-times concentrated wastewater, > 80% COD (2307 mg L-1 h-1) and > 60% N (60 mg L-1 h-1) was removed at a hydraulic retention time (HRT) of 7 h. A double application in the same reactor enabled > 95% COD and 85% N-removal, at an overall HRT of 14 h which is substantially shorter than what traditional activated sludge-based systems would require for the treatment of such concentrated feeds. Microbial community analysis showed Candidatus competibacter (27%) and nitrifying bacteria (Nitrosomonas, and Nitrospira) as key microbes involved in COD and N-removal, respectively.

RevDate: 2019-03-22

Jovanovic M, Radivojevic J, O'Connor K, et al (2019)

Rhamnolipid inspired lipopeptides effective in preventing adhesion and biofilm formation of Candida albicans.

Bioorganic chemistry, 87:209-217 pii:S0045-2068(18)31574-8 [Epub ahead of print].

Rhamnolipids are biodegradable low toxic biosurfactants which exert antimicrobial and anti-biofilm properties. They have attracted much attention recently due to potential applications in areas of bioremediation, therapeutics, cosmetics and agriculture, however, the full potential of these versatile molecules is yet to be explored. Based on the facts that many naturally occurring lipopeptides are potent antimicrobials, our study aimed to explore the potential of replacing rhamnose in rhamnolipids with amino acids thus creating lipopeptides that would mimic or enhance properties of the parent molecule. This would allow not only for more economical and greener production but also, due to the availability of structurally different amino acids, facile manipulation of physico-chemical and biological properties. Our synthetic efforts produced a library of 43 lipopeptides revealing biologically more potent molecules. The structural changes significantly increased, in particular, anti-biofilm properties against Candida albicans, although surface activity of the parent molecule was almost completely abolished. Our findings show that the most active compounds are leucine derivatives of 3-hydroxy acids containing benzylic ester functionality. The SAR study demonstrated a further increase in activity with aliphatic chain elongation. The most promising lipopeptides 15, 23 and 36 at 12.5 µg/mL concentration allowed only 14.3%, 5.1% and 11.2% of biofilm formation, respectively after 24 h. These compounds inhibit biofilm formation by preventing adhesion of C. albicans to abiotic and biotic surfaces.

RevDate: 2019-03-22

Velmourougane K, Prasanna R, Chawla G, et al (2019)

Trichoderma-Azotobacter biofilm inoculation improves soil nutrient availability and plant growth in wheat and cotton.

Journal of basic microbiology [Epub ahead of print].

Microbial biofilms are gaining importance in agriculture, due to their multifaceted agronomic benefits and resilience to environmental fluctuations. This study focuses on comparing the influence of single inoculation -Azotobacter chroococcum (Az) or Trichoderma viride (Tv) and their biofilm (Tv-Az), on soil and plant metabolic activities in wheat and cotton grown under Phytotron conditions. Tv-Az proved superior to all the other treatments in terms of better colonisation, plant growth attributes and 10-40% enhanced availability of macro- and micronutrients in soil, over control. Confocal and scanning electron microscopy showed that the cells attached to the root tips initially, followed by their proliferation along the surface of the roots. Soil polysaccharides, proteins and dehydrogenase activity showed several fold enhancement in Tv-Az biofilm inoculated samples. Time course studies revealed that the population of Az and Tv in the rhizoplane and rhizosphere was significantly higher with a 0.14-0.31 log colony forming unit (CFU) increase in the biofilm-inoculated treatment in both crops. Enhancement in soil biological activities facilitated by the improved colonisation of the biofilm, due to the synergistic association between Tv and Az. This demonstrates the utility of Tv-Az biofilm as a multifunctional plant growth promoting and soil fertility enhancing option in agriculture. This article is protected by copyright. All rights reserved.

RevDate: 2019-03-21

Umezawa T, Ryu M, Tasaka A, et al (2017)

Effect of water containing organic acids on aspiration pneumonia-causative bacteria in the biofilm on the tooth surface.

Journal of dental sciences, 12(3):268-274.

Background/purpose: The tooth surface is a source of oral microbes in dentulous individuals, it is difficult for elderly people requiring nursing care to perform mechanical tooth cleaning by themselves. The objective of this study was to investigate the antimicrobial effect of water containing organic acids (WOA) made by some organic acids as food additives on chemical cleaning for elderly people on aspiration pneumonia-causative bacteria in the biofilm on the tooth surface.

Materials and methods: Ninety-six specimens made from bovine incisors were divided into four groups and incubated with one of four aspiration pneumonia-causative bacteria. Each group was further divided into six subgroups according to treatment as follows: control group (DW), chlorhexidine gluconate solution group (CHX), WOA group (WOA), ultrasonic treatment in distilled water group (DW-U), ultrasonic treatment in chlorhexidine gluconate solution group (CHX-U) or ultrasonic treatment in WOA group (WOA-U). After treatment, the levels of viable microbes in the biofilm were evaluated by quantitative adenosine triphosphate analysis and compared among the six groups.

Results: For every evaluated microbe, there were significant differences between DW and WOA, and DW and WOA-U. However, there was no significant difference among the WOA, DW-U, CHX-U and WOA-U groups. These results suggested that the antimicrobial effect of WOA on microbes attached to the tooth surface was similar to that of ultrasonic cleaning.

Conclusion: WOA has an antimicrobial effect on microbes in the biofilm on the tooth surface.

RevDate: 2019-03-21

Bachtiar EW, Dewiyani S, Surono Akbar SM, et al (2016)

Inhibition of Candida albicans biofilm development by unencapsulated Enterococcus faecalis cps2.

Journal of dental sciences, 11(3):323-330.

Background/purpose: In the oral environment, Candida albicans interacts with many bacteria, including Enterococcus faecalis. We investigated the susceptibility of C. albicans biofilm development to the presence of unencapsulated E. faecalis cps2 in comparison with reference strains (E. faecalis ATCC 29212) or their respective spent medium (collected at 6 hours).

Material and methods: Crystal violet stain was used to measure the total biofilm mass, whereas quantitative real-time polymerase chain reaction was used to analyze the change in expression of the mRNA of hypha morphology (ALS1 and ALS3) and biofilm maturation (EFB1).

Results: At the intermediate stage, C. albicans resisted the presence of each E. faecalis strain tested and their spent medium. However, at the maturation stage, the unencapsulated strain was stronger in reducing C. albicans biofilms than the reference strain (P < 0.05). At this maturation stage, the transcription levels of each gene tested decreased in the presence of either E. faecalis strains or their respective spent medium. The unencapsulated strain was more pronounced in reducing ALS1/ALS3 expression, whereas the respective spent medium had a similar capability to restrict the expression of EFB1.

Conclusion: This study showed, the unencapsulated strain is more effective in inhibiting C. albicans biofilm development compared with the reference strains. In contrast, the secreted molecules produced by each strain tested are necessary in controlling the growths of C. albicans biofilm.

RevDate: 2019-03-21

Robinson VH, Paterson S, Bennett C, et al (2019)

Biofilm production of Pseudomonas spp. isolates from canine otitis in three different enrichment broths.

Veterinary dermatology [Epub ahead of print].

BACKGROUND: Pseudomonas spp. are commonly isolated from dogs with clinical otitis and have been shown to produce biofilm. There is a paucity of studies demonstrating biofilm growth in veterinary medicine.

HYPOTHESIS/OBJECTIVES: To compare biofilm production of Pseudomonas spp. isolated from dogs with otitis using three different enrichment broths at two different time points. Speciation was performed.

ANIMALS: One hundred isolates from 98 animals with clinical otitis were assessed for biofilm production.

METHODS AND MATERIALS: One hundred isolates were assessed for biofilm production using a microtitre plate assay. Biofilm production in Luria-Bertani Broth (LBB), Mueller-Hinton Broth (MHB) and Tryptic Soy Broth (TSB) were assessed after 18 and 24 h of incubation.

RESULTS: At 18 h, biofilm production was demonstrated in 87% of LBB, 91% of TSB and 93% of MHB grown isolates. By 24 h, this was 92% of LBB, 96% of TSB and 99% of MHB isolates. Biofilm production was significantly increased after 24 h incubation compared to 18 h. A significant difference was noted in biofilm production between LBB and MHB (P = 0.0349), but not between LBB and TSB (P = 0.3727) or MHB and TSB (P = 0.3687) at 24 h incubation. Two isolates were speciated as P. fluorescens and 98 as P. aeruginosa.

Not all enrichment broths were equivalent with one another and 24 h incubation was superior to 18 h. Presence of a biofilm is likely in otic Pseudomonas spp. isolates.

RevDate: 2019-03-21

Maillard JY, A McBain (2019)

Biofilm in healthcare settings and their control.

Letters in applied microbiology, 68(4):268.

RevDate: 2019-03-21

Sterniša M, Klančnik A, SS Možina (2019)

Temperature and surface material can promote Pseudomonas fragi and Pseudomonas psychrophila biofilm production, with protection under refrigeration conditions of growth and persistence of Escherichia coli in fish meat.

Journal of the science of food and agriculture [Epub ahead of print].

BACKGROUND: Pseudomonas are part of the indigenous microbiota of different foods, where they gradually cause spoilage. In fish meat, Pseudomonas fragi and Pseudomonas psychrophila have been identified as important spoilers. The initial aim of this study was to investigate the physiological characteristics, adhesion and biofilm of P. fragi and P. psychrophila under temperatures related to the fish processing industry. The further aim was to define the problem of increased growth of pathogenic bacteria in the presence of spoilage bacteria in-vitro and in fish meat.

RESULTS: Temperature dependence on physiological characteristics, adhesion and biofilm was observed. Hydrophobicity and autoaggregation were most prominent at 15 °C, and at this temperature also floating biofilm was formed. The adhesion of these Pseudomonas was up to 2 log CFU cm-1 more pronounced on stainless steel than polystyrene, with up to 5-times greater biofilm biomass production at 5 °C on polystyrene. Furthermore, this paralleled at least 0.5 log CFU g-1 increase of pathogenic bacterium Escherichia coli in fish meat.

CONCLUSIONS: P. fragi and P. psychrophila adhesion and biofilm depends on the temperature, and is stimulated by temperatures that can occur during processing and storage of fish meat. Strong Pseudomonas biofilm formation under refrigeration conditions is protective for E. coli, potentially through providing more favourable conditions by ensuring higher concentration of nutrients. The interactions between spoilage Pseudomonas and pathogenic bacteria can occur through different mechanisms, and understanding of these is of particular importance to assure the overall quality and safety of fish meat and other proteinaceous foods. This article is protected by copyright. All rights reserved.

RevDate: 2019-03-21

Yang J, Cheng S, Li C, et al (2019)

Shear Stress Affects Biofilm Structure and Consequently Current Generation of Bioanode in Microbial Electrochemical Systems (MESs).

Frontiers in microbiology, 10:398.

Shear stress is an important factor that affects the formation and structure of anode biofilms, which are strongly related to the extracellular electron transfer phenomena and bioelectric performance of bioanodes. Here, we show that using nitrogen sparging to induce shear stress during anode biofilm formation increases the linear sweep voltammetry peak current density of the mature anode biofilm from 2.37 ± 0.15 to 4.05 ± 0.25 A/m2. Electrochemical impedance spectroscopy results revealed that the shear-stress-enriched anode biofilm had a low charge transfer resistance of 46.34 Ω compared to that of the unperturbed enriched anode biofilm (72.2 Ω). Confocal laser scanning microscopy observations showed that the shear-stress-enriched biofilms were entirely viable, whereas the unperturbed enriched anode biofilm consisted of a live outer layer covering a dead inner-core layer. Based on biomass and community analyses, the shear-stress-enriched biofilm had four times the biofilm density (136.0 vs. 27.50 μg DNA/cm3) and twice the relative abundance of Geobacteraceae (over 80 vs. 40%) in comparison with those of the unperturbed enriched anode biofilm. These results show that applying high shear stress during anode biofilm enrichment can result in an entirely viable and dense biofilm with a high relative abundance of exoelectrogens and, consequently, better performance.

RevDate: 2019-03-21

Zhao T, Zhang J, Tang M, et al (2019)

Development of an effective fluorescence probe for discovery of aminopeptidase inhibitors to suppress biofilm formation.

The Journal of antibiotics pii:10.1038/s41429-019-0166-z [Epub ahead of print].

The human pathogen Pseudomonas aeruginosa can easily form biofilms. The extracellular matrix produced by the bacterial cells acts as a physical barrier to hinder the antibiotics treatment. It is necessary to destroy the biofilm in order to improve the efficacy of antibiotics. However, it has been a significant challenge to develop effective small molecules targeting the components of biofilm matrix. In this study, we report the development of a new effective fluorescence probe that could be used in the high throughput screening to identify novel small molecule inhibitors targeting the most abundant component in the biofilm formation: P. aeruginosa aminopeptidase (PaAP). Through screening of an in-house chemical library, a commercially available drug, balsalazide, has been identified as a novel PaAP inhibitor, which exhibited remarkable anti-biofilm effect. Our study indicated that the newly developed fluorescence probe is applicable in exploring new aminopeptidase inhibitors, and it also warrants further investigation of balsalazide as a new anti-biofilm agent to treat P. aeruginosa infection in combination with known antibiotics.

RevDate: 2019-03-20

Morgan SJ, Lippman SI, Bautista GE, et al (2019)

Bacterial fitness in chronic wounds appears to be mediated by the capacity for high-density growth,not virulence or biofilm functions.

PLoS pathogens, 15(3):e1007511 pii:PPATHOGENS-D-17-02421 [Epub ahead of print].

While much is known about acute infection pathogenesis, the understanding of chronic infections has lagged. Here we sought to identify the genes and functions that mediate fitness of the pathogen Pseudomonas aeruginosa in chronic wound infections, and to better understand the selective environment in wounds. We found that clinical isolates from chronic human wounds were frequently defective in virulence functions and biofilm formation, and that many virulence and biofilm formation genes were not required for bacterial fitness in experimental mouse wounds. In contrast, genes involved in anaerobic growth, some metabolic and energy pathways, and membrane integrity were critical. Consistent with these findings, the fitness characteristics of some wound impaired-mutants could be represented by anaerobic, oxidative, and membrane-stress conditions ex vivo, and more comprehensively by high-density bacterial growth conditions, in the absence of a host. These data shed light on the bacterial functions needed in chronic wound infections, the nature of stresses applied to bacteria at chronic infection sites, and suggest therapeutic targets that might compromise wound infection pathogenesis.

RevDate: 2019-03-20

Zhang J, Huang H, Zhou X, et al (2019)

N-Benzylanilines as Fatty Acid Synthesis Inhibitors against Biofilm-related Methicillin-resistant Staphylococcus aureus.

ACS medicinal chemistry letters, 10(3):329-333.

Bacterial fatty acid synthase system is a well validated target for the development of novel antimicrobial agents. This study reports the synthesis of Schiff bases and their reductive N-benzylanilines. Most N-benzylanilines were active against Gram-positive bacteria, among which compound 4k performed best against both S. aureus and MRSA with the MIC value at 0.5 mg/L. Moreover, we identified the strong antibacterial activity for compound 4k against 19 clinical MRSA strains isolated from different specimen, which indicated its potential in clinical application. In vitro biofilm inhibition and microscopy assay revealed compound 4k inhibits biofilm formation and eradicates preformed biofilm effectively. The size-exclusion chromatography and docking study indicated that compound 4k mimics the binding mode of triclosan with saFabI. The efficiency of the protein-inhibitor interaction was evaluated by measuring NADPH reduction using trans-2-octenoyl-CoA as substrate. Overall, our data demonstrate that N-benzylaniline is a promising scaffold for anti-staphylococcal drug development.

RevDate: 2019-03-20

Sigurlásdóttir S, Wassing GM, Zuo F, et al (2019)

Deletion of D-Lactate Dehydrogenase A in Neisseria meningitidis Promotes Biofilm Formation Through Increased Autolysis and Extracellular DNA Release.

Frontiers in microbiology, 10:422.

Neisseria meningitidis is a Gram-negative bacterium that asymptomatically colonizes the human nasopharyngeal mucosa. Pilus-mediated initial adherence of N. meningitidis to the epithelial mucosa is followed by the formation of three-dimensional aggregates, called microcolonies. Dispersal from microcolonies contributes to the transmission of N. meningitidis across the epithelial mucosa. We have recently discovered that environmental concentrations of host cell-derived lactate influences N. meningitidis microcolony dispersal. Here, we examined the ability of N. meningitidis mutants deficient in lactate metabolism to form biofilms. A lactate dehydrogenease A (ldhA) mutant had an increased level of biofilm formation. Deletion of ldhA increased the N. meningitidis cell surface hydrophobicity and aggregation. In this study, we used FAM20, which belongs to clonal complex ST-11 that forms biofilms independently of extracellular DNA (eDNA). However, treatment with DNase I abolished the increased biofilm formation and aggregation of the ldhA-deficient mutant, suggesting a critical role for eDNA. Compared to wild-type, the ldhA-deficient mutant exhibited an increased autolytic rate, with significant increases in the eDNA concentrations in the culture supernatants and in biofilms. Within the ldhA mutant biofilm, the transcription levels of the capsule, pilus, and bacterial lysis genes were downregulated, while norB, which is associated with anaerobic respiration, was upregulated. These findings suggest that the absence of ldhA in N. meningitidis promotes biofilm formation and aggregation through autolysis-mediated DNA release.

RevDate: 2019-03-19

Mostafavi SKS, Najar-Peerayeh S, Mobarez AM, et al (2019)

Characterization of uropathogenic E. coli O25b-B2-ST131, O15:K52:H1, and CGA: Neutrophils apoptosis, serum bactericidal assay, biofilm formation, and virulence typing.

Journal of cellular physiology [Epub ahead of print].

Pathogenic and drug-resistant strains of Escherichia coli (E. coli) O25b-B2-ST131, O15:H1-D-ST393, and CGA (clonal group A) clonal groups have spread worldwide. This study aimed at determining E. coli epidemic clonal groups, their virulence factors, biofilm formation, neutrophils apoptosis, and antimicrobial resistance pattern of uropathogenic E. coli. A total of 95 CTX-M-1-producing E. coli clinical isolates were enrolled. E. coli O25b-B2-ST131, CGA, and O15:K52:H1 were identified by serotyping and phylogrouping and allele-specific polymerase chain reaction-based assay. Antibiotic susceptibility, biofilm formation, hemolysis, and human serum bactericidal assay were performed. Neutrophil apoptosis was assayed by flow cytometry. Nine E. coli clonal groups including six O25b-B2-ST131 strains, two CGA, and one O15:K52:H1-D-ST393 strains were detected. One O25b-B2-ST131 isolate was a strong biofilm-producer. Three ST131 isolates had type I fimbriae. Furthermore, all the CGA and O15:K52:H1 and three of ST131 isolates harbored the P fimbriae. The virulence genes ompT, fimH, and traT were detected among all the clonal groups. The apoptosis was induced by O25b-B2-ST131, CGA, and O15:K52:H1 E. coli. There was no significant difference regarding apoptosis induction among clonal groups. Furthermore, the presence of the cdt, usp, and vat genes was significantly associated with the apoptosis of neutrophils by O25b-B2-ST131, CGA, and O15:K52:H1-D-ST393 clonal groups.

RevDate: 2019-03-19

Rajamohamed BS, S Siddharthan (2019)

Modulatory effects of Amukkara Choornam on Candida albicans biofilm: in vitro and in vivo study.

Molecular biology reports pii:10.1007/s11033-019-04757-z [Epub ahead of print].

In the present study, Amukkara Chooram (AC) a well known herbal medicine was investigated for their antibiofilm efficacy against biofilm of Candida albicans. The biofilm inhibitory concentration of 20 µg/mL of AC showed promising effect by inhibiting the biofilm upto 60%. Morphogenic transition state of C. albicans from yeast cells to hyphal transition was prevented by AC was revealed from light microscopic images. In addition, the inhibition of yeast hyphae was examined in the induction medium supplemented with AC. Consequently, atomic force microscope (AFM) also documented the morphological changes observed during the transition state of C. albicans in the presence and absence of AC. Furthermore, scanning electron microscope (SEM) and confocal laser scanning microscopic (CLSM) images showed reduction in the biomass and thickness of the mature biofilm of C. albicans. In vivo investigation of C. albicans with zebrafish infection model presented the clearance of biofilm from the epithelium of the intestinal tissues. Later, the histological changes in liver and kidney due to C. albicans infection open up that treatment with AC was able to significantly rejuvenate the tissues. Altogether, the study presents AC as potent antibiofilm agent with potential ability as alternative medicine to treat C. albicans biofilm mediated infections.

RevDate: 2019-03-19

Ciszek-Lenda M, Strus M, Walczewska M, et al (2019)

Pseudomonas aeruginosa biofilm is a potent inducer of phagocyte hyperinflammation.

Inflammation research : official journal of the European Histamine Research Society ... [et al.] pii:10.1007/s00011-019-01227-x [Epub ahead of print].

OBJECTIVE: Pseudomonas aeruginosa effectively facilitate resistance to phagocyte killing by biofilm formation. However, the cross talk between biofilm components and phagocytes is still unclear. We hypothesize that a biofilm provides a concentrated extracellular source of LPS, DNA and exopolysaccharides (EPS), which polarize neighbouring phagocytes into an adverse hyperinflammatory state of activation.

METHODS: We measured the release of a panel of mediators produced in vitro by murine neutrophils and macrophages exposed to various biofilm components of P. aeruginosa cultures.

RESULTS: We found that conditioned media from a high biofilm-producing strain of P. aeruginosa, PAR5, accumulated high concentrations of extracellular bacterial LPS, DNA and EPS by 72 h. These conditioned media induced phagocytes to release a hyperinflammatory pattern of mediators, with enhanced levels of TNF-α, IL-6, IL12p40, PGE2 and NO. Moreover, the phagocytes also upregulated COX-2 and iNOS with no influence on the expression of arginase-1.

CONCLUSIONS: Phagocytes exposed to biofilm microenvironment, called by us biofilm-associated neutrophils/macrophages (BANs/BAMs), display secretory properties similar to that of N1/M1-type phagocytes. These results suggest that in vivo high concentrations of LPS and DNA, trapped in biofilm by EPS, might convert infiltrating phagocytes into cells responsible for tissue injury without direct contact with bacteria and phagocytosis.

RevDate: 2019-03-19

Okaro U, Green R, Mohapatra S, et al (2019)

The trimeric autotransporter adhesin BadA is required for in vitro biofilm formation by Bartonella henselae.

NPJ biofilms and microbiomes, 5:10 pii:83.

Bartonellahenselae (Bh) is a Gram-negative rod transmitted to humans by a scratch from the common house cat. Infection of humans with Bh can result in a range of clinical diseases including lymphadenopathy observed in cat-scratch disease and more serious disease from persistent bacteremia. It is a common cause of blood-culture negative endocarditis as the bacterium is capable of growing as aggregates, and forming biofilms on infected native and prosthetic heart valves. The aggregative growth requires a trimeric autotransporter adhesin (TAA) called Bartonella adhesin A (BadA). TAAs are found in all Bartonella species and many other Gram-negative bacteria. Using Bh Houston-1, Bh Houston-1 ∆badA and Bh Houston-1 ∆badA/pNS2PTrcbadA (a partial complement of badA coding for a truncated protein of 741 amino acid residues), we analyze the role of BadA in adhesion and biofilm formation. We also investigate the role of environmental factors such as temperature on badA expression and biofilm formation. Real-time cell adhesion monitoring and electron microscopy show that Bh Houston-1 adheres and forms biofilm more efficiently than the Bh Houston-1 ∆badA. Deletion of the badA gene significantly decreases adhesion, the first step in biofilm formation in vitro, which is partially restored in Bh Houston-1 ∆badA/pNS2PTrcbadA. The biofilm formed by Bh Houston-1 includes polysaccharides, proteins, and DNA components and is susceptible to enzymatic degradation of these components. Furthermore, both pH and temperature influence both badA expression and biofilm formation. We conclude that BadA is required for optimal adhesion, agglutination and biofilm formation.

RevDate: 2019-03-19

Brislawn CJ, Graham EB, Dana K, et al (2019)

Forfeiting the priority effect: turnover defines biofilm community succession.

The ISME journal pii:10.1038/s41396-019-0396-x [Epub ahead of print].

Microbial community succession is a fundamental process that affects underlying functions of almost all ecosystems; yet the roles and fates of the most abundant colonizers are often poorly understood. Does early abundance spur long term persistence? How do deterministic and stochastic processes influence the ecological contribution of colonizers? We performed a succession experiment within a hypersaline ecosystem to investigate how different processes contributed to the turnover of founder species. Bacterial and eukaryotic colonizers were identified during primary succession and tracked through a defined, 79-day biofilm maturation period using 16S and 18S rRNA gene sequencing in combination with high resolution imaging that utilized stable isotope tracers to evaluate successional patterns of primary producers and nitrogen fixers. The majority of the founder species did not maintain high abundance throughout succession. Species replacement (versus loss) was the dominant process shaping community succession. We also asked if different ecological processes acted on bacteria versus Eukaryotes during succession and found deterministic and stochastic forces corresponded more with microeukaryote and bacterial colonization, respectively. Our results show that taxa and functions belonging to different kingdoms, which share habitat in the tight spatial confines of a biofilm, were influenced by different ecological processes and time scales of succession.

RevDate: 2019-03-19

Nakamura K, Shirato M, Tenkumo T, et al (2019)

Hydroxyl radicals generated by hydrogen peroxide photolysis recondition biofilm-contaminated titanium surfaces for subsequent osteoblastic cell proliferation.

Scientific reports, 9(1):4688 pii:10.1038/s41598-019-41126-z.

Titanium dental implants have been successfully used for decades; however, some implants are affected by peri-implantitis due to bacterial infection, resulting in loss of supporting bone. This study aimed to evaluate the effect of an antimicrobial chemotherapy employing H2O2 photolysis-developed to treat peri-implantitis-on biofilm-contaminated titanium surfaces in association with osteoblastic cell proliferation on the treated surface. Titanium discs were sandblasted and acid-etched, followed by contamination with a three-species biofilm composed of Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mitis. This biofilm model was used as a simplified model of clinical peri-implantitis biofilm. The discs were subjected to ultrasound scaling, followed by H2O2 photolysis, wherein 365-nm LED irradiation of the disc immersed in 3% H2O2 was performed for 5 min. We analysed proliferation of mouse osteoblastic cells (MC3T3-E1) cultured on the treated discs. Compared with intact discs, biofilm contamination lowered cell proliferation on the specimen surface, whereas H2O2 photolysis recovered cell proliferation. Thus, H2O2 photolysis can recover the degraded biocompatibility of biofilm-contaminated titanium surfaces and can potentially be utilised for peri-implantitis treatment. However, to verify the findings of this study in relation to clinical settings, assessment using a more clinically relevant multi-species biofilm model is necessary.

RevDate: 2019-03-19

Ferreira RBR, Ferreira MCS, Glatthardt T, et al (2019)

Osmotic stress induces biofilm production by Staphylococcus epidermidis isolates from neonates.

Diagnostic microbiology and infectious disease pii:S0732-8893(18)30577-7 [Epub ahead of print].

Staphylococcus epidermidis is one of the leading causes of bloodstream infections, particularly in premature neonates, and biofilm formation is a major virulence factor. We characterized biofilm formation by 50 S. epidermidis neonatal isolates under osmotic stress and evaluated the expression of biofilm-associated genes. Phenotypical analyses of biofilm production were performed in culture medium with or without addition of NaCl or glucose. In control medium (no additions), most isolates (84%) were nonproducers or weak biofilm producers. Growth in NaCl-containing medium increased the number of moderate/strong producers, and this increase was even greater in medium containing glucose. Most of the protein-enriched biofilms (60%) could be observed only during growth in glucose, whereas 50% of the polysaccharide-enriched biofilms were observed during growth in NaCl. Studies that evaluate the conditions used to characterize biofilm production are important to help us understand the dynamics of this important virulence factor in S. epidermidis and their impact on neonatal infections.

RevDate: 2019-03-19

Sadiq FA, Flint S, Sakandar HA, et al (2019)

Molecular regulation of adhesion and biofilm formation in high and low biofilm producers of Bacillus licheniformis using RNA-Seq.

Biofouling [Epub ahead of print].

RNA sequencing was used to reveal transcriptional changes during the motile-to-sessile switch in high and low biofilm-forming dairy strains of B. licheniformis isolated from Chinese milk powders. A significant part of the whole gene content was affected during this transition in both strains. In terms of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, seven metabolic pathways were significantly downregulated in the planktonic state compared to the biofilm state in both strains. Lipid and sugar metabolism seemed to play an important role in matrix production. Several genes involved in adhesion, matrix production and the matrix coating were either absent or less expressed in the biofilm state of the low biofilm producer compared to the high biofilm producer. Genes related to sporulation and the production of extracellular polymeric substances were concomitantly expressed in the biofilm state of both strains. These comprehensive insights will be helpful for future research into mechanisms and targets.

RevDate: 2019-03-19

Trotsko N, Kosikowska U, Andrzejczuk S, et al (2019)

Influence of Thiazolidine-2,4-Dione Derivatives with Azolidine or Thiosemicarbazone Moieties on Haemophilus spp. Planktonic or Biofilm-Forming Cells.

Molecules (Basel, Switzerland), 24(6): pii:molecules24061051.

Biofilm, naturally formed by microorganisms as integrated surface-bound communities, is one of the reasons for the development of antimicrobial resistance. Haemophilus spp. are common and representative opportunistic Gram-negative rods forming from the upper respiratory tract microbiota. The aim of this paper was to evaluate the influence of thiazolidine-2,4-dionebased azolidine and chlorophenylthiosemicarbazone hybrids against both planktonic and biofilm-forming Haemophilus spp. cells. The in vitro activity against planktonic and biofilm-forming cells of the tested compounds were evaluated by using the broth microdilution method. These activities were detected against reference and clinical strains of Haemophilus spp. on the basis of MICs (minimal inhibitory concentrations) and MBICs (minimal biofilm inhibitory concentrations). In addition, anti-adhesive properties of these compounds were examined. The target compounds showed potential activity against planktonic cells with MIC = 62.5⁻500 mg/L and biofilm-forming cells with MBIC = 62.5⁻1000 mg/L. The observed anti-adhesive properties of the tested compounds were reversible during long-term incubation in a lower concentration of compounds.

RevDate: 2019-03-19

Merino L, Procura F, Trejo FM, et al (2019)

Biofilm formation by Salmonella sp. in the poultry industry: Detection, control and eradication strategies.

Food research international (Ottawa, Ont.), 119:530-540.

Salmonella represents an important global public health problem and it is an emerging zoonotic bacterial threat in the poultry industry. Diverse registered human cases of salmonellosis shown poultry origins. Various control measures have been employed both at the farming and processing levels to address it. This review focuses on traditional and new detection techniques of biofilm formation by Salmonella spp. and different approaches that can be used to prevent and/or control biofilm formation by these bacteria. A number of methodologies based on different approximations have been recently employed to detect and evaluate bacteria attached to surfaces, including real-time polymerase chain reaction (PCR), confocal laser scanning microscopy and Optical Coherence Tomography. Due to persistence of Salmonella biofilm in food processing environments after cleaning and sanitation, control and eradication strategies in poultry industry should be constantly studied. In this sense, the use of several alternatives to control Salmonella biofilm formation, such as lactic acid bacteria, phagetherapy, extracts from aromatic plants, quorum sensing inhibitors, bacteriocins and nanomaterials, have been successfully tested and will be reviewed.

RevDate: 2019-03-18

Del Rio M, de la Canal L, Pinedo M, et al (2019)

Effects of the binding of a Helianthus annuus lectin to Candida albicans cell wall on biofilm development and adhesion to host cells.

Phytomedicine : international journal of phytotherapy and phytopharmacology, 58:152875 pii:S0944-7113(19)30046-7 [Epub ahead of print].

BACKGROUND: In our previous study, we isolated and characterized a lectin called Helja from Helianthus annuus (sunflower) and then, in a further study, demonstrated its antifungal activity against Candida spp. Since Candida infections are a major health concern due to the increasing emergence of antifungal resistant strains, the search for new antifungal agents offers a promising opportunity for improving the treatment strategies against candidiasis.

PURPOSE: The aim of this work was to get insights about the mechanism of action of Helja, an antifungal lectin of H. annuus, and to explore its ability to inhibit Candida albicans biofilm development and adherence to buccal epithelial cells (BEC).

STUDY DESIGN/METHODS: Yeast viability was evaluated by Evans Blue uptake and counting of colony forming units (CFU). The yeast cell integrity was assessed using Calcofluor White (CFW) as a cell wall perturbing agent and sorbitol as osmotic protectant. The induction of oxidative stress was evaluated using 3,3'-diaminobenzidine (DAB) for detection of hydrogen peroxide. The adherence was determined by counting the yeast cells attached to BEC after methylene blue staining. The biofilms were developed on polystyrene microplates, visualized by confocal laser scanning microscopy and the viable biomass was quantified by CFU counting. The binding lectin-Candida was assessed using Helja conjugated to fluorescein isothiocyanate (Helja-FITC) and simultaneous staining with CFW. The cellular surface hydrophobicity (CSH) was determined using a microbial adhesion to hydrocarbons method.

RESULTS: C. albicans cells treated with 0.1 µg/µl of Helja showed a drastic decrease in yeast survival. The lectin affected the fungal cell integrity, induced the production of hydrogen peroxide and inhibited the morphological transition from yeast to filamentous forms. Helja caused a significant reduction of adherent cells and a decrease in biofilm biomass and coverage area. The treatment with the protein also reduced the surface hydrophobicity of fungal cells. We show the binding of Helja-FITC to yeast cells distributed as a thin outer layer to the CFW signal, and this interaction was displaced by mannose and Concanavalin A.

CONCLUSION: The results demonstrate the interaction of Helja with the mannoproteins of C. albicans cell wall, the disruption of the cell integrity, the induction of oxidative stress, the inhibition of the morphological transition from yeast to filamentous forms and the fungal cell viability loss. The binding Helja-Candida also provides a possible explanation of the lectin effect on cell adherence, biofilm development and CSH, relevant features related to virulence of the pathogen.

RevDate: 2019-03-18

Tang R, Zhu J, Feng L, et al (2018)

Characterization of LuxI/LuxR and their regulation involved in biofilm formation and stress resistance in fish spoilers Pseudomonas fluorescens.

International journal of food microbiology, 297:60-71 pii:S0168-1605(18)30690-1 [Epub ahead of print].

Quorum sensing (QS) is crucial for adaption and development of foodborne bacteria in diverse environments. Pseudomonas fluorescens PF07 with QS mediated acylated homoserine lactones (AHLs) activity was isolated from spoiled large yellow croaker (Pseudosciaena crocea). In this study AHL-mediated QS system was characterized and their roles in biofilm formation, motility, stress response and spoilage of P. fluorescens were evaluated. A LuxI/LuxR homolog consisting of a conserved AHL synthase gene (luxI) and a transcriptional regulator gene (luxR) was identified in the strain. Two in-frame deletion mutants of luxI and luxR, ∆luxI and ∆luxR, were constructed to explore their QS signaling function in P. fluorescens. Three types of AHLs were detected in PF07 culture by LC-MS/MS, and N-butanoyl-l-homoserine lactone (C4-HSL) was a major signal molecule. The C4-HSL activities was almost abolished in ∆luxI, and decreased greatly in ∆luxR. Compared with wild type (WT) strain, both ∆luxI and ∆luxR showed the significant decrease of biofilm biomass and expolysaccharide production, resulting in thinner and incompact biofilm structure, but promoted swimming motility. The resistance of P. fluorescens to H2O2, heat, NaCl and crystal violet apparently declined in two mutants compared to WT. Spoilage factors, siderophore and protease, apparently attenuated due to deletion of luxI or luxR gene, while the growth and TVB-N production did not differ. Furthermore, the changes of the biofilm formation, motility and protease in ∆luxI strain were partially restored by the exogenous C4-HSL. In agreement with the effect of two mutants on various phenotypes, the transcriptions of alg, lapA, flgA, rpoS, and aprX were significantly down-regulated, and flgA was up-regulated in ∆luxI and ∆luxR. Therefore, the present study highlighted that the co-operation of LuxI/LuxR homolog was an important QS regulator in biofilm formation, motility and spoilage potential, and hinted its positive regulation of stress resistance with RpoS in P. fluorescens.

RevDate: 2019-03-18

Percival SL, Mayer D, Kirsner RS, et al (2019)

Surfactants: Role in biofilm management and cellular behaviour.

International wound journal [Epub ahead of print].

Appropriate and effective wound cleaning represents an important process that is necessary for preparing the wound for improved wound healing and for helping to dislodge biofilms. Wound cleaning is of paramount importance to wound bed preparation for helping to enhance wound healing. Surfactant applications in wound care may represent an important area in the cleaning continuum. However, understanding of the role and significance of surfactants in wound cleansing, biofilm prevention and control, and enhancing cellular viability and proliferation is currently lacking. Despite this, some recent evidence on poloxamer-based surfactants where the surfactants are present in high concentration have been shown to have an important role to play in biofilm management; matrix metalloproteinase modulation; reducing inflammation; and enhancing cellular proliferation, behaviour, and viability. Consequently, this review aims to discuss the role, mode of action, and clinical significance of the use of medically accepted surfactants, with a focus on concentrated poloxamer-based surfactants, to wound healing but, more specifically, the role they may play in biofilm management and effects on cellular repair.

RevDate: 2019-03-18

Junka A, Bartoszewicz M, Dziadas M, et al (2019)

Application of bacterial cellulose experimental dressings saturated with gentamycin for management of bone biofilm in vitro and ex vivo.

Journal of biomedical materials research. Part B, Applied biomaterials [Epub ahead of print].

Bacterial cellulose is one of the most promising polymers of recent years. Herein, we present a possibility of BC application as a carrier of gentamycin antibiotic for the treatment and prevention of bone infections. We have shown that BC saturated with gentamycin significantly reduces the level of biofilm-forming bone pathogens, namely Staphylococcus aureus and Pseudomonas aeruginosa, and displays very low cytotoxicity in vitro against osteoblast cell cultures. Another beneficial feature of our prototype dressing is prolonged release of gentamycin, which provides efficient protection from microbial contamination and subsequent infection. Moreover, it seems that bacterial cellulose (BC) alone without any antimicrobial added, may serve as a barrier by significantly hampering the ability of the pathogen to penetrate to the bone structure. Therefore, a gentamycin-saturated BC dressing may be considered as a possible alternative for gentamycin collagen sponge broadly used in clinical setting. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B, 2019.

RevDate: 2019-03-18

Luo TL, Hayashi M, Zsiska M, et al (2019)

Introducing BAIT (Biofilm Architecture Inference Tool): a software program to evaluate the architecture of oral multi-species biofilms.

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

Biofilm model systems are used to study biofilm growth and predict the effects of anti-biofilm interventions within the human oral cavity. Many in vitro biofilm model systems use a confocal laser scanning microscope (CLSM) in conjunction with image analysis tools to study biofilms. The aim of this study was to evaluate an in-house developed image analysis software program that we call BAIT (Biofilm Architecture Inference Tool) to quantify the architecture of oral multi-species biofilms following anti-biofilm interventions using a microfluidic biofilm system. Differences in architecture were compared between untreated biofilms and those treated with water (negative control), sodium gluconate ('placebo') or stannous fluoride (SnF2). The microfluidic system was inoculated with pooled human saliva and biofilms were developed over 22 h in filter-sterilized 25 % pooled human saliva. During this period, biofilms were treated with water, sodium gluconate, or SnF2 (1000, 3439 or 10 000 p.p.m. Sn2+) 8 and 18 h post-inoculation. After 22 h of growth, biofilms were stained with LIVE/DEAD stain, and imaged by CLSM. BAIT was used to calculate biofilm biovolume, total number of objects, surface area, fluffiness, connectivity, convex hull porosity and viability. Image analysis showed oral biofilm architecture was significantly altered by 3439 and 10 000 p.p.m. Sn2+ treatment regimens, resulting in decreased biovolume, surface area, number of objects and connectivity, while fluffiness increased (P<0.01). In conclusion, BAIT was shown to be able to measure the changes in biofilm architecture and detects possible antimicrobial and anti-biofilm effects of candidate agents.

RevDate: 2019-03-18

Pate M, Mičunovič J, Golob M, et al (2019)

Salmonella Infantis in Broiler Flocks in Slovenia: The Prevalence of Multidrug Resistant Strains with High Genetic Homogeneity and Low Biofilm-Forming Ability.

BioMed research international, 2019:4981463.

For almost a decade, the number of Salmonella enterica subspecies enterica serovar Infantis-positive broiler flocks has been steadily increasing in Slovenia, doubling the number of positive holdings in only a few years. Since multidrug resistant S. Infantis isolates are highly prevalent in the broiler meat industry and may represent a public health concern through the food chain, we aimed to investigate the antimicrobial susceptibility, genetic diversity, and biofilm-forming ability of S. Infantis from Slovenian broiler flocks. A total of 87 S. Infantis strains isolated from broiler faeces in the period between 2007 and 2013 were studied. The samples originated from 41 farms which were subcontractors of three major food business operators and from two autonomously operating holdings (farms). Isolates were phenotypically tested for their susceptibility to 14 antimicrobials from nine classes by determining the minimum inhibitory concentration with the microdilution method. Only 8% of the isolates were susceptible to all of the antimicrobial agents tested, while 88.5% of the isolates were multidrug resistant, with the most common resistance pattern CipNxSSuT (65.5%) followed by CipNxSuT (17.2%). Pulsed-field gel electrophoresis (PFGE) divided the strains into five clusters (A-E) comprising 16 distinct XbaI PFGE profiles. Sixty-five out of 87 isolates were grouped in clusters A and B, with the predominant PFGE profiles A1 and B1 encompassing 33 and 28 isolates, respectively. A vast majority of the isolates (75/87) showed >90% PFGE profile similarity. The biofilm-forming capacity of the tested isolates, determined with crystal violet assay in polystyrene microwell plates, was generally weak. The average biofilm formation for persistent strains was higher than for presumably nonpersistent strains; however, the difference was not significant. It seems that S. Infantis persistence on broiler farms is more related to its widespread occurrence in the broiler production chain and ineffective disinfection protocols than to its ability to form biofilm.

RevDate: 2019-03-18

Patil PC, Tan J, Demuth DR, et al (2019)

'Second-generation' 1,2,3-triazole-based inhibitors of Porphyromonas gingivalis adherence to oral streptococci and biofilm formation.

MedChemComm, 10(2):268-279 pii:c8md00405f.

Several 'second-generation' click inhibitors of the multi-species biofilm propagated by the adherence of the oral pathogen Porphyromonas gingivalis to Streptococcus gordonii were synthesized and evaluated. The design of the structures was based on the results obtained with the first-generation diphenyloxazole 'click' inhibitors which bear suitable hydrophobic and polar groups within a dual scaffold molecule bearing a 1,2,3-triazole spacer. The structures of the synthetic targets reported herein now consist of a triazolyl(phenylsulfonylmethyl) and a triazolyl(phenylsulfinylmethyl) spacer which joins a 4,5-diphenyloxazole with both phenyl rings bearing lipophilic substituents. The triazolyl "linker" group is formed by a click reaction between the 4-azido(phenylsulfonyl/sulfinylmethyl) oxazoles and acetylenic components having aryl groups bearing hydrophobic substituents. The 1,3,5-trisubstituted-2,4,6-triazine scaffold of the most active click compounds were modeled after the structural motif termed the VXXLL nuclear receptor (NR) box. When substituted at the 3- and 5-positions with 2- and 4-fluorophenylamino and N,N-diethylamino units, the candidates bearing the 1,3,5-trisubstituted-2,4,6-triazine scaffold formed a substantial subset of the second-generation click candidates. Four of the click products, compounds 95, 111, 115 and 122 showed inhibition of the adherence of P. gingivalis to S. gordonii with an IC50 range of 2.3-4.3 μM and only 111 exhibited cytotoxic activity against telomerase immortalized gingival keratinocytes at 60 μM. These results suggest that compounds 95, 115, 122, and possibly 111 represent the most suitable compounds to evaluate for activity in vivo.

RevDate: 2019-03-18

Awoke N, Kassa T, L Teshager (2019)

Magnitude of Biofilm Formation and Antimicrobial Resistance Pattern of Bacteria Isolated from Urinary Catheterized Inpatients of Jimma University Medical Center, Southwest Ethiopia.

International journal of microbiology, 2019:5729568.

Biofilm formation is one of the features of most bacteria. Catheterization in medicine is a source of highly resistant bacterial infections, and those bacteria respond poorly to antimicrobial therapy. Bacterial biofilm features were not described from catheterized inpatients in Ethiopia as its formation is known to afford antimicrobial resistance and challenge patient management. The aim of this study was to isolate catheter-associated urinary bacterial pathogens, their biofilm formation, and antimicrobial susceptibility pattern among inpatients of Jimma University Medical Center (JUMC) in Southwest Ethiopia. A prospective cross-sectional study was conducted among urinary catheterized inpatients of JUMC from February to August 2016. A total of 143 study participants were enrolled consecutively in this study. Urine samples were collected from catheterized patients and processed using a standard bacteriological protocol for isolation and identification. Evaluation of in vitro biofilm formation and antimicrobial susceptibility pattern of uropathogenic bacteria was done using microtiter plates and disk diffusion method, respectively. Data were cleaned, coded, and entered into SPSS version 20 for analysis. All statistical test values of p < 0.05 were considered statistically significant. From all study participants, mean age was 44 years. Sixty bacterial strains were recovered from 57 urinary catheterized inpatients among which 54 of them were monomicrobial (94.7%). The remaining six bacterial strains were recovered from three study participants each with two bacterial isolates. The predominant bacterial isolates were Gram-negative bacteria with E. coli turning out first. About 80% of bacterial isolates were biofilm formers. The majority of the bacteria were resistant to commonly prescribed antimicrobial agents. In conclusion, the majority of bacterial uropathogen isolates were Gram-negative, biofilm formers, and resistant to commonly prescribed antimicrobial agents. Relatively ciprofloxacin, nitrofurantoin, and amikacin were highly effective against most isolated bacteria.

RevDate: 2019-03-18

Fu YY, Zhang L, Yang Y, et al (2019)

Synergistic antibacterial effect of ultrasound microbubbles combined with chitosan-modified polymyxin B-loaded liposomes on biofilm-producing Acinetobacter baumannii.

International journal of nanomedicine, 14:1805-1815 pii:ijn-14-1805.

Purpose: Resistant strains of Acinetobacter baumannii (AB) that can form biofilms are resistant to polymyxin. Therefore, effective and safe polymyxin preparations against biofilm-producing AB are urgently needed. This study aims to prepare chitosan-modified polymyxin B-loaded liposomes (CLPs) and ultrasound microbubbles (USMBs) and then explore the synergistic antibacterial effects of USMBs combined with CLPs in vitro.

Methods: CLPs were prepared using a modified injection method, and microbubbles were prepared using a simple mechanical vibration method. Minimal biofilm inhibitory concentration (MBIC) of CLPs against resistant biofilm-producing AB was determined. Antibacterial activities of CLPs with or without USMBs were analyzed by crystal violet staining and resazurin assays to evaluate biofilm mass and viable counts, respectively. Then, the anti-biofilm effects of CLPs with or without USMBs on biofilm-producing AB were confirmed via scanning electron microscopy (SEM) analysis.

Results: We prepared CLPs that were 225.17±17.85 nm in size and carried positive charges of 12.64±1.44 mV. These CLPs, with higher encapsulation efficiency and drug loading, could exhibit a sustained release effect. We prepared microbubbles that were 2.391±0.052 µm in size and carried negative charges of -4.32±0.43 mV. The MBICs of the CLPs on the biofilm-producing AB was 8±2 µg/mL, while that of polymyxin B was 32±2 µg/mL. USMBs in combination with 2 µg/mL of polymyxin B could completely eliminate the biofilm-producing AB and achieve the maximum antimicrobial effects (P>0.05 vs sterile blank control). SEM imaging revealed some scattered bacteria without a biofilm structure in the USMB combined with the CLP group, confirming that this combination has the greatest anti-biofilm effects.

Conclusion: In this research, we successfully prepared USMBs and CLPs that have a more significant antibacterial effect on biofilm-forming AB than polymyxin B alone. Experiments in vitro indicate that the synergistic antibacterial effect of combining USMBs with CLPs containing as little as 2 µg/mL of polymyxin B is sufficient to almost eliminate drug-resistant biofilm-producing AB.

RevDate: 2019-03-16

Roeslan MO, Ayudhya TDN, Yingyongnarongkul BE, et al (2019)

Anti-biofilm, nitric oxide inhibition and wound healing potential of purpurin-18 phytyl ester isolated from Clinacanthus nutans leaves.

Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 113:108724 pii:S0753-3322(18)34156-8 [Epub ahead of print].

AIMS: Clinacanthus nutans (C. nutans) has demonstrated anti-inflammatory activity, however, the active compound generating this activity remains unknown. The aim of this study was to identify the bioactive compound in C. nutans responsible for its anti-inflammatory, in-vitro wound healing, and anti-biofilm activities.

MAIN METHODS: A pure compound was isolated from the chloroform extract (CE) of C. nutans leaves by chromatographic techniques and bioassay-guided fractionation. This compound's structure was determined by spectroscopic analyses (FTIR/NMR/HRES-MS). Biological activities were evaluated using cytotoxicity, nitric oxide (NO), wound scratch, anti-microbial activity, and anti-biofilm assays; and the compound's bactericidal depth into the biofilm was visualized by confocal laser scanning microscopy.

KEY FINDINGS: CE and its pure isolated compound, purpurin-18 phytyl ester (P18PE), significantly inhibited lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells at concentrations of 100 μg/ml and 10-100 μg/ml, respectively. These concentrations significantly induced wound closure by human gingival fibroblasts. CE (100-1000μg/ml) and P18PE (1-500 μg/ml) did not inhibit Streptococcus (S.) mutans growth. However, these concentrations significantly reduced S. mutans biofilm formation below 50% at 250 μg/ml for CE, and 25 μg/ml for P18PE (p<0.05).

SIGNIFICANCE: C. nutans contains a bioactive compound, P18PE, which exhibits anti-inflammatory, in-vitro wound healing, and anti-biofilm activities.

RevDate: 2019-03-16

Khider M, Hjerde E, Hansen H, et al (2019)

Differential expression profiling of ΔlitR and ΔrpoQ mutants reveals insight into QS regulation of motility, adhesion and biofilm formation in Aliivibrio salmonicida.

BMC genomics, 20(1):220 pii:10.1186/s12864-019-5594-4.

BACKGROUND: The coordination of group behaviors in bacteria is achieved by a cell-cell signaling process called quorum sensing (QS). QS is an intercellular communication system, which synchronously controls expression of a vast range of genes in response to changes in cell density and is mediated by autoinducers that act as extracellular signals. Aliivibrio salmonicida, the causative agent of cold-water vibrosis in marine aquacultures, uses QS to regulate several activities such as motility, biofilm formation, adhesion and rugose colony morphology. However, little is known about either genes or detailed mechanisms involved in the regulation of these phenotypes.

RESULTS: Differential expression profiling allowed us to define the genes involved in controlling phenotypes related to QS in A. salmonicida LFI1238. RNA sequencing data revealed that the number of expressed genes in A. salmonicida, ΔlitR and ΔrpoQ mutants were significantly altered due to changes in cell density. These included genes that were distributed among the 21 functional groups, mainly presented in cell envelope, cell processes, extrachromosomal/foreign DNA and transport-binding proteins functional groups. The comparative transcriptome of A. salmonicida wild-type at high cell density relative to low cell density revealed 1013 genes to be either up- or downregulated. Thirty-six downregulated genes were gene clusters encoding biosynthesis of the flagellar and chemotaxis genes. Additionally we identified significant expression for genes involved in acyl homoserine lactone (AHL) synthesis, adhesion and early colonization. The transcriptome profile of ΔrpoQ compared to the wild-type revealed 384 differensially expressed genes (DEGs) that allowed us to assign genes involved in regulating motility, adhesion and colony rugosity. Indicating the importance of RpoQ in controlling several QS related activities. Furthermore, the comparison of the transcriptome profiles of ΔlitR and ΔrpoQ mutants, exposed numerous overlapping DEGs that were essential for motility, exopolysaccharide production via syp operon and genes associated with tad operon.

CONCLUSION: Our findings indicate previously unexplained functional roles for LitR and RpoQ in regulation of different phenotypes related to QS. Our transcriptome data provide a better understanding of the regulation cascade of motility, wrinkling colony morphology and biofilm formation and will offer a major source for further research and analysis on this important field.

RevDate: 2019-03-15

Liu N, Skauge T, Landa-Marbán D, et al (2019)

Microfluidic study of effects of flow velocity and nutrient concentration on biofilm accumulation and adhesive strength in the flowing and no-flowing microchannels.

Journal of industrial microbiology & biotechnology pii:10.1007/s10295-019-02161-x [Epub ahead of print].

Biofilm accumulation in porous media can cause pore plugging and change many of the physical properties of porous media. Engineering bioplugging may have significant applications for many industrial processes, while improved knowledge on biofilm accumulation in porous media at porescale in general has broad relevance for a range of industries as well as environmental and water research. The experimental results by means of microscopic imaging over a T-shape microchannel clearly show that increase in fluid velocity could facilitate biofilm growth, but that above a velocity threshold, biofilm detachment and inhibition of biofilm formation due to high shear stress were observed. High nutrient concentration prompts the biofilm growth; however, the generated biofilm displays a weak adhesive strength. This paper provides an overview of biofilm development in a hydrodynamic environment for better prediction and modelling of bioplugging processes associated with porous systems in petroleum industry, hydrogeology and water purification.

RevDate: 2019-03-15

Yang J, Qiu L, Huang Y, et al (2019)

[The inhibition of accessory gene regulator C specific binding peptides on biofilm formation of Staphylococcus epidermidis on the surface of polyvinyl chloride in vitro].

Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery, 33(3):349-355.

Objective: To investigate the effect of accessory gene regulator C (agr C) specific binding peptides (named N1) on the biofilm formation of Staphylococcus epidermidis on the surface of polyvinyl chloride (PVC) materials in vitro.

Methods: Firstly, the two strains (ATCC35984, ATCC12228) were cultured with N1 at concentrations of 100, 200, 400, 800, and 1 600 μg/mL, respectively. The control group was cultured with agrC specific binding unrelated peptides (named N0) at the same concentrations and the absorbance (A) value was measured after 24 hours to determine the optimal bacteriostatic concentration of N1. The two strains were cultured with N1 and N0 of the optimal concentration, respectively. The A values were measured at 6, 12, 18, 24, 30, and 48 hours to observe the effect of N1 on the biofilm formation ability of Staphylococcus epidermidis. On this basis, the surface structure of the biofilm on the surface of PVC material was observed by scanning electron microscopy after 6, 12, 18, 24, and 30 hours of incubation with PVC material sheet. The thickness of the biofilm was observed by laser confocal microscopy after 6, 12, 18, and 24 hours of incubation with ATCC35984 strain.

Results: The optimal bacteriostatic concentration of N1 was 800 μg/mL. ATCC 12228 strain did not form obvious biofilm after being cultured with N1 and N0. When ATCC35984 strain was cultured with N1 and N0 for 12 hours, the difference in biofilm formation ability between groups N1 and N0 was statistically significant (P<0.05), but there was no significant difference at 6, 18, 24, 30, and 48 hours (P>0.05). Scanning electron microscopy examination showed that mature biofilm structure was observed in ATCC35984 strain and was not observed in ATCC12228 strain. Laser confocal microscopy observation showed that the number of bacteria in the group N1 was significantly lower than that in the group N0 at 12 hours, and the most of bacteria were dead bacteria. There was no significant difference in the number of bacteria at 6, 18, and 24 hours, and the most of them were live bacteria. The biofilm thickness of group N1 was significantly lower than that of group N0 at 12 and 18 hours (P<0.05).

Conclusion: The intensity of N1 inhibiting the formation of Staphylococcus epidermidis biofilm is dose-dependent. During the aggregation period, N1 can inhibit the biofilm formation by hindering the bacterial growth and aggregation. The inhibition effect on mature biofilm is not obvious.

RevDate: 2019-03-15

Lerch MF, Schoenfelder SMK, Marincola G, et al (2019)

A non-coding RNA from the intercellular adhesin (ica) locus of Staphylococcus epidermidis controls polysaccharide intercellular adhesin (PIA)-mediated biofilm formation.

Molecular microbiology [Epub ahead of print].

Polysaccharide intercellular adhesin (PIA)-associated biofilm formation is mediated by the intercellular adhesin (ica) locus and represents a major pathomechanism of Staphylococcus epidermidis. Here we report on a novel long non-coding (nc)RNA, named IcaZ, which is approximately 400 nucleotides in size. icaZ is located downstream of the ica repressor gene icaR and partially overlaps with the icaR 3' UTR. icaZ exclusively exists in ica-positive S. epidermidis, but not in S. aureus or other staphylococci. Inactivation of the gene completely abolishes PIA production. IcaZ is transcribed as a primary transcript from its own promoter during early- and mid-exponential growth and its transcription is induced by low temperature, ethanol and salt stress. IcaZ targets the icaR 5' UTR and hampers icaR mRNA translation, which alleviates repression of icaADBC operon transcription and results in PIA production. Interestingly, other than in S. aureus, posttranscriptional control of icaR mRNA in S. epidermidis does not involve icaR mRNA 5'/ 3' UTR base pairing. This suggests major structural and functional differences in icaADBC operon regulation between the two species that also involve the recruitment of ncRNAs. Together, the IcaZ ncRNA represents an unprecedented novel species-specific player involved in the control of PIA production in S. epidermidis. This article is protected by copyright. All rights reserved.

RevDate: 2019-03-15

Hosseini SS, Ghaemi E, F Koohsar (2018)

Influence of ZnO nanoparticles on Candida albicans isolates biofilm formed on the urinary catheter.

Iranian journal of microbiology, 10(6):424-432.

Background and Objectives: The aim of this study was to determine the effect of zinc oxide nanoparticle (ZnO-np) solution in the surface catheter on C. albicans adhesion and biofilm formation.

Materials and Methods: Out of 260 isolates from urinary catheter, 133 were determined as C. albicans by common phenotypic and genotyping methods. ZnO nanoparticles with 30 nm were made by the sol-gel method, which was confirmed by XRD (X-ray diffraction) and scanning electron microscope (SEM) methods. Candidal adhesion and biofilm assays were performed on catheter surfaces for 2 and 48 hours, respectively. The effect of sub-MIC (minimum inhibitory concentrations) and MIC concentrations of ZnO-np on biofilm formation was evaluated after 24 hours using Crystal violet (CV), colony-forming unit (CFU), and SEM.

Results: Out of 133 C. albicans isolates, 20 (15%) fluconazole-resistant and 113 (85%) susceptible isolates were determined by the disk diffusion method. Results showed that both isolates adhered to biofilm formation on the catheter surfaces. A significantly (P< 0.05) higher number of CFUs was evident in fluconazole-resistant biofilms compared to those formed by susceptible isolates. ZnO-np reduced biofilm biomass and CFUs of dual isolate biofilms (P< 0.05). ZnO nanoparticles had a significantly (P< 0.05) greater effect on reducing fluconazole-resistant C. albicans biofilm biomass compared to susceptible isolates.

Conclusion: Zno-np exhibits inhibitory effects on biofilms of both isolates. These findings provide an important advantage of ZnO that may be useful in the treatment of catheter-related urinary tract infection.

RevDate: 2019-03-15

Baghini GS, Sepahi AA, Tabatabaei RR, et al (2018)

The combined effects of ethanolic extract of Artemisia aucheri and Artemisia oliveriana on biofilm genes expression of methicillin resistant Staphylococcus aureus.

Iranian journal of microbiology, 10(6):417-423.

Background and Objectives: One of the most important antibiotic-resistant bacteria is methicillin-resistant Staphylococcus aureus (MRSA) biofilm that has caused significant problems in treating the patients. Therefore, the aim of this study was to evaluate the levels of expression of genes involved in biofilm formation in MRSA (ATCC 33591) while being treated by a combination of Artemisia aucheri and Artemisia oliveriana.

Materials and Methods: The minimum inhibitory concentration (MIC) of ethanolic extract of A. aucheri and A. oliveriana and also the minimum inhibitory concentration of combination of both extracts were 512, 1024 and 256 μg/ml, respectively; then at concentrations lower than the MIC, expression levels of the desired genes were determined by Real Time PCR.

Results: Based on results, using a combination of two ethanolic extracts had a significant effect on expression of genes involved in biofilm formation in MRSA. The expression level of icaA at 4, 8, 16 h after being treated by herbal extracts of A. aucheri and A. oliveriana was 0.293, 0.121, 0.044, respectively. The expression level of icaD was 0.285, 0.097, 0.088, respectively, while that of ebps was 0.087, 0.042, 0.009 at 4, 8 and 16 h, respectively.

Conclusion: This study provided evidence that ethanol extract of A. oliveriava and A. aucheri can inhibit the biofilm formation of S. aureus. As a traditional Iranian medicine, A. oliveriava and A. aucheri extracts have a potential antibiofilm formation against MRSA strains.

RevDate: 2019-03-15

Calderón CE, Tienda S, Heredia-Ponce Z, et al (2019)

The Compound 2-Hexyl, 5-Propyl Resorcinol Has a Key Role in Biofilm Formation by the Biocontrol Rhizobacterium Pseudomonas chlororaphis PCL1606.

Frontiers in microbiology, 10:396.

The production of the compound 2-hexyl-5-propyl resorcinol (HPR) by the biocontrol rhizobacterium Pseudomonas chlororaphis PCL1606 (PcPCL1606) is crucial for fungal antagonism and biocontrol activity that protects plants against the phytopathogenic fungus Rosellinia necatrix. The production of HPR is also involved in avocado root colonization during the biocontrol process. This pleiotrophic response prompted us to study the potential role of HPR production in biofilm formation. The swimming motility of PcPLL1606 is enhanced by the disruption of HPR production. Mutants impaired in HPR production, revealed that adhesion, colony morphology, and typical air-liquid interphase pellicles were all dependent on HPR production. The role of HPR production in biofilm architecture was also analyzed in flow chamber experiments. These experiments revealed that the HPR mutant cells had less tight unions than those producing HPR, suggesting an involvement of HPR in the production of the biofilm matrix.

RevDate: 2019-03-15

Ansari FA, I Ahmad (2019)

Fluorescent Pseudomonas -FAP2 and Bacillus licheniformis interact positively in biofilm mode enhancing plant growth and photosynthetic attributes.

Scientific reports, 9(1):4547 pii:10.1038/s41598-019-40864-4.

Compatible interaction between commonly used plant growth promoting rhizobacteria (PGPR) in biofilm mode in vitro and in the rhizosphere is expected to provide better understanding for the development of effective consortium. With the above hypothesis, the present study evaluated two characterized PGPR (Pseudomonas fluorescens FAP2 and Bacillus licheniformis B642) for their biofilm-related functions using standard protocols. The interaction between the FAP2 and B642 in planktonic mode was studied by plate spot/overlay method and competitive growth assessment. Biofilm development on a microtitre plate and a glass surface was studied by standard methods. Biofilm formation was characterized by SEM. Rhizosphere and rhizoplane colonization of wheat seedlings by both isolates individually and by co-inoculation was studied by determining CFU/g of soil/root samples. Biofilm development on the root surface was further analyzed by SEM. Both isolates demonstrated multiple plant growth promoting (PGP) traits (production of IAA, siderophore, and ammonia; phosphate solubilization) and biofilm-related functions such as production of EPS, alginate, cell surface hydrophobicity and swarming motility. Both strains formed strong biofilms on a glass cover slip in vitro. Interaction between the two strains under the planktonic mode revealed no antagonism in terms of growth inhibition and competitive growth kinetics. Similarly, FAP2 and B642 strains formed a mixed biofilm on a glass cover slip as well as on seedling roots. Wheat rhizosphere and rhizoplane were colonized by both isolates as evidenced from their viable counts in single and co-inoculation. The effect of single and co inoculation revealed the significant enhancement of vegetative growth and photosynthetic parameters such as chlorophyll content, transpiration rate (E), internal CO2 concentration (Ci), stomatal conductance (gs), and net photosynthetic rate (PN) and leaf water potential (LWP) as compared to uninoculated control. Indigenous Pseudomonas fluorescens FAP2 strain and Bacillus licheniformis B642 are compatible PGPR in both planktonic and biofilm modes of growth and threfore could be developed effective consortium of PGPR. Further indepth investigation is required to understand molecular mechanism of the interaction in biofilm mode of growth under natural condition.

RevDate: 2019-03-15

Siddique A, Suraraksa B, Horprathum M, et al (2019)

Wastewater biofilm formation on self-assembled monolayer surfaces using elastomeric flow cells.

Anaerobe pii:S1075-9964(19)30044-7 [Epub ahead of print].

In anaerobic wastewater treatment, microbial biofilm is beneficial for efficient substrate utilization and for preventing the wash-out of key microorganisms. By providing solid supports, biofilm formation can be accelerated due to the early initial adhesion of residing microbes. Alteration in surface properties is therefore one such approach that helps us understand microbial interfacial interaction. Here, self-assembled monolayers of alkanethiols with carboxyl (-COOH), hydroxyl (-OH), and amine (-NH2) terminal moieties on gold (Au) substrates were employed to study the initial adhesion of wastewater microbes. An elastomeric flow cell was also utilized to simulate the environment of wastewater bioreactor. Results from fluorescence in situ hybridization (FISH) portrayed more enhanced microbial adhesion after 2 h on -NH2 functional group with the calculated surface coverage of 12.8 ± 2.4% as compared to 7.7 ± 1.6% on -COOH, 11.0 ± 2.0% on -OH, and 1.2% on unmodified Au surfaces. This might be because of concomitant electrostatic attraction between negatively-charged bacteria and positively-charged (-NH3+) functional groups. Nevertheless, the average surface coverage by individual biofilm clusters was 28.0 ± 5.0 μm2 and 32.0 ± 9.0 μm2 on -NH2 and -OH surfaces, respectively, while -COOH surfaces resulted in higher value (60.0 ± 5.0 μm2) and no significant cluster formation was observed on Au surfaces. Accordingly, the average inter-cluster distance observed on -NH2 surfaces was relatively smaller (3.0 ± 0.6 μm) as compared to that on other surfaces. Overall, these data suggest favorable initial biofilm growth on more hydrophilic and positively-charged surfaces. Furthermore, the analysis of the mean fluorescence intensity revealed preferred initial adhesion of key microbes (archaea) on -OH and -NH2 surfaces. Indeed, results obtained from this study would be beneficial in designing selective biointerfaces for certain biofilm carriers in a typical wastewater bioreactor. Importantly, our elastomeric flow cell integrated with SAM-modified surfaces demonstrated an ideal platform for high-throughput investigation of wastewater biofilm under controlled environments.

RevDate: 2019-03-15

Modiri M, Khodavaisy S, Barac A, et al (2019)

Comparison of biofilm-producing ability of clinical isolates of Candida parapsilosis species complex.

Journal de mycologie medicale pii:S1156-5233(18)30367-6 [Epub ahead of print].

OBJECTIVE: Candida parapsilosis is one of the main emerging non-Candida albicans species leading to superficial and systemic fungal infections in humans. Candida has the ability to produce biofilms associated with pathogenesis. The aim of the study was to estimate biofilm-producing ability of clinical isolates of C. parapsilosis sp. complex.

METHODS: Clinical samples of C. parapsilosis complex have been analyzed. Crystal violet (CV) staining and tetrazolium reduction assay (MTT) have been used to analyze the clinical isolates ability to produce biofilms. The biofilm's structural characteristics have been assessed by using scanning electron microscopy.

RESULTS: All 65 isolates were able to form biofilm. In addition, no significant difference was found between biofilm quantification based on two assays at different time intervals (24h, 48h, 72h, 96h) (P>0.05), with the exception of Candida orthopsilosis, which exhibited higher metabolic activity at 24h time point (P<0.05). Moreover, metabolic activity and production of biofilm biomass demonstrated statistically significant correlation (r=0.685, P<0.01). According to microscopic observations, the investigated clinical strains formed the similar surface topography with the slight differences in morphology; in addition, there was no statistically significant difference between efficiency of two assays to quantify biofilm.

CONCLUSION: It was shown that, similar to C. parapsilosissensu stricto, two cryptic identified species (C. orthopsilosis and Candida metapsilosis) obtained from different clinical samples, were biofilm producers, while C. parapsilosissensu stricto exhibited the highest biofilm production.

RevDate: 2019-03-15

Henry M, A Fouladkhah (2019)

Outbreak History, Biofilm Formation, and Preventive Measures for Control of Cronobacter sakazakii in Infant Formula and Infant Care Settings.

Microorganisms, 7(3): pii:microorganisms7030077.

Previously known as Enterobacter sakazakii from 1980 to 2007, Cronobacter sakazakii is an opportunistic bacterium that survives and persists in dry and low-moisture environments, such as powdered infant formula. Although C. sakazakii causes disease in all age groups, infections caused by this pathogen are particularly fatal in infants born premature and those younger than two months. The pathogen has been isolated from various environments such as powdered infant formula manufacturing facilities, healthcare settings, and domestic environments, increasing the chance of infection through cross-contamination. The current study discusses the outbreak history of C. sakazakii and the ability of the microorganism to produce biofilms on biotic and abiotic surfaces. The study further discusses the fate of the pathogen in low-moisture environments, articulates preventive measures for healthcare providers and nursing parents, and delineates interventions that could be utilized in infant formula manufacturing to minimize the risk of contamination with Cronobacter sakazakii.

RevDate: 2019-03-14

Schoenfelder SMK, Lange C, Prakash SA, et al (2019)

The small non-coding RNA RsaE influences extracellular matrix composition in Staphylococcus epidermidis biofilm communities.

PLoS pathogens, 15(3):e1007618 pii:PPATHOGENS-D-18-02380 [Epub ahead of print].

RsaE is a conserved small regulatory RNA (sRNA) which was previously reported to represent a riboregulator of central carbon flow and other metabolic pathways in Staphylococcus aureus and Bacillus subtilis. Here we show that RsaE contributes to extracellular (e)DNA release and biofilm-matrix switching towards polysaccharide intercellular adhesin (PIA) production in a hypervariable Staphylococcus epidermidis isolate. Transcriptome analysis through differential RNA sequencing (dRNA-seq) in combination with confocal laser scanning microscopy (CLSM) and reporter gene fusions demonstrate that S. epidermidis protein- and PIA-biofilm matrix producers differ with respect to RsaE and metabolic gene expression. RsaE is spatiotemporally expressed within S. epidermidis PIA-mediated biofilms, and its overexpression triggers a PIA biofilm phenotype as well as eDNA release in an S. epidermidis protein biofilm matrix-producing strain background. dRNA-seq and Northern blot analyses revealed RsaE to exist as a major full-length 100-nt transcript and a minor processed species lacking approximately 20 nucleotides at the 5'-end. RsaE processing results in expansion of the mRNA target spectrum. Thus, full-length RsaE interacts with S. epidermidis antiholin-encoding lrgA mRNA, facilitating bacterial lysis and eDNA release. Processed RsaE, however, interacts with the 5'-UTR of icaR and sucCD mRNAs, encoding the icaADBC biofilm operon repressor IcaR and succinyl-CoA synthetase of the tricarboxylic acid (TCA) cycle, respectively. RsaE augments PIA-mediated biofilm matrix production, most likely through activation of icaADBC operon expression via repression of icaR as well as by TCA cycle inhibition and re-progamming of staphylococcal central carbon metabolism towards PIA precursor synthesis. Additionally, RsaE supports biofilm formation by mediating the release of eDNA as stabilizing biofilm matrix component. As RsaE itself is heterogeneously expressed within biofilms, we consider this sRNA to function as a factor favoring phenotypic heterogeneity and supporting division of labor in S. epidermidis biofilm communities.

RevDate: 2019-03-14

Williams DL, Smith SR, Peterson BR, et al (2019)

Growth substrate may influence biofilm susceptibility to antibiotics.

PloS one, 14(3):e0206774 pii:PONE-D-18-29985.

The CDC biofilm reactor is a robust culture system with high reproducibility in which biofilms can be grown for a wide variety of analyses. Multiple material types are available as growth substrates, yet data from biofilms grown on biologically relevant materials is scarce, particularly for antibiotic efficacy against differentially supported biofilms. In this study, CDC reactor holders were modified to allow growth of biofilms on collagen, a biologically relevant substrate. Susceptibility to multiple antibiotics was compared between biofilms of varying species grown on collagen versus standard polycarbonate coupons. Data indicated that in 13/18 instances, biofilms on polycarbonate were more susceptible to antibiotics than those on collagen, suggesting that when grown on a complex substrate, biofilms may be more tolerant to antibiotics. These outcomes may influence the translatability of antibiotic susceptibility profiles that have been collected for biofilms on hard plastic materials. Data may also help to advance information on antibiotic susceptibility testing of biofilms grown on biologically relevant materials for future in vitro and in vivo applications.

RevDate: 2019-03-14

Vinson LA, Gilbert PR, Sanders BJ, et al (2018)

Silver Diamine Fluoride and Potassium Iodide Disruption of In Vitro Streptococcus mutans Biofilm.

Journal of dentistry for children (Chicago, Ill.), 85(3):120-124.

Purpose: The purpose of this study was to investigate the inhibitory in vitro effects of silver diamine fluoride (SDF) with and without a saturated solution of potassium iodide (SSKI) on established Streptococcus mutans biofilm.Methods: Fifty μl of an overnight S. mutans culture (106 CFU per mL) in Tryptic Soy Broth (TSB) and three ml of fresh TSB supplemented with one percent sucrose (TSBS) were incubated for 24 hours to establish an S. mutans biofilm in six-well tissue culture plates. Four treatments (SDF, SSKI, SDF plus SSKI, and untreated control) were used to disrupt the biofilm. The biofilm groups were each treated with reagent and washed; the biofilm was collected, diluted, and spiral-plated onto blood agar plates; and an automated counting machine was used to determine the bacterial colony forming units (CFU).Results: The control had significantly more CFU than the SSKI, SDF, and SDF plus SSKI groups (P<.0001). The SSKI group had significantly more CFU than the SDF and SDF plus SSKI groups (P<.0001). The SDF group had significantly fewer CFU than the SDF plus SSKI group (P=.02). The reduction from the control was more than seven-fold for SDF, four-fold for SDF plus SSKI, and two-fold for SSKI.Conclusions: SDF alone, SDF plus SSKI, and SSKI disrupted an established S. mutans biofilm. SDF alone had the greatest overall disruption.

RevDate: 2019-03-14

Roche ED, Woodmansey EJ, Yang Q, et al (2019)

Cadexomer iodine effectively reduces bacterial biofilm in porcine wounds ex vivo and in vivo.

International wound journal [Epub ahead of print].

Biofilms are prevalent in non-healing chronic wounds and implicated in delayed healing. Tolerance to antimicrobial treatments and the host's immune system leave clinicians with limited interventions against biofilm populations. It is therefore essential that effective treatments be rigorously tested and demonstrate an impact on biofilm across multiple experimental models to guide clinical investigations and protocols. Cadexomer iodine has previously been shown to be effective against biofilm in various in vitro models, against methicillin-resistant Staphylococcus aureus biofilm in mouse wounds, and clinically in diabetic foot ulcers complicated by biofilm. Similarities between porcine and human skin make the pig a favoured model for cutaneous wound studies. Two antiseptic dressings and a gauze control were assessed against mature biofilm grown on ex vivo pig skin and in a pig wound model. Significant reductions in biofilm were observed following treatment with cadexomer iodine across both biofilm models. In contrast, silver carboxymethylcellulose dressings had minimal impact on biofilm in the models, with similar results to the control in the ex vivo model. Microscopy and histopathology indicate that the depth of organisms in wound tissue may impact treatment effectiveness. Further work on the promising biofilm efficacy of cadexomer iodine is needed to determine optimal treatment durations against biofilm.

RevDate: 2019-03-14

Parnasa R, Sendersky E, Simkovsky R, et al (2019)

A microcin processing peptidase-like protein of the cyanobacterium Synechococcus elongatus is essential for secretion of biofilm-promoting proteins.

Environmental microbiology reports [Epub ahead of print].

Small secreted compounds, e.g. microcins, are characterized by a double glycine secretion motif that is cleaved off upon maturation. Genomic analysis suggests that small proteins that possess a double glycine motif are widespread in cyanobacteria; however, the roles of these proteins are largely unknown. Using a biofilm-proficient mutant of the cyanobacterium Synechococcus elongatus PCC 7942 in which the constitutive biofilm self-suppression mechanism is inactivated, we previously demonstrated that four small proteins, EbfG1-4, each with a double glycine motif, enable biofilm formation. Furthermore, a peptidase belonging to the C39 family, PteB, is required for secretion of these proteins. Here we show that the microcin processing peptidase-like protein encoded by gene Synpcc7942_1127 is also required for biofilm development - inactivation of this gene in the biofilm-proficient mutant abrogates biofilm development. Additionally, this peptidase-like protein (denoted EbfE - enables biofilm formation peptidase) is required for secretion of the EbfG biofilm-promoting small proteins. Given their protein-domain characteristics, we suggest that PteB and EbfE take part in a maturation-secretion system, with PteB being located to the cell membrane while EbfE is directed to the periplasmic space via its secretion signal. This article is protected by copyright. All rights reserved.

RevDate: 2019-03-14

Yu Z, Kong Y, Luo Z, et al (2019)

Anti-bacterial activity of mutant chensinin-1 peptide against multidrug-resistant Pseudomonas aeruginosa and its effects on biofilm-associated gene expression.

Experimental and therapeutic medicine, 17(3):2031-2038.

Nosocomial infections with Pseudomonas aeruginosa (PA) are difficult to treat due to the low outer membrane permeability of the bacterium and the development of resistance. In the present study, the anti-microbial peptide (AMP) mutant chensinin-1 (MC1) was revealed to exhibit anti-bacterial activity against a multidrug-resistant PA (MRPA) strain in vitro, and the minimum inhibitory concentration was 25 µM, which was 4-fold higher than that of the native strain. MC1 was able to disrupt the integrity of the cytoplasmic membrane in the native PA strain and MRPA and had a similar membrane depolarization ability in these strains, but the outer membrane permeability of MRPA cells was lower than that of native PA cells, as determined by a 1-N-phenylnaphthylamine assay. In addition, the abundance of the gene Psl encoding for biofilm-associated polysaccharides was detected using Congo red, and a high concentration of MC1 inhibited the formation of MRPA biofilms. Furthermore, the expression levels of biofilm-associated genes affected by the AMP, MC1, were quantified by polymerase chain reaction analysis. The results indicated that MC1 induced biofilm inhibition by downregulating the relative expression of specific biofilm polysaccharide-associated genes, including pelA, algD and pslA. The present results indicated that the AMP MC1 may be an effective antibiotic against MRPA strains.

RevDate: 2019-03-14

Smith AR, Kieft B, Mueller R, et al (2019)

Carbon fixation and energy metabolisms of a subseafloor olivine biofilm.

The ISME journal pii:10.1038/s41396-019-0385-0 [Epub ahead of print].

Earth's largest aquifer ecosystem resides in igneous oceanic crust, where chemosynthesis and water-rock reactions provide the carbon and energy that support an active deep biosphere. The Calvin Cycle is the predominant carbon fixation pathway in cool, oxic, crust; however, the energy and carbon metabolisms in the deep thermal basaltic aquifer are poorly understood. Anaerobic carbon fixation pathways such as the Wood-Ljungdahl pathway, which uses hydrogen (H2) and CO2, may be common in thermal aquifers since water-rock reactions can produce H2 in hydrothermal environments and bicarbonate is abundant in seawater. To test this, we reconstructed the metabolisms of eleven bacterial and archaeal metagenome-assembled genomes from an olivine biofilm obtained from a Juan de Fuca Ridge basaltic aquifer. We found that the dominant carbon fixation pathway was the Wood-Ljungdahl pathway, which was present in seven of the eight bacterial genomes. Anaerobic respiration appears to be driven by sulfate reduction, and one bacterial genome contained a complete nitrogen fixation pathway. This study reveals the potential pathways for carbon and energy flux in the deep anoxic thermal aquifer ecosystem, and suggests that ancient H2-based chemolithoautotrophy, which once dominated Earth's early biosphere, may thus remain one of the dominant metabolisms in the suboceanic aquifer today.

RevDate: 2019-03-14

Bartnicka D, Karkowska-Kuleta J, Zawrotniak M, et al (2019)

Adhesive protein-mediated cross-talk between Candida albicans and Porphyromonas gingivalis in dual species biofilm protects the anaerobic bacterium in unfavorable oxic environment.

Scientific reports, 9(1):4376 pii:10.1038/s41598-019-40771-8.

The oral cavity contains different types of microbial species that colonize human host via extensive cell-to-cell interactions and biofilm formation. Candida albicans-a yeast-like fungus that inhabits mucosal surfaces-is also a significant colonizer of subgingival sites in patients with chronic periodontitis. It is notable however that one of the main infectious agents that causes periodontal disease is an anaerobic bacterium-Porphyromonas gingivalis. In our study, we evaluated the different strategies of both pathogens in the mutual colonization of an artificial surface and confirmed that a protective environment existed for P. gingivalis within developed fungal biofilm formed under oxic conditions where fungal cells grow mainly in their filamentous form i.e. hyphae. A direct physical contact between fungi and P. gingivalis was initiated via a modulation of gene expression for the major fungal cell surface adhesin Als3 and the aspartic proteases Sap6 and Sap9. Proteomic identification of the fungal surfaceome suggested also an involvement of the Mp65 adhesin and a "moonlighting" protein, enolase, as partners for the interaction with P. gingivalis. Using mutant strains of these bacteria that are defective in the production of the gingipains-the proteolytic enzymes that also harbor hemagglutinin domains-significant roles of these proteins in the formation of bacteria-protecting biofilm were clearly demonstrated.

RevDate: 2019-03-14

Sánchez MC, Romero-Lastra P, Ribeiro-Vidal H, et al (2019)

Comparative gene expression analysis of planktonic Porphyromonas gingivalis ATCC 33277 in the presence of a growing biofilm versus planktonic cells.

BMC microbiology, 19(1):58 pii:10.1186/s12866-019-1423-9.

BACKGROUND: Porphyromonas gingivalis, a microorganism residing in the oral cavity within complex multispecies biofilms, is one of the keystone pathogens in the onset and progression of periodontitis. In this in vitro study, using DNA microarray, we investigate the differential gene expression of Porphyromonas gingivalis ATCC 33277 when growing in the presence or in absence of its own monospecies biofilm.

RESULTS: Approximately 1.5% of genes (28 out of 1909 genes, at 1.5 fold change or more, p-value < 0.05) were differentially expressed by P. gingivalis cells when in the presence of a biofilm. These genes were predominantly related to the metabolism of iron, bacterial adhesion, invasion, virulence and quorum-sensing system. The results from microarrays were consistent with those obtained by RT-qPCR.

CONCLUSION: This study provides insight on the transcriptional changes of planktonic P. gingivalis cells when growing in the presence of a biofilm. The resulting phenotypes provide information on changes occurring in the gene expression of this pathogen.

RevDate: 2019-03-14

Corte L, Casagrande Pierantoni D, Tascini C, et al (2019)

Biofilm Specific Activity: A Measure to Quantify Microbial Biofilm.

Microorganisms, 7(3): pii:microorganisms7030073.

Microbes growing onto solid surfaces form complex 3-D biofilm structures characterized by the production of extracellular polymeric compounds and an increased resistance to drugs. The quantification of biofilm relays currently on a number of different approaches and techniques, often leading to different evaluations of the ability to form biofilms of the studied microbial strains. Measures of biofilm biomass were carried out with crystal violet (CV) and a direct reading at 405 nm, whereas the activity was assessed with the XTT ((2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) method. The strains of four pathogenic species of the genus Candida (C. albicans, C. glabrata, C. parapsilosis and C. tropicalis) and of Staphylococcus aureus were employed to determine the effective relatedness among techniques and the specific activity of the biofilm, as a ratio between the XTT and the CV outcomes. Since the ability to form biomass and to be metabolically active are not highly related, their simultaneous use allowed for a categorization of the strains. This classification is putatively amenable of further study by comparing the biofilm type and the medical behavior of the strains.

RevDate: 2019-03-13

Szell T, Dressler FF, Goelz H, et al (2019)

Response to Tailly and Van Haute: In Vitro Effects of a Novel Coating Agent on Bacterial Biofilm Development on Ureteral Stent by Schoeb et al. (From: Tailly T, Van Haute C. J Endourol 2019;33:232-233; DOI: 10.1089/end.2018.0907).

Journal of endourology, 33(3):234.

RevDate: 2019-03-13

Córdoba A, Graue-Hernandez EO, Bermudez-Magner JA, et al (2019)

Corneal Biofilm Plaques: A Novel Clinical Presentation.

Cornea [Epub ahead of print].

PURPOSE: To report a novel clinical presentation of corneal biofilms, consisting of formation of superficial and recurrent corneal plaques.

METHODS: Interventional case report. A 9-year-old boy presented with subepithelial, whitish, avascular, and recurrent corneal plaques without any clinical manifestations of active corneal inflammation and/or infection. He had a history of minor ocular trauma; otherwise, his medical history was unremarkable.

RESULTS: An excisional biopsy was performed under topical anesthesia. Histological analysis identified these plaques as clusters of gram-negative bacilli surrounded by an extracellular matrix. Samples were further evaluated with special stains (calcofluor white, Flamingo fluorescent dye, propidium iodide, and Gomori-Grocott) that demonstrated biofilm structures.

CONCLUSIONS: Corneal plaques are a very rare clinical presentation of corneal biofilms that allow prolonged survival of microorganisms even in the absence of prosthetic material and clinical signs or symptoms of corneal active inflammation and/or infection.

RevDate: 2019-03-13

Rezende G, Arthur RA, Lamers ML, et al (2019)

Structural Organization of Dental Biofilm Formed in situ in the Presence of Sucrose Associated to Maltodextrin.

Brazilian dental journal, 30(1):36-42.

Maltodextrins, derived from corn starch, have been added to industrialized food combined with sucrose. However it is not clear the diffusion properties of the dental biofilm matrix and the tridimensional structure of multispecies biofilms formed in the presence of these carbohydrates. Therefore, the aim of study was to investigate by confocal laser scanning microscopy (CLSM) the structural organization of the multispecies dental biofilm formed in situ under exposure to sucrose associated to maltodextrin. Adult volunteers wore an intraoral palatal appliance containing bovine enamel blocks. They were instructed to remove the appliance 8 times per day and drop the following solutions on the enamel blocks: deionized distilled water (DDW), maltodextrin, sucrose + maltodextrin or sucrose. Biofilms formed were stained and the percentage of extracellular polysaccharide (%EPS) and thickness were determined by CLSM. Biofilm formed in the presence of sucrose and sucrose + maltodextrin presented similar %EPS and higher than DDW and maltodextrin. Regarding to the biofilm thickness, sucrose and sucrose + maltodextrin treatments were thicker than DDW and maltodextrin and similar between them. The structural organization of the multispecies dental biofilm formed in situ in the presence of sucrose does not change when this carbohydrate is associated to maltodextrin.

RevDate: 2019-03-13

Peel TN (2019)

Studying Biofilm and Clinical Issues in Orthopedics.

Frontiers in microbiology, 10:359.

The association between biofilm-forming microorganisms and prosthetic joint infection influences all aspect of management including approaches to diagnosis, management and prevention. This article will provide an overview of new anti-biofilm strategies for management of prosthetic joint infection.

RevDate: 2019-03-13

Lopes LQS, de Almeida Vaucher R, Giongo JL, et al (2019)

Characterisation and anti-biofilm activity of glycerol monolaurate nanocapsules against Pseudomonas aeruginosa.

Microbial pathogenesis pii:S0882-4010(18)31898-9 [Epub ahead of print].

Pseudomonas aeruginosa is a ubiquitous microorganism that commonly causes hospital-acquired infections, including pneumonia, bloodstream and urinary tract infections and it is well known for chronically colonising the respiratory tract of patients with cystic fibrosis, causing severe intermittent exacerbation of the condition. P. aeruginosa may appear in the free form cell but also grows in biofilm communities adhered to a surface. An alternative to conventional antimicrobial agents are nanoparticles that can act as carriers for antibiotics and other drugs. In this context, the study aimed to characterise and verify the anti-biofilm potential of GML Nanocapsules against P. aeruginosa. The nanocapsules showed a mean diameter of 190.7 nm, polydispersion index of 0.069, the zeta potential of -23.3 mV. The microdilution test showed a MIC of 62.5 μg/mL to GML and 15.62 μg/mL to GML Nanocapsules. The anti-biofilm experiments demonstrated the significant reduction of biomass, proteins, polysaccharide and viable P. aeruginosa in biofilm treated with GML Nanocapsules while the free GML did not cause an effect. The AFM images showed a decrease in a biofilm which received GML. The positive results suggest an alternative for the public health trouble related to infections associated with biofilm.

RevDate: 2019-03-12

Kugaji MS, Kumbar VM, Peram MR, et al (2019)

Effect of Resveratrol on biofilm formation and virulence factor gene expression of Porphyromonas gingivalis in periodontal disease.

APMIS : acta pathologica, microbiologica, et immunologica Scandinavica [Epub ahead of print].

Periodontal disease is an oral inflammatory disease that destroys the tooth supporting periodontal tissues resulting in tooth loss. Porphyromonas gingivalis is a keystone pathogen that plays a significant role in periodontitis. In previous studies, resveratrol has shown significant results by targeting inflammatory and adhesive markers. Virulence factors of P. gingivalis play an important role in the bacterial adhesion and colonization. In this study, we aimed to demonstrate the anti-biofilm and anti-bacterial activity of resveratrol and also study the effect of resveratrol on the expression of virulence factor genes of P. gingivalis using reverse transcriptase polymerase chain reaction (RT-PCR). The anti-microbial and anti-biofilm activity of resveratrol on P. gingivalis was carried out by broth microdilution assay and biofilm adhesion reduction-crystal violet assay, respectively. We carried out the gene expression analysis by RT-PCR with the P. gingivalis treated compound to analyze the change in the expression of virulence factors: fimbriae and gingipain. Minimal inhibitory concentrations (MIC) of resveratrol against P. gingivalis and other clinical strains are in the range of 78.12-156.25 μg/mL. Resveratrol dose-dependently prevented the biofilm formation and also attenuated the virulence of P. gingivalis by reducing the expression of virulence factor genes such as fimbriae (type II and IV) and proteinases (kgp and rgpA). Resveratrol demonstrated superior anti-bacterial and anti-biofilm activity against P. gingivalis. There was significant reduction in the expression of fimbriae and gingipain with the resveratrol-treated compound. The results suggest that resveratrol, due to its multiple actions, may become a simple and inexpensive therapeutic strategy for treating periodontal disease.

RevDate: 2019-03-12

Quidant R, de Miguel I, Prieto I, et al (2019)

Plasmon-based biofilm inhibition on surgical implants.

Nano letters [Epub ahead of print].

The insertion of an implant in the body of a patient raises the risk of a posterior infection and formation of a biofilm, which can have critical consequences on the patient health and be associated to a high sanitary cost. While antibacterial agents can be used to prevent the infection, such a strategy is time-limited and causes bacteria resistance. As an alternative to biochemical approaches, we propose here to use light-induced local hyperthermia with plasmonic nanoparticles. This strategy is implemented on surgical meshes, extensively used in the context of hernia repairing, one of the most common general surgeries. Surgical meshes were homogeneously coated with gold nanorods designed to efficiently convert near-infrared light into heat. The modified mesh was exposed to a biofilm of Staphylococcus aureus (S. aureus) bacteria before being treated with a train of light pulses. We systematically study how the illumination parameters, namely fluence, peak intensity and pulse length, influence the elimination of attached bacteria. Additionally, fluorescence confocal microscopy provides us some insight on the mechanism involved in the degradation of the biofilm. This proof-of-principle study opens a new set of opportunities for the development of novel disinfection approaches combining light and nanotechnology.

RevDate: 2019-03-12

Butini ME, Abbandonato G, Di Rienzo C, et al (2019)

Isothermal Microcalorimetry Detects the Presence of Persister Cells in a Staphylococcus aureus Biofilm After Vancomycin Treatment.

Frontiers in microbiology, 10:332.

Staphylococcus aureus biofilm plays a major role in implant-associated infections. Here, the susceptibility of biofilm S. aureus to daptomycin, fosfomycin, vancomycin, trimethoprim/sulfamethoxazole, linezolid, and rifampicin was investigated by isothermal microcalorimetry (IMC). Moreover, the persister status of cells isolated from S. aureus biofilm after treatment with vancomycin was also analyzed. S. aureus biofilm was tolerant to all the antibiotics tested [minimum biofilm bactericidal concentration (MBBC) > 256 μg/ml], except to daptomycin [MBBC and minimum biofilm eradicating concentration (MBEC) = 32 μg/ml] and rifampin (MBBC and MBEC = 128 μg/ml). After the treatment of MRSA biofilm with 1024 μg/ml vancomycin, ∼5% cells survived, although metabolically inactive (persisters). Interestingly, IMC revealed that persister bacteria reverted to a normal-growing phenotype when inoculated into fresh medium without antibiotics. A staggered treatment of MRSA biofilm with vancomycin to kill all the metabolically active cells and daptomycin to kill persister cells eradicated the whole bacterial population. These results support the use in the clinical practice of a therapeutic regimen based on the use of two antibiotics to kill persister cells and eradicate MRSA biofilms. IMC represents a suitable technique to characterize in real-time the reversion from persister to metabolically-active cells.

RevDate: 2019-03-12

Valle J, Echeverz M, I Lasa (2019)

σB inhibits PNAG exopolysaccharide synthesis and biofilm formation in Staphylococcus aureus.

Journal of bacteriology pii:JB.00098-19 [Epub ahead of print].

Staphylococcus aureus clinical strains are able to produce at least two distinct types of biofilm matrixes: biofilm matrixes made of PIA/PNAG exopolysaccharide whose synthesis is mediated by the icaADBC locus, and biofilm matrixes built of proteins (polysaccharide-independent). σB is a conserved alternative sigma factor that regulates the expression of more than a hundred genes in response to changes in environmental conditions. While numerous studies agree that σB is required for polysaccharide-independent biofilms, a controversy persists over the role of σB in the regulation of PIA/PNAG dependent biofilm development. Here, we showed that genetically unrelated S. aureus σB deficient strains produced stronger biofilms both in static and flow conditions and accumulated higher levels of PIA/PNAG exopolysaccharide than their corresponding wild type strains. The increased accumulation of PIA/PNAG in the σB mutants correlated with a higher accumulation of the IcaC protein that it is not due to adjustments in icaADBC operon transcription and/or icaADBC mRNA stability. Overall, our results reveal that in the presence of an active σB, the turnover of Ica proteins is accelerated reducing the synthesis of PIA/PNAG exopolysaccharide and consequently the PIA/PNAG dependent biofilm formation capacity.IMPORTANCE Due to its multifaceted lifestyle Staphylococcus aureus needs a complex regulatory network to connect environmental signals with cellular physiology. One particular transcription factor, named σB (SigB), is involved in the general stress response and the expression of virulence factors. For many years, a great confusion has existed about the role of σB in the regulation of the biofilm lifestyle in S. aureus Our study demonstrated that σB is not necessary for exopolysaccharide-dependent biofilms and even more, that S. aureus produce stronger biofilms in the absence of σB The increased accumulation of exopolysaccharide correlates with a higher stability of the proteins responsible for its synthesis. The present findings reveal an additional regulatory layer to control biofilm exopolysaccharide synthesis under stress conditions.

RevDate: 2019-03-12

Wong SS, Lau WY, Chan PK, et al (2019)

Extended Experience in the Use of Antibiotic Lock for Eradication of Biofilm Bacteria on Tenckhoff Catheter.

Peritoneal dialysis international : journal of the International Society for Peritoneal Dialysis, 39(2):187-190.

Whilst antibiotic lock is effective to eradicate biofilm bacteria on hemodialysis catheters, this adjunctive method has scarcely been tested in peritoneal dialysis (PD) patients. After our previous successful experience of its use to salvage two Tenckhoff catheters, we encountered another patient with problematic biofilm-associated PD peritonitis who strongly refused catheter removal. As a result, antibiotic lock was given once daily, initially, with continuation of the usual PD schedule. However, relapsing peritonitis could not be prevented until we administered antibiotic lock without dialysate in the abdomen, which led to successful eradication of biofilm bacteria. To investigate the significance of having "dry abdomen" during antibiotic lock treatment, we injected an equivalent amount of contrast into the Tenckhoff catheter under fluoroscopy. We observed that the catheter lock solution could be retained over a long period of time only with "dry abdomen," whereas rapid dissipation of the lock solution occurred in the presence of dialysate. We concluded that whilst antibiotic lock in a once-daily regimen can be highly effective against biofilm bacteria on a Tenckhoff catheter, it is essential to withhold PD exchanges during the dwell of antibiotic lock to prevent it from dissolving into the surrounding dialysate.

RevDate: 2019-03-11

Di Tommaso C, Taylor-Edmonds L, Andrews SA, et al (2019)

The contribution of biofilm to nitrogenous disinfection by-product formation in full-scale cyclically-operated drinking water biofilters.

Water research, 155:403-409 pii:S0043-1354(19)30150-2 [Epub ahead of print].

Biofiltration has been shown to be effective for disinfection by-product (DBP) precursor control, however few studies have considered its role in the potential formation of DBPs. Biofilm is composed of heterogeneous bacteria as well as extracellular polymeric substances (EPS). The objective of this study was to determine the contribution of biofilm-related materials such as EPS to form nitrogen-containing DBPs upon chloramination, and to determine the influence of cyclical (scheduled on-off) biofilter operation on DBP precursor removal. Biologically active media was sampled from a full-scale biofilter operating under cold-water conditions (3.6 ± 0.5 °C) and extracted using a cation exchange resin into a phosphate buffer solution. Biomass concentrations, as determined using adenosine triphosphate (ATP) measurements, remained stable at 298 ± 55 ng ATP/g media over the trial period. N-nitrosodimethylamine (NDMA) and haloacetonitrile (HAN4) formation potential (FP) tests conducted under uniform formation conditions (UFC) using extracted biofilm yielded 0.80 ± 0.27 ng NDMA/g media and 18.7 ± 3.3 ng dichloroacetonitrile (DCAN)/g media. Further analyses of extracted biofilm using fluorescence spectroscopy and liquid chromatography-organic carbon detection indicated the presence of proteins above 20 kDa and humic-like substances. Extracted proteins (93.5 ± 8.1 μg/g media) correlated well (R = 0.90) with UV 280 measurements, indicating that spectrophotometry may serve as a valuable tool to quantify proteins in extracted biofilms. While substances in biofilms can serve as NDMA and DCAN precursors, the full-scale cyclically-operated biofilter that was examined did not show release of NDMA precursors during start-up following stagnation periods of 6 h or more. These biofilters consistently removed 6.9 ± 4.3 ng/L of NDMA precursors; typical NDMA UFC-FP of biofilter effluent was 8.5 ± 2.6 ng/L.

RevDate: 2019-03-11

Pakkulnan R, Anutrakunchai C, Kanthawong S, et al (2019)

Extracellular DNA facilitates bacterial adhesion during Burkholderia pseudomallei biofilm formation.

PloS one, 14(3):e0213288 pii:PONE-D-18-28288.

The biofilm-forming ability of Burkholderia pseudomallei is crucial for its survival in unsuitable environments and is correlated with antibiotic resistance and relapsing cases of melioidosis. Extracellular DNA (eDNA) is an essential component for biofilm development and maturation in many bacteria. The aim of this study was to investigate the eDNA released by B. pseudomallei during biofilm formation using DNase treatment. The extent of biofilm formation and quantity of eDNA were assessed by crystal-violet staining and fluorescent dye-based quantification, respectively, and visualized by confocal laser scanning microscopy (CLSM). Variation in B. pseudomallei biofilm formation and eDNA quantity was demonstrated among isolates. CLSM images of biofilms stained with FITC-ConA (biofilm) and TOTO-3 (eDNA) revealed the localization of eDNA in the biofilm matrix. A positive correlation of biofilm biomass with quantity of eDNA during the 2-day biofilm-formation observation period was found. The increasing eDNA quantity over time, despite constant living/dead ratios of bacterial cells during the experiment suggests that eDNA is delivered from living bacterial cells. CLSM images demonstrated that depletion of eDNA by DNase I significantly lessened bacterial attachment (if DNase added at 0 h) and biofilm developing stages (if added at 24 h) but had no effect on mature biofilm (if added at 45 h). Collectively, our results reveal that eDNA is released from living B. pseudomallei and is correlated with biofilm formation. It was also apparent that eDNA is essential during bacterial cell attachment and biofilm-forming steps. The depletion of eDNA by DNase may provide an option for the prevention or dispersal of B. pseudomallei biofilm.

RevDate: 2019-03-11

Aldrich A, Kuss MA, Duan B, et al (2019)

3D bioprinted scaffolds containing viable macrophages and antibiotics promote clearance of Staphylococcus aureus craniotomy-associated biofilm infection.

ACS applied materials & interfaces [Epub ahead of print].

A craniotomy involves the removal of a skull fragment to access the brain, such as during tumor or epilepsy surgery, which is immediately replaced intra-operatively. The infection incidence after craniotomy ranges from 0.8-3%, with approximately half caused by Staphylococcus aureus (S. aureus). To mitigate infectious complications following craniotomy, we engineered a 3D bioprinted bone scaffold to harness the potent antibacterial activity of macrophages (MΦs) together with antibiotics using a mouse S. aureus craniotomy-associated biofilm model that establishes persistent infection on the bone flap, subcutaneous galea, and brain. The 3D scaffold contained rifampin and daptomycin printed in a composite slurry, with viable MΦs incorporated into a hydrogel-based bioink, which was assessed for both the treatment and prevention of craniotomy-associated infections in the mouse model. For the treatment paradigm, the bone flap was removed at day 7 post-infection after a mature biofilm had formed, and replaced with a 3D printed antibiotic scaffold, with or without MΦ incorporation. Bacterial burdens in the galea and brain were reduced by at least 100-fold at early time points, which was potentiated by bioprinting viable MΦs into the 3D antibiotic scaffold. We also examined a prevention paradigm, where scaffolds were placed at the time of surgery and challenged with S. aureus one day later at the surgical site. Interestingly, unlike the treatment paradigm, the incorporation of viable MΦs into the 3D antibiotic scaffold did not enhance bacterial clearance compared to antibiotic alone. With further refinement, our 3D bioprinted scaffold represents a potential treatment modality, since it delivers therapeutic antibiotic levels more rapidly than systemic administration, based on its proximity to the infection site. In addition, the incorporation of viable MΦs into the 3D scaffold is an important advance, which demonstrated improved therapeutic benefit for the treatment of established biofilms that represent the most clinically challenging scenario.

RevDate: 2019-03-11

Hussain A, Alajmi MF, Khan MA, et al (2019)

Biosynthesized Silver Nanoparticle (AgNP) From Pandanus odorifer Leaf Extract Exhibits Anti-metastasis and Anti-biofilm Potentials.

Frontiers in microbiology, 10:8.

Cancer and the associated secondary bacterial infections are leading cause of mortality, due to the paucity of effective drugs. Here, we have synthesized silver nanoparticles (AgNPs) from organic resource and confirmed their anti-cancer and anti-microbial potentials. Microwave irradiation method was employed to synthesize AgNPs using Pandanus odorifer leaf extract. Anti-cancer potential of AgNPs was evaluated by scratch assay on the monolayer of rat basophilic leukemia (RBL) cells, indicating that the synthesized AgNPs inhibit the migration of RBL cells. The synthesized AgNPs showed MIC value of 4-16 μg/mL against both Gram +ve and Gram -ve bacterial strains, exhibiting the anti-microbial potential. Biofilm inhibition was recorded at sub-MIC values against Gram +ve and Gram -ve bacterial strains. Violacein and alginate productions were reduced by 89.6 and 75.6%, respectively at 4 and 8 μg/mL of AgNPs, suggesting anti-quorum sensing activity. Exopolysaccharide production was decreased by 61-79 and 84% for Gram -ve and Gram +ve pathogens respectively. Flagellar driven swarming mobility was also reduced significantly. Furthermore, In vivo study confirmed their tolerability in mice, indicating their clinical perspective. Collective, we claim that the synthesized AgNPs have anti-metastasis as well as anti-microbial activities. Hence, this can be further tested for therapeutic options to treat cancer and secondary bacterial infections.

RevDate: 2019-03-11

Novotny LA, Brockman KL, Mokrzan EM, et al (2019)

Biofilm biology and vaccine strategies for otitis media due to nontypeable Haemophilus influenzae.

Journal of pediatric infectious diseases, 14(2):69-77.

Otitis media (OM) is one of the most common diseases of childhood, and nontypeable Haemophilus influenzae (NTHI) is the predominant causative agent of chronic and recurrent OM, as well as OM for which treatment has failed. Moreover, NTHI is now as important a causative agent of acute OM as the pneumococcus. NTHI colonizes the human nasopharynx asymptomatically. However, upon perturbation of the innate and physical defenses of the airway by upper respiratory tract viral infection, NTHI can replicate, ascend the Eustachian tube, gain access to the normally sterile middle ear space, and cause disease. Bacterial biofilms within the middle ear, including those formed by NTHI, contribute to the chronic and recurrent nature of this disease. These multicomponent structures are highly resistant to clearance by host defenses and elimination by traditional antimicrobial therapies. Herein, we review several strategies utilized by NTHI in order to persist within the human host and interventions currently under investigation to prevent and/or resolve NTHI-induced diseases of the middle ear and uppermost airway.

RevDate: 2019-03-10

Meng Y, Sheng B, F Meng (2019)

Changes in nitrogen removal and microbiota of anammox biofilm reactors under tetracycline stress at environmentally and industrially relevant concentrations.

The Science of the total environment, 668:379-388 pii:S0048-9697(19)30897-6 [Epub ahead of print].

Anammox-related processes are often applied for the wastewater treatment which contains both ammonium and antibiotics. Herein, the long-term effects of tetracycline (TC), at environmentally and industrially relevant concentrations, on the performance, anammox activity and microbial community of anammox reactors were investigated for 518 days. The control reactor (without TC exposure) was stable for nitrogen removal during the long-term operation (a nitrogen removal rate of 0.56 ± 0.05 kg-N·m-3·d-1). In the TC-added reactor, the nitrogen removal efficiency increased slightly at low TC levels (1-100 μg/L), whereas poor anammox performance occurred at high TC concentration (1000 μg/L). Furthermore, the concentrations of extracellular polymeric substances (EPS) were much higher at 10 μg/L than those in the control reactor (P < 0.01), whereas rapidly decreased at 1000 μg-TC/L. Furthermore, the reactor performance was highly consistent with the variations of the heme c contents. Consistently, exposure to TC changed the abundance of anammox bacteria, e.g., an increase in Candidatus Jettenia abundance occurred from 2.20 ± 0.97% (0-10 μg/L) to 12.13 ± 1.66% (100 μg/L). Similarly, the genus Denitratisoma, the most predominant denitrification bacteria, also had a higher abundance at a TC concentration of 100 μg/L (15.60 ± 6.42%) than other TC concentrations (5.40 ± 2.50% and 7.65 ± 0.55% at concentrations of 10 and 1000 μg/L, respectively). The results can explain why the exposure of anammox bacteria to a lower TC concentration (100 μg/L) resulted in a better nitrogen removal rate. In contrast, exposure to a high TC level (1000 μg/L) led to a decline in the abundance of anammox bacteria and denitrifiers (1.53 ± 0.64% and 8.18 ± 0.63%, respectively) but an increased abundance in the nitrifier population (8.07 ± 1.21%; P < 0.01). Therefore, this study can aid in the design and operation of anammox-based processes treating sewage and industrial wastewater.

RevDate: 2019-03-09

Skowron K, Wiktorczyk N, Grudlewska K, et al (2019)

Drug-susceptibility, biofilm-forming ability and biofilm survival on stainless steel of Listeria spp. strains isolated from cheese.

International journal of food microbiology, 296:75-82 pii:S0168-1605(18)30814-6 [Epub ahead of print].

The aim of the study was to analyze the contamination of mold cheese (Brie, Camembert, Gorgonzola, Munster and Roquefort) with Listeria spp. and assessment of culturable cells number recovered from the biofilm formed on the surface of stainless steel by obtained strains. Identified isolates (MALDI TOF MS technique) were subjected to susceptibility testing (disk-diffusion method) and their genetic similarity (PFGE method), ability to form biofilm (quantitative method), biofilm dry weight, and biofilm survival on stainless steel were evaluated. Out of 250 samples of cheese 26 (10.4%) were Listeria spp. positive, including 15 isolates (6.0% of samples) of L. monocytogenes, 7 isolates of L. innocua (2.8% of samples) and 4 isolates of L. welshimeri species (1.6% of samples). Of the 26 isolates tested, 22 strains were genetically different. It was shown that L. innocua and L. welshimeri strains were sensitive to all antibiotics tested, while two (16.7%) L. monocytogenes strains were resistant to penicillin and one (8.3%) to erythromycin. L. monocytogenes formed biofilm most intensively on stainless steel, while L. welshimeri the least effectively. The median of bacteria number recovered from the biofilm for L. monocytogenes was 6.81 log CFU × cm-2, for L. innocua - 5.63 log CFU × cm-2, and for L. welshimeri - 4.93 log CFU × cm-2. The survival in the biofilm of Listeria spp. strains decreased along with the increase in a storage temperature of steel coupons. The longest survival time was reported at 4 °C, i.e. 47.58-124.41 days, with an elimination rate of 0.06-0.13 log CFU × day-1. Collectively, L. monocytogenes is the most prevalent species of Listeria genus in the mold cheese. The ability of L. monocytogenes strains to form biofilm on stainless steel and survive in the food processing environment increases chance of the secondary contamination of food posing risk to the consumer health.

RevDate: 2019-03-09

Calvillo-Medina RP, Reyes-Grajeda JP, Barba-Escoto L, et al (2019)

Proteome analysis of biofilm produced by a Fusarium falciforme keratitis infectious agent.

Microbial pathogenesis pii:S0882-4010(18)31580-8 [Epub ahead of print].

Biofilms are structures that confer adaptive ability to and facilitate the virulence of fungal pathogens. Certain multi-functional proteins have been shown to be involved in fungal pathogenesis and these proteins may also be implicated in biofilm formation. The aim of this study was to identify a fungal agent isolated from the human cornea, to analyze the ability of this organism to form biofilms in vitro and to investigate protein expression in this condition. The fungus was identified by phylogenetic inference analysis. Biofilm formation and structure were evaluated by colorimetric methods and by optical and electron microscopy. We also resolved proteins obtained from biofilms and planktonic cultures by two-dimensional gel electrophoresis and identified those proteins by mass spectrometry. The fungus was identified as Fusarium falciforme. Colorimetric analysis and microscopy revealed that the highest level of biofilm formation was obtained at a concentration of 1 × 106 conidia/mL with 96 h of incubation at 28 °C. The biofilm architecture consisted of an extracellular matrix that embedded fungal filaments. We found nineteen proteins that were over-expressed in biofilms, as compared with planktonic cultures, and six proteins with unique expression in biofilms. Among the more abundant proteins identified were: transketolase, a putative antigen 1, enolase, phosphoglycerate kinase and ATP-citrate synthase. Some of these proteins are involved in basal metabolism, function as multi-functional proteins or have been described as potential virulence factors. We focused on the expression in biofilm of the enzyme, enolase, which was determined by real-time PCR. Our findings provide a perspective on the proteins associated with the formation of biofilms in vitro by an F. falciforme keratitis isolate.

RevDate: 2019-03-09

Graf AC, Leonard A, Schäuble M, et al (2019)

Virulence factors produced by Staphylococcus aureus biofilms have a moonlighting function contributing to biofilm integrity.

Molecular & cellular proteomics : MCP pii:RA118.001120 [Epub ahead of print].

Staphylococcus aureus is the causative agent of various biofilm-associated infections in humans causing major healthcare problems worldwide. This type of infection is inherently difficult to treat due to a reduced metabolic activity of biofilm-embedded cells and the protective nature of a surrounding extracellular matrix (ECM). However, little is known about S. aureus biofilm physiology and in particular the proteinaceous composition of the ECM. Thus, we cultivated S. aureus biofilms in a flow system and comprehensively profiled intracellular and extracellular (ECM and flow-through (FT)) biofilm proteomes, as well as the extracellular metabolome in comparison to planktonic cultures. Our analyses revealed the expression of many pathogenicity factors within S. aureus biofilms as indicated by a high abundance of capsule biosynthesis proteins along with various secreted virulence factors, including hemolysins, leukotoxins, and lipases as a part of the ECM. The activity of ECM virulence factors was confirmed in a hemolysis assay and a Galleria mellonella pathogenicity model. In addition, we uncovered a so far unacknowledged moonlighting function of secreted virulence factors and ribosomal proteins trapped in the ECM: namely their contribution to biofilm integrity. Mechanistically, it was revealed that this stabilizing effect is mediated by the strong positive charge of alkaline virulence factors and ribosomal proteins in an acidic ECM environment, which is caused by the release of fermentation products like formate, lactate, and acetate as a consequence of oxygen limitation in biofilms. The strong positive charge of these proteins most likely mediates electrostatic interactions with anionic cell surface components, eDNA, and anionic metabolites. In consequence, this leads to strong cell aggregation and biofilm stabilization. Collectively, our study identified a new molecular mechanism during S. aureus biofilm formation and thus significantly widens the understanding of biofilm-associated S. aureus infections - an essential prerequisite for the development of novel antimicrobial therapies.

RevDate: 2019-03-08

Osorio JHM, Benettoni P, Schmidt M, et al (2019)

Investigation of architecture development and phosphate distribution in Chlorella biofilm by complementary microscopy techniques.

FEMS microbiology ecology pii:5372415 [Epub ahead of print].

Microalgae biofilms may play an important role in the mitigation and prevention of eutrophication caused by domestic, agricultural and industrial wastewater effluents. Despite their potential, the biofilm development and role in nutrient removal are not well understood. Its clarification requires comprehensive studies of the complex three-dimensional architecture of the biofilm. In this study, we established a multimodal imaging approach to provide key information regarding architecture development and nutrient distribution in the biofilm of two green algae organisms: Chlorella pyrenoidosa and Chlorella vulgaris. Helium ion microscopy (HIM), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed for i) elucidation of spatial arrangement, ii) elemental mapping and iii) 3D chemical imaging of the biofilm. The fine structure of the algal biofilm was resolved by HIM, the evidence of the accumulation of phosphate in hot spots was provided by SEM-EDX and the localization of phosphate oxides granules throughout the whole sample was clarified by ToF-SIMS. The reported results shed light on the phosphorus distribution during Chlorella's biofilm formation and highlight the potential of such correlative approach to solve fundamental question in algal biotechnology research.

RevDate: 2019-03-08

Yan J, Fei C, Mao S, et al (2019)

Mechanical instability and interfacial energy drive biofilm morphogenesis.

eLife, 8: pii:43920 [Epub ahead of print].

Surface-attached bacterial communities called biofilms display a diversity of morphologies. Although structural and regulatory components required for biofilm formation are known, it is not understood how these essential constituents promote biofilm surface morphology. Here, using Vibrio cholerae as our model system, we combine mechanical measurements, theory and simulation, quantitative image analyses, surface energy characterizations, and mutagenesis to show that mechanical instabilities, including wrinkling and delamination, underlie the morphogenesis program of growing biofilms. We also identify interfacial energy as a key driving force for mechanomorphogenesis because it dictates the generation/annihilation of new/existing interfaces. Finally, we discover feedback between mechanomorphogenesis and biofilm expansion, which shapes the overall biofilm contour. The morphogenesis principles we discover in bacterial biofilms, relying on mechanical instabilities and interfacial energies, should be generally applicable to morphogenesis processes in tissues in higher organisms.

RevDate: 2019-03-08

Azman AS, Mawang CI, Khairat JE, et al (2019)

Actinobacteria-a promising natural source of anti-biofilm agents.

International microbiology : the official journal of the Spanish Society for Microbiology pii:10.1007/s10123-019-00066-4 [Epub ahead of print].

A biofilm is a community of microorganisms attached to a surface and embedded in a matrix of extracellular polymeric substances. Biofilms confer resistance towards conventional antibiotic treatments; thus, there is an urgent need for newer and more effective antimicrobial agents that can act against these biofilms. Due to this situation, various studies have been done to investigate the anti-biofilm effects of natural products including bioactive compounds extracted from microorganisms such as Actinobacteria. This review provides an insight into the anti-biofilm potential of Actinobacteria against various pathogenic bacteria, which hopefully provides useful information, guidance, and improvements for future antimicrobial studies. Nevertheless, further research on the anti-biofilm mechanisms and compound modifications to produce more potent anti-biofilm effects are required.

RevDate: 2019-03-08

Sahar-Helft S, Erez A, Shay B, et al (2019)

Enhancing Er:YAG bactericidal effect against Enterococcus faecalis biofilm in vitro.

Lasers in medical science pii:10.1007/s10103-019-02763-y [Epub ahead of print].

RevDate: 2019-03-08

Xiros C, Shahab RL, MH Studer (2019)

A cellulolytic fungal biofilm enhances the consolidated bioconversion of cellulose to short chain fatty acids by the rumen microbiome.

Applied microbiology and biotechnology pii:10.1007/s00253-019-09706-1 [Epub ahead of print].

The ability of the multispecies biofilm membrane reactors (MBM reactors) to provide distinguished niches for aerobic and anaerobic microbes at the same time was used for the investigation of the consolidated bioprocessing of cellulose to short chain fatty acids (SCFAs). A consortium based consolidated bioprocess (CBP) was designed. The rumen microbiome was used as the converting microbial consortium, co-cultivated with selected individual aerobic fungi which formed a biofilm on the tubular membrane flushed with oxygen. The beneficial effect of the fungal biofilm on the process yields and productivities was attributed to the enhanced cellulolytic activities compared with those achieved by the rumen microbiome alone. At 30 °C, the MBM system with Trichoderma reesei biofilm reached a concentration 39% higher (7.3 g/L SCFAs), than the rumen microbiome alone (5.1 g/L) using 15 g/L crystalline cellulose as the substrate. Fermentation temperature was crucial especially for the composition of the short chain fatty acids produced. The temperature increase resulted in shorter fatty acids produced. While a mixture of acetic, propionic, butyric, and caproic acids was produced at 30 °C with Trichoderma reesei biofilm, butyric and caproic acids were not detected during the fermentations at 37.5 °C carried out with Coprinopsis cinerea as the biofilm forming fungus. Apart from the presence of the fungal biofilm, no parameter studied had a significant impact on the total yield of organic acids produced, which reached 0.47 g of total SCFAs per g of cellulose (at 30 °C and at pH 6, with rumen inoculum to total volume ratio equal to 0.372).

RevDate: 2019-03-08

Lee DH, Mai HN, Thant PP, et al (2019)

Effects of different surface finishing protocols for zirconia on surface roughness and bacterial biofilm formation.

The journal of advanced prosthodontics, 11(1):41-47.

PURPOSE: Surface finishing of a zirconia restoration is essential after clinical adjustment. Herein, we investigated the effects of a surface finishing protocol for monolithic zirconia on final roughness and bacterial adherence.

MATERIALS AND METHODS: Forty-eight disk-shaped monolithic zirconia specimens were fabricated and divided into four groups (n = 12) based on initial surface treatment, finishing, and polishing protocols: diamond bur+polishing bur (DP group), diamond bur+stone grinding bur+polishing bur (DSP group), no diamond bur+polishing bur (NP group), and no diamond bur+stone grinding bur+polishing bur (NSP group). Initial and final surface roughness was measured with a profilometer, and shown using scanning electron microscope. Bacterial adhesion was evaluated by quantifying Streptococcus mutans in the biofilm. Kruskal-Wallis and Mann-Whitney U tests were used to compare results among groups, and two-way analysis of variance was used to evaluate the effects of grinding burs on final roughness (α=.05).

RESULTS: The DP group had the highest final Ra value, followed by the DSP, NP, and NSP groups. Use of the stone grinding bur as a coarse-finishing step significantly decreased final Ra values when a diamond bur was used (P<.001). Omission of the stone grinding bur increased biofilm formation on specimen surfaces. Combining a stone grinding bur with silicone polishing burs produced the smallest final biofilm values, regardless of the use of a diamond bur in initial surface treatment.

CONCLUSION: Coarse finishing of monolithic zirconia with a stone grinding bur significantly decreased final Ra values and bacterial biofilm formation when surfaces had been roughened by a diamond bur.

RevDate: 2019-03-07

Fritz B, Stavnsbjerg C, Markvart M, et al (2019)

Shotgun sequencing of clinical biofilm following scanning electron microscopy identifies bacterial community composition.

Pathogens and disease pii:5371122 [Epub ahead of print].

Bacterial biofilm infections often involve aggregates of bacteria heterogeneously distributed throughout a tissue or on a surface (such as an implanted medical device). Identification of a biofilm infection requires direct visualization via microscopy, followed by characterization of the microbial community by culturing or sequencing-based approaches. A sample, therefore, must be divided prior to analysis, often leading to inconsistent results. We demonstrate a combined approach, using scanning electron microscopy and next-generation shotgun sequencing, to visually identify a biofilm and characterize the microbial community, without dividing the sample. A clinical sample recovered from a patient following a dental root-filling procedure was prepared and visualized by scanning electron microscopy. DNA was then extracted from the sample several years later and analyzed by shotgun sequencing. The method was subsequently validated on in vitro cultures of Pseudomonas aeruginosa biofilm. Between 19 and 21 different genera and species were identified in the clinical sample with an estimated relative abundance greater than 1% by two different estimation approaches. Only eight genera identified were not associated with endodontic infections. This provides a proof-of-concept for a dual, microscopy and sequencing-based approach to identify and characterize bacterial biofilms, which could also easily be implemented in other scientific fields.

RevDate: 2019-03-07

Zetzmann M, Bucur FI, Crauwels P, et al (2019)

Characterization of the biofilm phenotype of a Listeria monocytogenes mutant deficient in agr peptide sensing.

MicrobiologyOpen [Epub ahead of print].

Listeria monocytogenes is a food-borne human pathogen and a serious concern in food production and preservation. Previous studies have shown that biofilm formation of L. monocytogenes and presence of extracellular DNA (eDNA) in the biofilm matrix varies with environmental conditions and may involve agr peptide sensing. Experiments in normal and diluted (hypoosmotic) complex media at different temperatures revealed reduced biofilm formation of L. monocytogenes EGD-e ΔagrD, a mutant deficient in agr peptide sensing, specifically in diluted Brain Heart Infusion at 25°C. This defect was not related to reduced sensitivity to DNase treatment suggesting sufficient levels of eDNA. Re-analysis of a previously published transcriptional profiling indicated that a total of 132 stress-related genes, that is 78.6% of the SigB-dependent stress regulon, are differentially expressed in the ΔagrD mutant. Additionally, a number of genes involved in flagellar motility and a large number of other surface proteins including internalins, peptidoglycan binding and cell wall modifying proteins showed agr-dependent gene expression. However, survival of the ΔagrD mutant in hypoosmotic conditions or following exposure to high hydrostatic pressure was comparable to the wild type. Also, flagellar motility and surface hydrophobicity were not affected. However, the ΔagrD mutant displayed a significantly reduced viability upon challenge with lysozyme. These results suggest that the biofilm phenotype of the ΔagrD mutant is not a consequence of reduced resistance to hypoosmotic or high pressure stress, motility or surface hydrophobicity. Instead, agr peptide sensing seems to be required for proper regulation of biosynthesis, structure and function of the cell envelope, adhesion to the substratum, and/or interaction of bacteria within a biofilm.

RevDate: 2019-03-07

Goodwine J, Gil J, Doiron A, et al (2019)

Pyruvate-depleting conditions induce biofilm dispersion and enhance the efficacy of antibiotics in killing biofilms in vitro and in vivo.

Scientific reports, 9(1):3763 pii:10.1038/s41598-019-40378-z.

The formation of biofilms is a developmental process initiated by planktonic cells transitioning to the surface, which comes full circle when cells disperse from the biofilm and transition to the planktonic mode of growth. Considering that pyruvate has been previously demonstrated to be required for the formation of P. aeruginosa biofilms, we asked whether pyruvate likewise contributes to the maintenance of the biofilm structure, with depletion of pyruvate resulting in dispersion. Here, we demonstrate that the enzymatic depletion of pyruvate coincided with the dispersion of established biofilms by S. aureus and laboratory and clinical P. aeruginosa isolates. The dispersion response was dependent on pyruvate fermentation pathway components but independent of proteins previously described to contribute to P. aeruginosa biofilm dispersion. Using porcine second-degree burn wounds infected with P. aeruginosa biofilm cells, we furthermore demonstrated that pyruvate depletion resulted in a reduction of biofilm biomass in vivo. Pyruvate-depleting conditions enhanced the efficacy of tobramycin killing of the resident wound biofilms by up to 5-logs. Our findings strongly suggest the management of pyruvate availability to be a promising strategy to combat biofilm-related infections by two principal pathogens associated with wound and cystic fibrosis lung infections.

RevDate: 2019-03-07

Taylor PK, Zhang L, TF Mah (2019)

Loss of the Two-Component System TctD-TctE in Pseudomonas aeruginosa Affects Biofilm Formation and Aminoglycoside Susceptibility in Response to Citric Acid.

mSphere, 4(2): pii:4/2/e00102-19.

The two-component system TctD-TctE is important for regulating the uptake of tricarboxylic acids in Pseudomonas aeruginosa TctD-TctE accomplishes this through derepression of the gene opdH, which encodes a tricarboxylic acid-specific porin. Previous work from our lab revealed that TctD-TctE in P. aeruginosa also has a role in resistance to aminoglycoside antibiotics. The aim of this study was to further characterize the role of TctD-TctE in P. aeruginosa in the presence of citric acid. Here it was found that deletion of P. aeruginosa PA14 TctD-TctE (ΔtctED) resulted in a 4-fold decrease in the biofilm bactericidal concentrations of the aminoglycosides tobramycin and gentamicin when citric acid was present in nutrient media. Tobramycin accumulation assays demonstrated that deletion of TctD-TctE resulted in an increase in the amount of tobramycin retained in biofilm cells. The PA14 wild type responded to increasing concentrations of citric acid by producing less biofilm. In contrast, the amount of ΔtctED mutant biofilm formation remained constant or enhanced. Furthermore, the ΔtctED strain was incapable of growing on citric acid as a sole carbon source and was highly reduced in its ability to grow in the presence of citric acid even when an additional carbon source was available. Use of phenotypic and genetic microarrays found that this growth deficiency of the ΔtctED mutant is unique to citric acid and that multiple metabolic genes are dysregulated. This work demonstrates that TctD-TctE in P. aeruginosa has a role in biofilm development that is dependent on citric acid and that is separate from the previously characterized involvement in resistance to antibiotics.IMPORTANCE Nutrient availability is an important contributor to the ability of bacteria to establish successful infections in a host. Pseudomonas aeruginosa is an opportunistic pathogen in humans causing infections that are difficult to treat. In part, its success is attributable to a high degree of metabolic versatility. P. aeruginosa is able to sense and respond to varied and limited nutrient stress in the host environment. Two-component systems are important sensors-regulators of cellular responses to environmental stresses, such as those encountered in the host. This work demonstrates that the response by the two-component system TctD-TctE to the presence of citric acid has a role in biofilm formation, aminoglycoside susceptibility, and growth in P. aeruginosa.

RevDate: 2019-03-06

Haesler E, Swanson T, Ousey K, et al (2019)

Clinical indicators of wound infection and biofilm: reaching international consensus.

Journal of wound care, 28(Sup3b):s4-s12.

OBJECTIVE: To achieve international consensus relating to clinical indicators for a chronic wound, wound infection and biofilm presence to inform the development of international clinical guidance for assessing and managing wound infection.

METHOD: An online Delphi consensus process of international key opinion leaders in infection was undertaken. A literature search underpinned the development of issue statements related to terminology, emerging topics and debate in the field of wound infection. Experts participated in three rounds of consensus voting, sharing their opinions and indicating their level of agreement with the issue statements. Votes were calculated using web-based software that implements a nominal group voting methodology previously published by Research and Development/University of California at Los Angeles.

RESULTS: A total of 14 experts took part in the development process. Consensus was reached on clinical indicators of wound chronicity, wound infection and biofilm presence. Agreement was also reached that the term 'critical colonisation' should no longer be used to refer to a stage in the wound infection continuum.

CONCLUSION: Outcomes from the consensus process were used to inform the development of international, evidence-informed guidance on the assessment and treatment of wound infection to promote improved outcomes for people with wounds.

RevDate: 2019-03-06

Hu MX, Li JN, Guo Q, et al (2019)

Probiotics Biofilm-Integrated Electrospun Nanofiber Membranes: A New Starter Culture for Fermented Milk Production.

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

Electrospun nanofiber membranes are widely investigated in the past few decades as candidates for tissue engineering, which can mimic natural extracellular matrix (ECM) and improve cell adhesion, proliferation, and expression on nanofiber membranes. However, the formation of bacterial biofilms on nanofiber membranes and application of the biofilm-integrated nanofiber membranes remain largely unknown. Here, electrospun cellulose acetate nanofiber membranes are first utilized as scaffold materials for Lactobacillus plantarum (L. plantarum) biofilm formation. Nanofiber membranes proved to be an excellent scaffold for bacteria biofilm with high stability, where biofilms were interlocked with nanofibers forming a cohesive structure. In comparison with planktonic bacteria, L. plantarum biofilms on nanofiber membranes show excellent gastrointestinal resistance. Instead of decreasing, the number of viable cells increased after 3 h digestion in vitro. The L. plantarum biofilm-integrated nanofiber membranes were used as reusable starter cultures for fermented milk production showing excellent fermentative ability and higher survival of L. plantarum during shelf life. The viable cells in fermented milk remained at 11 log CFU/g throughout the reusable batches, which is far above the required value of 7 log CFU/g in commercial products. In addition, the produced fermented milk possesses shorter fermentation time and higher survival of probiotics during shelf life. The results suggest electrospun nanofiber membranes are ideal scaffold materials for bacteria biofilms immobilization in biotechnology and fermentation engineering, which broaden the potential use of electrospun nanofiber membranes in microbiology and strengthen the application of biofilms in fermentation engineering.

RevDate: 2019-03-06

Divaris K, Shungin D, Rodríguez-Cortés A, et al (2019)

The Supragingival Biofilm in Early Childhood Caries: Clinical and Laboratory Protocols and Bioinformatics Pipelines Supporting Metagenomics, Metatranscriptomics, and Metabolomics Studies of the Oral Microbiome.

Methods in molecular biology (Clifton, N.J.), 1922:525-548.

Early childhood caries (ECC) is a biofilm-mediated disease. Social, environmental, and behavioral determinants as well as innate susceptibility are major influences on its incidence; however, from a pathogenetic standpoint, the disease is defined and driven by oral dysbiosis. In other words, the disease occurs when the natural equilibrium between the host and its oral microbiome shifts toward states that promote demineralization at the biofilm-tooth surface interface. Thus, a comprehensive understanding of dental caries as a disease requires the characterization of both the composition and the function or metabolic activity of the supragingival biofilm according to well-defined clinical statuses. However, taxonomic and functional information of the supragingival biofilm is rarely available in clinical cohorts, and its collection presents unique challenges among very young children. This paper presents a protocol and pipelines available for the conduct of supragingival biofilm microbiome studies among children in the primary dentition, that has been designed in the context of a large-scale population-based genetic epidemiologic study of ECC. The protocol is being developed for the collection of two supragingival biofilm samples from the maxillary primary dentition, enabling downstream taxonomic (e.g., metagenomics) and functional (e.g., transcriptomics and metabolomics) analyses. The protocol is being implemented in the assembly of a pediatric precision medicine cohort comprising over 6000 participants to date, contributing social, environmental, behavioral, clinical, and biological data informing ECC and other oral health outcomes.

RevDate: 2019-03-06

Khelissa SO, Abdallah M, Jama C, et al (2019)

Actively detached Pseudomonas aeruginosa biofilm cell susceptibility to benzalkonium chloride and associated resistance mechanism.

Archives of microbiology pii:10.1007/s00203-019-01643-x [Epub ahead of print].

The present work aimed at studying physiological properties of Pseudomonas aeruginosa cells actively detached from biofilm formed on stainless steel and comparing them with their planktonic counterparts as a function of growth temperature (20 °C and 37 °C). The susceptibility of P. aeruginosa cells to benzalkonium chloride (BAC) was studied. Furthermore, the effect of BAC on the cell membrane integrity and the role of the cell membrane fluidity in the cell-scale-resistance mechanism were investigated. Our results showed that actively detached biofilm cells were more susceptible to BAC treatment than planktonic ones. A greater leakage of intracellular potassium after BAC addition was observed in actively detached biofilm cells, which reflects their membrane vulnerability. The rise of the growth temperature from 20 to 37 °C increased the membrane rigidity of planktonic cells comparatively to their actively detached biofilm ones. Under experimental conditions developed in this work, our data highlighted that actively biofilm-detached and planktonic P. aeruginosa cells have distinguishable phenotypes.

RevDate: 2019-03-06

Fonseca BB, Silva PLAPA, Silva ACA, et al (2019)

Nanocomposite of Ag-Doped ZnO and AgO Nanocrystals as a Preventive Measure to Control Biofilm Formation in Eggshell and Salmonella spp. Entry Into Eggs.

Frontiers in microbiology, 10:217.

Salmonella spp. is an important foodborne agent of salmonellosis, whose sources in humans often include products of avian origin. The control of this bacterium is difficult especially when Salmonella spp. is organized into biofilms. We hypothesized that the novel nanocomposites of ZnO nanocrystals doped with silver (Ag) and silver oxide (AgO) nanocrystals (ZnO:Ag-AgO) synthesized by the coprecipitation method could control or prevent the formation of Salmonella Enteritidis (SE) and Salmonella Heidelberg (SH) biofilm and its entry into turkey eggs. The diffraction characteristics of ZnO and AgO showed sizes of 28 and 30 nm, respectively. The Zn to Ag substitution into the ZnO crystalline structure was evidenced by the ionic radius of Ag+2 (1.26 Å), which is greater than Zn+2 (0.74 Å). For the SE analyses post-biofilm formation, the ZnO:Ag-AgO was not able to eliminate the biofilm, but the bacterial load was lower than that of the control group. Additionally, SE was able to infiltrate into the eggs and was found in both albumen and yolk. For the SH analyses applied onto the eggshells before biofilm formation, the ZnO:Ag-AgO treatment prevented biofilm formation, and although the bacterium infiltration into the eggs was observed in all treated groups, it was significantly smaller in ZnO:Ag-AgO pre-treated eggs, and SH could not reach the yolk. There was no difference in pore size between groups; therefore, the inhibition of biofilm formation and the prevention of bacterium entry into the egg were attributable to the use of ZnO:Ag-AgO, which was not influenced by the egg structure. Although the amount of Ag and Zn in the shell of the ZnO:Ag-AgO group was greater in relation to the control, this difference was not detected in the other egg components. In the search for new measures that are effective, safe and viable for controlling microorganisms in poultry farming, the application of a nanocomposite of Ag-doped ZnO and AgO nanocrystals appears as an alternative of great potential to prevent Salmonella sp biofilms in eggshells and other surfaces.

RevDate: 2019-03-06

Ghosh S, Qureshi A, H Purohit (2019)

D-Tryptophan governs biofilm formation rates and bacterial interaction in P. mendocina and S. aureus.

Journal of biosciences, 44(1):.

Biofilm genesis by Pseudomonasand Staphylococcus sp is associated with biofouling in natural settings. D-Tryptophan (D-Trp) inhibits bacterial biofilms and have been proposed for biofouling control applications. In this study, D-Trp significantly inhibited Pseudomonas mendocina and Staphylococcus aureuscell attachment (biofilm formation) rates on polystyrene96-well microtiter plates in comparison with L-Tryptophan (L-Trp) and mixtures of D-/L-Tryptophan (D-/L-Trp). Theinhibitory effect was greater on P. mendocina,where the rate of cell adherence was declined to 8.79105cells/h from8.09106cells/h (control) inP. mendocina.InS. aureusit was declined to 4.29107cells/h from 9.29107cells/h(control) at 1 mM concentration. It hindered the intracellular communication and adherence in both the strains, as con-firmed by SEM and real time PCR analysis. Addition of D-Trp to preformed biofilms also caused partial disassembly. Intraand interbacterial aggregation were decreased subsequently upon treatment with D-Trp. It repressed the genes involved incell-cell communication, which could be responsible for the diminished biofilm formation of the selected strains. HenceD-Tryptophan has proved to be an effective strategy to control biofilm and may support in the development of surfacecoating technologies.

RevDate: 2019-03-06

Li F, Cimdins A, Rohde M, et al (2019)

DncV Synthesizes Cyclic GMP-AMP and Regulates Biofilm Formation and Motility in Escherichia coli ECOR31.

mBio, 10(2): pii:mBio.02492-18.

Cyclic dinucleotides (cDNs) act as intracellular second messengers, modulating bacterial physiology to regulate the fundamental life style transition between motility and sessility commonly known as biofilm formation. Cyclic GMP-AMP (cGAMP), synthesized by the dinucleotide cyclase DncV, is a newly discovered cDN second messenger involved in virulence and chemotaxis in Vibrio cholerae O1 biovar El Tor. Here we report a novel role for horizontally transferred DncV in cGAMP production and regulation of biofilm formation and motility in the animal commensal strain Escherichia coli ECOR31. ECOR31 expresses a semiconstitutive temperature-independent rdar (red, dry, and rough) morphotype on Congo red agar plates characterized by the extracellular matrix components cellulose and curli fimbriae which requires activation by the major biofilm regulator CsgD and cyclic di-GMP signaling. In contrast, C-terminal His-tagged DncV negatively regulates the rdar biofilm morphotype and cell aggregation via downregulation of csgD mRNA steady-state level. Furthermore, DncV sequentially promotes and inhibits adhesion to the abiotic surface after 24 h and 48 h of growth, respectively. DncV also suppresses swimming and swarming motility posttranscriptional of the class 1 flagellum regulon gene flhD Purified DncV produced different cDNs, cyclic di-GMP, cyclic di-AMP, an unknown product(s), and the dominant species 3'3'-cGAMP. In vivo, only the 3'3'-cGAMP concentration was elevated upon short-term overexpression of dncV, making this work a first report on cGAMP production in E. coli Regulation of rdar biofilm formation and motility upon overexpression of untagged DncV in combination with three adjacent cotransferred gene products suggests a novel temperature-dependent cGAMP signaling module in E. coli ECOR31.IMPORTANCE The ability of bacteria to sense and respond to environmental signals is critical for survival. Bacteria use cyclic dinucleotides as second messengers to regulate a number of physiological processes, such as the fundamental life style transition between motility and sessility (biofilm formation). cGAMP, which is synthesized by a dinucleotide cyclase called DncV, is a newly discovered second messenger involved in virulence and chemotaxis in the Vibrio cholerae biovar El Tor causing the current 7th cholera pandemic. However, to what extent cGAMP exists and participates in physiological processes in other bacteria is still unknown. In this study, we found an elevated cGAMP level to possibly regulate biofilm formation and motility in the animal commensal E. coli strain ECOR31. Thus, we detected a novel role for cGAMP signaling in regulation of physiological processes other than those previously reported in proteobacterial species.

RevDate: 2019-03-05

Melander CC, Nguyen TV, Minrovic BM, et al (2019)

Identification of novel anti-mycobacterial biofilm agents based upon the 2-aminoimidazole scaffold.

ChemMedChem [Epub ahead of print].

Tuberculosis (TB) remains a significant global health problem for which new therapeutic options are sorely needed. The ability of the causative agent, Mycobacterium tuberculosis, to reside within host macrophages and form biofilm-like communities contributes to the persistent and drug tolerant nature of the disease. Compounds that can prevent or reverse the biofilm-like phenotype have the potential to serve alongside TB antibiotics to overcome this tolerance and reduce treatment duration. Using Mycobacterium smegmatis as a surrogate organism, we report the identification of two new 2-aminoimidazole compounds that both inhibit and disperse mycobacterial biofilms, work synergistically with isoniazid and rifampicin to eradicate preformed M. smegmatis biofilms in vitro, are non-toxic against Galleria mellonella, and exhibit stability in mouse plasma.

RevDate: 2019-03-05

Bashir A, Azeem A, Stedman Y, et al (2019)

Pet Food Factory Isolates of Salmonella Serotypes Do Not Demonstrate Enhanced Biofilm Formation Compared to Serotype-Matched Clinical and Veterinary Isolates.

BioMed research international, 2019:8569459.

Environmentally persistent Salmonella in the pet food factory environment has been described, with biofilm formation suggested as a candidate mechanism contributing to their persistence. In this study the ability of a panel of Salmonella isolates from factory, clinical, and veterinary sources was investigated for their ability to form biofilms at 24 and 48 hours. The effect of nutrient availability and incubation time on biofilm formation was investigated using full strength and diluted 1/20 TSB media at 37°C, 25°C, 15°C, and 10°C. Results highlighted that all the Salmonella isolates were able to form biofilms in both nutrient conditions and this was highly correlated with temperature. At 25°C, biofilm formation was enhanced in diluted 1/20 TSB and increased incubation time (48h) (p= <0.001). However, this was not observed at 10°C, 15°C, or 37°C. None of the factory isolates demonstrated enhanced biofilm formation in comparison to serotype-matched isolates from veterinary and clinical sources. Salmonella enterica Senftenberg 775W was the strongest biofilm former at 15°C, 25°C, and 37°C in all the conditions tested (p=<0.05). Biofilm formation is an important mechanism of environmental persistence in the food manufacturing environment; however, there is no evidence of an enhanced biofilm-producing phenotype in factory persistent strains.

RevDate: 2019-03-05

Balhaddad AA, Melo MAS, RL Gregory (2019)

Inhibition of nicotine-induced Streptococcus mutans biofilm formation by salts solutions intended for mouthrinses.

Restorative dentistry & endodontics, 44(1):e4 pii:2019440107.

Objectives: Biofilm formation is critical to dental caries initiation and development. The aim of this study was to investigate the effects of nicotine exposure on Streptococcus mutans (S. mutans) biofilm formation concomitantly with the inhibitory effects of sodium chloride (NaCl), potassium chloride (KCl) and potassium iodide (KI) salts. This study examined bacterial growth with varying concentrations of NaCl, KCl, and KI salts and nicotine levels consistent with primary levels of nicotine exposure.

Materials and Methods: A preliminary screening experiment was performed to investigate the appropriate concentrations of NaCl, KCl, and KI to use with nicotine. With the data, a S. mutans biofilm growth assay was conducted using nicotine (0-32 mg/mL) in Tryptic Soy broth supplemented with 1% sucrose with and without 0.45 M of NaCl, 0.23 M of KCl, and 0.113 M of KI. The biofilm was stained with crystal violet dye and the absorbance measured to determine biofilm formation.

Results: The presence of 0.45 M of NaCl, 0.23 M of KCl, and 0.113 M of KI significantly inhibited (p < 0.05) nicotine-induced S. mutans biofilm formation by 52%, 79.7%, and 64.1%, respectively.

Conclusions: The results provide additional evidence regarding the biofilm-enhancing effects of nicotine and demonstrate the inhibitory influence of these salts in reducing the nicotine-induced biofilm formation. A short-term exposure to these salts may inhibit S. mutans biofilm formation.

RevDate: 2019-03-05

Courrol DDS, Lopes CRB, Pereira CBP, et al (2019)

Tryptophan Silver Nanoparticles Synthesized by Photoreduction Method: Characterization and Determination of Bactericidal and Anti-Biofilm Activities on Resistant and Susceptible Bacteria.

International journal of tryptophan research : IJTR, 12:1178646919831677 pii:10.1177_1178646919831677.

The high rates of antibiotics use in hospitals have resulted in a condition where multidrug-resistant pathogens have become a severe threat to the human health worldwide. Therefore, there is an increasing necessity to identify new antimicrobial agents that can inhibit the multidrug-resistant bacteria and biofilm formation. In this study, antibacterial and anti-biofilm activities of tryptophan silver nanoparticles (TrpAgNP) were investigated. The TrpAgNPs were synthesized by photoreduction method, and the influence of irradiation time and concentration of reagents were analyzed. The nanoparticles were characterized by transmission electron microscopy, Zeta Potential and (UV)-absorption spectra. The antibacterial activity of TrpAgNPs was tested for antibiotic-resistant and susceptible pathogens, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Citrobacter freundii, Klebsiella pneumoniae, Salmonella typhimurium, and Pseudomonas aeruginosa, evaluating the influence of photoreduction parameters in bactericidal effect. The results have shown that TrpAgNPs solutions with lower tryptophan/silver nitrate (AgNO3) ratio and higher AgNO3 concentration have higher bactericidal action against bacteria with inhibition of ~100% in almost all studied bacterial strains. The antimicrobial activity of TrpAgNPs within biofilms generated under static conditions of antibiotic-resistant and susceptible strains of S. aureus, S. epidermidis, E. coli, K. pneumoniae, C. freundii, and P. aeruginosa was also investigated. The results showed that TrpAgNPs have an inhibitory effect against biofilm formation, exceeding 50% in the case of Gram-negative bacteria (E. coli, K. pneumoniae, C. freundii, and P. aeruginosa-54.8% to 98.8%). For Gram-positive species, an inhibition of biofilm formation of 68.7% to 72.2 % was observed for S. aureus and 20.0% to 40.2% for S. epidermidis.

RevDate: 2019-03-05

Mihajlovic J, Bechon N, Ivanova C, et al (2019)

A putative type V pilus contributes to Bacteroides thetaiotaomicron biofilm formation capacity.

Journal of bacteriology pii:JB.00650-18 [Epub ahead of print].

Bacteroides thetaiotaomicron is a prominent anaerobe member of the healthy human gut microbiota. While the majority of functional studies on B. thetaiotaomicron addressed its impact on the immune system and the utilization of diet polysaccharide, B. thetaiotaomicron biofilm capacity and its contribution to intestinal colonization are still poorly characterized. We tested the natural adhesion of 34 B. thetaiotaomicron isolates and showed that, although biofilm capacity is widespread among B. thetaiotaomicron strains, this phenotype is masked or repressed in the widely used reference strain VPI 5482. Using transposon mutagenesis followed by a biofilm positive selection procedure we identified VPI 5482 mutants with increased biofilm capacity corresponding to an alteration in the C-terminal region of BT3147, encoded by the BT3148-BT3147 locus, which displays homology with mfa-like typeV pili found in many Bacteroidetes We showed that BT3147 is exposed on B. thetaiotaomicron surface and that BT3147-dependent adhesion also requires BT3148, suggesting that BT3148-BT3147 correspond to the anchor and stalk subunits of a new type V pilus involved in B. thetaiotaomicron adhesion. This study therefore introduces B. thetaiotaomicron as a model to study proteinaceous adhesins and biofilm-related phenotypes in this important intestinal symbiont.IMPORTANCE Although the gut anaerobe Bacteroides thetaiotaomicron is a prominent member of the healthy human gut microbiota, little is known on its capacity adhere to surfaces and form biofilms. Here, we identified that alteration of a surface exposed protein corresponding to a type of pili found in many Bacteroidetes increases B. thetaiotaomicron biofilm formation. This study lays the ground for establishing this bacterium as a model organism for in vitro and in vivo study of biofilm-related phenotypes in gut anaerobes.

RevDate: 2019-03-05

Yannarell SM, Grandchamp GM, Chen SY, et al (2019)

A dual-species biofilm with emergent mechanical and protective properties.

Journal of bacteriology pii:JB.00670-18 [Epub ahead of print].

Many microbes coexist within biofilms, or multispecies communities of cells encased in an extracellular matrix. However, little is known about the microbe-microbe interactions relevant to creating these structures. In this study, we explored a striking dual-species biofilm between Bacillus subtilis and Pantoea agglomerans that exhibited characteristics that were not predictable from previous work examining monoculture biofilms. Coculture wrinkle formation required a P. agglomerans exopolysaccharide as well as the B. subtilis amyloid-like protein TasA. Unexpectedly, other B. subtilis matrix components essential for monoculture biofilm formation were not necessary for coculture wrinkling (e.g. the exopolysaccharide EPS, the hydrophobin BslA, and cell chaining). In addition, B. subtilis cell chaining prevented coculture wrinkling, even though chaining has previously been associated with more robust monoculture biofilms. We also observed that increasing the relative proportion of P. agglomerans (which forms completely featureless monoculture colonies) increased coculture wrinkling. Using microscopy and rheology, we observed that these two bacteria assemble into an organized layered structure that reflects the physical properties of both monocultures. This partitioning into distinct regions negatively affected the survival of P. agglomerans while also serving as a protective mechanism in the presence of antibiotic stress. Taken together, these data indicate that studying cocultures is a productive avenue to identify novel mechanisms that drive the formation of structured microbial communities.IMPORTANCE In the environment, many microbes form biofilms. However, the interspecies interactions underlying bacterial coexistence within these biofilms remain understudied. Here, we mimic environmentally relevant biofilms by studying a dual-species biofilm formed between Bacillus subtilis and Pantoea agglomerans and subjecting the coculture to chemical and physical stressors that it may experience in the natural world. We determined that both bacteria contribute structural elements to the coculture, which is reflected in its overall viscoelastic behavior. Existence within the coculture can be either beneficial or detrimental depending on the context. Many of the features and determinants of the coculture biofilm appear distinct from those identified in monoculture biofilm studies, highlighting the importance of characterizing multispecies consortia to understand naturally occurring bacterial interactions.


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

long standard version

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