Extracellular DNA as matrix component in microbial biofilms

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Tolker-Nielsen, Tim

2010-01-01

Bacteria in nature primarily live in surface-associated communities commonly known as biofilms. Because bacteria in biofilms, in many cases, display tolerance to host immune systems, antibiotics, and biocides, they are often difficult or impossible to eradicate. Biofilm formation, therefore, leads...... to various persistent infections in humans and animals, and to a variety of complications in industry, where solid–water interfaces occur. Knowledge about the molecular mechanisms involved in biofilm formation is necessary for creating strategies to control biofilms. Recent studies have shown...... that extracellular DNA is an important component of the extracellular matrix of microbial biofilms. The present chapter is focussed on extracellular DNA as matrix component in biofilms formed by Pseudomonas aeruginosa as an example from the Gram-negative bacteria, and Streptococcus and Staphylococcus as examples...

Natural antigenic differences in the functionally equivalent extracellular DNABII proteins of bacterial biofilms provide a means for targeted biofilm therapeutics

Science.gov (United States)

Rocco, Christopher J.; Davey, Mary Ellen; Bakaletz, Lauren O.; Goodman, Steven D.

2016-01-01

SUMMARY Bacteria that persist in the oral cavity exist within complex biofilm communities. A hallmark of biofilms is the presence of an extracellular polymeric substance (EPS), which consists of polysaccharides, extracellular DNA (eDNA), and proteins, including the DNABII family of proteins. The removal of DNABII proteins from a biofilm results in the loss of structural integrity of the eDNA and the collapse of the biofilm structure. We examined the role of DNABII proteins in the biofilm structure of the periodontal pathogen Porphyromonas gingivalis and the oral commensal Streptococcus gordonii. Co-aggregation with oral streptococci is thought to facilitate the establishment of P. gingivalis within the biofilm community. We demonstrate that DNABII proteins are present in the EPS of both S. gordonii and P. gingivalis biofilms, and that these biofilms can be disrupted through the addition of antisera derived against their respective DNABII proteins. We provide evidence that both eDNA and DNABII proteins are limiting in S. gordonii but not in P. gingivalis biofilms. In addition, these proteins are capable of complementing one another functionally. We also found that while antisera derived against most DNABII proteins are capable of binding a wide variety of DNABII proteins, the P. gingivalis DNABII proteins are antigenically distinct. The presence of DNABII proteins in the EPS of these biofilms and the antigenic uniqueness of the P. gingivalis proteins provide an opportunity to develop therapies that are targeted to remove P. gingivalis and biofilms that contain P. gingivalis from the oral cavity. PMID:26988714

Hydraulic resistance of biofilms

KAUST Repository

Dreszer, C.; Vrouwenvelder, Johannes S.; Paulitsch-Fuchs, Astrid H.; Zwijnenburg, Arie; Kruithof, Joop C.; Flemming, Hans Curt

2013-01-01

resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric

The Extracellular Matrix of Candida albicans Biofilms Impairs Formation of Neutrophil Extracellular Traps.

Science.gov (United States)

Johnson, Chad J; Cabezas-Olcoz, Jonathan; Kernien, John F; Wang, Steven X; Beebe, David J; Huttenlocher, Anna; Ansari, Hamayail; Nett, Jeniel E

2016-09-01

Neutrophils release extracellular traps (NETs) in response to planktonic C. albicans. These complexes composed of DNA, histones, and proteins inhibit Candida growth and dissemination. Considering the resilience of Candida biofilms to host defenses, we examined the neutrophil response to C. albicans during biofilm growth. In contrast to planktonic C. albicans, biofilms triggered negligible release of NETs. Time lapse imaging confirmed the impairment in NET release and revealed neutrophils adhering to hyphae and migrating on the biofilm. NET inhibition depended on an intact extracellular biofilm matrix as physical or genetic disruption of this component resulted in NET release. Biofilm inhibition of NETosis could not be overcome by protein kinase C activation via phorbol myristate acetate (PMA) and was associated with suppression of neutrophil reactive oxygen species (ROS) production. The degree of impaired NET release correlated with resistance to neutrophil attack. The clinical relevance of the role for extracellular matrix in diminishing NET production was corroborated in vivo using a rat catheter model. The C. albicans pmr1Δ/Δ, defective in production of matrix mannan, appeared to elicit a greater abundance of NETs by scanning electron microscopy imaging, which correlated with a decreased fungal burden. Together, these findings show that C. albicans biofilms impair neutrophil response through an inhibitory pathway induced by the extracellular matrix.

The characteristics of extracellular polymeric substances and soluble microbial products in moving bed biofilm reactor-membrane bioreactor.

Science.gov (United States)

Duan, Liang; Jiang, Wei; Song, Yonghui; Xia, Siqing; Hermanowicz, Slawomir W

2013-11-01

The characteristics of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in conventional membrane bioreactor (MBR) and in moving bed biofilm reactor-membrane bioreactors (MBBR-MBR) were investigated in long-term (170 days) experiments. The results showed that all reactors had high removal efficiency of ammonium and COD, despite very different fouling conditions. The MBBR-MBR with media fill ratio of 26.7% had much lower total membrane resistance and no obvious fouling were detected during the whole operation. In contrast, MBR and MBBR-MBR with lower and higher media fill experienced more significant fouling. Low fouling at optimum fill ratio may be due to the higher percentage of small molecular size (100 kDa) of EPS and SMP in the reactor. The composition of EPS and SMP affected fouling due to different O-H bonds in hydroxyl functional groups, and less polysaccharides and lipids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low Concentrations of Vitamin C Reduce the Synthesis of Extracellular Polymers and Destabilize Bacterial Biofilms

KAUST Repository

Pandit, Santosh

2017-12-26

Extracellular polymeric substances (EPS) produced by bacteria form a matrix supporting the complex three-dimensional architecture of biofilms. This EPS matrix is primarily composed of polysaccharides, proteins and extracellular DNA. In addition to supporting the community structure, the EPS matrix protects bacterial biofilms from the environment. Specifically, it shields the bacterial cells inside the biofilm, by preventing antimicrobial agents from getting in contact with them, thereby reducing their killing effect. New strategies for disrupting the formation of the EPS matrix can therefore lead to a more efficient use of existing antimicrobials. Here we examined the mechanism of the known effect of vitamin C (sodium ascorbate) on enhancing the activity of various antibacterial agents. Our quantitative proteomics analysis shows that non-lethal concentrations of vitamin C inhibit bacterial quorum sensing and other regulatory mechanisms underpinning biofilm development. As a result, the EPS biosynthesis in reduced, and especially the polysaccharide component of the matrix is depleted. Once the EPS content is reduced beyond a critical point, bacterial cells get fully exposed to the medium. At this stage, the cells are more susceptible to killing, either by vitamin C-induced oxidative stress as reported here, or by other antimicrobials or treatments.

Low Concentrations of Vitamin C Reduce the Synthesis of Extracellular Polymers and Destabilize Bacterial Biofilms

KAUST Repository

Pandit, Santosh; Ravikumar, Vaishnavi; Abdel-Haleem, Alyaa M.; Derouiche, Abderahmane; Mokkapati, V. R. S. S.; Sihlbom, Carina; Mineta, Katsuhiko; Gojobori, Takashi; Gao, Xin; Westerlund, Fredrik; Mijakovic, Ivan

2017-01-01

Extracellular polymeric substances (EPS) produced by bacteria form a matrix supporting the complex three-dimensional architecture of biofilms. This EPS matrix is primarily composed of polysaccharides, proteins and extracellular DNA. In addition to supporting the community structure, the EPS matrix protects bacterial biofilms from the environment. Specifically, it shields the bacterial cells inside the biofilm, by preventing antimicrobial agents from getting in contact with them, thereby reducing their killing effect. New strategies for disrupting the formation of the EPS matrix can therefore lead to a more efficient use of existing antimicrobials. Here we examined the mechanism of the known effect of vitamin C (sodium ascorbate) on enhancing the activity of various antibacterial agents. Our quantitative proteomics analysis shows that non-lethal concentrations of vitamin C inhibit bacterial quorum sensing and other regulatory mechanisms underpinning biofilm development. As a result, the EPS biosynthesis in reduced, and especially the polysaccharide component of the matrix is depleted. Once the EPS content is reduced beyond a critical point, bacterial cells get fully exposed to the medium. At this stage, the cells are more susceptible to killing, either by vitamin C-induced oxidative stress as reported here, or by other antimicrobials or treatments.

Extracellular matrix assembly in extreme acidic eukaryotic biofilms and their possible implications in heavy metal adsorption

Energy Technology Data Exchange (ETDEWEB)

Aguilera, Angeles [Centro de Astrobiologia (INTA-CSIC), Carretera de Ajalvir Km 4, Torrejon de Ardoz, 28850 Madrid (Spain)], E-mail: aguileraba@inta.es; Souza-Egipsy, Virginia [Centro de Astrobiologia (INTA-CSIC), Carretera de Ajalvir Km 4, Torrejon de Ardoz, 28850 Madrid (Spain); San Martin-Uriz, Patxi [Centro de Biologia Molecular (UAM-CSIC), Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Amils, Ricardo [Centro de Astrobiologia (INTA-CSIC), Carretera de Ajalvir Km 4, Torrejon de Ardoz, 28850 Madrid (Spain); Centro de Biologia Molecular (UAM-CSIC), Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

2008-07-30

To evaluate the importance of the extracellular matrix in relation to heavy metal binding capacity in extreme acidic environments, the extracellular polymeric substances (EPS) composition of 12 biofilms isolated from Rio Tinto (SW, Spain) was analyzed. Each biofilm was composed mainly by one or two species of eukaryotes, although other microorganisms were present. EPS ranged from 130 to 439 mg g{sup -1} biofilm dry weight, representing between 15% and the 40% of the total biofilm dry weight (DW). Statistically significant differences (p < 0.05) were found in the amount of total EPS extracted from biofilms dominated by the same organism at different sampling points. The amount of EPS varied among different biofilms collected from the same sampling location. Colloidal EPS ranged from 42 to 313 mg g{sup -1} dry weight; 10% to 30% of the total biofilm dry weight. Capsular EPS ranged from 50 to 318 mg g{sup -1} dry weight; 5% to 30% of the total biofilm dry weight. Seven of the 12 biofilms showed higher amounts of capsular than colloidal EPS (p < 0.05). Total amount of EPS decreased when total cell numbers and pH increased. There was a positive correlation between EPS concentration and heavy metal concentration in the water. Observations by low temperature scanning electron microscopy (LTSEM) revealed the mineral adsorption in the matrix of EPS and onto the cell walls. EPS in all biofilms were primarily composed of carbohydrates, heavy metals and humic acid, plus small quantities of proteins and DNA. After carbohydrates, heavy metals were the second main constituents of the extracellular matrix. Their total concentrations ranged from 3 to 32 mg g{sup -1} biofilm dry weight, reaching up to 16% of the total composition. In general, the heavy metal composition of the EPS extracted from the biofilms closely resembled the metal composition of the water from which the biofilms were collected.

Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Nilsson, Martin; Jensen, Peter Østrup

2013-01-01

Within recent years, it has been established that extracellular DNA is a key constituent of the matrix of microbial biofilms. In addition, it has recently been demonstrated that DNA binds positively charged antimicrobials such as aminoglycosides and antimicrobial peptides. In the present study, we...... provide evidence that extracellular DNA shields against aminoglycosides in Pseudomonas aeruginosa biofilms. We show that exogenously supplemented DNA integrates into P. aeruginosa biofilms and increases their tolerance toward aminoglycosides. We provide evidence that biofilms formed by a DNA release......-deficient P. aeruginosa quorum-sensing mutant are more susceptible to aminoglycoside treatment than wild-type biofilms but become rescued from the detrimental action of aminoglycosides upon supplementation with exogenous DNA. Furthermore, we demonstrate that exposure to lysed polymorphonuclear leukocytes...

Microbial ecology of phototrophic biofilms

NARCIS (Netherlands)

Roeselers, G.

2007-01-01

Biofilms are layered structures of microbial cells and an extracellular matrix of polymeric substances, associated with surfaces and interfaces. Biofilms trap nutrients for growth of the enclosed microbial community and help prevent detachment of cells from surfaces in flowing systems. Phototrophic

Ciliates as engineers of phototrophic biofilms

NARCIS (Netherlands)

Weerman, Ellen J.; van der Geest, Harm G.; van der Meulen, Myra D.; Manders, Erik M. M.; van de Koppel, Johan; Herman, Peter M. J.; Admiraal, Wim

1. Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the 'engineering'

Microscopic monitoring of extracellular pH in dental biofilms

DEFF Research Database (Denmark)

Schlafer, Sebastian; Garcia, Javier; Greve, Matilde

pH in dental biofilm is a key virulence factor for the development of caries lesions. The complex three-dimensional architecture of dental biofilms leads to steep gradients of nutrients and metabolites, including organic acids, across the biofilm. For decades, measuring pH in dental biofilm has...... been limited to monitoring bulk pH with electrodes. Although pH microelectrodes with a better spatial resolution have been developed, they do not permit to monitor horizontal pH gradients in real-time. Quantitative fluorescent microscopic techniques, such as fluorescence lifetime imaging or pH...... ratiometry, can be employed to map the pH landscape in dental biofilm with more detail. However, when pH sensitive fluorescent probes are used to visualize pH in biofilms, it is crucial to differentiate between extracellular and intracellular pH. Intracellular microbial pH and pH in the extracellular matrix...

Escherichia coli biofilms have an organized and complex extracellular matrix structure.

Science.gov (United States)

Hung, Chia; Zhou, Yizhou; Pinkner, Jerome S; Dodson, Karen W; Crowley, Jan R; Heuser, John; Chapman, Matthew R; Hadjifrangiskou, Maria; Henderson, Jeffrey P; Hultgren, Scott J

2013-09-10

Bacterial biofilms are ubiquitous in nature, and their resilience is derived in part from a complex extracellular matrix that can be tailored to meet environmental demands. Although common developmental stages leading to biofilm formation have been described, how the extracellular components are organized to allow three-dimensional biofilm development is not well understood. Here we show that uropathogenic Escherichia coli (UPEC) strains produce a biofilm with a highly ordered and complex extracellular matrix (ECM). We used electron microscopy (EM) techniques to image floating biofilms (pellicles) formed by UPEC. EM revealed intricately constructed substructures within the ECM that encase individual, spatially segregated bacteria with a distinctive morphology. Mutational and biochemical analyses of these biofilms confirmed curli as a major matrix component and revealed important roles for cellulose, flagella, and type 1 pili in pellicle integrity and ECM infrastructure. Collectively, the findings of this study elucidated that UPEC pellicles have a highly organized ultrastructure that varies spatially across the multicellular community. Bacteria can form biofilms in diverse niches, including abiotic surfaces, living cells, and at the air-liquid interface of liquid media. Encasing these cellular communities is a self-produced extracellular matrix (ECM) that can be composed of proteins, polysaccharides, and nucleic acids. The ECM protects biofilm bacteria from environmental insults and also makes the dissolution of biofilms very challenging. As a result, formation of biofilms within humans (during infection) or on industrial material (such as water pipes) has detrimental and costly effects. In order to combat bacterial biofilms, a better understanding of components required for biofilm formation and the ECM is required. This study defined the ECM composition and architecture of floating pellicle biofilms formed by Escherichia coli.

Ciliates as engineers of phototrophic biofilms.

NARCIS (Netherlands)

Weerman, E.J.; van der Geest, H.G.; van der Meulen, M.D; Manders, E.M.M.; van de Koppel, J.; Herman, P.M.J.; Admiraal, W.

2011-01-01

1. Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the ‘engineering’

Ciliates as engineers of phototrophic biofilms.

NARCIS (Netherlands)

Weerman, E.J.; Geest, H.G.; Meulen, M.D.; Manders, E.M.M.; Van de Koppel, J.; Herman, P.M.J.; Admiraal, W.

2011-01-01

1.Phototrophic biofilms consist of a matrix of phototrophs, non-photosynthetic bacteria and extracellular polymeric substances (EPS) which is spatially structured. Despite widespread exploitation of algae and bacteria within phototrophic biofilms, for example by protozoans, the ‘engineering’ effects

Interaction of Nanoparticles with Biofilms

Science.gov (United States)

In this work we have studied the interaction and adsorption of engineered nanoparticles such as TiO2, ZnO, CeO2 , and carbon nanotubes with biofilms. Biofilm is an extracellular polymeric substance coating comprised of living material and it is an aggregation of bacteria, algae, ...

Streptococcus suis Serotype 2 Biofilms Inhibit the Formation of Neutrophil Extracellular Traps.

Science.gov (United States)

Ma, Fang; Yi, Li; Yu, Ningwei; Wang, Guangyu; Ma, Zhe; Lin, Huixing; Fan, Hongjie

2017-01-01

Invasive infections caused by Streptococcus suis serotype 2 (SS2) has emerged as a clinical problem in recent years. Neutrophil extracellular traps (NETs) are an important mechanism for the trapping and killing of pathogens that are resistant to phagocytosis. Biofilm formation can protect bacteria from being killed by phagocytes. Until now, there have only been a few studies that focused on the interactions between bacterial biofilms and NETs. SS2 in both a biofilm state and a planktonic cell state were incubated with phagocytes and NETs, and bacterial survival was assessed. DNase I and cytochalasin B were used to degrade NET DNA or suppress phagocytosis, respectively. Extracellular DNA was stained with impermeable fluorescent dye to quantify NET formation. Biofilm formation increased up to 6-fold in the presence of neutrophils, and biofilms were identified in murine tissue. Both planktonic and biofilm cells induced neutrophils chemotaxis to the infection site, with neutrophils increasing by 85.1 and 73.8%, respectively. The bacteria in biofilms were not phagocytized. The bactericidal efficacy of NETs on the biofilms and planktonic cells were equal; however, the biofilm extracellular matrix can inhibit NET release. Although biofilms inhibit NETs release, NETs appear to be an important mechanism to eliminate SS2 biofilms. This knowledge advances the understanding of biofilms and may aid in the development of treatments for persistent infections with a biofilm component.

Ratiometric Imaging of Extracellular pH in Dental Biofilms Using C-SNARF-4

DEFF Research Database (Denmark)

Dige, Irene

pH in dental biofilms plays a central role for the development of caries lesions. For decades, pH measurements in biofilms have been limited to recording pH with electrodes/microelectrodes that do not permit monitoring horizontal pH gradients in biofilms in real-time. Quantitative fluorescent...... microscopy can overcome these problems. Objective: The aim of this demonstration study was to monitor extracellular biofilm pH microscopically with the ratiometric pH-sensitive dye C-SNARF-4 in in-situ-grown dental biofilms. Methods: Using confocal microscopy, the dye C-SNARF-4 was employed both as p...... the microscopic images in order to exclusively determine extracellular pH. We monitored the pH drop at the biofilm-substratum interface in six microscopic fields of view per biofilm for 1h after exposure to 0.4% glucose. Results: Extracellular pH dropped rapidly in all specimens. In both individuals, analysis...

Light Regimes Shape Utilization of Extracellular Organic C and N in a Cyanobacterial Biofilm

Energy Technology Data Exchange (ETDEWEB)

Stuart, Rhona K.; Mayali, Xavier; Boaro, Amy A.; Zemla, Adam; Everroad, R. Craig; Nilson, Daniel; Weber, Peter K.; Lipton, Mary; Bebout, Brad M.; Pett-Ridge, Jennifer; Thelen, Michael P.

2016-06-28

Although it is becoming clear that many microbial primary producers can also play a role as organic consumers, we know very little about the metabolic regulation of photoautotroph organic matter consumption. Cyanobacteria in phototrophic biofilms can reuse extracellular organic carbon, but the metabolic drivers of extracellular processes are surprisingly complex. We investigated the metabolic foundations of organic matter reuse by comparing exoproteome composition and incorporation of¹³C-labeled and¹⁵N-labeled cyanobacterial extracellular organic matter (EOM) in a unicyanobacterial biofilm incubated using different light regimes. In the light and the dark, cyanobacterial direct organic C assimilation accounted for 32% and 43%, respectively, of all organic C assimilation in the community. Under photosynthesis conditions, we measured increased excretion of extracellular polymeric substances (EPS) and proteins involved in micronutrient transport, suggesting that requirements for micronutrients may drive EOM assimilation during daylight hours. This interpretation was supported by photosynthesis inhibition experiments, in which cyanobacteria incorporated N-rich EOM-derived material. In contrast, under dark, C-starved conditions, cyanobacteria incorporated C-rich EOM-derived organic matter, decreased excretion of EPS, and showed an increased abundance of degradative exoproteins, demonstrating the use of the extracellular domain for C storage. Sequence-structure modeling of one of these exoproteins predicted a specific hydrolytic activity that was subsequently detected, confirming increased EOM degradation in the dark. Associated heterotrophic bacteria increased in abundance and upregulated transport proteins under dark relative to light conditions. Taken together, our results indicate that biofilm cyanobacteria are successful competitors for organic C and N and that cyanobacterial nutrient and energy requirements control the use of EOM.

Biosorption of Cadmium by Non-Toxic Extracellular Polymeric Substances (EPS Synthesized by Bacteria from Marine Intertidal Biofilms

Directory of Open Access Journals (Sweden)

Juan Carlos Camacho-Chab

2018-02-01

Full Text Available Cadmium is a major heavy metal found in polluted aquatic environments, mainly derived from industrial production processes. We evaluated the biosorption of solubilized Cd2+ using the extracellular polymeric substances (EPS produced by Bacillus sp. MC3B-22 and Microbacterium sp. MC3B-10 (Microbactan; these bacteria were originally isolated from intertidal biofilms off the coast of Campeche, Mexico. EPS were incubated with different concentrations of cadmium in ultrapure water. Residual Cd2+ concentrations were determined by Inductive Coupled Plasma-Optic Emission Spectrometry and the maximum sorption capacity (Qmax was calculated according to the Langmuir model. EPS were characterized by X-ray photoelectron spectroscopy (XPS before and after sorption. The Qmax of Cd2+ was 97 mg g−1 for Microbactan and 141 mg g−1 for MC3B-22 EPS, these adsorption levels being significantly higher than previously reported for other microbial EPS. In addition, XPS analysis revealed changes in structure of EPS after biosorption and showed that amino functional groups contributed to the binding of Cd2+, unlike other studies that show the carbohydrate fraction is responsible for this activity. This work expands the current view of bacterial species capable of synthesizing EPS with biosorbent potential for cadmium and provides evidence that different chemical moieties, other than carbohydrates, participate in this process.

Characterisation of Lactobacillus plantarum single and multi-strain biofilms

NARCIS (Netherlands)

Fernández Ramírez, Mónica D.

2016-01-01

Biofilms consist of microorganisms attached to a surface and embedded in a protective matrix of extracellular polymeric substances. Within a biofilm, micro-organisms are protected from harsh environmental conditions including those resulting from cleaning and disinfecting agents leading to food

Prevention of biofilm formation and removal of existing biofilms by extracellular DNases of Campylobacter jejuni.

Science.gov (United States)

Brown, Helen L; Reuter, Mark; Hanman, Kate; Betts, Roy P; van Vliet, Arnoud H M

2015-01-01

The fastidious nature of the foodborne bacterial pathogen Campylobacter jejuni contrasts with its ability to survive in the food chain. The formation of biofilms, or the integration into existing biofilms by C. jejuni, is thought to contribute to food chain survival. As extracellular DNA (eDNA) has previously been proposed to play a role in C. jejuni biofilms, we have investigated the role of extracellular DNases (eDNases) produced by C. jejuni in biofilm formation. A search of 2791 C. jejuni genomes highlighted that almost half of C. jejuni genomes contains at least one eDNase gene, but only a minority of isolates contains two or three of these eDNase genes, such as C. jejuni strain RM1221 which contains the cje0256, cje0566 and cje1441 eDNase genes. Strain RM1221 did not form biofilms, whereas the eDNase-negative strains NCTC 11168 and 81116 did. Incubation of pre-formed biofilms of NCTC 11168 with live C. jejuni RM1221 or with spent medium from a RM1221 culture resulted in removal of the biofilm. Inactivation of the cje1441 eDNase gene in strain RM1221 restored biofilm formation, and made the mutant unable to degrade biofilms of strain NCTC 11168. Finally, C. jejuni strain RM1221 was able to degrade genomic DNA from C. jejuni NCTC 11168, 81116 and RM1221, whereas strain NCTC 11168 and the RM1221 cje1441 mutant were unable to do so. This was mirrored by an absence of eDNA in overnight cultures of C. jejuni RM1221. This suggests that the activity of eDNases in C. jejuni affects biofilm formation and is not conducive to a biofilm lifestyle. These eDNases do however have a potential role in controlling biofilm formation by C. jejuni strains in food chain relevant environments.

Assembly and development of the Pseudomonas aeruginosa biofilm matrix.

Directory of Open Access Journals (Sweden)

Luyan Ma

2009-03-01

Full Text Available Virtually all cells living in multicellular structures such as tissues and organs are encased in an extracellular matrix. One of the most important features of a biofilm is the extracellular polymeric substance that functions as a matrix, holding bacterial cells together. Yet very little is known about how the matrix forms or how matrix components encase bacteria during biofilm development. Pseudomonas aeruginosa forms environmentally and clinically relevant biofilms and is a paradigm organism for the study of biofilms. The extracellular polymeric substance of P. aeruginosa biofilms is an ill-defined mix of polysaccharides, nucleic acids, and proteins. Here, we directly visualize the product of the polysaccharide synthesis locus (Psl exopolysaccharide at different stages of biofilm development. During attachment, Psl is anchored on the cell surface in a helical pattern. This promotes cell-cell interactions and assembly of a matrix, which holds bacteria in the biofilm and on the surface. Chemical dissociation of Psl from the bacterial surface disrupted the Psl matrix as well as the biofilm structure. During biofilm maturation, Psl accumulates on the periphery of 3-D-structured microcolonies, resulting in a Psl matrix-free cavity in the microcolony center. At the dispersion stage, swimming cells appear in this matrix cavity. Dead cells and extracellular DNA (eDNA are also concentrated in the Psl matrix-free area. Deletion of genes that control cell death and autolysis affects the formation of the matrix cavity and microcolony dispersion. These data provide a mechanism for how P. aeruginosa builds a matrix and subsequently a cavity to free a portion of cells for seeding dispersal. Direct visualization reveals that Psl is a key scaffolding matrix component and opens up avenues for therapeutics of biofilm-related complications.

Influence of bacterial exopolymers on cell adhesion of Desulfovibrio vulgaris on high alloyed steel: Corrosion inhibition by extracellular polymeric substances (EPS)

Energy Technology Data Exchange (ETDEWEB)

Stadler, R.; Wei, L.; Fuerbeth, W. [Karl-Winnacker-Institut, DECHEMA e.V., Theodor-Heuss-Allee 25, 60486 Frankfurt am Main (Germany); Grooters, M.; Kuklinski, A. [University of Duisburg-Essen, Biofilm Centre, Geibelstrasse 41, 47057 Duisburg (Germany)

2010-12-15

Extracellular polymeric substances (EPS) were studied with regard to their potential application as inhibitors of biocorrosion. EPS that have been isolated from biofilms of sulphate-reducing bacteria (SRB) were adsorbed on samples of high alloyed steel (type 1.4301) at different temperatures. The samples were exposed to SRB containing solution and afterwards analysed by fluorescence microscopy (FM). The results show that the EPS form an incomplete layer and lead to a smaller amount of cell adhesion when compared to pure surfaces. The results are discussed with regard to the application of EPS for the prevention of biofilm formation. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

A Functional DNase I Coating to Prevent Adhesion of Bacteria and the Formation of Biofilm

NARCIS (Netherlands)

Swartjes, Jan J. T. M.; Das, Theerthankar; Sharifi, Shahriar; Subbiahdoss, Guruprakash; Sharma, Prashant K.; Krom, Bastiaan P.; Busscher, Henk J.; van der Mei, Henny C.

2013-01-01

Biofilms are detrimental in many industrial and biomedical applications and prevention of biofilm formation has been a prime challenge for decades. Biofilms consist of communities of adhering bacteria, supported and protected by extracellular-polymeric-substances (EPS), the so-called house of

Artificial biofilms establish the role of matrix interactions in staphylococcal biofilm assembly and disassembly

Science.gov (United States)

Stewart, Elizabeth J.; Ganesan, Mahesh; Younger, John G.; Solomon, Michael J.

2015-01-01

We demonstrate that the microstructural and mechanical properties of bacterial biofilms can be created through colloidal self-assembly of cells and polymers, and thereby link the complex material properties of biofilms to well understood colloidal and polymeric behaviors. This finding is applied to soften and disassemble staphylococcal biofilms through pH changes. Bacterial biofilms are viscoelastic, structured communities of cells encapsulated in an extracellular polymeric substance (EPS) comprised of polysaccharides, proteins, and DNA. Although the identity and abundance of EPS macromolecules are known, how these matrix materials interact with themselves and bacterial cells to generate biofilm morphology and mechanics is not understood. Here, we find that the colloidal self-assembly of Staphylococcus epidermidis RP62A cells and polysaccharides into viscoelastic biofilms is driven by thermodynamic phase instability of EPS. pH conditions that induce phase instability of chitosan produce artificial S. epidermidis biofilms whose mechanics match natural S. epidermidis biofilms. Furthermore, pH-induced solubilization of the matrix triggers disassembly in both artificial and natural S. epidermidis biofilms. This pH-induced disassembly occurs in biofilms formed by five additional staphylococcal strains, including three clinical isolates. Our findings suggest that colloidal self-assembly of cells and matrix polymers produces biofilm viscoelasticity and that biofilm control strategies can exploit this mechanism. PMID:26272750

Did Mineral Surface Chemistry and Toxicity Contribute to Evolution of Microbial Extracellular Polymeric Substances?

Science.gov (United States)

Campbell, Jay M.; Zhang, Nianli; Hickey, William J.

2012-01-01

Abstract Modern ecological niches are teeming with an astonishing diversity of microbial life in biofilms closely associated with mineral surfaces, which highlights the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral–water interface. Biofilm formation capability likely evolved on early Earth because biofilms provide crucial cell survival functions. The potential toxicity of mineral surfaces toward cells and the complexities of the mineral–water–cell interface in determining the toxicity mechanisms, however, have not been fully appreciated. Here, we report a previously unrecognized role for extracellular polymeric substances (EPS), which form biofilms in shielding cells against the toxicity of mineral surfaces. Using colony plating and LIVE/DEAD staining methods in oxide suspensions versus oxide-free controls, we found greater viability of wild-type, EPS-producing strains of Pseudomonas aeruginosa PAO1 compared to their isogenic knockout mutant with defective biofilm-producing capacity. Oxide toxicity was specific to its surface charge and particle size. High resolution transmission electron microscopy (HRTEM) images and assays for highly reactive oxygen species (hROS) on mineral surfaces suggested that EPS shield via both physical and chemical mechanisms. Intriguingly, qualitative as well as quantitative measures of EPS production showed that toxic minerals induced EPS production in bacteria. By determining the specific toxicity mechanisms, we provide insight into the potential impact of mineral surfaces in promoting increased complexity of cell surfaces, including EPS and biofilm formation, on early Earth. Key Words: Mineral toxicity—Bacteria—EPS evolution—Biofilms—Cytotoxicity—Silica—Anatase—Alumina. Astrobiology 12, 785–798. PMID:22934560

Extracellular DNA contributes to dental biofilm formation: An ex vivo study

DEFF Research Database (Denmark)

Schlafer, Sebastian; Meyer, Rikke Louise; Dige, Irene

2016-01-01

The extracellular matrix of dental biofilms plays an important role during caries development. It increases the mechanical stability of the biofilm, it prevents desiccation, it serves as a reservoir for nutrients and it contributes to the long-term preservation of acidic microenvironments. Research...

Extracellular DNases of Ralstonia solanacearum modulate biofilms and facilitate bacterial wilt virulence.

Science.gov (United States)

Minh Tran, Tuan; MacIntyre, April; Khokhani, Devanshi; Hawes, Martha; Allen, Caitilyn

2016-11-01

Ralstonia solanacearum is a soil-borne vascular pathogen that colonizes plant xylem vessels, a flowing, low-nutrient habitat where biofilms could be adaptive. Ralstonia solanacearum forms biofilm in vitro, but it was not known if the pathogen benefits from biofilms during infection. Scanning electron microscopy revealed that during tomato infection, R. solanacearum forms biofilm-like masses in xylem vessels. These aggregates contain bacteria embedded in a matrix including chromatin-like fibres commonly observed in other bacterial biofilms. Chemical and enzymatic assays demonstrated that the bacterium releases extracellular DNA in culture and that DNA is an integral component of the biofilm matrix. An R. solanacearum mutant lacking the pathogen's two extracellular nucleases (exDNases) formed non-spreading colonies and abnormally thick biofilms in vitro. The biofilms formed by the exDNase mutant in planta contained more and thicker fibres. This mutant was also reduced in virulence on tomato plants and did not spread in tomato stems as well as the wild-type strain, suggesting that these exDNases facilitate biofilm maturation and bacterial dispersal. To our knowledge, this is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Biofilms in wounds

DEFF Research Database (Denmark)

Cooper, R A; Bjarnsholt, Thomas; Alhede, M

2014-01-01

Following confirmation of the presence of biofilms in chronic wounds, the term biofilm became a buzzword within the wound healing community. For more than a century pathogens have been successfully isolated and identified from wound specimens using techniques that were devised in the nineteenth...... extracellular polymeric substances (EPS). Cells within such aggregations (or biofilms) display varying physiological and metabolic properties that are distinct from those of planktonic cells, and which contribute to their persistence. There are many factors that influence healing in wounds and the discovery...... of biofilms in chronic wounds has provided new insight into the reasons why. Increased tolerance of biofilms to antimicrobial agents explains the limited efficacy of antimicrobial agents in chronic wounds and illustrates the need to develop new management strategies. This review aims to explain the nature...

Extracellular-matrix-mediated osmotic pressure drives Vibrio cholerae biofilm expansion and cheater exclusion.

Science.gov (United States)

Yan, Jing; Nadell, Carey D; Stone, Howard A; Wingreen, Ned S; Bassler, Bonnie L

2017-08-23

Biofilms, surface-attached communities of bacteria encased in an extracellular matrix, are a major mode of bacterial life. How the material properties of the matrix contribute to biofilm growth and robustness is largely unexplored, in particular in response to environmental perturbations such as changes in osmotic pressure. Here, using Vibrio cholerae as our model organism, we show that during active cell growth, matrix production enables biofilm-dwelling bacterial cells to establish an osmotic pressure difference between the biofilm and the external environment. This pressure difference promotes biofilm expansion on nutritious surfaces by physically swelling the colony, which enhances nutrient uptake, and enables matrix-producing cells to outcompete non-matrix-producing cheaters via physical exclusion. Osmotic pressure together with crosslinking of the matrix also controls the growth of submerged biofilms and their susceptibility to invasion by planktonic cells. As the basic physicochemical principles of matrix crosslinking and osmotic swelling are universal, our findings may have implications for other biofilm-forming bacterial species.Most bacteria live in biofilms, surface-attached communities encased in an extracellular matrix. Here, Yan et al. show that matrix production in Vibrio cholerae increases the osmotic pressure within the biofilm, promoting biofilm expansion and physical exclusion of non-matrix producing cheaters.

Mycobacterium biofilms: factors involved in development, dispersal, and therapeutic strategies against biofilm-relevant pathogens.

Science.gov (United States)

Xiang, Xiaohong; Deng, Wanyan; Liu, Minqiang; Xie, Jianping

2014-01-01

Many bacteria can develop biofilm (BF), a multicellular structure largely combining bacteria and their extracellular polymeric substances (EPS). The formation of biofilm results in an alternative existence in which microbes ensure their survival in adverse environments. Biofilm-relevant infections are more persistent, resistant to most antibiotics, and more recalcitrant to host immunity. Mycobacterium tuberculosis, the causative agent of tuberculosis, can develop biofilm, though whether M. tuberculosis can form biofilm within tuberculosis patients has yet to be determined. Here, we summarize the factors involved in the development and dispersal of mycobacterial biofilms, as well as underlying regulatory factors and inhibitors against biofilm to deepen our understanding of their development and to elucidate potential novel modes of action for future antibiotics. Key factors in biofilm formation identified as drug targets represent a novel and promising avenue for developing better antibiotics.

Biofilm-specific extracellular matrix proteins of non-typeable Haemophilus influenzae

Science.gov (United States)

Wu, Siva; Baum, Marc M.; Kerwin, James; Guerrero-Given, Debbie; Webster, Simon; Schaudinn, Christoph; VanderVelde, David; Webster, Paul

2014-01-01

Non-typeable Haemophilus influenzae (NTHi), a human respiratory tract pathogen can form colony biofilms in vitro. Bacterial cells and the amorphous extracellular matrix (ECM) constituting the biofilm can be separated using sonication. The ECM from 24 hr and 96 hr NTHi biofilms contained polysaccharides and proteinaceous components as detected by NMR and FTIR spectroscopy. More conventional chemical assays on the biofilm ECM confirmed the presence of these components and also DNA. Proteomics revealed eighteen proteins present in biofilm ECM that were not detected in planktonic bacteria. One ECM protein was unique to 24 hr biofilms, two were found only in 96 hr biofilms, and fifteen were present in the ECM of both 24 hr and 96 hr NTHi biofilms. All proteins identified were either associated with bacterial membranes or were cytoplasmic proteins. Immunocytochemistry showed two of the identified proteins, a DNA-directed RNA polymerase and the outer membrane protein OMP P2, associated with bacteria and biofilm ECM. Identification of biofilm-specific proteins present in immature biofilms is an important step in understanding the in vitro process of NTHi biofilm formation. The presence of a cytoplasmic protein and a membrane protein in the biofilm ECM of immature NTHi biofilms suggests that bacterial cell lysis may be a feature of early biofilm formation. PMID:24942343

Biofilm extracellular DNA enhances mixed species biofilms of Staphylococcus epidermidis and Candida albicans.

Science.gov (United States)

Pammi, Mohan; Liang, Rong; Hicks, John; Mistretta, Toni-Ann; Versalovic, James

2013-11-14

Polymicrobial infections are responsible for significant mortality and morbidity in adults and children. Staphylococcus epidermidis and Candida albicans are the most frequent combination of organisms isolated from polymicrobial infections. Vascular indwelling catheters are sites for mixed species biofilm formation and pose a significant risk for polymicrobial infections. We hypothesized that enhancement of biofilms in a mixed species environment increases patient mortality and morbidity. Mixed species biofilms of S. epidermidis and C. albicans were evaluated in vitro and in a subcutaneous catheter infection model in vivo. Mixed species biofilms were enhanced compared to single species biofilms of either S. epidermidis or C. albicans. A mixed species environment increased catheter infection and increased dissemination of S. epidermidis in mice. Microarrays were used to explore differential gene expression of S. epidermidis in the mixed species biofilms. In mixed species biofilms, compared to single species S. epidermidis biofilms, 2.7% of S. epidermidis genes were upregulated and 6% were down regulated. Staphylococcal autolysis repressors lrgA and lrgB were down regulated 36-fold and 27-fold respectively. The role of biofilm extracellular DNA was investigated by quantitation and by evaluating the effects of DNAse in a concentration and time dependent manner. S. epidermidis specific eDNA was increased in mixed species biofilms and further confirmed by degradation with DNAse. Mixed-species biofilms are enhanced and associated with increased S. epidermidis-specific eDNA in vitro and greater systemic dissemination of S. epidermidis in vivo. Down regulation of the lrg operon, a repressor of autolysis, associated with increased eDNA suggests a possible role for bacterial autolysis in mixed species biofilms. Enhancement and systemic dissemination of S. epidermidis may explain adverse outcomes after clinical polymicrobial infections of S. epidermidis and C. albicans.

Biofilm extracellular DNA enhances mixed species biofilms of Staphylococcus epidermidis and Candida albicans

Science.gov (United States)

2013-01-01

Background Polymicrobial infections are responsible for significant mortality and morbidity in adults and children. Staphylococcus epidermidis and Candida albicans are the most frequent combination of organisms isolated from polymicrobial infections. Vascular indwelling catheters are sites for mixed species biofilm formation and pose a significant risk for polymicrobial infections. We hypothesized that enhancement of biofilms in a mixed species environment increases patient mortality and morbidity. Results Mixed species biofilms of S. epidermidis and C. albicans were evaluated in vitro and in a subcutaneous catheter infection model in vivo. Mixed species biofilms were enhanced compared to single species biofilms of either S. epidermidis or C. albicans. A mixed species environment increased catheter infection and increased dissemination of S. epidermidis in mice. Microarrays were used to explore differential gene expression of S. epidermidis in the mixed species biofilms. In mixed species biofilms, compared to single species S. epidermidis biofilms, 2.7% of S. epidermidis genes were upregulated and 6% were down regulated. Staphylococcal autolysis repressors lrgA and lrgB were down regulated 36-fold and 27-fold respectively. The role of biofilm extracellular DNA was investigated by quantitation and by evaluating the effects of DNAse in a concentration and time dependent manner. S. epidermidis specific eDNA was increased in mixed species biofilms and further confirmed by degradation with DNAse. Conclusions Mixed-species biofilms are enhanced and associated with increased S. epidermidis-specific eDNA in vitro and greater systemic dissemination of S. epidermidis in vivo. Down regulation of the lrg operon, a repressor of autolysis, associated with increased eDNA suggests a possible role for bacterial autolysis in mixed species biofilms. Enhancement and systemic dissemination of S. epidermidis may explain adverse outcomes after clinical polymicrobial infections of S

Neutrophil extracellular trap formation in supragingival biofilms.

Science.gov (United States)

Hirschfeld, Josefine; Dommisch, Henrik; Skora, Philipp; Horvath, Gabor; Latz, Eicke; Hoerauf, Achim; Waller, Tobias; Kawai, Toshihisa; Jepsen, Søren; Deschner, James; Bekeredjian-Ding, Isabelle

2015-01-01

Oral biofilms are the causative agents of the highly prevalent oral diseases periodontitis and caries. Additionally, the host immune response is thought to play a critical role in disease onset. Neutrophils are known to be a key host response factor to bacterial challenge on host surfaces. Release of neutrophil extracellular traps (NETs) as a novel antimicrobial defense strategy has gained increasing attention in the past years. Here, we investigated the influx of neutrophils into the dental plaque and the ability of oral bacteria to trigger intra-biofilm release of NETs and intracellular proteins. Supragingival biofilms and whole saliva were sampled from systemically healthy subjects participating in an experimental gingivitis study. Biofilms were analysed by immunofluorescence followed by confocal and fluorescence microscopy. Moreover, concentrations of cytokines and immune-associated proteins in biofilm suspensions and saliva were assessed by ELISA. Neutrophils obtained from blood were stimulated with twelve bacterial species isolated from cultured biofilms or with lipopolysaccharide to monitor NET formation. Neutrophils, NETs, neutrophil-associated proteins (myeloperoxidase, elastase-2, cathepsin G, cathelicidin LL-37), interleukin-8, interleukin-1β and tumor necrosis factor were detected within plaque samples and saliva. All tested bacterial species as well as the polymicrobial samples isolated from the plaque of each donor induced release of NETs and interleukin-8. The degree of NET formation varied among different subjects and did not correlate with plaque scores or clinical signs of local inflammation. Our findings indicate that neutrophils are attracted towards dental biofilms, in which they become incorporated and where they are stimulated by microbes to release NETs and immunostimulatory proteins. Thus, neutrophils and NETs may be involved in host biofilm control, although their specific role needs to be further elucidated. Moreover, inter

Atomic Force Microscopy (AFM) for In-Situ Biofilm Surface Characterization during Free Chlorine and Monochloramine Exposure

Science.gov (United States)

Drinking water distribution system biofilm are attached to pipe walls and found in sediments. These biofilms are complex and contain a variety of microorganisms embedded in a matrix with extracellular polymeric substances (EPS), providing protection from disinfection. Without pro...

Role of Extracellular DNA during Biofilm Formation by Listeria monocytogenes

DEFF Research Database (Denmark)

Harmsen, Morten; Lappann, Martin; Knøchel, S

2010-01-01

(eDNA) may be the only central component of the biofilm matrix and that it is necessary for both initial attachment and early biofilm formation for 41 L. monocytogenes strains that were tested. DNase I treatment resulted in dispersal of biofilms, not only in microtiter tray assays but also in flow......Listeria monocytogenes is a food-borne pathogen that is capable of living in harsh environments. It is believed to do this by forming biofilms, which are surface-associated multicellular structures encased in a self-produced matrix. In this paper we show that in L. monocytogenes extracellular DNA...... cell biofilm assays. However, it was also demonstrated that in a culture without eDNA, neither Listeria genomic DNA nor salmon sperm DNA by itself could restore the capacity to adhere. A search for additional necessary components revealed that peptidoglycan (PG), specifically N-acetylglucosamine (NAG...

The mutual co-regulation of extracellular polymeric substances and iron ions in biocorrosion of cast iron pipes.

Science.gov (United States)

Jin, Juntao; Guan, Yuntao

2014-10-01

New insights into the biocorrosion process may be gained through understanding of the interaction between extracellular polymeric substances (EPS) and iron. Herein, the effect of iron ions on the formation of biofilms and production of EPS was investigated. Additionally, the impact of EPS on the corrosion of cast iron coupons was explored. The results showed that a moderate concentration of iron ions (0.06 mg/L) promoted both biofilm formation and EPS production. The presence of EPS accelerated corrosion during the initial stage, while inhibited corrosion at the later stage. The functional groups of EPS acted as electron shuttles to enable the binding of iron ions. Binding of iron ions with EPS led to anodic dissolution and promoted corrosion, while corrosion was later inhibited through oxygen reduction and availability of phosphorus from EPS. The presence of EPS also led to changes in crystalline phases of corrosion products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Interaction of acetamiprid with extracellular polymeric substances ...

African Journals Online (AJOL)

Extracellular polymeric substances (EPS) are important components of activated sludge and it plays an important role in removing pollutants. The interaction between EPS and organic pollutants is still little known. In the present study, the interaction of soluble/bound EPS with acetamiprid, a neonicotinoid insecticide, was ...

Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity

International Nuclear Information System (INIS)

Thuptimdang, Pumis; Limpiyakorn, Tawan; McEvoy, John; Prüß, Birgit M.; Khan, Eakalak

2015-01-01

Highlights: • Biofilm stages in static batch conditions were similar to dynamic conditions. • Expression of csgA gene increased earlier than alg8 gene in biofilm maturation. • AgNPs had higher effect on less mature biofilms. • Removal of extracellular polymeric substance made biofilms susceptible to AgNPs. - Abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1–3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms

Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity

Energy Technology Data Exchange (ETDEWEB)

Thuptimdang, Pumis, E-mail: pumis.th@gmail.com [International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok 10330 (Thailand); Center of Excellence on Hazardous Substance Management, Bangkok 10330 (Thailand); Limpiyakorn, Tawan, E-mail: tawan.l@chula.ac.th [Center of Excellence on Hazardous Substance Management, Bangkok 10330 (Thailand); Department of Environmental Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Research Unit Control of Emerging Micropollutants in Environment, Chulalongkorn University, Bangkok 10330 (Thailand); McEvoy, John, E-mail: john.mcevoy@ndsu.edu [Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108 (United States); Prüß, Birgit M., E-mail: birgit.pruess@ndsu.edu [Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108 (United States); Khan, Eakalak, E-mail: eakalak.khan@ndsu.edu [Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58108 (United States)

2015-06-15

Highlights: • Biofilm stages in static batch conditions were similar to dynamic conditions. • Expression of csgA gene increased earlier than alg8 gene in biofilm maturation. • AgNPs had higher effect on less mature biofilms. • Removal of extracellular polymeric substance made biofilms susceptible to AgNPs. - Abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1–3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms.

Bacterial biofilms with emphasis on coagulase-negative staphylococci

Directory of Open Access Journals (Sweden)

A Oliveira

2008-01-01

Full Text Available In addition to their capacity to attach to surfaces, various groups of microorganisms also produce an extracellular polymeric substance known as "slime". This slime forms a thin layer around cells known as biofilm. Thus, biofilm structure comprises bacterial cells and an extracellular polymeric substance. It also presents a defined architecture, providing the microorganisms with an excellent protective environment and favoring the exchange of genetic material between cells as well as intercellular communication. The ability to produce biofilm is observed in a large group of bacteria, including coagulase-negative staphylococci (CNS which are the predominant microorganisms of normal skin flora and have been implicated as the causative agents of hospital infections. Bacteremia caused by these agents is common in immunodepressed persons, in patients with cancer, in adult and neonatal intensive care units (ICU and in patients using catheters or other prosthetic devices. The pathogenicity of CNS infections is probably related to the production of slime, which adheres preferentially to plastic and smooth surfaces, forming a biofilm that protects against attacks from the immune system and against antibiotic treatment, a fact hindering the eradication of these infections. The main objective of the present review was to describe basic and genetic aspects of biofilm formation and methods for its detection, with emphasis on biofilm creation by CNS and its relationship with diseases caused by these microorganisms which are becoming increasingly more frequent in the hospital environment.

Extracellular DNA Release Acts as an Antifungal Resistance Mechanism in Mature Aspergillus fumigatus Biofilms

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Rajendran, Ranjith; Williams, Craig; Lappin, David F.; Millington, Owain; Martins, Margarida

2013-01-01

Aspergillus fumigatus has been shown to form biofilms that are associated with adaptive antifungal resistance mechanisms. These include multidrug efflux pumps, heat shock proteins, and extracellular matrix (ECM). ECM is a key structural and protective component of microbial biofilms and in bacteria has been shown to contain extracellular DNA (eDNA). We therefore hypothesized that A. fumigatus biofilms also possess eDNA as part of the ECM, conferring a functional role. Fluorescence microscopy and quantitative PCR analyses demonstrated the presence of eDNA, which was released phase dependently (8 autolysis, were significantly upregulated as the biofilm matured and that inhibition of chitinases affected biofilm growth and stability, indicating mechanistically that autolysis was possibly involved. Finally, using checkerboard assays, it was shown that combinational treatment of biofilms with DNase plus amphotericin B and caspofungin significantly improved antifungal susceptibility. Collectively, these data show that eDNA is an important structural component of A. fumigatus ECM that is released through autolysis, which is important for protection from environmental stresses, including antifungal therapy. PMID:23314962

Extracellular DNA and lipoteichoic acids interact with exopolysaccharides in the extracellular matrix of Streptococcus mutans biofilms

Science.gov (United States)

Castillo Pedraza, Midian C.; Novais, Tatiana F.; Faustoferri, Roberta C.; Quivey, Robert G.; Terekhov, Anton; Hamaker, Bruce R.; Klein, Marlise I.

2018-01-01

Streptococcus mutans -derived exopolysaccharides are virulence determinants in the matrix of biofilms that cause caries. Extracellular DNA (eDNA) and lipoteichoic acid (LTA) are found in cariogenic biofilms, but their functions are unclear. Therefore, strains of S. mutans carrying single deletions that would modulate matrix components were used: eDNA – ΔlytS and ΔlytT; LTA – ΔdltA and ΔdltD; and insoluble exopolysaccharide – ΔgtfB. Single-species (parental strain S. mutans UA159 or individual mutant strains) and mixed-species (UA159 or mutant strain, Actinomyces naeslundii and Streptococcus gordonii) biofilms were evaluated. Distinct amounts of matrix components were detected, depending on the inactivated gene. eDNA was found to be cooperative with exopolysaccharide in early phases, while LTA played a larger role in the later phases of biofilm development. The architecture of mutant strains biofilms was distinct (vs UA159), demonstrating that eDNA and LTA influence exopolysaccharide distribution and microcolony organization. Thus, eDNA and LTA may shape exopolysaccharide structure, affecting strategies for controlling pathogenic biofilms. PMID:28946780

Extracellular DNA and lipoteichoic acids interact with exopolysaccharides in the extracellular matrix of Streptococcus mutans biofilms.

Science.gov (United States)

Castillo Pedraza, Midian C; Novais, Tatiana F; Faustoferri, Roberta C; Quivey, Robert G; Terekhov, Anton; Hamaker, Bruce R; Klein, Marlise I

2017-10-01

Streptococcus mutans-derived exopolysaccharides are virulence determinants in the matrix of biofilms that cause caries. Extracellular DNA (eDNA) and lipoteichoic acid (LTA) are found in cariogenic biofilms, but their functions are unclear. Therefore, strains of S. mutans carrying single deletions that would modulate matrix components were used: eDNA - ∆lytS and ∆lytT; LTA - ∆dltA and ∆dltD; and insoluble exopolysaccharide - ΔgtfB. Single-species (parental strain S. mutans UA159 or individual mutant strains) and mixed-species (UA159 or mutant strain, Actinomyces naeslundii and Streptococcus gordonii) biofilms were evaluated. Distinct amounts of matrix components were detected, depending on the inactivated gene. eDNA was found to be cooperative with exopolysaccharide in early phases, while LTA played a larger role in the later phases of biofilm development. The architecture of mutant strains biofilms was distinct (vs UA159), demonstrating that eDNA and LTA influence exopolysaccharide distribution and microcolony organization. Thus, eDNA and LTA may shape exopolysaccharide structure, affecting strategies for controlling pathogenic biofilms.

DNA builds and strengthens the extracellular matrix in Myxococcus xanthus biofilms by interacting with exopolysaccharides.

Directory of Open Access Journals (Sweden)

Wei Hu

Full Text Available One intriguing discovery in modern microbiology is the extensive presence of extracellular DNA (eDNA within biofilms of various bacterial species. Although several biological functions have been suggested for eDNA, including involvement in biofilm formation, the detailed mechanism of eDNA integration into biofilm architecture is still poorly understood. In the biofilms formed by Myxococcus xanthus, a Gram-negative soil bacterium with complex morphogenesis and social behaviors, DNA was found within both extracted and native extracellular matrices (ECM. Further examination revealed that these eDNA molecules formed well organized structures that were similar in appearance to the organization of exopolysaccharides (EPS in ECM. Biochemical and image analyses confirmed that eDNA bound to and colocalized with EPS within the ECM of starvation biofilms and fruiting bodies. In addition, ECM containing eDNA exhibited greater physical strength and biological stress resistance compared to DNase I treated ECM. Taken together, these findings demonstrate that DNA interacts with EPS and strengthens biofilm structures in M. xanthus.

Extracellular polymeric substances mediate bioleaching/biocorrosion via interfacial processes involving iron(III) ions and acidophilic bacteria.

Science.gov (United States)

Sand, Wolfgang; Gehrke, Tilman

2006-01-01

Extracellular polymeric substances seem to play a pivotal role in biocorrosion of metals and bioleaching, biocorrosion of metal sulfides for the winning of precious metals as well as acid rock drainage. For better control of both processes, the structure and function of extracellular polymeric substances of corrosion-causing or leaching bacteria are of crucial importance. Our research focused on the extremophilic bacteria Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, because of the "simplicity" and knowledge about the interactions of these bacteria with their substrate/substratum and their environment. For this purpose, the composition of the corresponding extracellular polymeric substances and their functions were analyzed. The extracellular polymeric substances of both species consist mainly of neutral sugars and lipids. The functions of the exopolymers seem to be: (i) to mediate attachment to a (metal) sulfide surface, and (ii) to concentrate iron(III) ions by complexation through uronic acids or other residues at the mineral surface, thus, allowing an oxidative attack on the sulfide. Consequently, dissolution of the metal sulfide is enhanced, which may result in an acceleration of 20- to 100-fold of the bioleaching process over chemical leaching. Experiments were performed to elucidate the importance of the iron(III) ions complexed by extracellular polymeric substances for strain-specific differences in oxidative activity for pyrite. Strains of A. ferrooxidans with a high amount of iron(III) ions in their extracellular polymeric substances possess greater oxidation activity than those with fewer iron(III) ions. These data provide insight into the function of and consequently the advantages that extracellular polymeric substances provide to bacteria. The role of extracellular polymeric substances for attachment under the conditions of a space station and resulting effects like biofouling, biocorrosion, malodorous gases, etc. will be discussed.

Extracellular-matrix-mediated osmotic pressure drives Vibrio cholerae biofilm expansion and cheater exclusion

OpenAIRE

Yan, Jing; Nadell, Carey D.; Stone, Howard A.; Wingreen, Ned S.; Bassler, Bonnie L.

2017-01-01

Biofilms, surface-attached communities of bacteria encased in an extracellular matrix, are a major mode of bacterial life. How the material properties of the matrix contribute to biofilm growth and robustness is largely unexplored, in particular in response to environmental perturbations such as changes in osmotic pressure. Here, using Vibrio cholerae as our model organism, we show that during active cell growth, matrix production enables biofilm-dwelling bacterial cells to establish an osmot...

Helicobacter pylori ATCC 43629/NCTC 11639 Outer Membrane Vesicles (OMVs) from Biofilm and Planktonic Phase Associated with Extracellular DNA (eDNA)

Science.gov (United States)

Grande, Rossella; Di Marcantonio, Maria C.; Robuffo, Iole; Pompilio, Arianna; Celia, Christian; Di Marzio, Luisa; Paolino, Donatella; Codagnone, Marilina; Muraro, Raffaella; Stoodley, Paul; Hall-Stoodley, Luanne; Mincione, Gabriella

2015-01-01

Helicobacter pylori persistence is associated with its capacity to develop biofilms as a response to changing environmental conditions and stress. Extracellular DNA (eDNA) is a component of H. pylori biofilm matrix but the lack of DNase I activity supports the hypothesis that eDNA might be protected by other extracellular polymeric substances (EPS) and/or Outer Membrane Vesicles (OMVs), which bleb from the bacteria surface during growth. The aim of the present study was to both identify the eDNA presence on OMVs segregated from H. pylori ATCC 43629/NCTC 11639 biofilm (bOMVs) and its planktonic phase (pOMVs) and to characterize the physical-chemical properties of the OMVs. The presence of eDNA in bOMVs and pOMVs was initially carried out using DNase I-gold complex labeling and Transmission Electron Microscope analysis (TEM). bOMVs and pOMVs were further isolated and physical-chemical characterization carried out using dynamic light scattering (DLS) analysis. eDNA associated with OMVs was detected and quantified using a PicoGreen spectrophotometer assay, while its extraction was performed with a DNA Kit. TEM images showed that eDNA was mainly associated with the OMV membrane surfaces; while PicoGreen staining showed a four-fold increase of dsDNA in bOMVs compared with pOMVs. The eDNA extracted from OMVs was visualized using gel electrophoresis. DLS analysis indicated that both planktonic and biofilm H. pylori phenotypes generated vesicles, with a broad distribution of sizes on the nanometer scale. The DLS aggregation assay suggested that eDNA may play a role in the aggregation of OMVs, in the biofilm phenotype. Moreover, the eDNA associated with vesicle membrane may impede DNase I activity on H. pylori biofilms. These results suggest that OMVs derived from the H. pylori biofilm phenotype may play a structural role by preventing eDNA degradation by nucleases, providing a bridging function between eDNA strands on OMV surfaces and promoting aggregation. PMID:26733944

The danger signal extracellular ATP is an inducer of Fusobacterium nucleatum biofilm dispersal

Directory of Open Access Journals (Sweden)

Qinfeng Ding

2016-11-01

Full Text Available Plaque biofilm is the primary etiological agent of periodontal disease. Biofilm formation progresses through multiple developmental stages beginning with bacterial attachment to a surface, followed by development of microcolonies and finally detachment and dispersal from a mature biofilm as free planktonic bacteria. Tissue damage arising from inflammatory response to biofilm is one of the hallmark features of periodontal disease. A consequence of tissue damage is the release of ATP from within the cell into the extracellular space. Extracellular ATP (eATP is an example of a danger associated molecular pattern (DAMP employed by mammalian cells to elicit inflammatory and damage healing responses. Although the roles of eATP as a signaling molecule in multi-cellular organisms have been relatively well studied, exogenous ATP also influences bacteria biofilm formation. Since plaque biofilms are continuously exposed to various stresses including exposure to the host damage factors eATP, we hypothesized that eATP, in addition to eliciting inflammation could potentially influence the biofilm lifecycle of periodontal associated bacteria. We found that eATP rather than nutritional factors or oxidative stress induced dispersal of Fusobacterium nucleatum, an organism associated with periodontal disease. eATP induced biofilm dispersal through chelating metal ions present in biofilm. Dispersed F. nucleatum biofilm, regardless of natural or induced dispersal by exogenous ATP, were significantly more adhesive and invasive compared to planktonic or biofilm counterparts, and correspondingly activated significantly more pro-inflammatory cytokine production in infected periodontal fibroblasts. Dispersed F. nucleatum also exhibited significantly higher expression of fadA, a virulence factor implicated in adhesion and invasion, compared to planktonic or biofilm bacteria. This study revealed for the first time that periodontal bacterium is capable of co-opting eATP, a

Physicochemical characteristics and microbial community evolution of biofilms during the start-up period in a moving bed biofilm reactor.

Science.gov (United States)

Zhu, Yan; Zhang, Yan; Ren, Hong-Qiang; Geng, Jin-Ju; Xu, Ke; Huang, Hui; Ding, Li-Li

2015-03-01

This study aimed to investigate biofilm properties evolution coupled with different ages during the start-up period in a moving bed biofilm reactor system. Physicochemical characteristics including adhesion force, extracellular polymeric substances (EPS), morphology as well as volatile solid and microbial community were studied. Results showed that the formation and development of biofilms exhibited four stages, including (I) initial attachment and young biofilm formation, (II) biofilms accumulation, (III) biofilm sloughing and updating, and (IV) biofilm maturation. During the whole start-up period, adhesion force was positively and significantly correlated with the contents of EPS, especially the content of polysaccharide. In addition, increased adhesion force and EPS were beneficial for biofilm retention. Gram-negative bacteria mainly including Sphaerotilus, Zoogloea and Haliscomenobacter were predominant in the initial stage. Actinobacteria was beneficial to resist sloughing. Furthermore, filamentous bacteria were dominant in maturation biofilm. Copyright © 2015 Elsevier Ltd. All rights reserved.

Extracellular DNA facilitates the formation of functional amyloids in Staphylococcus aureus biofilms.

Science.gov (United States)

Schwartz, Kelly; Ganesan, Mahesh; Payne, David E; Solomon, Michael J; Boles, Blaise R

2016-01-01

Persistent staphylococcal infections often involve surface-associated communities called biofilms. Staphylococcus aureus biofilm development is mediated by the co-ordinated production of the biofilm matrix, which can be composed of polysaccharides, extracellular DNA (eDNA) and proteins including amyloid fibers. The nature of the interactions between matrix components, and how these interactions contribute to the formation of matrix, remain unclear. Here we show that the presence of eDNA in S. aureus biofilms promotes the formation of amyloid fibers. Conditions or mutants that do not generate eDNA result in lack of amyloids during biofilm growth despite the amyloidogeneic subunits, phenol soluble modulin peptides, being produced. In vitro studies revealed that the presence of DNA promotes amyloid formation by PSM peptides. Thus, this work exposes a previously unacknowledged interaction between biofilm matrix components that furthers our understanding of functional amyloid formation and S. aureus biofilm biology. © 2015 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

The effect of nutrients on extracellular polymeric substance ...

African Journals Online (AJOL)

The effect of nutrients on extracellular polymeric substance (EPS) production and its impact on sludge properties and removal efficiencies were investigated in an in-depth field survey of wastewater treatment plants. Thereafter, laboratory studies were performed to evaluate the effect of a combination of nutrients - nitrogen ...

Biofilm architecture of Phanerozoic cryptic carbonate marine veneers

Science.gov (United States)

Riding, Robert

2002-01-01

Thin (mushrooms, and plumes. All can be interpreted as characteristics of attached bacterial communities, i.e., aggregates as microcolonies, originally embedded in a matrix of extracellular polymeric substances; channels as water conduits and/or uncolonized nutrient-poor spaces; external protuberances as localized growths; and plumes as surface streamers. Cryptic habitat favored pristine biofilm preservation by precluding disturbance and overgrowth, and suggests aphotic and anoxic conditions. These examples provide diagnostic morphologic criteria for wider recognition of biofilm in Phanerozoic and older carbonates.

Cold Plasmas for Biofilm Control: Opportunities and Challenges.

Science.gov (United States)

Gilmore, Brendan F; Flynn, Padrig B; O'Brien, Séamus; Hickok, Noreen; Freeman, Theresa; Bourke, Paula

2018-06-01

Bacterial biofilm infections account for a major proportion of chronic and medical device associated infections in humans, yet our ability to control them is compromised by their inherent tolerance to antimicrobial agents. Cold atmospheric plasma (CAP) represents a promising therapeutic option. CAP treatment of microbial biofilms represents the convergence of two complex phenomena: the production of a chemically diverse mixture of reactive species and intermediates, and their interaction with a heterogeneous 3D interface created by the biofilm extracellular polymeric matrix. Therefore, understanding these interactions and physiological responses to CAP exposure are central to effective management of infectious biofilms. We review the unique opportunities and challenges for translating CAP to the management of biofilms. Copyright © 2018. Published by Elsevier Ltd.

Extracellular Polymeric Substances Govern the Surface Charge of Biogenic Elemental Selenium Nanoparticles

KAUST Repository

Jain, Rohan; Jordan, Norbert; Weiss, Stephan; Foerstendorf, Harald; Heim, Karsten; Kacker, Rohit; Hü bner, René ; Kramer, Herman; van Hullebusch, Eric D.; Farges, Franç ois; Lens, Piet N. L.

2015-01-01

investigated the presence of extracellular polymeric substances (EPS) on BioSeNPs. The role of EPS in capping the extracellularly available BioSeNPs was also examined. Fourier transform infrared (FT-IR) spectroscopy and colorimetric measurements confirmed

Quantitative proteomic analysis of extracellular matrix extracted from mono- and dual-species biofilms of Fusobacterium nucleatum and Porphyromonas gingivalis.

Science.gov (United States)

Mohammed, Marwan Mansoor Ali; Pettersen, Veronika Kuchařová; Nerland, Audun H; Wiker, Harald G; Bakken, Vidar

2017-04-01

The Gram-negative bacteria Fusobacterium nucleatum and Porphyromonas gingivalis are members of a complex dental biofilm associated with periodontal disease. In this study, we cultured F. nucleatum and P. gingivalis as mono- and dual-species biofilms, and analyzed the protein composition of the biofilms extracellular polymeric matrix (EPM) by high-resolution liquid chromatography-tandem mass spectrometry. Label-free quantitative proteomic analysis was used for identification of proteins and sequence-based functional characterization for their classification and prediction of possible roles in EPM. We identified 542, 93 and 280 proteins in the matrix of F. nucleatum, P. gingivalis, and the dual-species biofilm, respectively. Nearly 70% of all EPM proteins in the dual-species biofilm originated from F. nucleatum, and a majority of these were cytoplasmic proteins, suggesting an enhanced lysis of F. nucleatum cells. The proteomic analysis also indicated an interaction between the two species: 22 F. nucleatum proteins showed differential levels between the mono and dual-species EPMs, and 11 proteins (8 and 3 from F. nucleatum and P. gingivalis, respectively) were exclusively detected in the dual-species EPM. Oxidoreductases and chaperones were among the most abundant proteins identified in all three EPMs. The biofilm matrices in addition contained several known and hypothetical virulence proteins, which can mediate adhesion to the host cells and disintegration of the periodontal tissues. This study demonstrated that the biofilm matrix of two important periodontal pathogens consists of a multitude of proteins whose amounts and functionalities vary largely. Relatively high levels of several of the detected proteins might facilitate their potential use as targets for the inhibition of biofilm development. Copyright © 2017 Elsevier Ltd. All rights reserved.

Extracellular matrix influence in Streptococcus mutans gene expression in a cariogenic biofilm.

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Florez Salamanca, E J; Klein, M I

2018-04-01

Caries etiology is biofilm-diet-dependent. Biofilms are highly dynamic and structured microbial communities enmeshed in a three-dimensional extracellular matrix. The study evaluated the expression dynamics of Streptococcus mutans genes associated with exopolysaccharides (EPS) (gtfBCD, gbpB, dexA), lipoteichoic acids (LTA) (dltABCD, SMU_775c) and extracellular DNA (eDNA) (lytST, lrgAB, ccpA) during matrix development within a mixed-species biofilm of S. mutans, Actinomyces naeslundii and Streptococcus gordonii. Mixed-species biofilms using S. mutans strains UA159 or ΔgtfB formed on saliva-coated hydroxyapatite discs were submitted to a nutritional challenge (providing an abundance of sucrose and starch). Biofilms were removed at eight developmental stages for gene expression analysis by quantitative polymerase chain reaction. The pH of spent culture media remained acidic throughout the experimental periods, being lower after sucrose and starch exposure. All genes were expressed at all biofilm developmental phases. EPS- and LTA-associated genes had a similar expression profile for both biofilms, presenting lower levels of expression at 67, 91 and 115 hours and a peak of expression at 55 hours, but having distinct expression magnitudes, with lower values for ΔgtfB (eg, fold-difference of ~382 for gtfC and ~16 for dltB at 43 hours). The eDNA-associated genes presented different dynamics of expression between both strains. In UA159 biofilms lrgA and lrgB genes were highly expressed at 29 hours (which were ~13 and ~5.4 times vs ΔgtfB, respectively), whereas in ΔgtfB biofilms an inverse relationship between lytS and lrgA and lrgB expression was detected. Therefore, the deletion of gtfB influences dynamics and magnitude of expression of genes associated with matrix main components. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A Rhizobium leguminosarum CHDL- (Cadherin-Like-) Lectin Participates in Assembly and Remodeling of the Biofilm Matrix

DEFF Research Database (Denmark)

Vozza, Nicolás F.; Abdian, Patricia L; Russo, Daniela M

2016-01-01

In natural environments most bacteria live in multicellular structures called biofilms. These cell aggregates are enclosed in a self-produced polymeric extracellular matrix, which protects the cells, provides mechanical stability and mediates cellular cohesion and adhesion to surfaces. Although...... important advances were made in the identification of the genetic and extracellular factors required for biofilm formation, the mechanisms leading to biofilm matrix assembly, and the roles of extracellular proteins in these processes are still poorly understood. The symbiont Rhizobium leguminosarum requires...... the synthesis of the acidic exopolysaccharide and the PrsDE secretion system to develop a mature biofilm. PrsDE is responsible for the secretion of the Rap family of proteins that share one or two Ra/CHDL (cadherin-like-) domains. RapA2 is a calcium-dependent lectin with a cadherin-like β sheet structure...

Polysaccharides serve as scaffold of biofilms formed by mucoid Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Yang, Liang; Hengzhuang, Wang; Wu, Hong

2012-01-01

Chronic lung infection by mucoid Pseudomonas aeruginosa is one of the major pathologic features in patients with cystic fibrosis. Mucoid P. aeruginosa is notorious for its biofilm forming capability and resistance to immune attacks. In this study, the roles of extracellular polymeric substances f...

Pseudomonas aeruginosa extracellular products inhibit staphylococcal growth, and disrupt established biofilms produced by Staphylococcus epidermidis

DEFF Research Database (Denmark)

Qin, Zhiqiang; Yang, Liang; Qu, Di

2009-01-01

Multiple bacterial species often coexist as communities, and compete for environmental resources. Here, we describe how an opportunistic pathogen, Pseudomonas aeruginosa, uses extracellular products to interact with the nosocomial pathogen Staphylococcus epidermidis. S. epidermidis biofilms and p...... of a novel strategy for controlling S. epidermidis biofilms....

Investigation of Aspergillus fumigatus biofilm formation by various omics approaches

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Laetitia eMuszkieta

2013-02-01

Full Text Available In the lung, Aspergillus fumigatus usually forms a dense colony of filaments embedded in a polymeric extracellular matrix called biofilm (BF. This extracellular matrix embeds and glues hyphae together and protects the fungus from an outside hostile environment. This extracellular matrix is absent in fungal colonies grown under classical liquid shake conditions (PL which were historically used to understand A. fumigatus pathobiology. Recent works have shown that the fungus in this aerial grown biofilm-like state exhibits reduced susceptibility to antifungal drugs and undergoes major metabolic changes that are thought to be associated to virulence. These differences in pathological and physiological characteristics between biofilm and liquid shake conditions suggest that the PL condition is a poor in vitro disease model. In the laboratory, A. fumigatus mycelium embedded by the extracellular matrix can be produced in vitro in aerial condition using an agar-based medium. To provide a global and accurate understanding of A. fumigatus in vitro biofilm growth, we utilized microarray, RNA-sequencing and proteomic analysis to compare the global gene and protein expression profiles of A. fumigatus grown under BF and PL conditions. In this review, we will present the different signatures obtained with these three omics methods. We will discuss the advantages and limitations of each method and their complementarity.

Corneal Biofilms: From Planktonic to Microcolony Formation in an Experimental Keratitis Infection with Pseudomonas Aeruginosa.

Science.gov (United States)

Saraswathi, Padmanabhan; Beuerman, Roger W

2015-10-01

Microbial biofilms commonly comprise part of the infectious scenario, complicating the therapeutic approach. The purpose of this study was to determine in a mouse model of corneal infection if mature biofilms formed and to visualize the stages of biofilm formation. A bacterial keratitis model was established using Pseudomonas aeruginosa ATCC 9027 (1 × 10(8) CFU/ml) to infect the cornea of C57BL/6 black mouse. Eyes were examined post-infection (PI) on days 1, 2, 3, 5, and 7, and imaged by slit lamp microscopy, and light, confocal, and electron microscopy to identify the stages of biofilm formation and the time of appearance. On PI day 1, Gram staining showed rod-shaped bacteria adherent on the corneal surface. On PI days 2 and 3, bacteria were seen within webs of extracellular polymeric substance (EPS) and glycocalyx secretion, imaged by confocal microscopy. Scanning electron microscopy demonstrated microcolonies of active infectious cells bound with thick fibrous material. Transmission electron microscopy substantiated the formation of classical biofilm architecture with P. aeruginosa densely packed within the extracellular polymeric substances on PI days 5 and 7. Direct visual evidence showed that biofilms routinely developed on the biotic surface of the mouse cornea. The mouse model can be used to develop new approaches to deal therapeutically with biofilms in corneal infections. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Effect of Extracellular Polymeric Substances on Surface Properties and Attachment Behavior of Acidithiobacillus ferrooxidans

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Qian Li

2016-09-01

Full Text Available Bacterial contact leaching of ores is more effective than non-contact leaching. Adhesion is the first step for leaching bacteria to form a biofilm on a mineral surface. Extracellular polymeric substances (EPS are pivotal for mediating bacterial adhesion to a substratum. In order to clarify the role of EPS, we measured the adhesion forces between chalcopyrite-, sulfur- or FeSO4·7H2O-grown cells of Acidithiobacillus ferrooxidans and chalcopyrite by an atomic force microscope (AFM before and after EPS removal. Surface properties of these cells were assessed by measurements of the contact angle, zeta potential, Fourier transform infrared spectroscopy (FTIR and acid-base titration. Bacterial attachment to chalcopyrite was monitored for 140 min. The results indicate that the EPS control the surface properties of the cells. In addition, the surface properties are decisive for adhesion. The adhesion forces and the amounts of attached cells decreased dramatically after removing EPS, which was not dependent on the preculture.

Bacteriophages as Weapons Against Bacterial Biofilms in the Food Industry.

Science.gov (United States)

Gutiérrez, Diana; Rodríguez-Rubio, Lorena; Martínez, Beatriz; Rodríguez, Ana; García, Pilar

2016-01-01

Microbiological contamination in the food industry is often attributed to the presence of biofilms in processing plants. Bacterial biofilms are complex communities of bacteria attached to a surface and surrounded by an extracellular polymeric material. Their extreme resistance to cleaning and disinfecting processes is related to a unique organization, which implies a differential bacterial growth and gene expression inside the biofilm. The impact of biofilms on health, and the economic consequences, has promoted the development of different approaches to control or remove biofilm formation. Recently, successful results in phage therapy have boosted new research in bacteriophages and phage lytic proteins for biofilm eradication. In this regard, this review examines the environmental factors that determine biofilm development in food-processing equipment. In addition, future perspectives for the use of bacteriophage-derived tools as disinfectants are discussed.

Activation of phagocytic cells by Staphylococcus epidermidis biofilms: effects of extracellular matrix proteins and the bacterial stress protein GroEL on netosis and MRP-14 release.

Science.gov (United States)

Dapunt, Ulrike; Gaida, Matthias M; Meyle, Eva; Prior, Birgit; Hänsch, Gertrud M

2016-07-01

The recognition and phagocytosis of free-swimming (planktonic) bacteria by polymorphonuclear neutrophils have been investigated in depth. However, less is known about the neutrophil response towards bacterial biofilms. Our previous work demonstrated that neutrophils recognize activating entities within the extracellular polymeric substance (EPS) of biofilms (the bacterial heat shock protein GroEL) and that this process does not require opsonization. Aim of this study was to evaluate the release of DNA by neutrophils in response to biofilms, as well as the release of the inflammatory cytokine MRP-14. Neutrophils were stimulated with Staphylococcus epidermidis biofilms, planktonic bacteria, extracted EPS and GroEL. Release of DNA and of MRP-14 was evaluated. Furthermore, tissue samples from patients suffering from biofilm infections were collected and evaluated by histology. MRP-14 concentration in blood samples was measured. We were able to show that biofilms, the EPS and GroEL induce DNA release. MRP-14 was only released after stimulation with EPS, not GroEL. Histology of tissue samples revealed MRP-14 positive cells in association with neutrophil infiltration and MRP-14 concentration was elevated in blood samples of patients suffering from biofilm infections. Our data demonstrate that neutrophil-activating entities are present in the EPS and that GroEL induces DNA release by neutrophils. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biofilms.

Science.gov (United States)

López, Daniel; Vlamakis, Hera; Kolter, Roberto

2010-07-01

The ability to form biofilms is a universal attribute of bacteria. Biofilms are multicellular communities held together by a self-produced extracellular matrix. The mechanisms that different bacteria employ to form biofilms vary, frequently depending on environmental conditions and specific strain attributes. In this review, we emphasize four well-studied model systems to give an overview of how several organisms form biofilms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. Using these bacteria as examples, we discuss the key features of biofilms as well as mechanisms by which extracellular signals trigger biofilm formation.

Susceptibility of Staphylococcus aureus biofilms to reactive discharge gases.

Science.gov (United States)

Traba, Christian; Liang, Jun F

2011-08-01

Formation of bacterial biofilms at solid-liquid interfaces creates numerous problems in both industrial and biomedical sciences. In this study, the susceptibility of Staphylococcus aureus biofilms to discharge gas generated from plasma was tested. It was found that despite distinct chemical/physical properties, discharge gases from oxygen, nitrogen, and argon demonstrated very potent and almost the same anti-biofilm activity. The bacterial cells in S. aureus biofilms were killed (>99.9%) by discharge gas within minutes of exposure. Under optimal experimental conditions, no bacteria and biofilm re-growth from discharge gas treated biofilms was found. Further studies revealed that the anti-biofilm activity of the discharge gas occurred by two distinct mechanisms: (1) killing bacteria in biofilms by causing severe cell membrane damage, and (2) damaging the extracellular polymeric matrix in the architecture of the biofilm to release biofilm from the surface of the solid substratum. Information gathered from this study provides an insight into the anti-biofilm mechanisms of plasma and confirms the applications of discharge gas in the treatment of biofilms and biofilm related bacterial infections.

Antibacterial activity of food-grade chitosan against Vibrio parahaemolyticus biofilms.

Science.gov (United States)

Xie, Ting; Liao, Zhenlin; Lei, Huan; Fang, Xiang; Wang, Jie; Zhong, Qingping

2017-09-01

Biofilm is a community composed of microbes and the extracellular polymeric substances. This special architecture poses a significant public health risk as it increases the fitness of bacteria in harsh conditions and renders bacterial resistance to antimicrobial agents and cleaning. In this study, we investigated the inhibition and eradication effects of chitosan on the biofilm of Vibrio parahaemolyticus, an important food-borne pathogen. The crystal violet staining, [2, 3-bis (2-methoxy-4-nitro-5- sulfophenyl)-2H-tetrazolium-5-carboxanilide] (XTT) reduction method, phenol-sulfuric acid method, fluorescence microscope and confocal laser scanning microscope (CLSM) observation were conducted. The results indicated that the minimum inhibitory concentration (MIC) of chitosan was 1.25 mg/mL. Sub-MIC of chitosan could significantly inhibit biofilm formation, reduce the metabolic activities and the secretion of extracellular polysaccharide (EPS). Moreover, chitosan at 4MIC could eradicate 85.06% mature biofilm of V. parahaemolyticus, and decrease 81.43% EPS in mature biofilm. These results were also confirmed by the visual images obtained from fluorescence microscopy and CLSM. This study elucidated that chitosan was not only effective to prevent biofilm formation, but also eradicate mature biofilms of V. parahaemolyticus. Copyright © 2017. Published by Elsevier Ltd.

Extracellular DNA is essential for maintaining Bordetella biofilm integrity on abiotic surfaces and in the upper respiratory tract of mice.

Directory of Open Access Journals (Sweden)

Matt S Conover

2011-02-01

Full Text Available Bacteria form complex and highly elaborate surface adherent communities known as biofilms which are held together by a self-produced extracellular matrix. We have previously shown that by adopting a biofilm mode of existence in vivo, the gram negative bacterial pathogens Bordetella bronchiseptica and Bordetella pertussis are able to efficiently colonize and persist in the mammalian respiratory tract. In general, the bacterial biofilm matrix includes polysaccharides, proteins and extracellular DNA (eDNA. In this report, we investigated the function of DNA in Bordetella biofilm development. We show that DNA is a significant component of Bordetella biofilm matrix. Addition of DNase I at the initiation of biofilm growth inhibited biofilm formation. Treatment of pre-established mature biofilms formed under both static and flow conditions with DNase I led to a disruption of the biofilm biomass. We next investigated whether eDNA played a role in biofilms formed in the mouse respiratory tract. DNase I treatment of nasal biofilms caused considerable dissolution of the biofilm biomass. In conclusion, these results suggest that eDNA is a crucial structural matrix component of both in vitro and in vivo formed Bordetella biofilms. This is the first evidence for the ability of DNase I to disrupt bacterial biofilms formed on host organs.

Biofilm formation in attached microalgal reactors.

Science.gov (United States)

Shen, Y; Zhu, W; Chen, C; Nie, Y; Lin, X

2016-08-01

The objective of this study was to investigate the fundamental question of biofilm formation. First, a drum biofilm reactor was introduced. The drums were coated with three porous substrates (cotton rope, canvas, and spandex), respectively. The relationships among the substrate, extracellular polymeric substances (EPS), and adhesion ratio were analyzed. Second, a plate biofilm reactor (PBR) was applied by replacing the drum with multiple parallel vertical plates to increase the surface area. The plates were coated with porous substrates on each side, and the nutrients were delivered to the cells by diffusion. The influence of nitrogen source and concentration on compositions of EPS and biofilm formation was analyzed using PBR under sunlight. The results indicated that both substrate and nitrogen were critical on the EPS compositions and biofilm formation. Under the optimal condition (glycine with concentration of 1 g l(-1) and substrate of canvas), the maximum biofilm productivity of 54.46 g m(-2) d(-1) with adhesion ratio of 84.4 % was achieved.

Biofilm extracellular polysaccharides degradation during starvation and enamel demineralization.

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Bárbara Emanoele Costa Oliveira

Full Text Available This study was conducted to evaluate if extracellular polysaccharides (EPS are used by Streptococcus mutans (Sm biofilm during night starvation, contributing to enamel demineralization increasing occurred during daily sugar exposure. Sm biofilms were formed during 5 days on bovine enamel slabs of known surface hardness (SH. The biofilms were exposed to sucrose 10% or glucose + fructose 10.5% (carbohydrates that differ on EPS formation, 8x/day but were maintained in starvation during the night. Biofilm samples were harvested during two moments, on the end of the 4th day and in the morning of the 5th day, conditions of sugar abundance and starvation, respectively. The slabs were also collected to evaluate the percentage of surface hardness loss (%SHL. The biofilms were analyzed for EPS soluble and insoluble and intracellular polysaccharides (IPS, viable bacteria (CFU, biofilm architecture and biomass. pH, calcium and acid concentration were determined in the culture medium. The data were analyzed by two-way ANOVA followed by Tukey's test or Student's t-test. The effect of the factor carbohydrate treatment for polysaccharide analysis was significant (p 0.05. Larger amounts of soluble and insoluble EPS and IPS were formed in the sucrose group when compared to glucose + fructose group (p < 0.05, but they were not metabolized during starvation time (S-EPS, p = 0.93; I-EPS, p = 0.11; and IPS = 0.96. Greater enamel %SHL was also found for the sucrose group (p < 0.05 but the demineralization did not increase during starvation (p = 0.09. In conclusion, the findings suggest that EPS metabolization by S. mutans during night starvation do not contribute to increase enamel demineralization occurred during the daily abundance of sugar.

Bacterial biofilm and associated infections

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Muhsin Jamal

2018-01-01

Full Text Available Microscopic entities, microorganisms that drastically affect human health need to be thoroughly investigated. A biofilm is an architectural colony of microorganisms, within a matrix of extracellular polymeric substance that they produce. Biofilm contains microbial cells adherent to one-another and to a static surface (living or non-living. Bacterial biofilms are usually pathogenic in nature and can cause nosocomial infections. The National Institutes of Health (NIH revealed that among all microbial and chronic infections, 65% and 80%, respectively, are associated with biofilm formation. The process of biofilm formation consists of many steps, starting with attachment to a living or non-living surface that will lead to formation of micro-colony, giving rise to three-dimensional structures and ending up, after maturation, with detachment. During formation of biofilm several species of bacteria communicate with one another, employing quorum sensing. In general, bacterial biofilms show resistance against human immune system, as well as against antibiotics. Health related concerns speak loud due to the biofilm potential to cause diseases, utilizing both device-related and non-device-related infections. In summary, the understanding of bacterial biofilm is important to manage and/or to eradicate biofilm-related diseases. The current review is, therefore, an effort to encompass the current concepts in biofilm formation and its implications in human health and disease.

Implications of Extracellular Polymeric Substance Matrices of Microbial Habitats Associated with Coastal Aquaculture Systems

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Juan Carlos Camacho-Chab

2016-08-01

Full Text Available Coastal zones support fisheries that provide food for humans and feed for animals. The decline of fisheries worldwide has fostered the development of aquaculture. Recent research has shown that extracellular polymeric substances (EPS synthesized by microorganisms contribute to sustainable aquaculture production, providing feed to the cultured species, removing waste and contributing to the hygiene of closed systems. As ubiquitous components of coastal microbial habitats at the air–seawater and seawater–sediment interfaces as well as of biofilms and microbial aggregates, EPS mediate deleterious processes that affect the performance and productivity of aquaculture facilities, including biofouling of marine cages, bioaccumulation and transport of pollutants. These biomolecules may also contribute to the persistence of harmful algal blooms (HABs and their impact on cultured species. EPS may also exert a positive influence on aquaculture activity by enhancing the settling of aquaculturally valuable larvae and treating wastes in bioflocculation processes. EPS display properties that may have biotechnological applications in the aquaculture industry as antiviral agents and immunostimulants and as a novel source of antifouling bioproducts.

Release of Extracellular Polymeric Substance and Disintegration of Anaerobic Granular Sludge under Reduced Sulfur Compounds-Rich Conditions

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Takuro Kobayashi

2015-07-01

Full Text Available The effect of reduced form of sulfur compounds on granular sludge was investigated. Significant release of extracellular polymeric substance (EPS from the granular sludge occurred in the presence of sulfide and methanethiol according to various concentrations. Granular sludge also showed a rapid increase in turbidity and decrease in diameter in accordance with sulfide concentration during the long-term shaking, suggesting that the strength of the granules was reduced with high-concentration sulfide. A continuous experiment of up-flow anaerobic sludge blanket reactors with different concentrations of sulfide (10, 200, 500 mg-S/L influence demonstrated that the reactor fed with higher concentration of sulfide allowed more washout of small particle-suspended solid (SS content and soluble carbohydrate and protein, which were considered as EPS released from biofilm. Finally, the presence of sulfide negatively affected methane production, chemical oxygen demand removal and sludge retention in operational performance.

Phosphoenolpyruvate phosphotransferase system components positively regulate Klebsiella biofilm formation

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Yu-Tze Horng

2018-04-01

Full Text Available Background/Purpose: Klebsiella pneumoniae is one of the leading causes of device-related infections (DRIs, which are associated with attachment of bacteria to these devices to form a biofilm. The latter is composed of not only bacteria but also extracellular polymeric substances (EPSes consisting of extracellular DNAs, polysaccharides, and other macromolecules. The phosphoenolpyruvate (PEP:carbohydrate phosphotransferase system (PTS regulates diverse processes of bacterial physiology. In the genome of K. pneumoniae MGH 78578, we found an uncharacterized enzyme II complex homolog of PTS: KPN00353 (EIIA homolog, KPN00352 (EIIB homolog, and KPN00351 (EIIC homolog. The aim of this study was to characterize the potential physiological role of KPN00353, KPN00352, and KPN00351 in biofilm formation by K. pneumoniae. Methods/Results: We constructed the PTS mutants and recombinant strains carrying the gene(s of PTS. The recombinant K. pneumoniae strain overexpressing KPN00353–KPN00352–KPN00351 produced more extracellular matrix than did the vector control according to transmission and scanning electron microscopy. Judging by quantification of biofilm formation, of extracellular DNA (eDNA, and of capsular polysaccharide, the recombinant strain overexpressing KPN00353-KPN00352-KPN00351 produced more biofilm and capsular polysaccharide after overnight culture and more eDNA in the log phase as compared to the vector control. Conclusion: The genes, KPN00353–KPN00352–KPN00351, encode a putative enzyme II complex in PTS and positively regulate biofilm formation by enhancing production of eDNA and capsular polysaccharide in K. pneumoniae. Five proteins related to chaperones, to the citric acid cycle, and to quorum sensing are upregulated by the KPN00353–KPN00352–KPN00351 system. Keywords: Klebsiella, PTS, Biofilm, eDNA, Polysaccharide

Isolation, characterization and localization of extracellular polymeric substances from the cyanobacterium

NARCIS (Netherlands)

Ahmed, M.; Wijnholds, A.; Stal, L.J.; Hasnain, S.

2014-01-01

Arthrospira platensis is a cyanobacterium known for its nutritional value and secondary metabolites. Extracellular polymeric substances (EPS) are an important trait of most cyanobacteria, including A. platensis. Here, we extracted and analysed different fractions of EPS from a locally isolated

Antibiofilm Effect of DNase against Single and Mixed Species Biofilm

Science.gov (United States)

Sharma, Komal

2018-01-01

Biofilms are aggregates of microorganisms that coexist in socially coordinated micro-niche in a self-produced polymeric matrix on pre-conditioned surfaces. The biofilm matrix reduces the efficacy of antibiofilm strategies. DNase degrades the extracellular DNA (e-DNA) present in the matrix, rendering the matrix weak and susceptible to antimicrobials. In the current study, the effect of DNase I was evaluated during biofilm formation (pre-treatment), on preformed biofilms (post-treatment) and both (dual treatment). The DNase I pre-treatment was optimized for P. aeruginosa PAO1 (model biofilm organism) at 10 µg/mL and post-treatment at 10 µg/mL with 15 min of contact duration. Inclusion of Mg2+ alongside DNase I post-treatment resulted in 90% reduction in biofilm within only 5 min of contact time (irrespective of age of biofilm). On extension of these findings, DNase I was found to be less effective against mixed species biofilm than individual biofilms. DNase I can be used as potent antibiofilm agent and with further optimization can be effectively used for biofilm prevention and reduction in situ. PMID:29562719

Effects of substrates on biofilm formation observed by atomic force microscopy

International Nuclear Information System (INIS)

Oh, Y.J.; Lee, N.R.; Jo, W.; Jung, W.K.; Lim, J.S.

2009-01-01

Formation of biofilm is known to be strongly dependent on substrates including topography, materials, and chemical treatment. In this study, a variety of substrates are tested for understanding biofilm formation. Sheets of aluminum, steel, rubber, and polypropylene have been used to examine their effects on formation of Pseudomonas aeruginosa biofilm. In particular, the morphological variation, transition, and adhesiveness of biofilm were investigated through local measurement by atomic force microscopy (AFM). Mechanism of removing biofilm from adhering to substrate is also analyzed, thus the understanding of the mechanism can be potentially useful to prevent the biofilm formation. The results reveal that formation of biofilm can remain on rough surface regardless of substrates in hot water, which may easily induce extra-polymeric substances detachment from bacterial surface. By probing using AFM, local force-distance characterization of extra-cellular materials extracted from the bacteria can exhibit the progress of the biofilm formation and functional complexities.

Nanowire arrays as cell force sensors to investigate adhesin-enhanced holdfast of single cell bacteria and biofilm stability

NARCIS (Netherlands)

Sahoo, P.K.; Janissen, R.; Monteiro, M.P.; Cavalli, A.; Murillo, D.M.; Merfa, M.V.; Cesar, C.L.; Carvalho, H.F.; de Souza, A.A.; Bakkers, E.P.A.M.; Cotta, M.A.

2016-01-01

Surface attachment of a planktonic bacteria, mediated by adhesins and extracellular polymeric substances (EPS), is a crucial step for biofilm formation. Some pathogens can modulate cell adhesiveness, impacting host colonization and virulence. A framework able to quantify cell-surface interaction

Inhibition of Streptococcus mutans biofilm formation, extracellular polysaccharide production, and virulence by an oxazole derivative.

Science.gov (United States)

Chen, Lulu; Ren, Zhi; Zhou, Xuedong; Zeng, Jumei; Zou, Jing; Li, Yuqing

2016-01-01

Dental caries, a biofilm-related oral disease, is a result of disruption of the microbial ecological balance in the oral environment. Streptococcus mutans, which is one of the primary cariogenic bacteria, produces glucosyltransferases (Gtfs) that synthesize extracellular polysaccharides (EPSs). The EPSs, especially water-insoluble glucans, contribute to the formation of dental plaque, biofilm stability, and structural integrity, by allowing bacteria to adhere to tooth surfaces and supplying the bacteria with protection against noxious stimuli and other environmental attacks. The identification of novel alternatives that selectively inhibit cariogenic organisms without suppressing oral microbial residents is required. The goal of the current study is to investigate the influence of an oxazole derivative on S. mutans biofilm formation and the development of dental caries in rats, given that oxazole and its derivatives often exhibit extensive and pharmacologically important biological activities. Our data shows that one particular oxazole derivative, named 5H6, inhibited the formation of S. mutans biofilms and prevented synthesis of extracellular polysaccharides by antagonizing Gtfs in vitro, without affecting the growth of the bacteria. In addition, topical applications with the inhibitor resulted in diminished incidence and severity of both smooth and sulcal surface caries in vivo with a lower percentage of S. mutans in the animals' dental plaque compared to the control group (P mutans.

Withania somnifera attenuates acid production, acid tolerance and extra-cellular polysaccharide formation of Streptococcus mutans biofilms.

Science.gov (United States)

Pandit, Santosh; Song, Kwang-Yeob; Jeon, Jae-Gyu

2014-01-01

Withania somnifera (Ashwagandha) is a plant of the Solanaceae family. It has been widely used as a remedy for a variety of ailments in India and Nepal. The plant has also been used as a controlling agent for dental diseases. The aim of the present study was to evaluate the activity of the methanol extract of W. somnifera against the physiological ability of cariogenic biofilms and to identify the components of the extract. To determine the activity of the extract, assays for sucrose-dependent bacterial adherence, glycolytic acid production, acid tolerance, and extracellular polysaccharide formation were performed using Streptococcus mutans biofilms. The viability change of S. mutans biofilms cells was also determined. A phytochemical analysis of the extract was performed using TLC and LC/MS/MS. The extract showed inhibitory effects on sucrose-dependent bacterial adherence (≥ 100 μg/ml), glycolytic acid production (≥ 300 μg/ml), acid tolerance (≥ 300 μg/ml), and extracellular polysaccharide formation (≥ 300 μg/ml) of S. mutans biofilms. However, the extract did not alter the viability of S. mutans biofilms cells in all concentrations tested. Based on the phytochemical analysis, the activity of the extract may be related to the presence of alkaloids, anthrones, coumarines, anthraquinones, terpenoids, flavonoids, and steroid lactones (withanolide A, withaferin A, withanolide B, withanoside IV, and 12-deoxy withastramonolide). These data indicate that W. somnifera may be a potential agent for restraining the physiological ability of cariogenic biofilms.

Characterization of Extracellular Polymeric Substances Produced by Pseudomonas fragi Under Air and Modified Atmosphere Packaging.

Science.gov (United States)

Wang, Guang-Yu; Ma, Fang; Wang, Hu-Hu; Xu, Xing-Lian; Zhou, Guang-Hong

2017-09-01

Extracellular polymeric substances (EPS) play an important role in bacterial biochemical properties. The characteristics of EPS from 2 strains of Pseudomonas fragi cultured in meat aerobically (control) and in modified atmosphere packaging (MAP) were studied. The amount and components of EPS, the surface properties, and the effect on biofilm formation of several spoilage organisms were evaluated. The results showed that MAP inhibited the growth of the P. fragi strains. Compared with the control, more loose and less bound EPS (containing protein and carbohydrate) were produced by P. fragi in MAP samples. MAP also caused increased cell autoaggregation and surface hydrophobicity. After the removal of the EPS, the surface property changes were strain-dependent, suggesting that membrane compositions were also changed. In addition, the EPS displayed significant antibiofilm activity on Pseudomonas fluorescens and Serratia liquefaciens. In conclusion, P. fragi strains not only modified the amount, components, and surface properties of EPS but also changed the cell membrane compositions to adapt to MAP stress. Moreover, EPS may play an important role in microbial community competitions. © 2017 Institute of Food Technologists®.

Influence of extracellular polymeric substances (EPS) on Cd adsorption by bacteria

Energy Technology Data Exchange (ETDEWEB)

Wei Xing [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Fang Linchuan [Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Cai Peng, E-mail: cp@mail.hzau.edu.cn [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Huang Qiaoyun [State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070 (China); Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China); Chen Hao [College of Science, Huazhong Agricultural University, Wuhan 430070 (China); Liang Wei; Rong, Xinming [Key Laboratory of Subtropical Agricultural Resources and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070 (China)

2011-05-15

The role of extracellular polymeric substances (EPS) in Cd adsorption by Bacillus subtilis and Pseudomonas putida was investigated using a combination of batch adsorption experiments, potentiometric titrations, Fourier transform infrared spectroscopy (FTIR). An increased adsorption capacity of Cd was observed for untreated bacteria relative to that for EPS-free bacteria. Surface complexation modeling of titration data showed the similar pK{sub a} values of functional groups (carboxyl, phosphate and hydroxyl) between untreated and EPS-free bacteria. However, site concentrations on the untreated bacteria were found to be higher than those on the EPS-free bacteria. FTIR spectra also showed that no significant difference in peak positions was observed between untreated and EPS-free bacteria and carboxyl and phosphate groups were responsible for Cd adsorption on bacterial cells. The information obtained in this study is of fundamental significance for understanding the interaction mechanisms between heavy metals and biofilms in natural environments. - Highlights: > The presence of EPS on bacterial surfaces facilitates the adsorption of Cd. > The promoting effects on Cd adsorption are more remarkable on Gram-positive B. subtilis cells than that on Gram-negative P. putida cells. > Carboxyl and phosphate groups are mostly responsible for Cd binding on untreated and EPS-free cells. > Intact bacterial cells and EPS-free cells have similar binding mechanisms for Cd. - Intact bacterial cells and EPS-free cells have similar binding mechanisms for Cd.

Characterization of Mechanical Properties of Microbial Biofilms

Science.gov (United States)

Callison, Elizabeth; Gose, James; Perlin, Marc; Ceccio, Steven

2017-11-01

The physical properties of microbial biofilms grown subject to shear flows determine the form and mechanical characteristics of the biofilm structure, and consequently, the turbulent interactions over and through the biofilm. These biofilms - sometimes referred to as slime - are comprised of microbial cells and extracellular polymeric substance (EPS) matrices that surround the multicellular communities. Some of the EPSs take the form of streamers that tend to oscillate in flows, causing increased turbulent mixing and drag. As the presence of EPS governs the compliance and overall stability of the filamentous streamers, investigation of the mechanical properties of biofilms may also inform efforts to understand hydrodynamic performance of fouled systems. In this study, a mixture of four diatom genera was grown under turbulent shear flow on test panels. The mechanical properties and hydrodynamic performance of the biofilm were investigated using rheology and turbulent flow studies in the Skin-Friction Flow Facility at the University of Michigan. The diatoms in the mixture of algae were identified, and the elastic and viscous moduli were determined from small-amplitude oscillations, while a creep test was used to evaluate the biofilm compliance.

SANITATION PROCESS OPTIMALIZATION IN RELATION TO THE MICROBIAL BIOFILM OF PSEUDOMONAS FLUORESCENS

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Vladimír Vietoris

2012-02-01

Full Text Available Biofilms have been of considerable interest in the context of food hygiene. Extracellular polymeric substances play an important role in the attachment and colonization of microorganisms to food-contact surfaces. If the microorganisms from food-contact surfaces are not completely removed, they may lead to biofilm formation and also increase the biotransfer potential. The experimental part was focused on the adhesion of bacterial cells under static conditions and testing the effectiveness of disinfectants on created biofilm. In laboratory conditions we prepared and formed the bacterial biofilms Pseudomonas fluorescens in the test surfaces of stainless steel. Over the 72 hours and the next 72 hours were observed numbers of adhesion bacterial cells of Pseudomonas fluorescens on solid surfaces of tested materials.

Mini-review: Biofilm responses to oxidative stress.

Science.gov (United States)

Gambino, Michela; Cappitelli, Francesca

2016-01-01

Biofilms constitute the predominant microbial style of life in natural and engineered ecosystems. Facing harsh environmental conditions, microorganisms accumulate reactive oxygen species (ROS), potentially encountering a dangerous condition called oxidative stress. While high levels of oxidative stress are toxic, low levels act as a cue, triggering bacteria to activate effective scavenging mechanisms or to shift metabolic pathways. Although a complex and fragmentary picture results from current knowledge of the pathways activated in response to oxidative stress, three main responses are shown to be central: the existence of common regulators, the production of extracellular polymeric substances, and biofilm heterogeneity. An investigation into the mechanisms activated by biofilms in response to different oxidative stress levels could have important consequences from ecological and economic points of view, and could be exploited to propose alternative strategies to control microbial virulence and deterioration.

Identification of anti-biofilm components in Withania somnifera and their effect on virulence of Streptococcus mutans biofilms.

Science.gov (United States)

Pandit, S; Cai, J N; Song, K Y; Jeon, J G

2015-08-01

The aim of this study was to identify components of the Withania somnifera that could show anti-virulence activity against Streptococcus mutans biofilms. The anti-acidogenic activity of fractions separated from W. somnifera was compared, and then the most active anti-acidogenic fraction was chemically characterized using gas chromatography-mass spectroscopy. The effect of the identified components on the acidogenicity, aciduricity and extracellular polymeric substances (EPS) formation of S. mutans UA159 biofilms was evaluated. The change in accumulation and acidogenicity of S. mutans UA159 biofilms by periodic treatments (10 min per treatment) with the identified components was also investigated. Of the fractions, n-hexane fraction showed the strongest anti-acidogenic activity and was mainly composed of palmitic, linoleic and oleic acids. Of the identified components, linoleic and oleic acids strongly affected the acid production rate, F-ATPase activity and EPS formation of the biofilms. Periodic treatment with linoleic and oleic acids during biofilm formation also inhibited the biofilm accumulation and acid production rate of the biofilms without killing the biofilm bacteria. These results suggest that linoleic and oleic acids may be effective agents for restraining virulence of S. mutans biofilms. Linoleic and oleic acids may be promising agents for controlling virulence of cariogenic biofilms and subsequent dental caries formation. © 2015 The Society for Applied Microbiology.

Chemical Analysis of Cellular and Extracellular Carbohydrates of a Biofilm-Forming Strain Pseudomonas aeruginosa PA14

Science.gov (United States)

Coulon, Charlène; Vinogradov, Evgeny; Filloux, Alain; Sadovskaya, Irina

2010-01-01

Background Pseudomonas aeruginosa is a Gram-negative bacterium and an opportunistic pathogen, which causes persisting life-threatening infections in cystic fibrosis (CF) patients. Biofilm mode of growth facilitates its survival in a variety of environments. Most P. aeruginosa isolates, including the non-mucoid laboratory strain PA14, are able to form a thick pellicle, which results in a surface-associated biofilm at the air-liquid (A–L) interface in standing liquid cultures. Exopolysaccharides (EPS) are considered as key components in the formation of this biofilm pellicle. In the non-mucoid P. aeruginosa strain PA14, the “scaffolding” polysaccharides of the biofilm matrix, and the molecules responsible for the structural integrity of rigid A–L biofilm have not been identified. Moreover, the role of LPS in this process is unclear, and the chemical structure of the LPS O-antigen of PA14 has not yet been elucidated. Principal Findings In the present work we carried out a systematic analysis of cellular and extracellular (EC) carbohydrates of P. aeruginosa PA14. We also elucidated the chemical structure of the LPS O-antigen by chemical methods and 2-D NMR spectroscopy. Our results showed that it is composed of linear trisaccharide repeating units, identical to those described for P. aeruginosa Lanýi type O:2a,c (Lanýi-Bergman O-serogroup 10a, 10c; IATS serotype 19) and having the following structure: -4)-α-L-GalNAcA-(1–3)-α-D-QuiNAc-(1–3)- α-L-Rha-(1-. Furthermore, an EC O-antigen polysaccharide (EC O-PS) and the glycerol-phosphorylated cyclic β-(1,3)-glucans were identified in the culture supernatant of PA14, grown statically in minimal medium. Finally, the extracellular matrix of the thick biofilm formed at the A-L interface contained, in addition to eDNA, important quantities (at least ∼20% of dry weight) of LPS-like material. Conclusions We characterized the chemical structure of the LPS O-antigen and showed that the O-antigen polysaccharide is

Characterization of biofilm formation by Borrelia burgdorferi in vitro.

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Eva Sapi

Full Text Available Borrelia burgdorferi, the causative agent of Lyme disease, has long been known to be capable of forming aggregates and colonies. It was recently demonstrated that Borrelia burgdorferi aggregate formation dramatically changes the in vitro response to hostile environments by this pathogen. In this study, we investigated the hypothesis that these aggregates are indeed biofilms, structures whose resistance to unfavorable conditions are well documented. We studied Borrelia burgdorferi for several known hallmark features of biofilm, including structural rearrangements in the aggregates, variations in development on various substrate matrices and secretion of a protective extracellular polymeric substance (EPS matrix using several modes of microscopic, cell and molecular biology techniques. The atomic force microscopic results provided evidence that multilevel rearrangements take place at different stages of aggregate development, producing a complex, continuously rearranging structure. Our results also demonstrated that Borrelia burgdorferi is capable of developing aggregates on different abiotic and biotic substrates, and is also capable of forming floating aggregates. Analyzing the extracellular substance of the aggregates for potential exopolysaccharides revealed the existence of both sulfated and non-sulfated/carboxylated substrates, predominately composed of an alginate with calcium and extracellular DNA present. In summary, we have found substantial evidence that Borrelia burgdorferi is capable of forming biofilm in vitro. Biofilm formation by Borrelia species might play an important role in their survival in diverse environmental conditions by providing refuge to individual cells.

Pel is a cationic exopolysaccharide that cross-links extracellular DNA in the Pseudomonas aeruginosa biofilm matrix.

Science.gov (United States)

Jennings, Laura K; Storek, Kelly M; Ledvina, Hannah E; Coulon, Charlène; Marmont, Lindsey S; Sadovskaya, Irina; Secor, Patrick R; Tseng, Boo Shan; Scian, Michele; Filloux, Alain; Wozniak, Daniel J; Howell, P Lynne; Parsek, Matthew R

2015-09-08

Biofilm formation is a complex, ordered process. In the opportunistic pathogen Pseudomonas aeruginosa, Psl and Pel exopolysaccharides and extracellular DNA (eDNA) serve as structural components of the biofilm matrix. Despite intensive study, Pel's chemical structure and spatial localization within mature biofilms remain unknown. Using specialized carbohydrate chemical analyses, we unexpectedly found that Pel is a positively charged exopolysaccharide composed of partially acetylated 1→4 glycosidic linkages of N-acetylgalactosamine and N-acetylglucosamine. Guided by the knowledge of Pel's sugar composition, we developed a tool for the direct visualization of Pel in biofilms by combining Pel-specific Wisteria floribunda lectin staining with confocal microscopy. The results indicate that Pel cross-links eDNA in the biofilm stalk via ionic interactions. Our data demonstrate that the cationic charge of Pel is distinct from that of other known P. aeruginosa exopolysaccharides and is instrumental in its ability to interact with other key biofilm matrix components.

Application of biofilm bioreactors in white biotechnology.

Science.gov (United States)

Muffler, K; Lakatos, M; Schlegel, C; Strieth, D; Kuhne, S; Ulber, R

2014-01-01

The production of valuable compounds in industrial biotechnology is commonly done by cultivation of suspended cells or use of (immobilized) enzymes rather than using microorganisms in an immobilized state. Within the field of wastewater as well as odor treatment the application of immobilized cells is a proven technique. The cells are entrapped in a matrix of extracellular polymeric compounds produced by themselves. The surface-associated agglomerate of encapsulated cells is termed biofilm. In comparison to common immobilization techniques, toxic effects of compounds used for cell entrapment may be neglected. Although the economic impact of biofilm processes used for the production of valuable compounds is negligible, many prospective approaches were examined in the laboratory and on a pilot scale. This review gives an overview of biofilm reactors applied to the production of valuable compounds. Moreover, the characteristics of the utilized materials are discussed with respect to support of surface-attached microbial growth.

Continuous Drip Flow System to Develop Biofilm of E. faecalis under Anaerobic Conditions

Directory of Open Access Journals (Sweden)

Ana Maria Gonzalez

2014-01-01

Full Text Available Purpose. To evaluate a structurally mature E. faecalis biofilm developed under anaerobic/dynamic conditions in an in vitro system. Methods. An experimental device was developed using a continuous drip flow system designed to develop biofilm under anaerobic conditions. The inoculum was replaced every 24 hours with a fresh growth medium for up to 10 days to feed the system. Gram staining was done every 24 hours to control the microorganism purity. Biofilms developed under the system were evaluated under the scanning electron microscope (SEM. Results. SEM micrographs demonstrated mushroom-shaped structures, corresponding to a mature E. faecalis biofilm. In the mature biofilm bacterial cells are totally encased in a polymeric extracellular matrix. Conclusions. The proposed in vitro system model provides an additional useful tool to study the biofilm concept in endodontic microbiology, allowing for a better understanding of persistent root canal infections.

A genomic region involved in the formation of adhesin fibers in Bacillus cereus biofilms

Directory of Open Access Journals (Sweden)

Joaquín eCaro-Astorga

2015-01-01

Full Text Available Bacillus cereus is a bacterial pathogen that is responsible for many recurrent disease outbreaks due to food contamination. Spores and biofilms are considered the most important reservoirs of B. cereus in contaminated fresh vegetables and fruits. Biofilms are bacterial communities that are difficult to eradicate from biotic and abiotic surfaces because of their stable and extremely strong extracellular matrix. These extracellular matrixes contain exopolysaccharides, proteins, extracellular DNA, and other minor components. Although B. cereus can form biofilms, the bacterial features governing assembly of the protective extracellular matrix are not known. Using the well-studied bacterium B. subtilis as a model, we identified two genomic loci in B. cereus, which encodes two orthologs of the amyloid-like protein TasA of B. subtilis and a SipW signal peptidase. Deletion of this genomic region in B. cereus inhibited biofilm assembly; notably, mutation of the putative signal peptidase SipW caused the same phenotype. However, mutations in tasA or calY did not completely prevent biofilm formation; strains that were mutated for either of these genes formed phenotypically different surface attached biofilms. Electron microscopy studies revealed that TasA polymerizes to form long and abundant fibers on cell surfaces, whereas CalY does not aggregate similarly. Heterologous expression of this amyloid-like cassette in a B. subtilis strain lacking the factors required for the assembly of TasA amyloid-like fibers revealed i the involvement of this B. cereus genomic region in formation of the air-liquid interphase pellicles and ii the intrinsic ability of TasA to form fibers similar to the amyloid-like fibers produced by its B. subtilis ortholog.

Microbial pathogenesis and biofilm development

DEFF Research Database (Denmark)

Reisner, A.; Høiby, N.; Tolker-Nielsen, Tim

2004-01-01

been termed 'maturation', which is thought to be mediated by a differentiation process. Maturation into late stages of biofilm development resulting in stable and robust structures may require the formation of a matrix of extracellular polymeric substances (EPS), which are most often assumed to consist...... a highly significant role in connection with chronic infections [1]. Bacterial growth on surfaces depends on several factors [2]. In nature, surfaces are probably often conditioned with a thin film of organic molecules, which may serve as attractants for bacterial chemotactic systems and which subsequently...... permit bacterial growth to occur. In laboratory model systems the growth of the surface-associated bacteria is supported by the nutrient supply in the moving or standing liquid. A benchmark of biofilm formation by several organisms in vitro is the development of three-dimensional structures that have...

Extracellular dextran and DNA affect the formation of Enterococcus faecalis biofilms and their susceptibility to 2% chlorhexidine.

Science.gov (United States)

Li, Weilan; Liu, Hongyan; Xu, Qiong

2012-07-01

Enterococcus faecalis is frequently recovered from root-filled teeth with refractory apical periodontitis. The ability of E. faecalis to form a matrix-encased biofilm contributes to its pathogenicity; however, the role of extracellular dextran and DNA in biofilm formation and its effect on the susceptibility of the biofilm to chlorhexidine remains poorly understood. E. faecalis biofilms were incubated on dentin blocks. The effect of a dextran-degrading enzyme (dextranase) and DNase I on the adhesion of E. faecalis to dentin was measured using the colony-forming unit (CFU) counting method. CFU assays and confocal laser scanning microscopy were used to investigate the influence of dextranase and DNase I on the antimicrobial activity of 2% chlorhexidine. The CFU count assays indicated that the formation of biofilms by E. faecalis was reduced in cells treated with dextranase or DNase I compared with that in untreated cells (P biofilms with dextranase or DNase I effectively sensitized the biofilms to 2% chlorhexidine (P biofilms to 2% chlorhexidine. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

International Nuclear Information System (INIS)

Zrelli, K; Galy, O; Henry, N; Latour-Lambert, P; Ghigo, J M; Beloin, C; Kirwan, L

2013-01-01

Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms. (paper)

Bacterial biofilm mechanical properties persist upon antibiotic treatment and survive cell death

Science.gov (United States)

Zrelli, K.; Galy, O.; Latour-Lambert, P.; Kirwan, L.; Ghigo, J. M.; Beloin, C.; Henry, N.

2013-12-01

Bacteria living on surfaces form heterogeneous three-dimensional consortia known as biofilms, where they exhibit many specific properties one of which is an increased tolerance to antibiotics. Biofilms are maintained by a polymeric network and display physical properties similar to that of complex fluids. In this work, we address the question of the impact of antibiotic treatment on the physical properties of biofilms based on recently developed tools enabling the in situ mapping of biofilm local mechanical properties at the micron scale. This approach takes into account the material heterogeneity and reveals the spatial distribution of all the small changes that may occur in the structure. With an Escherichia coli biofilm, we demonstrate using in situ fluorescent labeling that the two antibiotics ofloxacin and ticarcillin—targeting DNA replication and membrane assembly, respectively—induced no detectable alteration of the biofilm mechanical properties while they killed the vast majority of the cells. In parallel, we show that a proteolytic enzyme that cleaves extracellular proteins into short peptides, but does not alter bacterial viability in the biofilm, clearly affects the mechanical properties of the biofilm structure, inducing a significant increase of the material compliance. We conclude that conventional biofilm control strategy relying on the use of biocides targeting cells is missing a key target since biofilm structural integrity is preserved. This is expected to efficiently promote biofilm resilience, especially in the presence of persister cells. In contrast, the targeting of polymer network cross-links—among which extracellular proteins emerge as major players—offers a promising route for the development of rational multi-target strategies to fight against biofilms.

Roles of Extracellular Polysaccharides and Biofilm Formation in Heavy Metal Resistance of Rhizobia

OpenAIRE

Natalia Nocelli; Pablo C. Bogino; Erika Banchio; Walter Giordano

2016-01-01

Bacterial surface components and extracellular compounds, particularly flagella, lipopolysaccharides (LPSs), and exopolysaccharides (EPSs), in combination with environmental signals and quorum-sensing signals, play crucial roles in bacterial autoaggregation, biofilm development, survival, and host colonization. The nitrogen-fixing species Sinorhizobium meliloti (S. meliloti) produces two symbiosis-promoting EPSs: succinoglycan (or EPS I) and galactoglucan (or EPS II). Studies of the S. melilo...

Haemophilus parainfluenzae Strain ATCC 33392 Forms Biofilms In Vitro and during Experimental Otitis Media Infections.

Science.gov (United States)

Pang, Bing; Swords, W Edward

2017-09-01

Haemophilus parainfluenzae is a nutritionally fastidious, Gram-negative bacterium with an oropharyngeal/nasopharyngeal carriage niche that is associated with a range of opportunistic infections, including infectious endocarditis and otitis media (OM). These infections are often chronic/recurrent in nature and typically involve bacterial persistence within biofilm communities that are highly resistant to host clearance. This study addresses the primary hypothesis that H. parainfluenzae forms biofilm communities that are important determinants of persistence in vivo The results from in vitro biofilm studies confirmed that H. parainfluenzae formed biofilm communities within which the polymeric matrix was mainly composed of extracellular DNA and proteins. Using a chinchilla OM infection model, we demonstrated that H. parainfluenzae formed surface-associated biofilm communities containing bacterial and host components that included neutrophil extracellular trap (NET) structures and that the bacteria mainly persisted in these biofilm communities. We also used this model to examine the possible interaction between H. parainfluenzae and its close relative Haemophilus influenzae , which is also commonly carried within the same host environments and can cause OM. The results showed that coinfection with H. influenzae promoted clearance of H. parainfluenzae from biofilm communities during OM infection. The underlying mechanisms for bacterial persistence and biofilm formation by H. parainfluenzae and knowledge about the survival defects of H. parainfluenzae during coinfection with H. influenzae are topics for future work. Copyright © 2017 American Society for Microbiology.

Iron Triggers λSo Prophage Induction and Release of Extracellular DNA in Shewanella oneidensis MR-1 Biofilms

OpenAIRE

Binnenkade, Lucas; Teichmann, Laura; Thormann, Kai M.

2014-01-01

Prophages are ubiquitous elements within bacterial chromosomes and affect host physiology and ecology in multiple ways. We have previously demonstrated that phage-induced lysis is required for extracellular DNA (eDNA) release and normal biofilm formation in Shewanella oneidensis MR-1. Here, we investigated the regulatory mechanisms of prophage λSo spatiotemporal induction in biofilms. To this end, we used a functional fluorescence fusion to monitor λSo activation in various mutant backgrounds...

Extracellular DNA Contributes to Dental Biofilm Stability

DEFF Research Database (Denmark)

Schlafer, Sebastian; Meyer, Rikke Louise; Dige, Irene

2017-01-01

dental biofilms. This study aimed to determine whether eDNA was part of the matrix in biofilms grown in situ in the absence of sucrose and whether treatment with DNase dispersed biofilms grown for 2.5, 5, 7.5, 16.5, or 24 h. Three hundred biofilms from 10 study participants were collected and treated...... the amount of biofilm in very early stages of growth (up to 7.5 h), but the treatment effect decreased with increasing biofilm age. This study proves the involvement of eDNA in dental biofilm formation and its importance for biofilm stability in the earliest stages. Further research is required to uncover...

Effect of secondary metabolite of Actinidia deliciosa on the biofilm and extra-cellular matrix components of Acinetobacter baumannii.

Science.gov (United States)

Tiwari, Vishvanath; Tiwari, Deepika; Patel, Varsha; Tiwari, Monalisa

2017-09-01

Acinetobacter baumannii, opportunistic nosocomial pathogen, increases gradually in the clinical setup. The high level of resistance mechanisms acquired by these bacteria makes their eradication difficult and biofilm formation is one of them. Biofilm comprises of closely packed bacterial population crowded together by extra-cellular matrix (ECM). ECM contains bacterial secreted polymers such as exopolysaccharides (EPS), proteins and extracellular-DNA (e-DNA) and rarely amyloidogenic proteins. Biofilm offers protection of underlying bacterial population against chemotherapeutic agents and host immune system. Therefore, present efforts are focused to find a novel therapeutic that targets biofilm-associated infections. Plants are used as a natural therapeutic for numerous ailments. In order to find an alternative of the available antibacterial drugs, we have focused on the natural herbal active compounds. In this study, we have extracted active compounds from various medicinal plants and screened its anti-biofilm activity against carbapenem resistant strain of A. baumannii. Results showed that polar extract of kiwi (Actinidia deliciosa) and clove (Syzygium aromaticum) exhibit effective anti-biofilm activity. These two plants were also used for their phytochemical screening and TLC profiling to find out the constituting secondary metabolites. Actinidia deliciosa extract contains an alkaloid (sanquinarine) as well as a flavonoid (hydroxyflavone). Anti-biofilm effect of this extract on the ECM of A. baumannii showed that it reduces EPS, protein and eDNA contents in the ECM. Proteins of ECM have also shown to form amyloid like structure, which was evident from its interaction with the Congo Red. CFU counting after Actinidia deliciosa extract treatment also supported the results. Therefore, it can be concluded that polar extract of A. deliciosa can be used to find suitable alternative therapeutic to control biofilm formation by carbapenem resistant strain of

Influence of culture conditions on Escherichia coli O157:H7 biofilm formation by atomic force microscopy

International Nuclear Information System (INIS)

Oh, Y.J.; Jo, W.; Yang, Y.; Park, S.

2007-01-01

Biofilms are complex microbial communities that are resistant against attacks by bacteriophages and removal by drugs and chemicals. In this study, biofilms of Escherichia coli O157:H7, a bacterial pathogen, were investigated using atomic force microscopy (AFM) in terms of the dynamic transition of morphology and surface properties of bacterial cells over the development of biofilms. The physical and topographical properties of biofilms are different, depending on nutrient availability. Compared to biofilms formed in a high nutrient medium, biofilms form faster and a higher number of bacterial cells were recovered on glass surface in a low nutrient medium. We demonstrate that AFM can obtain high-resolution images and the elastic information about biofilms. As E. coli biofilm becomes mature, the magnitude of the force between a tip and the surface of the biofilm gets stronger, suggesting that extracellular polymeric substances (EPSs), sticky components of biofilms, accumulate over the surface of cells upon the initial attachment of bacterial cells to surfaces

Adaptation of intertidal biofilm communities is driven by metal ion and oxidative stresses

KAUST Repository

Zhang, Weipeng; Wang, Yong; Lee, On On; Tian, Renmao; Cao, Huiluo; Gao, Zhaoming; Li, Yongxin; Yu, Li; Xu, Ying; Qian, Pei-Yuan

2013-01-01

Marine organisms in intertidal zones are subjected to periodical fluctuations and wave activities. To understand how microbes in intertidal biofilms adapt to the stresses, the microbial metagenomes of biofilms from intertidal and subtidal zones were compared. The genes responsible for resistance to metal ion and oxidative stresses were enriched in both 6-day and 12-day intertidal biofilms, including genes associated with secondary metabolism, inorganic ion transport and metabolism, signal transduction and extracellular polymeric substance metabolism. In addition, these genes were more enriched in 12-day than 6-day intertidal biofilms. We hypothesize that a complex signaling network is used for stress tolerance and propose a model illustrating the relationships between these functions and environmental metal ion concentrations and oxidative stresses. These findings show that bacteria use diverse mechanisms to adapt to intertidal zones and indicate that the community structures of intertidal biofilms are modulated by metal ion and oxidative stresses.

Adaptation of intertidal biofilm communities is driven by metal ion and oxidative stresses

KAUST Repository

Zhang, Weipeng

2013-11-11

Marine organisms in intertidal zones are subjected to periodical fluctuations and wave activities. To understand how microbes in intertidal biofilms adapt to the stresses, the microbial metagenomes of biofilms from intertidal and subtidal zones were compared. The genes responsible for resistance to metal ion and oxidative stresses were enriched in both 6-day and 12-day intertidal biofilms, including genes associated with secondary metabolism, inorganic ion transport and metabolism, signal transduction and extracellular polymeric substance metabolism. In addition, these genes were more enriched in 12-day than 6-day intertidal biofilms. We hypothesize that a complex signaling network is used for stress tolerance and propose a model illustrating the relationships between these functions and environmental metal ion concentrations and oxidative stresses. These findings show that bacteria use diverse mechanisms to adapt to intertidal zones and indicate that the community structures of intertidal biofilms are modulated by metal ion and oxidative stresses.

Comparison of RNA extraction methods from biofilm samples of Staphylococcus epidermidis

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França Angela

2011-12-01

Full Text Available Abstract Background Microbial biofilms are communities of bacteria adhered to a surface and surrounded by an extracellular polymeric matrix. Biofilms have been associated with increased antibiotic resistance and tolerance to the immune system. Staphylococcus epidermidis is the major bacterial species found in biofilm-related infections on indwelling medical devices. Obtaining high quality mRNA from biofilms is crucial to validate the transcriptional measurements associated with the switching to the biofilm mode of growth. Therefore, we selected three commercially available RNA extraction kits with distinct characteristics, including those using silica membrane or organic extraction methods, and enzymatic or mechanical cell lysis, and evaluated the RNA quality obtained from two distinct S. epidermidis bacterial biofilms. Results RNA extracted using the different kits was evaluated for quantity, purity, integrity, and functionally. All kits were able to extract intact and functional total RNA from the biofilms generated from each S. epidermidis strain. The results demonstrated that the kit based on mechanical lysis and organic extraction (FastRNA® Pro Blue was the only one that was able to isolate pure and large quantities of RNA. Normalized expression of the icaA virulence gene showed that RNA extracted with PureLink™ had a significant lower concentration of icaA mRNA transcripts than the other kits tested. Conclusions When working with complex samples, such as biofilms, that contain a high content extracellular polysaccharide and proteins, special care should be taken when selecting the appropriate RNA extraction system, in order to obtain accurate, reproducible, and biologically significant results. Among the RNA extraction kits tested, FastRNA® Pro Blue was the best option for both S. epidermidis biofilms used.

Removal of Foodborne Pathogen Biofilms by Acidic Electrolyzed Water

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Qiao Han

2017-06-01

Full Text Available Biofilms, which are complex microbial communities embedded in the protective extracellular polymeric substances (EPS, are difficult to remove in food production facilities. In this study, the use of acidic electrolyzed water (AEW to remove foodborne pathogen biofilms was evaluated. We used a green fluorescent protein-tagged Escherichia coli for monitoring the efficiency of AEW for removing biofilms, where under the optimal treatment conditions, the fluorescent signal of cells in the biofilm disappeared rapidly and the population of biofilm cells was reduced by more than 67%. Additionally, AEW triggered EPS disruption, as indicated by the deformation of the carbohydrate C-O-C bond and deformation of the aromatic rings in the amino acids tyrosine and phenylalanine. These deformations were identified by EPS chemical analysis and Raman spectroscopic analysis. Scanning electron microscopy (SEM images confirmed that the breakup and detachment of biofilm were enhanced after AEW treatment. Further, AEW also eradicated biofilms formed by both Gram-negative bacteria (Vibrio parahaemolyticus and Gram-positive bacteria (Listeria monocytogenes and was observed to inactivate the detached cells which are a potential source of secondary pollution. This study demonstrates that AEW could be a reliable foodborne pathogen biofilm disrupter and an eco-friendly alternative to sanitizers traditionally used in the food industry.

Investigating electrochemical removal of bacterial biofilms from stainless steel substrates.

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Dargahi, Mahdi; Hosseinidoust, Zeinab; Tufenkji, Nathalie; Omanovic, Sasha

2014-05-01

Electrochemical removal of biofilms deserves attention because of its ease of use and environmentally friendly nature. We investigated the influence of electrode potential and treatment time on the removal of a 10-day old Pseudomonas aeruginosa biofilm formed on stainless steel 316 L substrates. At electrode potentials more positive than -1.5 V vs. Ag/AgCl, lower removal rates were observed and only partial removal of the biofilm was achieved during a 1-min time interval. Electrostatic repulsion between the film and electrode surface is believed to drive biofilm detachment under these conditions. However, when the biofilm-coated substrates were treated at potentials negative of -1.5 V vs. Ag/AgCl, complete removal of a biofilm was achieved within seconds. Under these conditions, vigorous evolution of hydrogen gas is believed to be responsible for the film removal, mechanically detaching the bacteria and extracellular polymeric matrix from the substrate. Stainless steel substrates were also subjected to repeated cycles of biofilm formation and electrochemical removal. High removal efficiencies were maintained throughout this process suggesting the potential of the proposed technology for application on conductive surfaces in various industrial settings. Copyright © 2014 Elsevier B.V. All rights reserved.

Mycobacterium avium Possesses Extracellular DNA that Contributes to Biofilm Formation, Structural Integrity, and Tolerance to Antibiotics.

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Sasha J Rose

Full Text Available Mycobacterium avium subsp. hominissuis is an opportunistic pathogen that is associated with biofilm-related infections of the respiratory tract and is difficult to treat. In recent years, extracellular DNA (eDNA has been found to be a major component of bacterial biofilms, including many pathogens involved in biofilm-associated infections. To date, eDNA has not been described as a component of mycobacterial biofilms. In this study, we identified and characterized eDNA in a high biofilm-producing strain of Mycobacterium avium subsp. hominissuis (MAH. In addition, we surveyed for presence of eDNA in various MAH strains and other nontuberculous mycobacteria. Biofilms of MAH A5 (high biofilm-producing strain and MAH 104 (reference strain were established at 22°C and 37°C on abiotic surfaces. Acellular biofilm matrix and supernatant from MAH A5 7 day-old biofilms both possess abundant eDNA, however very little eDNA was found in MAH 104 biofilms. A survey of MAH clinical isolates and other clinically relevant nontuberculous mycobacterial species revealed many species and strains that also produce eDNA. RAPD analysis demonstrated that eDNA resembles genomic DNA. Treatment with DNase I reduced the biomass of MAH A5 biofilms when added upon biofilm formation or to an already established biofilm both on abiotic surfaces and on top of human pharyngeal epithelial cells. Furthermore, co-treatment of an established biofilm with DNase 1 and either moxifloxacin or clarithromycin significantly increased the susceptibility of the bacteria within the biofilm to these clinically used antimicrobials. Collectively, our results describe an additional matrix component of mycobacterial biofilms and a potential new target to help treat biofilm-associated nontuberculous mycobacterial infections.

Single particle tracking reveals spatial and dynamic organization of the Escherichia coli biofilm matrix

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Birjiniuk, Alona; Doyle, Patrick S; Billings, Nicole; Ribbeck, Katharina; Nance, Elizabeth; Hanes, Justin

2014-01-01

Biofilms are communities of surface-adherent bacteria surrounded by secreted polymers known as the extracellular polymeric substance. Biofilms are harmful in many industries, and thus it is of great interest to understand their mechanical properties and structure to determine ways to destabilize them. By performing single particle tracking with beads of varying surface functionalization it was found that charge interactions play a key role in mediating mobility within biofilms. With a combination of single particle tracking and microrheological concepts, it was found that Escherichia coli biofilms display height dependent charge density that evolves over time. Statistical analyses of bead trajectories and confocal microscopy showed inter-connecting micron scale channels that penetrate throughout the biofilm, which may be important for nutrient transfer through the system. This methodology provides significant insight into a particular biofilm system and can be applied to many others to provide comparisons of biofilm structure. The elucidation of structure provides evidence for the permeability of biofilms to microscale objects, and the ability of a biofilm to mature and change properties over time. (paper)

Genotypic and Phenotypic Characteristics Associated with Biofilm Formation by Human Clinical Escherichia coli Isolates of Different Pathotypes.

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Schiebel, Juliane; Böhm, Alexander; Nitschke, Jörg; Burdukiewicz, Michał; Weinreich, Jörg; Ali, Aamir; Roggenbuck, Dirk; Rödiger, Stefan; Schierack, Peter

2017-12-15

Bacterial biofilm formation is a widespread phenomenon and a complex process requiring a set of genes facilitating the initial adhesion, maturation, and production of the extracellular polymeric matrix and subsequent dispersal of bacteria. Most studies on Escherichia coli biofilm formation have investigated nonpathogenic E. coli K-12 strains. Due to the extensive focus on laboratory strains in most studies, there is poor information regarding biofilm formation by pathogenic E. coli isolates. In this study, we genotypically and phenotypically characterized 187 human clinical E. coli isolates representing various pathotypes (e.g., uropathogenic, enteropathogenic, and enteroaggregative E. coli ). We investigated the presence of biofilm-associated genes ("genotype") and phenotypically analyzed the isolates for motility and curli and cellulose production ("phenotype"). We developed a new screening method to examine the in vitro biofilm formation ability. In summary, we found a high prevalence of biofilm-associated genes. However, we could not detect a biofilm-associated gene or specific phenotype correlating with the biofilm formation ability. In contrast, we did identify an association of increased biofilm formation with a specific E. coli pathotype. Enteroaggregative E. coli (EAEC) was found to exhibit the highest capacity for biofilm formation. Using our image-based technology for the screening of biofilm formation, we demonstrated the characteristic biofilm formation pattern of EAEC, consisting of thick bacterial aggregates. In summary, our results highlight the fact that biofilm-promoting factors shown to be critical for biofilm formation in nonpathogenic strains do not reflect their impact in clinical isolates and that the ability of biofilm formation is a defined characteristic of EAEC. IMPORTANCE Bacterial biofilms are ubiquitous and consist of sessile bacterial cells surrounded by a self-produced extracellular polymeric matrix. They cause chronic and device

Toxicity and transformation of graphene oxide and reduced graphene oxide in bacteria biofilm.

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Guo, Zhiling; Xie, Changjian; Zhang, Peng; Zhang, Junzhe; Wang, Guohua; He, Xiao; Ma, Yuhui; Zhao, Bin; Zhang, Zhiyong

2017-02-15

Impact of graphene based material (GNMs) on bacteria biofilm has not been well understood yet. In this study, we compared the impact of graphene oxide (GO) and reduced graphene oxide (rGO) on biofilm formation and development in Luria-Bertani (LB) medium using Escherichia coli and Staphylococcus aureus as models. GO significantly enhanced the cell growth, biofilm formation, and biofilm development even up to a concentration of 500mg/L. In contrast, rGO (≥50mg/L) strongly inhibited cell growth and biofilm formation. However, the inhibitory effects of rGO (50mg/L and 100mg/L) were attenuated in the mature phase (>24h) and eliminated at 48h. GO at 250mg/L decreased the reactive oxygen species (ROS) levels in biofilm and extracellular region at mature phase. ROS levels were significantly increased by rGO at early phase, while they returned to the same levels as control at mature phase. These results suggest that oxidative stress contributed to the inhibitory effect of rGO on bacterial biofilm. We further found that supplement of extracellular polymeric substances (EPS) in the growth medium attenuated the inhibitory effect of rGO on the growth of developed biofilm. XPS results showed that rGO were oxidized to GO which can enhance the bacterial growth. We deduced that the elimination of the toxicity of rGO at mature phase was contributed by EPS protection and the oxidation of rGO. This study provides new insights into the interaction of GNMs with bacteria biofilm. Copyright © 2016 Elsevier B.V. All rights reserved.

Inhibition of biofilm formation by D-tyrosine: Effect of bacterial type and D-tyrosine concentration.

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Yu, Cong; Li, Xuening; Zhang, Nan; Wen, Donghui; Liu, Charles; Li, Qilin

2016-04-01

D-Tyrosine inhibits formation and triggers disassembly of bacterial biofilm and has been proposed for biofouling control applications. This study probes the impact of D-tyrosine in different biofilm formation stages in both G+ and G- bacteria, and reveals a non-monotonic correlation between D-tyrosine concentration and biofilm inhibition effect. In the attachment stage, cell adhesion was studied in a flow chamber, where D-tyrosine caused significant reduction in cell attachment. Biofilms formed by Pseudomonas aeruginosa and Bacillus subtilis were characterized by confocal laser scanning microscopy as well as quantitative analysis of cellular biomass and extracellular polymeric substances. D-Tyrosine exhibited strong inhibitive effects on both biofilms with an effective concentration as low as 5 nM; the biofilms responded to D-tyrosine concentration change in a non-monotonic, bi-modal pattern. In addition, D-tyrosine showed notable and different impact on EPS production by G+ and G- bacteria. Extracellular protein was decreased in P. aeruginosa biofilms, but increased in those of B. subtilis. Exopolysaccharides production by P. aeruginosa was increased at low concentrations and reduced at high concentrations while no impact was found in B. subtilis. These results suggest that distinct mechanisms are at play at different D-tyrosine concentrations and they may be species specific. Dosage of D-tyrosine must be carefully controlled for biofouling control applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biofilms

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López, Daniel; Vlamakis, Hera; Kolter, Roberto

2010-01-01

The ability to form biofilms is a universal attribute of bacteria. Biofilms are multicellular communities held together by a self-produced extracellular matrix. The mechanisms that different bacteria employ to form biofilms vary, frequently depending on environmental conditions and specific strain attributes. In this review, we emphasize four well-studied model systems to give an overview of how several organisms form biofilms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and ...

Characterization of a mycobacterial cellulase and its impact on biofilm- and drug-induced cellulose production.

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Van Wyk, Niël; Navarro, David; Blaise, Mickaël; Berrin, Jean-Guy; Henrissat, Bernard; Drancourt, Michel; Kremer, Laurent

2017-05-01

It was recently shown that Mycobacterium tuberculosis produces cellulose which forms an integral part of its extracellular polymeric substances within a biofilm set-up. Using Mycobacterium smegmatis as a proxy model organism, we demonstrate that M. smegmatis biofilms treated with purified MSMEG_6752 releases the main cellulose degradation-product (cellobiose), detected by using ionic chromatography, suggesting that MSMEG_6752 encodes a cellulase. Its overexpression in M. smegmatis prevents spontaneous biofilm formation. Moreover, the method reported here allowed detecting cellobiose when M. smegmatis cultures were exposed to a subinhibitory dose of rifampicin. Overall, this study highlights the role of the MSMEG_6752 in managing cellulose production induced during biofilm formation and antibiotic stress response. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Label-free in situ SERS imaging of biofilms.

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Ivleva, Natalia P; Wagner, Michael; Szkola, Agathe; Horn, Harald; Niessner, Reinhard; Haisch, Christoph

2010-08-12

Surface-enhanced Raman scattering (SERS) is a promising technique for the chemical characterization of biological systems. It yields highly informative spectra, can be applied directly in aqueous environment, and has high sensitivity in comparison with normal Raman spectroscopy. Moreover, SERS imaging can provide chemical information with spatial resolution in the micrometer range (chemical imaging). In this paper, we report for the first time on the application of SERS for in situ, label-free imaging of biofilms and demonstrate the suitability of this technique for the characterization of the complex biomatrix. Biofilms, being communities of microorganisms embedded in a matrix of extracellular polymeric substances (EPS), represent the predominant mode of microbial life. Knowledge of the chemical composition and the structure of the biofilm matrix is important in different fields, e.g., medicine, biology, and industrial processes. We used colloidal silver nanoparticles for the in situ SERS analysis. Good SERS measurement reproducibility, along with a significant enhancement of Raman signals by SERS (>10(4)) and highly informative SERS signature, enables rapid SERS imaging (1 s for a single spectrum) of the biofilm matrix. Altogether, this work illustrates the potential of SERS for biofilm analysis, including the detection of different constituents and the determination of their distribution in a biofilm even at low biomass concentration.

Biofilm Production in Carbapenem Resistant Isolates from Chronic Wound Infections

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Swarna SR

2017-02-01

Full Text Available Biofilms are communities of microorganisms covered with extracellular polymeric substances. Such biofilm phenotype makes the microorganism resistant to antibiotics and plays a role in wound chronicity. This results in prolonged hospital stays in ICU, greater cost, and increased mortality. Methods: Pus swabs (59 were collected from a tertiary care hospital near Chennai were processed and identified using standard procedure followed by antibiotic susceptibility testing and identification of carbapenem resistance by Modified Hodge test as per CLSI guidelines. The biofilm formation was tested using plastic microtiter plate method. Results: Out of 59 pus swabs, 51 yielded growth with 69 isolates and 8 yielded no growth. Among the 69 isolates, 51 were GNB and 18 were GPC. Biofilm detection was noted in 84.31% (43/51 GNB isolates with 0.1% crystal violet whereas 100% (51/51 showed biofilm positive with 0.1% safranin. About 74.50% (38/51 isolates of GNB were carbapenem resistant by screening with disk diffusion method. Only 24% (6/25 of GNB isolates among Enterobacteriaceae were positive by Modified Hodge test method. Conclusion: The result shows the association of biofilm production among carbapenem resistant isolates obtained from chronic wound infections.

Candida Biofilms: Threats, Challenges, and Promising Strategies

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Mafalda Cavalheiro

2018-02-01

Full Text Available Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed.

Candida Biofilms: Threats, Challenges, and Promising Strategies.

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Cavalheiro, Mafalda; Teixeira, Miguel Cacho

2018-01-01

Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis , and Candida parapsilosis , highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed.

Candida Biofilms: Threats, Challenges, and Promising Strategies

Science.gov (United States)

Cavalheiro, Mafalda; Teixeira, Miguel Cacho

2018-01-01

Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed. PMID:29487851

Emergent pattern formation in an interstitial biofilm

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Zachreson, Cameron; Wolff, Christian; Whitchurch, Cynthia B.; Toth, Milos

2017-01-01

Collective behavior of bacterial colonies plays critical roles in adaptability, survivability, biofilm expansion and infection. We employ an individual-based model of an interstitial biofilm to study emergent pattern formation based on the assumptions that rod-shaped bacteria furrow through a viscous environment and excrete extracellular polymeric substances which bias their rate of motion. Because the bacteria furrow through their environment, the substratum stiffness is a key control parameter behind the formation of distinct morphological patterns. By systematically varying this property (which we quantify with a stiffness coefficient γ ), we show that subtle changes in the substratum stiffness can give rise to a stable state characterized by a high degree of local order and long-range pattern formation. The ordered state exhibits characteristics typically associated with bacterial fitness advantages, even though it is induced by changes in environmental conditions rather than changes in biological parameters. Our findings are applicable to a broad range of biofilms and provide insights into the relationship between bacterial movement and their environment, and basic mechanisms behind self-organization of biophysical systems.

Raffinose Induces Biofilm Formation by Streptococcus mutans in Low Concentrations of Sucrose by Increasing Production of Extracellular DNA and Fructan.

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Nagasawa, Ryo; Sato, Tsutomu; Senpuku, Hidenobu

2017-08-01

Streptococcus mutans is the primary etiological agent of dental caries and causes tooth decay by forming a firmly attached biofilm on tooth surfaces. Biofilm formation is induced by the presence of sucrose, which is a substrate for the synthesis of extracellular polysaccharides but not in the presence of oligosaccharides. Nonetheless, in this study, we found that raffinose, which is an oligosaccharide with an intestinal regulatory function and antiallergic effect, induced biofilm formation by S. mutans in a mixed culture with sucrose, which was at concentrations less than those required to induce biofilm formation directly. We analyzed the possible mechanism behind the small requirement for sucrose for biofilm formation in the presence of raffinose. Our results suggested that sucrose contributed to an increase in bacterial cell surface hydrophobicity and biofilm formation. Next, we examined how the effects of raffinose interacted with the effects of sucrose for biofilm formation. We showed that the presence of raffinose induced fructan synthesis by fructosyltransferase and aggregated extracellular DNA (eDNA, which is probably genomic DNA released from dead cells) into the biofilm. eDNA seemed to be important for biofilm formation, because the degradation of DNA by DNase I resulted in a significant reduction in biofilm formation. When assessing the role of fructan in biofilm formation, we found that fructan enhanced eDNA-dependent cell aggregation. Therefore, our results show that raffinose and sucrose have cooperative effects and that this induction of biofilm formation depends on supportive elements that mainly consist of eDNA and fructan. IMPORTANCE The sucrose-dependent mechanism of biofilm formation in Streptococcus mutans has been studied extensively. Nonetheless, the effects of carbohydrates other than sucrose are inadequately understood. Our findings concerning raffinose advance the understanding of the mechanism underlying the joint effects of sucrose and

Conductive properties of methanogenic biofilms.

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Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

2018-02-01

Extracellular electron transfer between syntrophic partners needs to be efficiently maintained in methanogenic environments. Direct extracellular electron transfer via electrical current is an alternative to indirect hydrogen transfer but requires construction of conductive extracellular structures. Conductive mechanisms and relationship between conductivity and the community composition in mixed-species methanogenic biofilms are not well understood. The present study investigated conductive behaviors of methanogenic biofilms and examined the correlation between biofilm conductivity and community composition between different anaerobic biofilms enriched from the same inoculum. Highest conductivity observed in methanogenic biofilms was 71.8±4.0μS/cm. Peak-manner response of conductivity upon changes over a range of electrochemical potentials suggests that electron transfer in methanogenic biofilms occurs through redox driven super-exchange. The strong correlation observed between biofilm conductivity and Geobacter spp. in the metabolically diverse anaerobic communities suggests that the efficiency of DEET may provide pressure for microbial communities to select for species that can produce electrical conduits. Copyright © 2017 Elsevier B.V. All rights reserved.

Ginger Extract Inhibits Biofilm Formation by Pseudomonas aeruginosa PA14

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Kim, Han-Shin; Park, Hee-Deung

2013-01-01

Bacterial biofilm formation can cause serious problems in clinical and industrial settings, which drives the development or screening of biofilm inhibitors. Some biofilm inhibitors have been screened from natural products or modified from natural compounds. Ginger has been used as a medicinal herb to treat infectious diseases for thousands of years, which leads to the hypothesis that it may contain chemicals inhibiting biofilm formation. To test this hypothesis, we evaluated ginger’s ability to inhibit Pseudomonas aeruginosa PA14 biofilm formation. A static biofilm assay demonstrated that biofilm development was reduced by 39–56% when ginger extract was added to the culture. In addition, various phenotypes were altered after ginger addition of PA14. Ginger extract decreased production of extracellular polymeric substances. This finding was confirmed by chemical analysis and confocal laser scanning microscopy. Furthermore, ginger extract formed noticeably less rugose colonies on agar plates containing Congo red and facilitated swarming motility on soft agar plates. The inhibition of biofilm formation and the altered phenotypes appear to be linked to a reduced level of a second messenger, bis-(3′-5′)-cyclic dimeric guanosine monophosphate. Importantly, ginger extract inhibited biofilm formation in both Gram-positive and Gram-negative bacteria. Also, surface biofilm cells formed with ginger extract detached more easily with surfactant than did those without ginger extract. Taken together, these findings provide a foundation for the possible discovery of a broad spectrum biofilm inhibitor. PMID:24086697

Biofilm and capsule formation of the diatom Achnanthidium minutissimum are affected by a bacterium.

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Windler, Miriam; Leinweber, Katrin; Bartulos, Carolina Rio; Philipp, Bodo; Kroth, Peter G

2015-04-01

Photoautotrophic biofilms play an important role in various aquatic habitats and are composed of prokaryotic and/or eukaryotic organisms embedded in extracellular polymeric substances (EPS). We have isolated diatoms as well as bacteria from freshwater biofilms to study organismal interactions between representative isolates. We found that bacteria have a strong impact on the biofilm formation of the pennate diatom Achnanthidium minutissimum. This alga produces extracellular capsules of insoluble EPS, mostly carbohydrates (CHO), only in the presence of bacteria (xenic culture). The EPS themselves also have a strong impact on the aggregation and attachment of the algae. In the absence of bacteria (axenic culture), A. minutissimum did not form capsules and the cells grew completely suspended. Fractionation and quantification of CHO revealed that the diatom in axenic culture produces large amounts of soluble CHO, whereas in the xenic culture mainly insoluble CHO were detected. For investigation of biofilm formation by A. minutissimum, a bioassay was established using a diatom satellite Bacteroidetes bacterium that had been shown to induce capsule formation of A. minutissimum. Interestingly, capsule and biofilm induction can be achieved by addition of bacterial spent medium, indicating that soluble hydrophobic molecules produced by the bacterium may mediate the diatom/bacteria interaction. With the designed bioassay, a reliable tool is now available to study the chemical interactions between diatoms and bacteria with consequences for biofilm formation. © 2015 Phycological Society of America.

In situ analysis of Bacillus licheniformis biofilms: amyloid-like polymers and eDNA are involved in the adherence and aggregation of the extracellular matrix.

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Randrianjatovo-Gbalou, I; Rouquette, P; Lefebvre, D; Girbal-Neuhauser, E; Marcato-Romain, C-E

2017-05-01

This study attempts to determine which of the exopolymeric substances are involved in the adherence and aggregation of a Bacillus licheniformis biofilm. The involvement of extracellular proteins and eDNA were particularly investigated using DNase and proteinase K treatment. The permeability of the biofilms increased fivefold after DNase I treatment. The quantification of the matrix components showed that, irrespective to the enzyme tested, eDNA and amyloid-like polymers were removed simultaneously. Size-exclusion chromatography analyses supported these observations and revealed the presence of associated nucleic acid and protein complexes in the biofilm lysates. These data suggest that some extracellular DNA and amyloid-like proteins were closely interlaced within the matrix. Finally, confocal laser scanning microscopy imaging gave supplementary clues about the 3D organization of the biofilms, confirming that eDNA and exoproteins were essentially layered under and around the bacterial cells, whereas the amyloid-like fractions were homogeneously distributed within the matrix. These results confirm that some DNA-amyloid complexes play a key role in the modulation of the mechanical resistance of B. licheniformis biofilms. The study highlights the need to consider the whole structure of biofilms and to target the interactions between matrix components. A better understanding of B. licheniformis biofilm physiology and the structural organization of the matrix will strengthen strategies of biofilm control. © 2017 The Society for Applied Microbiology.

Treatment of Biofilm Communities: An Update on New Tools from the Nanosized World

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Federico Bertoglio

2018-05-01

Full Text Available Traditionally regarded as single cell organisms, bacteria naturally and preferentially build multicellular communities that enable them to react efficiently to external stimuli in a coordinated fashion and with extremely effective outcomes. These communities are bacterial biofilms, where single cells or microcolonies are embedded in self-built Extracellular Polymeric Substance (EPS, composed of different macromolecules, e.g., polysaccharides, proteins, lipids, and extracellular DNA (eDNA. Despite being the most common form in nature and having many biotechnologically useful applications, biofilm is often regarded as a life-threatening form of bacterial infection. Since this form of bacterial life is intrinsically more resistant to antibiotic treatment and antimicrobial resistance is reaching alarming levels, we will focus our attention on how nanotechnology made new tools available to the medical community for the prevention and treatment of these infections. After a brief excursus on biofilm formation and its main characteristics, different types of nanomaterials developed to prevent or counteract these multicellular forms of bacterial infection will be described. A comparison of different classifications adopted for nanodrugs and a final discussion of challenges and future perspectives are also presented.

Viscoelastic Properties of Extracellular Polymeric Substances Can Strongly Affect Their Washing Efficiency from Reverse Osmosis Membranes.

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Ferrando Chavez, Diana Lila; Nejidat, Ali; Herzberg, Moshe

2016-09-06

The role of the viscoelastic properties of biofouling layers in their removal from the membrane was studied. Model fouling layers of extracellular polymeric substances (EPS) originated from microbial biofilms of Pseudomonas aeruginosa PAO1 differentially expressing the Psl polysaccharide were used for controlled washing experiments of fouled RO membranes. In parallel, adsorption experiments and viscoelastic modeling of the EPS layers were conducted in a quartz crystal microbalance with dissipation (QCM-D). During the washing stage, as shear rate was elevated, significant differences in permeate flux recovery between the three different EPS layers were observed. According to the amount of organic carbon remained on the membrane after washing, the magnitude of Psl production provides elevated resistance of the EPS layer to shear stress. The highest flux recovery during the washing stage was observed for the EPS with no Psl. Psl was shown to elevate the layer's shear modulus and shear viscosity but had no effect on the EPS adhesion to the polyamide surface. We conclude that EPS retain on the membrane as a result of the layer viscoelastic properties. These results highlight an important relation between washing efficiency of fouling layers from membranes and their viscoelastic properties, in addition to their adhesion properties.

Does Extracellular DNA Production Vary in Staphylococcal Biofilms Isolated From Infected Implants versus Controls?

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Zatorska, Beata; Groger, Marion; Moser, Doris; Diab-Elschahawi, Magda; Lusignani, Luigi Segagni; Presterl, Elisabeth

2017-08-01

Prosthetic implant infections caused by Staphylococcus aureus and epidermidis are major challenges for early diagnosis and treatment owing to biofilm formation on the implant surface. Extracellular DNA (eDNA) is actively excreted from bacterial cells in biofilms, contributing to biofilm stability, and may offer promise in the detection or treatment of such infections. (1) Does DNA structure change during biofilm formation? (2) Are there time-dependent differences in eDNA production during biofilm formation? (3) Is there differential eDNA production between clinical and control Staphylococcal isolates? (4) Is eDNA production correlated to biofilm thickness? We investigated eDNA presence during biofilm formation in 60 clinical and 30 control isolates of S aureus and S epidermidis. The clinical isolates were isolated from patients with infections of orthopaedic prostheses and implants: 30 from infected hip prostheses and 30 from infected knee prostheses. The control isolates were taken from healthy volunteers who had not been exposed to antibiotics and a hospital environment during the previous 3 and 12 months, respectively. Control S epidermidis was isolated from the skin of the antecubital fossa, and control S aureus was isolated from the nares. For the biofilm experiments the following methods were used to detect eDNA: (1) fluorescent staining with 4',6-diamidino-2-phenylindole (DAPI), (2) eDNA extraction using a commercial kit, and (3) confocal laser scanning microscopy for 24-hour biofilm observation using propidium iodide and concanavalin-A staining; TOTO ® -1 and SYTO ® 60 staining were used for observation and quantification of eDNA after 6 and 24 hours of biofilm formation. Additionally antibiotic resistance was described. eDNA production as observed by confocal laser scanning microscopy was greater in clinical isolates than controls (clinical isolates mean ± SD: 1.84% ± 1.31%; control mean ± SD: 1.17% ± 1.37%; p biofilm formation. After 24 hours, the

Effect of Electrolyzed Water on the Disinfection of Bacillus cereus Biofilms: The Mechanism of Enhanced Resistance of Sessile Cells in the Biofilm Matrix.

Science.gov (United States)

Hussain, Mohammad Shakhawat; Kwon, Minyeong; Tango, Charles Nkufi; Oh, Deog Hwan

2018-05-01

This study examined the disinfection efficacy and mechanism of electrolyzed water (EW) on Bacillus cereus biofilms. B. cereus strains, ATCC 14579 and Korean Collection for Type Cultures (KCTC) 13153 biofilms, were formed on stainless steel (SS) and plastic slide (PS) coupons. Mature biofilms were treated with slightly acidic EW (SAEW), acidic EW (AEW), and basic EW (BEW). SAEW (available chlorine concentration, 25 ± 1.31 mg L -1 ; pH 5.71 ± 0.16; and oxidation reduction potential, 818 to 855 mV) reduced ATCC 14579 biofilms on plastic slides to below the detection limit within 30 s. However, biofilms on SS coupons showed a higher resistance to the SAEW treatment. When the disinfection activities of three types of EW on biofilms were compared, AEW showed a higher bactericidal activity, followed by SAEW and BEW. In contrast, BEW showed a significantly ( P biofilm dispersal activity than AEW and SAEW. SAEW disinfection of the B. cereus biofilms was due to the disruption of the B. cereus plasma membrane. The higher resistance of biofilms formed on the SS coupon might be due to the higher number of attached cells and extracellular polymeric substances formation that reacts with the active chlorine ions, such as hypochlorous acid and hypochlorite ion of SAEW, which decreased the disinfection efficacy of SAEW. This study showed that the EW treatment effectively disinfected B. cereus biofilms, providing insight into the potential use of EW in the food processing industry to control the biofilm formation of B. cereus.

Antimicrobial peptide AMPNT-6 from Bacillus subtilis inhibits biofilm formation by Shewanella putrefaciens and disrupts its preformed biofilms on both abiotic and shrimp shell surfaces.

Science.gov (United States)

Deng, Qi; Pu, Yuehua; Sun, Lijun; Wang, Yaling; Liu, Yang; Wang, Rundong; Liao, Jianmeng; Xu, Defeng; Liu, Ying; Ye, Riying; Fang, Zhijia; Gooneratne, Ravi

2017-12-01

Shewanella putrefaciens biofilm formation is of great concern for the shrimp industry because it adheres easily to food and food-contact surfaces and is a source of persistent and unseen contamination that causes shrimp spoilage and economic losses to the shrimp industry. Different concentrations of an antimicrobial lipopeptide, the fermentation product of Bacillus subtilis, AMPNT-6, were tested for the ability to reduce adhesion and disrupt S. putrefaciens preformed biofilms on two different contact surfaces (shrimp shell, stainless steel sheet). AMPNT-6 displayed a marked dose- and time-dependent anti-adhesive effect>biofilm removal. 3MIC AMPNT-6 was able both to remove biofilm and prevent bacteria from forming biofilm in a 96-well polystyrene microplate used as the model surface. 2MIC AMPNT-6 prevented bacteria from adhering to the microplate surface to form biofilm for 3h and removed already existing biofilm within 24h. Secretion of extracellular polymeric substances incubated in LB broth for 24h by S. putrefaciens was minimal at 3× MIC AMPNT-6. Scanning electron microscopy showed that damage to S. putrefaciens bacteria by AMPNT-6 possibly contributed to the non-adherence to the surfaces. Disruption of the mature biofilm structure by AMPNT-6 contributed to biofilm removal. It is concluded that AMPNT-6 can be used effectively to prevent attachment and also detach S. putrefaciens biofilms from shrimp shells, stainless steel sheets and polystyrene surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative proteomic analysis of extracellular proteins expressed by various clonal types of Staphylococcus aureus and during planktonic growth and biofilm development.

Science.gov (United States)

Atshan, Salman S; Shamsudin, Mariana N; Sekawi, Zamberi; Thian Lung, Leslie T; Barantalab, Fatemeh; Liew, Yun K; Alreshidi, Mateg Ali; Abduljaleel, Salwa A; Hamat, Rukman A

2015-01-01

Staphylococcus aureus is well known for its biofilm formation with rapid emergence of new clones circulating worldwide. The main objectives of the study were (1) to identify possible differences in protein expression among various and closely related clonal types of S. aureus, (2) to establish the differences in protein expression in terms of size of protein spots and its intensities between bacteria which are grown statically (biofilm formation) with that of under aeration and agitation, and (3) to compare the differences in protein expression as a function of time (in hours). In this study, we selected six clinical isolates comprising two similar (MRSA-527 and MRSA-524) and four different (MRSA-139, MSSA-12E, MSSA-22d, and MSSA-10E) types identified by spa typing, MLST and SCCmec typing. We performed 2D gel migration comparison. Also, two MRSA isolates (527 and 139) were selected to determine quantitative changes in the level of extracellular proteins at different biofilm growth time points of 12, 24, and 48 h. The study was done using a strategy that combines 2-DGE and LC-MS/MS analysis for absolute quantification and identification of the extracellular proteins. The 2DGE revealed that the proteomic profiles for the isolates belonging to the similar spa, MLST, and SCCmec types were still quite different. Among the extracellular proteins secreted at different time points of biofilm formation, significant changes in protein expression were observed at 48 h incubation as compared to the exponential growth at 12 h incubation. The main conclusion of the work is that the authors do observe differences among isolates, and growth conditions do influence the protein content at different time points of biofilm formation.

Influence of extracellular polymeric substances on deposition and redeposition of Pseudomonas aeruginosa to surfaces

NARCIS (Netherlands)

Gomez-Suarez, C; Pasma, J; van der Borden, AJ; Wingender, J; Flemming, HC; Busscher, HJ; van der Mei, HC

In this study, the role of extracellular polymeric substances (EPS) in the initial adhesion of EPS-producing Pseudomonas aeruginosa SG91 and SG81R1, a non-EPS-producing strain, to substrata with different hydrophobicity was investigated. The release of EPS by SG81 was concurrent with a decrease in

Bacterial biofilm formation in different surfaces of food industries

Directory of Open Access Journals (Sweden)

Karine Angélica Dalla Costa

2017-06-01

Full Text Available The term biofilm describes the sessile microbial life form, characterized by microorganism adhesion to any surface and with the production of extracellular polymeric substances. In food industries, the formation of biofilms results in serious problems, since it can be a contamination source of the food product, compromising the final product quality and consumer health. The aim of this study was to verify the adhesion of biofilms (sessile cells of pathogenic and/or deteriorating bacteria against surfaces of the food industry. The bacterial species tested were Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Listeria monocytogenes ATCC 19117 and Salmonella Typhimurium ATCC 14028. It was used stainless steel and polypropylene coupons as contact surfaces. The results demonstrated that P. aeruginosa and S. Typhimurium showed higher biofilm formation capacity. Statistically, there was no difference in count of P. aeruginosa and S. Typhimurium (p > 0.05 cells. The same occurred between L. monocytogenes and S. aureus. However, the counts of P. aeruginosa and S. Typhimurium cells were statistically higher than S. aureus and L. monocytogenes (p < 0.05. By means of scanning electron microscopy it was also found increased adhesion of P. aeruginosa. The results revealed that P. aeruginosa was the bacterial species with higher biofilm formation capacity among the others.

Surface Chemical Characterisation of Pyrite Exposed to Acidithiobacillus ferrooxidans and Associated Extracellular Polymeric Substances

Directory of Open Access Journals (Sweden)

Sian M. La Vars

2018-03-01

Full Text Available A. ferrooxidans and their metabolic products have previously been explored as a viable alternative depressant of pyrite for froth flotation; however, the mechanism by which separation is achieved is not completely understood. Scanning electron microscopy (SEM, photoemission electron microscopy (PEEM, time-of-flight secondary ion mass spectrometry (ToF-SIMS and captive bubble contact angle measurements have been used to examine the surface physicochemical properties of pyrite upon exposure to A. ferrooxidans grown in HH medium at pH 1.8. C K-edge near edge X-ray absorption fine structure (NEXAFS spectra collected from PEEM images indicate hydrophilic lipids, fatty acids and biopolymers are formed at the mineral surface during early exposure. After 168 h, the spectra indicate a shift towards protein and DNA, corresponding to an increase in cell population and biofilm formation on the surface, as observed by SEM. The Fe L-edge NEXAFS show gradual oxidation of the mineral surface from Fe(II sulfide to Fe(III oxyhydroxides. The oxidation of the iron species at the pyrite surface is accelerated in the presence of A. ferrooxidans and extracellular polymeric substances (EPS as compared to HH medium controls. The surface chemical changes induced by the interaction with A. ferrooxidans show a significant decrease in surface hydrophobicity within the first 2 h of exposure. The implications of these findings are the potential use of EPS produced during early attachment of A. ferrooxidans, as a depressant for bioflotation.

Analysis of Dissolved Organic Nutrients in the Interstitial Water of Natural Biofilms.

Science.gov (United States)

Tsuchiya, Yuki; Eda, Shima; Kiriyama, Chiho; Asada, Tomoya; Morisaki, Hisao

2016-07-01

In biofilms, the matrix of extracellular polymeric substances (EPSs) retains water in the interstitial region of the EPS. This interstitial water is the ambient environment for microorganisms in the biofilms. The nutrient condition in the interstitial water may affect microbial activity in the biofilms. In the present study, we measured the concentrations of dissolved organic nutrients, i.e., saccharides and proteins, contained in the interstitial water of biofilms formed on the stones. We also analyzed the molecular weight distribution, chemical species, and availability to bacteria of some saccharides in the interstitial water. Colorimetric assays showed that the concentrations of saccharides and proteins in the biofilm interstitial water were significantly higher (ca. 750 times) than those in the surrounding lake waters (p Chromatographic analyses demonstrated that the saccharides in the interstitial waters were mainly of low molecular-weight saccharides such as glucose and maltose, while proteins in the interstitial water were high molecular-weight proteins (over 7000 Da). Bacterial growth and production of EPS occurred simultaneously with the decrease in the low molecular-weight saccharide concentrations when a small portion of biofilm suspension was inoculated to the collected interstitial water, suggesting that the dissolved saccharides in the interstitial water support bacterial growth and formation of biofilms.

Comparison of SEM and VPSEM imaging techniques with respect to Streptococcus mutans biofilm topography.

Science.gov (United States)

Weber, Kathryn; Delben, Juliana; Bromage, Timothy G; Duarte, Simone

2014-01-01

The study compared images of mature Streptococcus mutans biofilms captured at increasing magnification to determine which microscopy method is most acceptable for imaging the biofilm topography and the extracellular polymeric substance (EPS). In vitro S. mutans biofilms were imaged using (1) scanning electron microscopy (SEM), which requires a dehydration process; (2) SEM and ruthenium red (SEM-RR), which has been shown to support the EPS of biofilms during the SEM dehydration; and (3) variable pressure scanning electron microscopy (VPSEM), which does not require the intensive dehydration process of SEM. The dehydration process and high chamber vacuum of both SEM techniques devastated the biofilm EPS, removed supporting structures, and caused cracking on the biofilm surface. The VPSEM offered the most comprehensive representation of the S. mutans biofilm morphology. VPSEM provides similar contrast and focus as the SEM, but the procedure is far less time-consuming, and the use of hazardous chemicals associated with SEM dehydration protocol is avoided with the VPSEM. The inaccurate representations of the biofilm EPS in SEM experimentation is a possible source of inaccurate data and impediments in the study of S. mutans biofilms. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Dependence of toxicity of silver nanoparticles on Pseudomonas putida biofilm structure.

Science.gov (United States)

Thuptimdang, Pumis; Limpiyakorn, Tawan; Khan, Eakalak

2017-12-01

Susceptibility of biofilms with different physical structures to silver nanoparticles (AgNPs) was studied. Biofilms of Pseudomonas putida KT2440 were formed in batch conditions under different carbon sources (glucose, glutamic acid, and citrate), glucose concentrations (5 and 50 mM), and incubation temperatures (25 and 30 °C). The biofilms were observed using confocal laser scanning microscopy for their physical characteristics (biomass amount, thickness, biomass volume, surface to volume ratio, and roughness coefficient). The biofilms forming under different growth conditions exhibited different physical structures. The biofilm thickness and the roughness coefficient were found negatively and positively correlated with the biofilm susceptibility to AgNPs, respectively. The effect of AgNPs on biofilms was low (1-log reduction of cell number) when the biofilms had high biomass amount, high thickness, high biomass volume, low surface to volume ratio, and low roughness coefficient. Furthermore, the extracellular polymeric substance (EPS) stripping process was applied to confirm the dependence of susceptibility to AgNPs on the structure of biofilm. After the EPS stripping process, the biofilms forming under different conditions showed reduction in thickness and biomass volume, and increases in surface to volume ratio and roughness coefficient, which led to more biofilm susceptibility to AgNPs. The results of this study suggest that controlling the growth conditions to alter the biofilm physical structure is a possible approach to reduce the impact of AgNPs on biofilms in engineered and natural systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Diversity and functions of bacterial community in drinking water biofilms revealed by high-throughput sequencing

Science.gov (United States)

Chao, Yuanqing; Mao, Yanping; Wang, Zhiping; Zhang, Tong

2015-06-01

The development of biofilms in drinking water (DW) systems may cause various problems to water quality. To investigate the community structure of biofilms on different pipe materials and the global/specific metabolic functions of DW biofilms, PCR-based 454 pyrosequencing data for 16S rRNA genes and Illumina metagenomic data were generated and analysed. Considerable differences in bacterial diversity and taxonomic structure were identified between biofilms formed on stainless steel and biofilms formed on plastics, indicating that the metallic materials facilitate the formation of higher diversity biofilms. Moreover, variations in several dominant genera were observed during biofilm formation. Based on PCA analysis, the global functions in the DW biofilms were similar to other DW metagenomes. Beyond the global functions, the occurrences and abundances of specific protective genes involved in the glutathione metabolism, the SoxRS system, the OxyR system, RpoS regulated genes, and the production/degradation of extracellular polymeric substances were also evaluated. A near-complete and low-contamination draft genome was constructed from the metagenome of the DW biofilm, based on the coverage and tetranucleotide frequencies, and identified as a Bradyrhizobiaceae-like bacterium according to a phylogenetic analysis. Our findings provide new insight into DW biofilms, especially in terms of their metabolic functions.

Evaluation of anti-Listeria meat borne Lactobacillus for biofilm formation on selected abiotic surfaces.

Science.gov (United States)

Pérez Ibarreche, Mariana; Castellano, Patricia; Vignolo, Graciela

2014-01-01

The ability of meat borne anti-Listeria Lactobacillus to form biofilms under different in vitro conditions and on abiotic surfaces was investigated. Biofilm formation by the adhesion to polystyrene microtiter plates was determined, this being higher for Lactobacillus curvatus CRL1532 and CRL705 and Lactobacillus sakei CRL1862. The physicochemical properties of the cell surface were relatively hydrophilic and acidic in character; L. sakei CRL1862 exhibiting the strongest autoaggregation. The adhesion of lactobacilli to stainless steel (SS) and polytetrafluoroethylene (PTFE) supports at 10°C was found to be maximal for L. sakei CRL1862 on SS after 6 days. When biofilm architecture was characterized by epifluorescence and SEM, L. sakei CRL1862 homogeneously covered the SS surface while cell clusters were observed on PTFE; the extracellular polymeric substance matrix adapted to the topography and hydrophilic/hydrophobic characteristics of each material. The feasibility of L. sakei CRL1862 to form biofilm on materials used in meat processing highlights its potential as a control strategy for Listeria monocytogenes biofilms. © 2013. Published by Elsevier Ltd. All rights reserved.

Isolation, characterization and localization of extracellular polymeric substances from the cyanobacterium Arthrospira platensis strain MMG-9

NARCIS (Netherlands)

Ahmed, M.; Moerdijk-Poortvliet, T.C.W.; Wijnholds, A.; Stal, L.J.; Hasnain, S.

2014-01-01

Arthrospira platensis is a cyanobacterium known for its nutritional value and secondary metabolites. Extracellular polymeric substances (EPS) are an important trait of most cyanobacteria, including A. platensis. Here, we extracted and analysed different fractions of EPS from a locally isolated

Nutrient depletion in Bacillus subtilis biofilms triggers matrix production

International Nuclear Information System (INIS)

Zhang, Wenbo; Seminara, Agnese; Suaris, Melanie; Angelini, Thomas E; Brenner, Michael P; Weitz, David A

2014-01-01

Many types of bacteria form colonies that grow into physically robust and strongly adhesive aggregates known as biofilms. A distinguishing characteristic of bacterial biofilms is an extracellular polymeric substance (EPS) matrix that encases the cells and provides physical integrity to the colony. The EPS matrix consists of a large amount of polysaccharide, as well as protein filaments, DNA and degraded cellular materials. The genetic pathways that control the transformation of a colony into a biofilm have been widely studied, and yield a spatiotemporal heterogeneity in EPS production. Spatial gradients in metabolites parallel this heterogeneity in EPS, but nutrient concentration as an underlying physiological initiator of EPS production has not been explored. Here, we study the role of nutrient depletion in EPS production in Bacillus subtilis biofilms. By monitoring simultaneously biofilm size and matrix production, we find that EPS production increases at a critical colony thickness that depends on the initial amount of carbon sources in the medium. Through studies of individual cells in liquid culture we find that EPS production can be triggered at the single-cell level by reducing nutrient concentration. To connect the single-cell assays with conditions in the biofilm, we calculate carbon concentration with a model for the reaction and diffusion of nutrients in the biofilm. This model predicts the relationship between the initial concentration of carbon and the thickness of the colony at the point of internal nutrient deprivation. (paper)

Temporal Changes in Extracellular Polymeric Substances on Hydrophobic and Hydrophilic Membrane Surfaces in a Submerged Membrane Bioreactor

KAUST Repository

Matar, Gerald Kamil

2016-03-02

Membrane surface hydrophilic modification has always been considered to mitigating biofouling in membrane bioreactors (MBRs). Four hollow-fiber ultrafiltration membranes (pore sizes ∼0.1 μm) differing only in hydrophobic or hydrophilic surface characteristics were operated at a permeate flux of 10 L/m2.h in the same lab-scale MBR fed with synthetic wastewater. In addition, identical membrane modules without permeate production (0 L/m2.h) were operated in the same lab-scale MBR. Membrane modules were autopsied after 1, 10, 20 and 30 days of MBR operation, and total extracellular polymeric substances (EPS) accumulated on the membranes were extracted and characterized in detail using several analytical tools, including conventional colorimetric tests (Lowry and Dubois), liquid chromatography with organic carbon detection (LC-OCD), fluorescence excitation - emission matrices (FEEM), fourier transform infrared (FTIR) and confocal laser scanning microscope (CLSM). The transmembrane pressure (TMP) quickly stabilized with higher values for the hydrophobic membranes than hydrophilic ones. The sulfonated polysulfone (SPSU) membrane had the highest negatively charged membrane surface, accumulated the least amount of foulants and displayed the lowest TMP. The same type of organic foulants developed with time on the four membranes and the composition of biopolymers shifted from protein dominance at early stages of filtration (day 1) towards polysaccharides dominance during later stages of MBR filtration. Nonmetric multidimensional scaling of LC-OCD data showed that biofilm samples clustered according to the sampling event (time) regardless of the membrane surface chemistry (hydrophobic or hydrophilic) or operating mode (with or without permeate flux). These results suggest that EPS composition may not be the dominant parameter for evaluating membrane performance and possibly other parameters such as biofilm thickness, porosity, compactness and structure should be considered

In Situ Molecular Imaging of the Biofilm and Its Matrix

Energy Technology Data Exchange (ETDEWEB)

Ding, Yuanzhao; Zhou, Yufan; Yao, Juan; Szymanski, Craig J.; Fredrickson, Jim K.; Shi, Liang; Cao, B.; Zhu, Zihua; Yu, Xiao-Ying

2016-11-15

Molecular mapping of live biofilms at submicron resolution presents a grand challenge. Here, we present the first chemical mapping results of biofilm extracellular polymeric sub-stance (EPS) components in biofilms using correlative imaging be-tween super resolution florescence microscopy and liquid time-of-flight secondary ion mass spectrometry (ToF-SIMS). Shewanella oneidensis is used as a model organism. Heavy metal anions chro-mate (Cr2O72-) consisting of chromium Cr (VI) was a model envi-ronmental stressor used to treat the biofilms. Of particular interest, biologically relevant water clusters have been first observed in the biofilms. Characteristic fragments of biofilm matrix components such as proteins, polysaccharides, and lipids can be spatially im-aged. Furthermore, characteristic fatty acids (e.g., palmitic acid), quinolone signal, and riboflavin fragments are found to respond af-ter the biofilm is treated with Cr (VI), leading to biofilm dispersion. Significant changes in water clusters and quorum sensing signals indicative of intercellular communication in the aqueous environ-ment are observed, suggesting that they might result in fatty acid synthesis and inhibit riboflavin production. The Cr (VI) reduction seems to follow the Mtr pathway leading to Cr (III) formation. Our approach potentially opens a new avenue for mechanistic insight of microbial community processes and communications using in situ imaging mass spectrometry and superresolution optical micros-copy.

Extracellular DNA as matrix component in microbial biofilms

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Tolker-Nielsen, Tim

2010-01-01

Bacteria in nature primarily live in surface-associated communities commonly known as biofilms. Because bacteria in biofilms, in many cases, display tolerance to host immune systems, antibiotics, and biocides, they are often difficult or impossible to eradicate. Biofilm formation, therefore, leads...

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

International Nuclear Information System (INIS)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-01-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

Energy Technology Data Exchange (ETDEWEB)

Nomura, Toshiyuki, E-mail: nomura@chemeng.osakafu-u.ac.jp; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro [Osaka Prefecture University, Department of Chemical Engineering (Japan)

2016-06-15

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

Science.gov (United States)

Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

2016-06-01

The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells ( Escherichia coli and Lactococcus lactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

Direct Comparison of Physical Properties of Bacillus subtilis NCIB 3610 and B-1 Biofilms

Science.gov (United States)

Kesel, Sara; Grumbein, Stefan; Gümperlein, Ina; Tallawi, Marwa; Marel, Anna-Kristina

2016-01-01

Many bacteria form surface-attached communities known as biofilms. Due to the extreme resistance of these bacterial biofilms to antibiotics and mechanical stresses, biofilms are of growing interest not only in microbiology but also in medicine and industry. Previous studies have determined the extracellular polymeric substances present in the matrix of biofilms formed by Bacillus subtilis NCIB 3610. However, studies on the physical properties of biofilms formed by this strain are just emerging. In particular, quantitative data on the contributions of biofilm matrix biopolymers to these physical properties are lacking. Here, we quantitatively investigated three physical properties of B. subtilis NCIB 3610 biofilms: the surface roughness and stiffness and the bulk viscoelasticity of these biofilms. We show how specific biomolecules constituting the biofilm matrix formed by this strain contribute to those biofilm properties. In particular, we demonstrate that the surface roughness and surface elasticity of 1-day-old NCIB 3610 biofilms are strongly affected by the surface layer protein BslA. For a second strain, B. subtilis B-1, which forms biofilms containing mainly γ-polyglutamate, we found significantly different physical biofilm properties that are also differently affected by the commonly used antibacterial agent ethanol. We show that B-1 biofilms are protected from ethanol-induced changes in the biofilm's stiffness and that this protective effect can be transferred to NCIB 3610 biofilms by the sole addition of γ-polyglutamate to growing NCIB 3610 biofilms. Together, our results demonstrate the importance of specific biofilm matrix components for the distinct physical properties of B. subtilis biofilms. PMID:26873313

Susceptibility patterns and the role of extracellular DNA in Staphylococcus epidermidis biofilm resistance to physico-chemical stress exposure.

Science.gov (United States)

Olwal, Charles Ochieng'; Ang'ienda, Paul Oyieng'; Onyango, David Miruka; Ochiel, Daniel Otieno

2018-05-02

Over 65% of human infections are ascribed to bacterial biofilms that are often highly resistant to antibiotics and host immunity. Staphylococcus epidermidis is the predominant cause of recurrent nosocomial and biofilm-related infections. However, the susceptibility patterns of S. epidermidis biofilms to physico-chemical stress induced by commonly recommended disinfectants [(heat, sodium chloride (NaCl), sodium hypochlorite (NaOCl) and hydrogen peroxide (H 2 O 2 )] in domestic and human healthcare settings remains largely unknown. Further, the molecular mechanisms of bacterial biofilms resistance to the physico-chemical stresses remain unclear. Growing evidence demonstrates that extracellular DNA (eDNA) protects bacterial biofilms against antibiotics. However, the role of eDNA as a potential mechanism underlying S. epidermidis biofilms resistance to physico-chemical stress exposure is yet to be understood. Therefore, this study aimed to evaluate the susceptibility patterns of and eDNA release by S. epidermidis biofilm and planktonic cells to physico-chemical stress exposure. S. epidermidis biofilms exposed to physico-chemical stress conditions commonly recommended for disinfection [heat (60 °C), 1.72 M NaCl, solution containing 150 μL of waterguard (0.178 M NaOCl) in 1 L of water or 1.77 M H 2 O 2 ] for 30 and 60 min exhibited lower log reductions of CFU/mL than the corresponding planktonic cells (p chemical stress induced by the four commonly recommended disinfectants than the analogous planktonic cells. Further, S. epidermidis biofilms enhanced eDNA release in response to the sub-lethal heat and oxidative stress exposure than the corresponding planktonic cells suggesting a role of eDNA in biofilms resistance to the physico-chemical stresses.

Effects of toxic metals and chemicals on biofilm and biocorrosion.

Science.gov (United States)

Fang, Herbert H P; Xu, Li-Chong; Chan, Kwong-Yu

2002-11-01

Microbes in marine biofilms aggregated into clusters and increased the production of extracellular polymeric substances (EPS), by over 100% in some cases, when the seawater media containing toxic metals and chemicals, such as Cd(II), Cu(II), Pb(II), Zn(II), AI(III), Cr(III), glutaraldehyde, and phenol. The formation of microbial cluster and the increased production of EPS, which contained 84-92% proteins and 8-16% polysaccharides, accelerated the corrosion of the mild steel. However, there was no quantitative relationship between the degree of increased corrosion and the toxicity of metals/chemicals towards sulfate-reducing bacteria, or the increased EPS production.

Bacteriophages and Biofilms

Directory of Open Access Journals (Sweden)

David R. Harper

2014-06-01

Full Text Available Biofilms are an extremely common adaptation, allowing bacteria to colonize hostile environments. They present unique problems for antibiotics and biocides, both due to the nature of the extracellular matrix and to the presence within the biofilm of metabolically inactive persister cells. Such chemicals can be highly effective against planktonic bacterial cells, while being essentially ineffective against biofilms. By contrast, bacteriophages seem to have a greater ability to target this common form of bacterial growth. The high numbers of bacteria present within biofilms actually facilitate the action of bacteriophages by allowing rapid and efficient infection of the host and consequent amplification of the bacteriophage. Bacteriophages also have a number of properties that make biofilms susceptible to their action. They are known to produce (or to be able to induce enzymes that degrade the extracellular matrix. They are also able to infect persister cells, remaining dormant within them, but re-activating when they become metabolically active. Some cultured biofilms also seem better able to support the replication of bacteriophages than comparable planktonic systems. It is perhaps unsurprising that bacteriophages, as the natural predators of bacteria, have the ability to target this common form of bacterial life.

Bacterial dynamics in a microphytobenthic biofilm: A tidal mesocosm approach

Science.gov (United States)

Agogué, Hélène; Mallet, Clarisse; Orvain, Francis; De Crignis, Margot; Mornet, Françoise; Dupuy, Christine

2014-09-01

In intertidal mudflats, during low tide exposure, microphytobenthos (MPB) migrate vertically through the surface sediment and form, with the heterotrophic bacteria, a transient biofilm. Inside this biofilm, multiple interactions exist between MPB and bacteria. These micro-organisms secrete a wide range of extracellular polymeric substances (EPS), which are major components of the biofilm matrix. In this study, we used a tidal mesocosm experiment in order to decipher the interactions of the MPB-EPS-bacteria complex within the biofilm. We tried to determine if the EPS could control bacterial activities and/or production and/or richness according to the age of the biofilm and to the immersion/emersion period. The dynamics of biomasses of MPB and prokaryotes, the bacterial production, the hydrolysis of predominating organic constituents in the dissolved organic carbon (DOC) pool (i.e., carbohydrates and polypeptides), and the bacterial structure were studied in relation to the different EPS fractions (carbohydrates and proteins: colloidal and bound) dynamics during 8 days. Our experiment had emphasized the influence of the environmental conditions (light, immersion/emersion) on the interactions within the biofilm and also on the effects on biofilm aging. Bacterial production was always inhibited by the bound EPS-carbohydrate, especially during low tide. Our results suggest that the concentration and composition of EPS had a major role in the bacterial/MPB interactions: these interactions can be either positive or negative in order to regulate the productive phases of MPB and bacteria.

Enzymes in therapy of biofilm-related oral diseases.

Science.gov (United States)

Pleszczyńska, Małgorzata; Wiater, Adrian; Bachanek, Teresa; Szczodrak, Janusz

2017-05-01

Biofilm-related infections of the oral cavity, including dental caries and periodontitis, represent the most prevalent health problems. For years, the treatment thereof was largely based on antibacterial chemical agents. Recently, however, there has been growing interest in the application of more preventive and minimally invasive biotechnological methods. This review focuses on the potential applications of enzymes in the treatment and prevention of oral diseases. Dental plaque is a microbial community that develops on the tooth surface, embedded in a matrix of extracellular polymeric substances of bacterial and host origin. Both cariogenic microorganisms and the key components of oral biofilm matrix may be the targets of the enzymes. Oxidative salivary enzymes inhibit or limit the growth of oral pathogens, thereby supporting the natural host defense system; polysaccharide hydrolases (mutanases and dextranases) degrade important carbohydrate components of the biofilm matrix, whereas proteases disrupt bacterial adhesion to oral surfaces or affect cell-cell interactions. The efficiency of the enzymes in in vitro and in vivo studies, advantages and limitations, as well as future perspectives for improving the enzymatic strategy are discussed. © 2016 International Union of Biochemistry and Molecular Biology, Inc.

msaABCR operon positively regulates biofilm development by repressing proteases and autolysis in Staphylococcus aureus.

Science.gov (United States)

Sahukhal, Gyan S; Batte, Justin L; Elasri, Mohamed O

2015-02-01

Staphylococcus aureus is an important human pathogen that causes nosocomial and community-acquired infections. One of the most important aspects of staphylococcal infections is biofilm development within the host, which renders the bacterium resistant to the host's immune response and antimicrobial agents. Biofilm development is very complex and involves several regulators that ensure cell survival on surfaces within the extracellular polymeric matrix. Previously, we identified the msaABCR operon as an additional positive regulator of biofilm formation. In this study, we define the regulatory pathway by which msaABCR controls biofilm formation. We demonstrate that the msaABCR operon is a negative regulator of proteases. The control of protease production mediates the processing of the major autolysin, Atl, and thus regulates the rate of autolysis. In the absence of the msaABCR operon, Atl is processed by proteases at a high rate, leading to increased cell death and a defect in biofilm maturation. We conclude that the msaABCR operon plays a key role in maintaining the balance between autolysis and growth within the staphylococcal biofilm. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Characterization of Desulfovibrio desulfuricans biofilm on high-alloyed stainless steel: XPS and electrochemical studies

Energy Technology Data Exchange (ETDEWEB)

Dec, Weronika [Institute of Industrial Organic Chemistry, Branch Pszczyna, Doświadczalna Street 27, 43-200 Pszczyna (Poland); Mosiałek, Michał; Socha, Robert P. [Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek Street 8, 30-239 Kraków (Poland); Jaworska-Kik, Marzena [Department of Biopharmacy, Medical University of Silesia, Jedności Street 8, 41-200 Sosnowiec (Poland); Simka, Wojciech [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice (Poland); Michalska, Joanna, E-mail: joanna.k.michalska@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego 6 Street, 44-100 Gliwice (Poland)

2017-07-01

Results on D. desulfuricans biofilm formation on austenitic-ferritic duplex (2205 DSS) and superaustenitic (904L) stainless steels are presented. Surface characterization including the structure, configuration and chemical composition of biofilms were carried out using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) measurements were used to monitor the attachment activity of bacteria on the steels' surface and to determine the effect of bacteria on passivity. It was proved that investigated steels are rapidly colonized by bacteria. The presence of biofilm caused significant ennoblement of 904L steel surface, while retarded the attainment of high passive state of 2205 DSS. XPS analysis revealed significant sulphidation of the biofilm and its layered structure. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C-N bonds were detected in the internal part of the biofilm. Irreversible bondings between steel matrix and biofilm had also been observed. - Highlights: • High-alloyed steels are rapidly colonized by sulphate-reducing bacteria. • Higher Ni content stimulates more intensive biofilm growth. • Extracellular polymeric substances indelibly bind to the high-alloyed steels. • Sulphate-reducing bacteria caused irreversible sulphidation of passive films.

Characterization of Desulfovibrio desulfuricans biofilm on high-alloyed stainless steel: XPS and electrochemical studies

International Nuclear Information System (INIS)

Dec, Weronika; Mosiałek, Michał; Socha, Robert P.; Jaworska-Kik, Marzena; Simka, Wojciech; Michalska, Joanna

2017-01-01

Results on D. desulfuricans biofilm formation on austenitic-ferritic duplex (2205 DSS) and superaustenitic (904L) stainless steels are presented. Surface characterization including the structure, configuration and chemical composition of biofilms were carried out using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS) measurements were used to monitor the attachment activity of bacteria on the steels' surface and to determine the effect of bacteria on passivity. It was proved that investigated steels are rapidly colonized by bacteria. The presence of biofilm caused significant ennoblement of 904L steel surface, while retarded the attainment of high passive state of 2205 DSS. XPS analysis revealed significant sulphidation of the biofilm and its layered structure. Accumulation of sulphides and hydroxides was proved in the outermost layer, while the increasing contents of disulphides, organometallic and C-N bonds were detected in the internal part of the biofilm. Irreversible bondings between steel matrix and biofilm had also been observed. - Highlights: • High-alloyed steels are rapidly colonized by sulphate-reducing bacteria. • Higher Ni content stimulates more intensive biofilm growth. • Extracellular polymeric substances indelibly bind to the high-alloyed steels. • Sulphate-reducing bacteria caused irreversible sulphidation of passive films.

Effects of humic acid on the interactions between zinc oxide nanoparticles and bacterial biofilms.

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Ouyang, Kai; Yu, Xiao-Ying; Zhu, Yunlin; Gao, Chunhui; Huang, Qiaoyun; Cai, Peng

2017-12-01

The effects of humic acid (HA) on interactions between ZnO nanoparticles (ZnO NPs) and Pseudomonas putida KT2440 biofilms at different maturity stages were investigated. Three stages of biofilm development were identified according to bacterial adenosine triphosphate (ATP) activity associated with biofilm development process. In the initial biofilm stage 1, the ATP content of bacteria was reduced by more than 90% when biofilms were exposed to ZnO NPs. However, in the mature biofilm stages 2 and 3, the ATP content was only slightly decreased. Biofilms at stage 3 exhibited less susceptibility to ZnO NPs than biofilms at stage 2. These results suggest that more mature biofilms have a significantly higher tolerance to ZnO NPs compared to young biofilms. In addition, biofilms with intact extracellular polymeric substances (EPS) showed higher tolerance to ZnO NPs than those without EPS, indicating that EPS play a key role in alleviating the toxic effects of ZnO NPs. In both pure ZnO NPs and ZnO-HA mixtures, dissolved Zn 2+ originating from the NPs significantly contributed to the overall toxicity. The presence of HA dramatically decreased the toxicity of ZnO NPs due to the binding of Zn 2+ on HA. The combined results from this work suggest that the biofilm maturity stages and environmental constituents (such as humic acid) are important factors to consider when evaluating potential risks of NPs to ecological systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of humic acid on the interactions between zinc oxide nanoparticles and bacterial biofilms

Energy Technology Data Exchange (ETDEWEB)

Ouyang, Kai; Yu, Xiao-Ying; Zhu, Yunlin; Gao, Chunhui; Huang, Qiaoyun; Cai, Peng

2017-12-01

The effects of humic acid (HA) on interactions between ZnO nanoparticles (ZnO NPs) and Pseudomonas putida KT2440 biofilms at different maturity stages were investigated. Three stages of biofilm development were identified according to bacterial adenosine triphosphate (ATP) activity associated with biofilm development process. In the initial biofilm stage 1, the ATP content of bacteria was reduced by more than 90% when biofilms were exposed to ZnO NPs. However, in the mature biofilm stages 2 and 3, the ATP content was only slightly decreased. Biofilms at stage 3 exhibited less susceptibility to ZnO NPs than biofilms at stage 2. These results suggest that more mature biofilms have a significantly higher tolerance to ZnO NPs compared to young biofilms. In addition, biofilms with intact extracellular poly-meric substances (EPS) showed higher tolerance to ZnO NPs than those without EPS, indicating that EPS play a key role in alleviating the toxic effects of ZnO NPs. In both pure ZnO NPs and ZnO-HA mixtures, dissolved Zn²⁺ originating from the NPs significantly contributed to the overall toxicity. The presence of HA dramatically decreased the toxicity of ZnO NPs due to the binding of Zn²⁺ on HA. The combined results from this work suggest that the biofilm maturity stages and environmental constituents (such as humic acid) are important factors to consider when evaluating potential risks of NPs to ecological systems.

A characterization of DNA release in Pseudomonas aeruginosa cultures and biofilms

DEFF Research Database (Denmark)

Allesen-Holm, Marie; Barken, Kim Bundvig; Yang, Liang

2006-01-01

-type P. aeruginosa biofilms stained with different DNA stains suggested that the extracellular DNA is located primarily in the stalks of mushroom-shaped multicellular structures, with a high concentration especially in the outer part of the stalks forming a border between the stalk-forming bacteria...... to whole-genome DNA. Evidence that the extracellular DNA in P. aeruginosa biofilms and cultures is generated via lysis of a subpopulation of the bacteria was obtained through experiments where extracellular beta-galactosidase released from lacZ-containing P. aeruginosa strains was assessed. Experiments...... and the cap-forming bacteria. Biofilms formed by lasIrhlI, pqsA and fliMpilA mutants contained less extracellular DNA than biofilms formed by the wild type, and the mutant biofilms were more susceptible to treatment with sodium dodecyl sulphate than the wild-type biofilm....

Ratiometric Imaging of Extracellular pH in Dental Biofilms

DEFF Research Database (Denmark)

Schlafer, Sebastian; Dige, Irene

2016-01-01

The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites are not distributed evenly in dental biofilms. A complex interplay of sorption to and reaction with organic matter in the biofilm reduces...... the diffusion paths of solutes and creates steep gradients of reactive molecules, including organic acids, across the biofilm. Quantitative fluorescent microscopic methods, such as fluorescence life time imaging or pH ratiometry, can be employed to visualize pH in different microenvironments of dental biofilms...... allows monitoring both vertical and horizontal pH gradients in real-time without mechanically disturbing the biofilm. However, care must be taken to differentiate accurately between extra- and intracellular compartments of the biofilm. Here, the ratiometric dye, seminaphthorhodafluor-4F 5-(and-6...

Helicobacter pylori Biofilm Formation and Its Potential Role in Pathogenesis.

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Hathroubi, Skander; Servetas, Stephanie L; Windham, Ian; Merrell, D Scott; Ottemann, Karen M

2018-06-01

Despite decades of effort, Helicobacter pylori infections remain difficult to treat. Over half of the world's population is infected by H. pylori , which is a major cause of duodenal and gastric ulcers as well as gastric cancer. During chronic infection, H. pylori localizes within the gastric mucosal layer, including deep within invaginations called glands; thanks to its impressive ability to survive despite the harsh acidic environment, it can persist for the host's lifetime. This ability to survive and persist in the stomach is associated with urease production, chemotactic motility, and the ability to adapt to the fluctuating environment. Additionally, biofilm formation has recently been suggested to play a role in colonization. Biofilms are surface-associated communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances. Biofilms pose a substantial health risk and are key contributors to many chronic and recurrent infections. This link between biofilm-associated bacteria and chronic infections likely results from an increased tolerance to conventional antibiotic treatments as well as immune system action. The role of this biofilm mode in antimicrobial treatment failure and H. pylori survival has yet to be determined. Furthermore, relatively little is known about the H. pylori biofilm structure or the genes associated with this mode of growth. In this review, therefore, we aim to highlight recent findings concerning H. pylori biofilms and the molecular mechanism of their formation. Additionally, we discuss the potential roles of biofilms in the failure of antibiotic treatment and in infection recurrence. Copyright © 2018 American Society for Microbiology.

Mechanisms of Candida biofilm drug resistance

Science.gov (United States)

Taff, Heather T; Mitchell, Kaitlin F; Edward, Jessica A; Andes, David R

2013-01-01

Candida commonly adheres to implanted medical devices, growing as a resilient biofilm capable of withstanding extraordinarily high antifungal concentrations. As currently available antifungals have minimal activity against biofilms, new drugs to treat these recalcitrant infections are urgently needed. Recent investigations have begun to shed light on the mechanisms behind the profound resistance associated with the biofilm mode of growth. This resistance appears to be multifactorial, involving both mechanisms similar to conventional, planktonic antifungal resistance, such as increased efflux pump activity, as well as mechanisms specific to the biofilm lifestyle. A unique biofilm property is the production of an extracellular matrix. Two components of this material, β-glucan and extracellular DNA, promote biofilm resistance to multiple antifungals. Biofilm formation also engages several stress response pathways that impair the activity of azole drugs. Resistance within a biofilm is often heterogeneous, with the development of a subpopulation of resistant persister cells. In this article we review the molecular mechanisms underlying Candida biofilm antifungal resistance and their relative contributions during various growth phases. PMID:24059922

Removal of Zn(II) from electroplating effluent using yeast biofilm formed on gravels: batch and column studies

Science.gov (United States)

2014-01-01

Background Present study deals with the removal of Zn(II) ions from effluent using yeast biofilm formed on gravels. Methods The biofilm forming ability of Candida rugosa and Cryptococcus laurentii was evaluated using XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay and monitored by scanning electron microscopy (SEM), and Confocal laser scanning microscopy (CLSM). Copious amount of extracellular polymeric substances (EPS) produced by yeast species was quantified and characterized by Fourier transform infrared spectroscopy (FT-IR). Results Yeast biofilm formed on gravels by C. rugosa and C. laurentii showed 88% and 74.2% removal of Zn(II) ions respectively in batch mode. In column mode, removal of Zn(II) ions from real effluent was found to be 95.29% by C. rugosa biofilm formed on gravels. Conclusion The results of the present study showed that there is a scope to develop a cost effective method for the efficient removal of Zn(II) from effluent using gravels coated with yeast biofilm. PMID:24397917

Metabolic differentiation in biofilms as indicated by carbon dioxide production rates.

Science.gov (United States)

Bester, Elanna; Kroukamp, Otini; Wolfaardt, Gideon M; Boonzaaier, Leandro; Liss, Steven N

2010-02-01

The measurement of carbon dioxide production rates as an indication of metabolic activity was applied to study biofilm development and response of Pseudomonas sp. biofilms to an environmental disturbance in the form of a moving air-liquid interface (i.e., shear). A differential response in biofilm cohesiveness was observed after bubble perturbation, and the biofilm layers were operationally defined as either shear-susceptible or non-shear-susceptible. Confocal laser scanning microscopy and image analysis showed a significant reduction in biofilm thickness and biomass after the removal of the shear-susceptible biofilm layer, as well as notable changes in the roughness coefficient and surface-to-biovolume ratio. These changes were accompanied by a 72% reduction of whole-biofilm CO2 production; however, the non-shear-susceptible region of the biofilm responded rapidly after the removal of the overlying cells and extracellular polymeric substances (EPS) along with the associated changes in nutrient and O2 flux, with CO2 production rates returning to preperturbation levels within 24 h. The adaptable nature and the ability of bacteria to respond to environmental conditions were further demonstrated by the outer shear-susceptible region of the biofilm; the average CO2 production rate of cells from this region increased within 0.25 h from 9.45 +/- 5.40 fmol of CO2 x cell(-1) x h(-1) to 22.6 +/- 7.58 fmol of CO2 x cell(-1) x h(-1) when cells were removed from the biofilm and maintained in suspension without an additional nutrient supply. These results also demonstrate the need for sufficient monitoring of biofilm recovery at the solid substratum if mechanical methods are used for biofouling control.

Roles of Extracellular Polysaccharides and Biofilm Formation in Heavy Metal Resistance of Rhizobia

Directory of Open Access Journals (Sweden)

Natalia Nocelli

2016-05-01

Full Text Available Bacterial surface components and extracellular compounds, particularly flagella, lipopolysaccharides (LPSs, and exopolysaccharides (EPSs, in combination with environmental signals and quorum-sensing signals, play crucial roles in bacterial autoaggregation, biofilm development, survival, and host colonization. The nitrogen-fixing species Sinorhizobium meliloti (S. meliloti produces two symbiosis-promoting EPSs: succinoglycan (or EPS I and galactoglucan (or EPS II. Studies of the S. meliloti/alfalfa symbiosis model system have revealed numerous biological functions of EPSs, including host specificity, participation in early stages of host plant infection, signaling molecule during plant development, and (most importantly protection from environmental stresses. We evaluated functions of EPSs in bacterial resistance to heavy metals and metalloids, which are known to affect various biological processes. Heavy metal resistance, biofilm production, and co-culture were tested in the context of previous studies by our group. A range of mercury (Hg II and arsenic (As III concentrations were applied to S. meliloti wild type strain and to mutant strains defective in EPS I and EPS II. The EPS production mutants were generally most sensitive to the metals. Our findings suggest that EPSs are necessary for the protection of bacteria from either Hg (II or As (III stress. Previous studies have described a pump in S. meliloti that causes efflux of arsenic from cells to surrounding culture medium, thereby protecting them from this type of chemical stress. The presence of heavy metals or metalloids in culture medium had no apparent effect on formation of biofilm, in contrast to previous reports that biofilm formation helps protect various microorganism species from adverse environmental conditions. In co-culture experiments, EPS-producing heavy metal resistant strains exerted a protective effect on AEPS-non-producing, heavy metal-sensitive strains; a phenomenon

A Nuclease from Streptococcus mutans Facilitates Biofilm Dispersal and Escape from Killing by Neutrophil Extracellular Traps.

Science.gov (United States)

Liu, Jia; Sun, Luping; Liu, Wei; Guo, Lihong; Liu, Zhaohui; Wei, Xi; Ling, Junqi

2017-01-01

Streptococcus mutans is the primary etiologic agent of dental caries and occasionally infective endocarditis, with the ability to form biofilms and disperse cells into distal sites to exacerbate and spread infection. In this study, we identified a nuclease (DeoC) as a S. mutans biofilm dispersal modulating factor through microarray analysis. In vitro assays revealed a dispersal defect of a deoC deletion mutant, and functional studies with purified protein were indicative of the biofilm dispersal activity of DeoC. Neutrophils are a key host response factor restraining bacterial spreading through the formation of neutrophil extracellular traps (NETs), which consist of a nuclear DNA backbone associated with antimicrobial peptides. Therefore, we hypothesized that the dispersed S. mutans might utilize DeoC to degrade NETs and escape killing by the immune system. It was found that S. mutans induced NET formation upon contact with neutrophils, while the presence of NETs in turn enhanced the deoC expression of S. mutans . Fluorescence microscopy inspection showed that deoC deletion resulted in a decreased NET degradation ability of S. mutans and enhanced susceptibility to neutrophil killing. Data obtained from this study assigned two important roles for DeoC in S. mutans : contributing to the spread of infection through mediating biofilm dispersal, and facilitating the escape of S. mutans from neutrophil killing through NET degradation.

Enterococcus faecium biofilm formation: identification of major autolysin AtlAEfm, associated Acm surface localization, and AtlAEfm-independent extracellular DNA Release.

Science.gov (United States)

Paganelli, Fernanda L; Willems, Rob J L; Jansen, Pamela; Hendrickx, Antoni; Zhang, Xinglin; Bonten, Marc J M; Leavis, Helen L

2013-04-16

Enterococcus faecium is an important multidrug-resistant nosocomial pathogen causing biofilm-mediated infections in patients with medical devices. Insight into E. faecium biofilm pathogenesis is pivotal for the development of new strategies to prevent and treat these infections. In several bacteria, a major autolysin is essential for extracellular DNA (eDNA) release in the biofilm matrix, contributing to biofilm attachment and stability. In this study, we identified and functionally characterized the major autolysin of E. faecium E1162 by a bioinformatic genome screen followed by insertional gene disruption of six putative autolysin genes. Insertional inactivation of locus tag EfmE1162_2692 resulted in resistance to lysis, reduced eDNA release, deficient cell attachment, decreased biofilm, decreased cell wall hydrolysis, and significant chaining compared to that of the wild type. Therefore, locus tag EfmE1162_2692 was considered the major autolysin in E. faecium and renamed atlAEfm. In addition, AtlAEfm was implicated in cell surface exposure of Acm, a virulence factor in E. faecium, and thereby facilitates binding to collagen types I and IV. This is a novel feature of enterococcal autolysins not described previously. Furthermore, we identified (and localized) autolysin-independent DNA release in E. faecium that contributes to cell-cell interactions in the atlAEfm mutant and is important for cell separation. In conclusion, AtlAEfm is the major autolysin in E. faecium and contributes to biofilm stability and Acm localization, making AtlAEfm a promising target for treatment of E. faecium biofilm-mediated infections. IMPORTANCE Nosocomial infections caused by Enterococcus faecium have rapidly increased, and treatment options have become more limited. This is due not only to increasing resistance to antibiotics but also to biofilm-associated infections. DNA is released in biofilm matrix via cell lysis, caused by autolysin, and acts as a matrix stabilizer. In this study

High Biofilm Conductivity Maintained Despite Anode Potential Changes in a Geobacter-Enriched Biofilm

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This study systematically assessed intracellular electron transfer (IET) and extracellular electron transfer (EET) kinetics with respect to anode potential (Eanode) in a mixed-culture biofilm anode enriched with Geobacter spp. High biofilm conductivity (0.96–1.24 mScm^-1) was mai...

Modeling of Mesoscale Variability in Biofilm Shear Behavior.

Directory of Open Access Journals (Sweden)

Pallab Barai

Full Text Available Formation of bacterial colonies as biofilm on the surface/interface of various objects has the potential to impact not only human health and disease but also energy and environmental considerations. Biofilms can be regarded as soft materials, and comprehension of their shear response to external forces is a key element to the fundamental understanding. A mesoscale model has been presented in this article based on digitization of a biofilm microstructure. Its response under externally applied shear load is analyzed. Strain stiffening type behavior is readily observed under high strain loads due to the unfolding of chains within soft polymeric substrate. Sustained shear loading of the biofilm network results in strain localization along the diagonal direction. Rupture of the soft polymeric matrix can potentially reduce the intercellular interaction between the bacterial cells. Evolution of stiffness within the biofilm network under shear reveals two regimes: a initial increase in stiffness due to strain stiffening of polymer matrix, and b eventual reduction in stiffness because of tear in polymeric substrate.

KinD is a checkpoint protein linking spore formation to extracellular-matrix production in Bacillus subtilis biofilms.

Science.gov (United States)

Aguilar, Claudio; Vlamakis, Hera; Guzman, Alejandra; Losick, Richard; Kolter, Roberto

2010-05-18

Bacillus subtilis cells form multicellular biofilm communities in which spatiotemporal regulation of gene expression occurs, leading to differentiation of multiple coexisting cell types. These cell types include matrix-producing and sporulating cells. Extracellular matrix production and sporulation are linked in that a mutant unable to produce matrix is delayed for sporulation. Here, we show that the delay in sporulation is not due to a growth advantage of the matrix-deficient mutant under these conditions. Instead, we show that the link between matrix production and sporulation is through the Spo0A signaling pathway. Both processes are regulated by the phosphorylated form of the master transcriptional regulator Spo0A. When cells have low levels of phosphorylated Spo0A (Spo0A~P), matrix genes are expressed; however, at higher levels of Spo0A~P, sporulation commences. We have found that Spo0A~P levels are maintained at low levels in the matrix-deficient mutant, thereby delaying expression of sporulation-specific genes. This is due to the activity of one of the components of the Spo0A phosphotransfer network, KinD. A deletion of kinD suppresses the sporulation defect of matrix mutants, while its overproduction delays sporulation. Our data indicate that KinD displays a dual role as a phosphatase or a kinase and that its activity is linked to the presence of extracellular matrix in the biofilms. We propose a novel role for KinD in biofilms as a checkpoint protein that regulates the onset of sporulation by inhibiting the activity of Spo0A until matrix, or a component therein, is sensed.

Sludge granulation in an UASB-moving bed biofilm hybrid reactor for efficient organic matter removal and nitrogen removal in biofilm reactor.

Science.gov (United States)

Chatterjee, Pritha; Ghangrekar, M M; Rao, Surampalli

2018-02-01

A hybrid upflow anaerobic sludge blanket (UASB)-moving bed biofilm (MBB) and rope bed biofilm (RBB) reactor was designed for treatment of sewage. Possibility of enhancing granulation in an UASB reactor using moving media to improve sludge retention was explored while treating low-strength wastewater. The presence of moving media in the top portion of the UASB reactor allowed a high solid retention time even at very short hydraulic retention times and helped in maintaining selection pressure in the sludge bed to promote formation of different sized sludge granules with an average settling velocity of 67 m/h. These granules were also found to contain plenty of extracellular polymeric substance (EPS) such as 58 mg of polysaccharides (PS) per gram of volatile suspended solids (VSS) and protein (PN) content of 37 mg/g VSS. Enriched sludge of nitrogen-removing bacteria forming a porous biofilm on the media in RBB was also observed in a concentration of around 894 g/m 2 . The nitrogen removing sludge also had a high EPS content of around 22 mg PS/g VSS and 28 mg PN/g VSS. This hybrid UASB-MBB-RBB reactor with enhanced anaerobic granular sludge treating both carbonaceous and nitrogenous matter may be a sustainable solution for decentralized sewage treatment.

Material properties of biofilms – key methods for understanding permeability and mechanics

Science.gov (United States)

Billings, Nicole; Birjiniuk, Alona; Samad, Tahoura S.; Doyle, Patrick S.; Ribbeck, Katharina

2015-01-01

Microorganisms can form biofilms, which are multicellular communities surrounded by a hydrated extracellular matrix of polymers. Central properties of the biofilm are governed by this extracellular matrix, which provides mechanical stability to the three-dimensional biofilm structure, regulates the ability of the biofilm to adhere to surfaces, and determines the ability of the biofilm to adsorb gasses, solutes, and foreign cells. Despite their critical relevance for understanding and eliminating of biofilms, the materials properties of the extracellular matrix are understudied. Here, we offer the reader a guide to current technologies that can be utilized to specifically assess the permeability and mechanical properties of the biofilm matrix and its interacting components. In particular, we highlight technological advances in instrumentation and interactions between multiple disciplines that have broadened the spectrum of methods available to conduct these studies. We review pioneering work that furthers our understanding of the material properties of biofilms. PMID:25719969

In vitro Determination of Extracellular Proteins from Xylella fastidiosa.

Science.gov (United States)

Mendes, Juliano S; Santiago, André S; Toledo, Marcelo A S; Horta, Maria A C; de Souza, Alessandra A; Tasic, Ljubica; de Souza, Anete P

2016-01-01

The phytopathogen Xylella fastidiosa causes economic losses in important agricultural crops. Xylem vessel occlusion caused by biofilm formation is the major mechanism underlying the pathogenicity of distinct strains of X. fastidiosa . Here, we provide a detailed in vitro characterization of the extracellular proteins of X. fastidiosa . Based on the results, we performed a comparison with a strain J1a12, which cannot induce citrus variegated chlorosis symptoms when inoculated into citrus plants. We then extend this approach to analyze the extracellular proteins of X. fastidiosa in media supplemented with calcium. We verified increases in extracellular proteins concomitant with the days of growth and, consequently, biofilm development (3-30 days). Outer membrane vesicles carrying toxins were identified beginning at 10 days of growth in the 9a5c strain. In addition, a decrease in extracellular proteins in media supplemented with calcium was observed in both strains. Using mass spectrometry, 71 different proteins were identified during 30 days of X. fastidiosa biofilm development, including proteases, quorum-sensing proteins, biofilm formation proteins, hypothetical proteins, phage-related proteins, chaperones, toxins, antitoxins, and extracellular vesicle membrane components.

Poly-N-acetylglucosamine matrix polysaccharide impedes fluid convection and transport of the cationic surfactant cetylpyridinium chloride through bacterial biofilms.

Science.gov (United States)

Ganeshnarayan, Krishnaraj; Shah, Suhagi M; Libera, Matthew R; Santostefano, Anthony; Kaplan, Jeffrey B

2009-03-01

Biofilms are composed of bacterial cells encased in a self-synthesized, extracellular polymeric matrix. Poly-beta(1,6)-N-acetyl-d-glucosamine (PNAG) is a major biofilm matrix component in phylogenetically diverse bacteria. In this study we investigated the physical and chemical properties of the PNAG matrix in biofilms produced in vitro by the gram-negative porcine respiratory pathogen Actinobacillus pleuropneumoniae and the gram-positive device-associated pathogen Staphylococcus epidermidis. The effect of PNAG on bulk fluid flow was determined by measuring the rate of fluid convection through biofilms cultured in centrifugal filter devices. The rate of fluid convection was significantly higher in biofilms cultured in the presence of the PNAG-degrading enzyme dispersin B than in biofilms cultured without the enzyme, indicating that PNAG decreases bulk fluid flow. PNAG also blocked transport of the quaternary ammonium compound cetylpyridinium chloride (CPC) through the biofilms. Binding of CPC to biofilms further impeded fluid convection and blocked transport of the azo dye Allura red. Bioactive CPC was efficiently eluted from biofilms by treatment with 1 M sodium chloride. Taken together, these findings suggest that CPC reacts directly with the PNAG matrix and alters its physical and chemical properties. Our results indicate that PNAG plays an important role in controlling the physiological state of biofilms and may contribute to additional biofilm-associated processes such as biocide resistance.

Medical biofilms--nanotechnology approaches.

Science.gov (United States)

Neethirajan, Suresh; Clond, Morgan A; Vogt, Adam

2014-10-01

Biofilms are colonies of bacteria or fungi that adhere to a surface, protected by an extracellular polymer matrix composed of polysaccharides and extracellular DNA. They are highly complex and dynamic multicellular structures that resist traditional means of killing planktonic bacteria. Recent developments in nanotechnology provide novel approaches to preventing and dispersing biofilm infections, which are a leading cause of morbidity and mortality. Medical device infections are responsible for approximately 60% of hospital acquired infections. In the United States, the estimated cost of caring for healthcare-associated infections is approximately between $28 billion and $45 billion per year. In this review, we will discuss our current understanding of biofilm formation and degradation, its relevance to challenges in clinical practice, and new technological developments in nanotechnology that are designed to address these challenges.

Application of fluorescently labelled lectins for the study of polysaccharides in biofilms with a focus on biofouling of nanofiltration membranes

Directory of Open Access Journals (Sweden)

Patrick Di Martino

2016-07-01

Full Text Available The biofilm state is the dominant microbial lifestyle in nature. A biofilm can be defined as cells organised as microcolonies embedded in an organic polymer matrix of microbial origin living at an interface between two different liquids, air and liquid, or solid and liquid. The biofilm matrix is made of extracellular polymeric substances, polysaccharides being considered as the major structural components of the matrix. Fluorescently labelled lectins have been widely used to stain microbial extracellular glycoconjugates in natural and artificial environments, and to study specific bacterial species or highly complex environments. Biofilm development at the membrane surface conducting to biofouling is one of the major problems encountered during drinking water production by filtration. Biofouling affects the durability and effectiveness of filtration membranes. Biofouling can be reduced by pretreatments in order to control two key parameters of water, the bioavailable organic matter concentration and the concentration of live bacteria. Nanofiltration (NF is a high technology process particularly suited to the treatment of surface waters to produce drinking water that is highly sensitive to biofouling. The development of strategies for fouling prevention and control requires characterizing the fouling material composition and organisation before and after NF membrane cleaning. The aim of this review is to present basics of biofilm analyses after staining with fluorescently labelled lectins and to focus on the use of fluorescent lectins and confocal laser scanning microscopy to analyse NF membrane biofouling.

Biofilms at work: Bio-, phyto- and rhizoremediation approaches for soils contaminated with polychlorinated biphenyls

Directory of Open Access Journals (Sweden)

Merily Horwat

2015-09-01

Full Text Available Organohalide contaminants such as polychlorinated biphenyls (PCBs have been released into the environment for decades due to anthropogenic activities, but are also naturally produced in small amounts through volcanic eruptions and geochemical processes. Although toxic to humans and other organisms, the natural production of these compounds has resulted in the evolution of naturally occurring organohalide-respiring bacteria that possess the enzymes necessary to degrade PCB compounds to non-toxic products. The efficiency of PCB degradation can be improved by facilitating the formation of organohalide-respiring biofilms. During biofilm colonization on a surface or interface, bacteria are encased in an extracellular polymeric substance (EPS or “slime,” which allows them to share nutrients and remain protected from environmental stresses. Effective bioremediation of PCBs involves facilitation of biofilm growth to promote cooperation between bacteria, which can be further enhanced by the presence of certain plant species. This review aims to give an overview of biofilm processes involved in the detoxification of PCBs including anaerobic and aerobic PCB degradation by bacteria as well as the ability of plants to stimulate microbial activity and degradation (rhizoremediation and phytoremediation.

Hydraulic resistance of biofilms

KAUST Repository

Dreszer, C.

2013-02-01

Biofilms may interfere with membrane performance in at least three ways: (i) increase of the transmembrane pressure drop, (ii) increase of feed channel (feed-concentrate) pressure drop, and (iii) increase of transmembrane passage. Given the relevance of biofouling, it is surprising how few data exist about the hydraulic resistance of biofilms that may affect the transmembrane pressure drop and membrane passage. In this study, biofilms were generated in a lab scale cross flow microfiltration system at two fluxes (20 and 100Lm-2h-1) and constant cross flow (0.1ms-1). As a nutrient source, acetate was added (1.0mgL-1 acetate C) besides a control without nutrient supply. A microfiltration (MF) membrane was chosen because the MF membrane resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric substances (EPS) were determined, it was demonstrated that no internal membrane fouling occurred and that the fouling layer actually consisted of a grown biofilm and was not a filter cake of accumulated bacterial cells. At 20Lm-2h-1 flux with a nutrient dosage of 1mgL-1 acetate C, the resistance after 4 days reached a value of 6×1012m-1. At 100Lm-2h-1 flux under the same conditions, the resistance was 5×1013m-1. No correlation of biofilm resistance to biofilm thickness was found; Biofilms with similar thickness could have different resistance depending on the applied flux. The cell number in biofilms was between 4×107 and 5×108 cellscm-2. At this number, bacterial cells make up less than a half percent of the overall biofilm volume and therefore did not hamper the water flow through the biofilm significantly. A flux of 100Lm-2h-1 with nutrient supply caused higher cell numbers, more biomass, and higher biofilm resistance than a flux of 20Lm-2h-1. However, the biofilm thickness

Monitoring in Real Time the Formation and Removal of Biofilms from Clinical Related Pathogens Using an Impedance-Based Technology

Science.gov (United States)

Gutiérrez, Diana; Hidalgo-Cantabrana, Claudio; Rodríguez, Ana; García, Pilar

2016-01-01

Bacteria found in diverse ecosystems grow in a community of aggregated cells that favors their survival and colonization. Different extracellular polymeric substances are used to entrap this multispecies community forming a biofilm, which can be associated to biotic and abiotic surfaces. This widespread and successful way of bacterial life, however, can lead to negative effects for human activity since many pathogen and spoiling bacteria form biofilms which are not easy to eradicate. Therefore, the search for novel anti-biofilm bio-active molecules is a very active research area for which simple, reliable, and fast screening methods are demanded. In this work we have successfully validated an impedance-based method, initially developed for the study of adherent eukaryotic cells, to monitor the formation of single-species biofilms of three model bacteria in real time. The xCelligence real time cell analyzer (RTCA) equipment uses specific microtiter E-plates coated with gold-microelectrodes that detect the attachment of adherent cells, thus modifying the impedance signal. In the current study, this technology allowed the distinction between biofilm-producers and non-producers of Staphylococcus aureus and Staphylococcus epidermidis, as well as the formation of Streptococcus mutans biofilms only when sucrose was present in the culture medium. Besides, different impedance values permitted discrimination among the biofilm-producing strains tested regardless of the nature of the polymeric biofilm matrix. Finally, we have continuously monitored the inhibition of staphylococcal biofilm formation by the bacteriophage phi-IPLA7 and the bacteriophage-encoded endolysin LysH5, as well as the removal of a preformed biofilm by this last antimicrobial treatment. Results observed with the impedance-based method showed high correlation with those obtained with standard approaches, such as crystal violet staining and bacteria enumeration, as well as with those obtained upon other

Monitoring in Real Time the Formation and Removal of Biofilms from Clinical Related Pathogens Using an Impedance-Based Technology.

Directory of Open Access Journals (Sweden)

Diana Gutiérrez

Full Text Available Bacteria found in diverse ecosystems grow in a community of aggregated cells that favors their survival and colonization. Different extracellular polymeric substances are used to entrap this multispecies community forming a biofilm, which can be associated to biotic and abiotic surfaces. This widespread and successful way of bacterial life, however, can lead to negative effects for human activity since many pathogen and spoiling bacteria form biofilms which are not easy to eradicate. Therefore, the search for novel anti-biofilm bio-active molecules is a very active research area for which simple, reliable, and fast screening methods are demanded. In this work we have successfully validated an impedance-based method, initially developed for the study of adherent eukaryotic cells, to monitor the formation of single-species biofilms of three model bacteria in real time. The xCelligence real time cell analyzer (RTCA equipment uses specific microtiter E-plates coated with gold-microelectrodes that detect the attachment of adherent cells, thus modifying the impedance signal. In the current study, this technology allowed the distinction between biofilm-producers and non-producers of Staphylococcus aureus and Staphylococcus epidermidis, as well as the formation of Streptococcus mutans biofilms only when sucrose was present in the culture medium. Besides, different impedance values permitted discrimination among the biofilm-producing strains tested regardless of the nature of the polymeric biofilm matrix. Finally, we have continuously monitored the inhibition of staphylococcal biofilm formation by the bacteriophage phi-IPLA7 and the bacteriophage-encoded endolysin LysH5, as well as the removal of a preformed biofilm by this last antimicrobial treatment. Results observed with the impedance-based method showed high correlation with those obtained with standard approaches, such as crystal violet staining and bacteria enumeration, as well as with those

Monitoring in Real Time the Formation and Removal of Biofilms from Clinical Related Pathogens Using an Impedance-Based Technology.

Science.gov (United States)

Gutiérrez, Diana; Hidalgo-Cantabrana, Claudio; Rodríguez, Ana; García, Pilar; Ruas-Madiedo, Patricia

2016-01-01

Bacteria found in diverse ecosystems grow in a community of aggregated cells that favors their survival and colonization. Different extracellular polymeric substances are used to entrap this multispecies community forming a biofilm, which can be associated to biotic and abiotic surfaces. This widespread and successful way of bacterial life, however, can lead to negative effects for human activity since many pathogen and spoiling bacteria form biofilms which are not easy to eradicate. Therefore, the search for novel anti-biofilm bio-active molecules is a very active research area for which simple, reliable, and fast screening methods are demanded. In this work we have successfully validated an impedance-based method, initially developed for the study of adherent eukaryotic cells, to monitor the formation of single-species biofilms of three model bacteria in real time. The xCelligence real time cell analyzer (RTCA) equipment uses specific microtiter E-plates coated with gold-microelectrodes that detect the attachment of adherent cells, thus modifying the impedance signal. In the current study, this technology allowed the distinction between biofilm-producers and non-producers of Staphylococcus aureus and Staphylococcus epidermidis, as well as the formation of Streptococcus mutans biofilms only when sucrose was present in the culture medium. Besides, different impedance values permitted discrimination among the biofilm-producing strains tested regardless of the nature of the polymeric biofilm matrix. Finally, we have continuously monitored the inhibition of staphylococcal biofilm formation by the bacteriophage phi-IPLA7 and the bacteriophage-encoded endolysin LysH5, as well as the removal of a preformed biofilm by this last antimicrobial treatment. Results observed with the impedance-based method showed high correlation with those obtained with standard approaches, such as crystal violet staining and bacteria enumeration, as well as with those obtained upon other

Confocal microscopy imaging of the biofilm matrix

DEFF Research Database (Denmark)

Schlafer, Sebastian; Meyer, Rikke L

2017-01-01

The extracellular matrix is an integral part of microbial biofilms and an important field of research. Confocal laser scanning microscopy is a valuable tool for the study of biofilms, and in particular of the biofilm matrix, as it allows real-time visualization of fully hydrated, living specimens...... the concentration of solutes and the diffusive properties of the biofilm matrix....

Roles of extracellular polymeric substances in enhanced biological phosphorus removal process.

Science.gov (United States)

Li, Wen-Wei; Zhang, Hai-Ling; Sheng, Guo-Ping; Yu, Han-Qing

2015-12-01

Enhanced biological phosphorus removal (EBPR) process is known to mainly rely on the ability of phosphorus-accumulating organisms to take up, transform and store excess amount of phosphorus (P) inside the cells. However, recent studies have revealed considerable accumulation of P also in the extracellular polymeric substances (EPS) of sludge, implying a non-negligible role of EPS in P removal by EBPR sludge. However, the contribution of EPS to P uptake and the forms of accumulated extracellular P vary substantially in different studies, and the underlying mechanism of P transformation and transportation in EPS remains poorly understood. This review provides a new recognition into the P removal process in EBPR system by incorporating the role of EPS. It overviews on the characteristics of P accumulation in EPS, explores the mechanism of P transformation and transportation in EBPR sludge and EPS, summarizes the main influential factors for the P-accumulation properties of EPS, and discusses the remaining knowledge gaps and needed future efforts that may lead to better understanding and use of such an EPS role for maximizing P recovery from wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

In vitro characterization of biofilms formed by Kingella kingae.

Science.gov (United States)

Kaplan, J B; Sampathkumar, V; Bendaoud, M; Giannakakis, A K; Lally, E T; Balashova, N V

2017-08-01

The Gram-negative bacterium Kingella kingae is part of the normal oropharyngeal mucosal flora of children biofilm formation has been coupled with pharyngeal colonization, osteoarticular infections, and infective endocarditis, no studies have investigated biofilm formation in K. kingae. In this study we measured biofilm formation by 79 K. kingae clinical isolates using a 96-well microtiter plate crystal violet binding assay. We found that 37 of 79 strains (47%) formed biofilms. All strains that formed biofilms produced corroding colonies on agar. Biofilm formation was inhibited by proteinase K and DNase I. DNase I also caused the detachment of pre-formed K. kingae biofilm colonies. A mutant strain carrying a deletion of the pilus gene cluster pilA1pilA2fimB did not produce corroding colonies on agar, autoaggregate in broth, or form biofilms. Biofilm forming strains have higher levels of pilA1 expression. The extracellular components of biofilms contained 490 μg cm -2 of protein, 0.68 μg cm -2 of DNA, and 0.4 μg cm -2 of total carbohydrates. We concluded that biofilm formation is common among K. kingae clinical isolates, and that biofilm formation is dependent on the production of proteinaceous pili and extracellular DNA. Biofilm development may have relevance to the colonization, transmission, and pathogenesis of this bacterium. Extracellular DNA production by K. kingae may facilitate horizontal gene transfer within the oral microbial community. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Iron triggers λSo prophage induction and release of extracellular DNA in Shewanella oneidensis MR-1 biofilms.

Science.gov (United States)

Binnenkade, Lucas; Teichmann, Laura; Thormann, Kai M

2014-09-01

Prophages are ubiquitous elements within bacterial chromosomes and affect host physiology and ecology in multiple ways. We have previously demonstrated that phage-induced lysis is required for extracellular DNA (eDNA) release and normal biofilm formation in Shewanella oneidensis MR-1. Here, we investigated the regulatory mechanisms of prophage λSo spatiotemporal induction in biofilms. To this end, we used a functional fluorescence fusion to monitor λSo activation in various mutant backgrounds and in response to different physiological conditions. λSo induction occurred mainly in a subpopulation of filamentous cells in a strictly RecA-dependent manner, implicating oxidative stress-induced DNA damage as the major trigger. Accordingly, mutants affected in the oxidative stress response (ΔoxyR) or iron homeostasis (Δfur) displayed drastically increased levels of phage induction and abnormal biofilm formation, while planktonic cells were not or only marginally affected. To further investigate the role of oxidative stress, we performed a mutant screen and identified two independent amino acid substitutions in OxyR (T104N and L197P) that suppress induction of λSo by hydrogen peroxide (H2O2). However, λSo induction was not suppressed in biofilms formed by both mutants, suggesting a minor role of intracellular H2O2 in this process. In contrast, addition of iron to biofilms strongly enhanced λSo induction and eDNA release, while both processes were significantly suppressed at low iron levels, strongly indicating that iron is the limiting factor. We conclude that uptake of iron during biofilm formation triggers λSo-mediated lysis of a subpopulation of cells, likely by an increase in iron-mediated DNA damage sensed by RecA. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation

Science.gov (United States)

Laverty, Garry; Gorman, Sean P.; Gilmore, Brendan F.

2014-01-01

Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl), pellicle Formation (Pel) and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides) that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation. PMID:25438014

Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation

Directory of Open Access Journals (Sweden)

Garry Laverty

2014-07-01

Full Text Available Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl, pellicle Formation (Pel and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation.

Identification of Genes Involved in Polysaccharide-Independent Staphylococcus aureus Biofilm Formation

Science.gov (United States)

Boles, Blaise R.; Thoendel, Matthew; Roth, Aleeza J.; Horswill, Alexander R.

2010-01-01

Staphylococcus aureus is a potent biofilm former on host tissue and medical implants, and biofilm growth is a critical virulence determinant for chronic infections. Recent studies suggest that many clinical isolates form polysaccharide-independent biofilms. However, a systematic screen for defective mutants has not been performed to identify factors important for biofilm formation in these strains. We created a library of 14,880 mariner transposon mutants in a S. aureus strain that generates a proteinaceous and extracellular DNA based biofilm matrix. The library was screened for biofilm defects and 31 transposon mutants conferred a reproducible phenotype. In the pool, 16 mutants overproduced extracellular proteases and the protease inhibitor α2-macroglobulin restored biofilm capacity to 13 of these mutants. The other 15 mutants in the pool displayed normal protease levels and had defects in genes involved in autolysis, osmoregulation, or uncharacterized membrane proteins. Two transposon mutants of interest in the GraRS two-component system and a putative inositol monophosphatase were confirmed in a flow cell biofilm model, genetically complemented, and further verified in a community-associated methicillin-resistant S. aureus (CA-MRSA) isolate. Collectively, our screen for biofilm defective mutants identified novel loci involved in S. aureus biofilm formation and underscored the importance of extracellular protease activity and autolysis in biofilm development. PMID:20418950

Hygrocin C from marine-derived Streptomyces sp. SCSGAA 0027 inhibits biofilm formation in Bacillus amyloliquefaciens SCSGAB0082 isolated from South China Sea gorgonian.

Science.gov (United States)

Wang, Jie; Nong, Xu-Hua; Amin, Muhammad; Qi, Shu-Hua

2018-02-01

Several ansamycins have been reported to inhibit bacterial biofilm formation and accelerate the eradication of developed biofilms, but little is known about the effect of hygrocin C, an ansamycin, on bacterial biofilm formation. Here, hygrocin C was isolated from the marine-derived Streptomyces sp. SCSGAA 0027 and reported for the first time to be capable of inhibiting the biofilm formation of Staphylococcus aureus and Bacillus amyloliquefaciens SCSGAB0082 with the production of anti-microbial lipopeptides from South China Sea gorgonian Subergorgia suberosa at concentrations of less than minimum inhibitory concentrations. Moreover, hygrocin C also promoted the eradication of developed biofilms, affected the biofilm architecture, and lowered the extracellular polymeric matrix formation, cell motility, and surface hydrophobicity in B. amyloliquefaciens, which was in accordance with the inhibition of biofilm formation. Furthermore, transcriptome analysis revealed that hygrocin C altered the transcripts of several genes associated with bacterial chemotaxis and flagellar, two-component system and the synthesis of arginine and histidine, which are important for bacterial biofilm formation. In conclusion, hygrocin C could be used as a potential biofilm inhibitor against S. aureus and B. amyloliquefaciens. But further genetic investigations are needed to provide more details for elucidation of the molecular mechanisms responsible for the effects of hygrocin C on B. amyloliquefaciens biofilm formation.

A new dry-surface biofilm model: An essential tool for efficacy testing of hospital surface decontamination procedures.

Science.gov (United States)

Almatroudi, Ahmad; Hu, Honghua; Deva, Anand; Gosbell, Iain B; Jacombs, Anita; Jensen, Slade O; Whiteley, Greg; Glasbey, Trevor; Vickery, Karen

2015-10-01

The environment has been shown to be a source of pathogens causing infections in hospitalised patients. Incorporation of pathogens into biofilms, contaminating dry hospital surfaces, prolongs their survival and renders them tolerant to normal hospital cleaning and disinfection procedures. Currently there is no standard method for testing efficacy of detergents and disinfectants against biofilm formed on dry surfaces. The aim of this study was to develop a reproducible method of producing Staphylococcus aureus biofilm with properties similar to those of biofilm obtained from dry hospital clinical surfaces, for use in efficacy testing of decontamination products. The properties (composition, architecture) of model biofilm and biofilm obtained from clinical dry surfaces within an intensive care unit were compared. The CDC Biofilm Reactor was adapted to create a dry surface biofilm model. S. aureus ATCC 25923 was grown on polycarbonate coupons. Alternating cycles of dehydration and hydration in tryptone soy broth (TSB) were performed over 12 days. Number of biofilm bacteria attached to individual coupons was determined by plate culture and the coefficient of variation (CV%) calculated. The DNA, glycoconjugates and protein content of the biofilm were determined by analysing biofilm stained with SYTO 60, Alexa-488-labelled Aleuria aurantia lectin and SyproOrange respectively using Image J and Imaris software. Biofilm architecture was analysed using live/dead staining and confocal microscopy (CM) and scanning electron microscopy (SEM). Model biofilm was compared to naturally formed biofilm containing S. aureus on dry clinical surfaces. The CDC Biofilm reactor reproducibly formed a multi-layered, biofilm containing about 10(7) CFU/coupon embedded in thick extracellular polymeric substances. Within run CV was 9.5% and the between run CV was 10.1%. Protein was the principal component of both the in vitro model biofilm and the biofilms found on clinical surfaces. Continued

Initial transport and retention behaviors of ZnO nanoparticles in quartz sand porous media coated with Escherichia coli biofilm

International Nuclear Information System (INIS)

Jiang, Xujia; Wang, Xueting; Tong, Meiping; Kim, Hyunjung

2013-01-01

The significance of biofilm on the transport and deposition behaviors of ZnO nanoparticles were examined under a series of environmentally relevant ionic strength at two fluid velocities of 4 m-d −1 and 8 m-d −1 . Biofilm enhanced nanoparticles retention in porous media under all examined conditions. The greater deposition was also observed in extracellular polymeric substances (EPS) coated surfaces by employment of quartz microbalance with dissipation (QCM-D) system. Derjaguin–Landau–Verwey–Overbeek (DLVO) failed to interpret more ZnO nanoparticles deposition on biofilm (EPS) coated silica surfaces. Chemical interaction and physical morphology of biofilm contributed to this greater deposition (retention). Biofilm affected the spacial distribution of retained ZnO nanoparticles as well. Relatively steeper slope of retained profiles were observed in the presence of biofilm, corresponding to the greater deviation from colloid filtration theory (CFT). Pore space constriction via biofilm induced more nanoparticle trapped in the column inlet, leading to greater deviations (σln k f ) from the CFT. Highlights: ► Biofilm reduced the mobility of ZnO nanoparticles in column. ► DLVO and non-DLVO interactions contributed the more nanoparticles deposition. ► Biofilm also affected the spacial distribution of ZnO nanoparticles in column. ► Greater deviation from classic filtration theory was observed with biofilm. ► Physical structure of biofilm induced greater deviation from log-linear prediction. -- Biofilm enhanced ZnO nanoparticle deposition and altered spacial distribution in porous media

Pseudomonas aeruginosa biofilm infections

DEFF Research Database (Denmark)

Tolker-Nielsen, Tim

2014-01-01

Bacteria in natural, industrial and clinical settings predominantly live in biofilms, i.e., sessile structured microbial communities encased in self-produced extracellular matrix material. One of the most important characteristics of microbial biofilms is that the resident bacteria display...... a remarkable increased tolerance toward antimicrobial attack. Biofilms formed by opportunistic pathogenic bacteria are involved in devastating persistent medical device-associated infections, and chronic infections in individuals who are immune-compromised or otherwise impaired in the host defense. Because...... the use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

AtlA Mediates Extracellular DNA Release, Which Contributes to Streptococcus mutans Biofilm Formation in an Experimental Rat Model of Infective Endocarditis.

Science.gov (United States)

Jung, Chiau-Jing; Hsu, Ron-Bin; Shun, Chia-Tung; Hsu, Chih-Chieh; Chia, Jean-San

2017-09-01

Host factors, such as platelets, have been shown to enhance biofilm formation by oral commensal streptococci, inducing infective endocarditis (IE), but how bacterial components contribute to biofilm formation in vivo is still not clear. We demonstrated previously that an isogenic mutant strain of Streptococcus mutans deficient in autolysin AtlA (Δ atlA ) showed a reduced ability to cause vegetation in a rat model of bacterial endocarditis. However, the role of AtlA in bacterial biofilm formation is unclear. In this study, confocal laser scanning microscopy analysis showed that extracellular DNA (eDNA) was embedded in S. mutans GS5 floes during biofilm formation on damaged heart valves, but an Δ atlA strain could not form bacterial aggregates. Semiquantification of eDNA by PCR with bacterial 16S rRNA primers demonstrated that the Δ atlA mutant strain produced dramatically less eDNA than the wild type. Similar results were observed with in vitro biofilm models. The addition of polyanethol sulfonate, a chemical lysis inhibitor, revealed that eDNA release mediated by bacterial cell lysis is required for biofilm initiation and maturation in the wild-type strain. Supplementation of cultures with calcium ions reduced wild-type growth but increased eDNA release and biofilm mass. The effect of calcium ions on biofilm formation was abolished in Δ atlA cultures and by the addition of polyanethol sulfonate. The VicK sensor, but not CiaH, was found to be required for the induction of eDNA release or the stimulation of biofilm formation by calcium ions. These data suggest that calcium ion-regulated AtlA maturation mediates the release of eDNA by S. mutans , which contributes to biofilm formation in infective endocarditis. Copyright © 2017 American Society for Microbiology.

Influence of phosphorus availability on the community structure and physiology of cultured biofilms.

Science.gov (United States)

Li, Shuangshuang; Wang, Chun; Qin, Hongjie; Li, Yinxia; Zheng, Jiaoli; Peng, Chengrong; Li, Dunhai

2016-04-01

Biofilms have important effects on nutrient cycling in aquatic ecosystems. However, publications about the community structure and functions under laboratory conditions are rare. This study focused on the developmental and physiological properties of cultured biofilms under various phosphorus concentrations performed in a closely controlled continuous flow incubator. The results showed that the biomass (Chl a) and photosynthesis of algae were inhibited under P-limitation conditions, while the phosphatase activity and P assimilation rate were promoted. The algal community structure of biofilms was more likely related to the colonization stage than with the phosphorus availability. Cyanobacteria were more competitive than other algae in biofilms, particularly when cultured under low P levels. A dominance shift occurred from non-filamentous algae in the early stage to filamentous algae in the mid and late stages under P concentrations of 0.01, 0.1 and 0.6 mg/L. However, the total N content, dry weight biomass and bacterial community structure of biofilms were unaffected by phosphorus availability. This may be attributed to the low respiration rate, high accumulation of extracellular polymeric substances and high alkaline phosphatase activity in biofilms when phosphorus availability was low. The bacterial community structure differed over time, while there was little difference between the four treatments, which indicated that it was mainly affected by the colonization stage of the biofilms rather than the phosphorus availability. Altogether, these results suggested that the development of biofilms was influenced by the phosphorus availability and/or the colonization stage and hence determined the role that biofilms play in the overlying water. Copyright © 2015. Published by Elsevier B.V.

Response of Muddy Sediments and Benthic Diatom-based Biofilms to Repeated Erosion Events

Science.gov (United States)

Valentine, K.; Mariotti, G.; Fagherazzi, S.

2016-02-01

Benthic biofilms, microbes aggregated within a matrix of Extracellular Polymeric Substances (EPS), are commonly found in shallow coastal areas and intertidal environments. Biofilms have the potential to stabilize sediments, hence reducing erosion and possibly mitigating land loss. The purpose of this study is to determine how repeated flow events that rework the bed affect biofilm growth and its ability to stabilize cohesive sediments. Natural mud devoid of grazers was used to create placed beds in four annular flumes; biofilms were allowed to grow on the sediment surface. Each flume was eroded at different time intervals (1 or 12 days) to allow for varied levels of biofilm growth and adjustment following erosion. In addition, experiments with abiotic mud were performed by adding bleach to the tank. Each erosion test consisted of step-wise increases in flow that were used to measured erodibility. In the experiments where the bed was eroded every day both the abiotic and biotic flumes exhibited a decrease in erodibility with time, likely due to consolidation, but the decrease in erodibility was greater in the flume with a biofilm. Specifically the presence of biofilm reduced bed erosion at low shear stresses ( 0.1 Pa). We attribute this progressive decrease in erodibility to the accumulation of EPS over time: even though the biofilm was eroded during each erosion event, the EPS was retained within the flume, mixed with the eroded sediment and eventually settled. Less frequent erosion allowed the growth of a stronger biofilm that decreased bed erosion at higher shear stresses ( 0.4 Pa). We conclude that the time between destructive flow events influences the ability of biofilms to stabilize sediments. This influence will likely be affected by biofilm growth conditions such as light, temperature, nutrients, salinity, and the microbial community.

Biofilm formation and disinfectant resistance of Salmonella sp. in mono- and dual-species with Pseudomonas aeruginosa.

Science.gov (United States)

Pang, X Y; Yang, Y S; Yuk, H G

2017-09-01

This study aimed to evaluate the biofilm formation and disinfectant resistance of Salmonella cells in mono- and dual-species biofilms with Pseudomonas aeruginosa, and to investigate the role of extracellular polymeric substances (EPS) in the protection of biofilms against disinfection treatment. The populations of Salmonella in mono- or dual-species biofilms with P. aeruginosa on stainless steel (SS) coupons were determined before and after exposure to commercial disinfectant, 50 μg ml -1 chlorine or 200 μg ml -1 Ecolab ® Whisper™ V (a blend of four effective quaternary ammonium compounds (QAC)). In addition, EPS amount from biofilms was quantified and biofilm structures were observed using scanning electron microscopy (SEM). Antagonistic interactions between Salmonella and P. aeruginosa resulted in lower planktonic population level of Salmonella, and lower density in dual-species biofilms compared to mono-species biofilms. The presence of P. aeruginosa significantly enhanced disinfectant resistance of S. Typhimurium and S. Enteritidis biofilm cells for 2 days, and led to an average of 50% increase in polysaccharides amount in dual-species biofilms than mono-species biofilms of Salmonella. Microscopy observation showed the presence of large microcolonies covered by EPS in dual-species biofilms but not in mono-species ones. The presence of P. aeruginosa in dual-species culture inhibited the growth of Salmonella cells in planktonic phase and in biofilms, but protected Salmonella cells in biofilms from disinfection treatment, by providing more production of EPS in dual-species biofilms than mono-species ones. This study provides insights into inter-species interaction, with regard to biofilm population dynamics and disinfectant resistance. Thus, a sanitation protocol should be designed considering the protective role of secondary species to pathogens in biofilms on SS surface which has been widely used at food surfaces and manufacturers. © 2017 The Society

Formation of Biofilms by Foodborne Pathogens and Development of Laboratory In Vitro Model for the Study of Campylobacter Genus Bacteria Based on These Biofilms.

Science.gov (United States)

Efimochkina, N R; Bykova, I B; Markova, Yu M; Korotkevich, Yu V; Stetsenko, V V; Minaeva, L P; Sheveleva, S A

2017-02-01

We analyzed the formation of biofilms by 7 strains of Campylobacter genus bacteria and 18 strains of Enterobacteriaceae genus bacteria that were isolated from plant and animal raw materials, from finished products, and swabs from the equipment of the food industry. Biofilm formation on glass plates, slides and coverslips, microtubes made of polymeric materials and Petri dishes, and polystyrene plates of different profiles were analyzed. When studying the process of films formation, different effects on bacterial populations were simulated, including variation of growth factor composition of culture media, technique of creating of anaerobiosis, and biocide treatment (active chlorine solutions in a concentration of 100 mg/dm 3 ). The formation of biofilms by the studied cultures was assessed by the formation of extracellular matrix stained with aniline dyes on glass and polystyrene surfaces after incubation; 0.1% crystal violet solution was used as the dye. The presence and density of biomatrix were assessed by staining intensity of the surfaces of contact with broth cultures or by optical density of the stained inoculum on a spectrophotometer. Biofilms were formed by 57% Campylobacter strains and 44% Enterobacteriaceae strains. The intensity of the film formation depended on culturing conditions and protocols, species and genus of studied isolates, and largely on adhesion properties of abiotic surfaces. In 30% of Enterobacteriaceae strains, the biofilm formation capacity tended to increase under the influence of chlorine-containing biocide solutions. Thus, we developed and tested under laboratory conditions a plate version of in vitro chromogenic model for evaluation of biofilm formation capacity of C. jejuni strains and studied stress responses to negative environmental factors.

Identification of genes involved in polysaccharide-independent Staphylococcus aureus biofilm formation.

Directory of Open Access Journals (Sweden)

Blaise R Boles

2010-04-01

Full Text Available Staphylococcus aureus is a potent biofilm former on host tissue and medical implants, and biofilm growth is a critical virulence determinant for chronic infections. Recent studies suggest that many clinical isolates form polysaccharide-independent biofilms. However, a systematic screen for defective mutants has not been performed to identify factors important for biofilm formation in these strains. We created a library of 14,880 mariner transposon mutants in a S. aureus strain that generates a proteinaceous and extracellular DNA based biofilm matrix. The library was screened for biofilm defects and 31 transposon mutants conferred a reproducible phenotype. In the pool, 16 mutants overproduced extracellular proteases and the protease inhibitor alpha(2-macroglobulin restored biofilm capacity to 13 of these mutants. The other 15 mutants in the pool displayed normal protease levels and had defects in genes involved in autolysis, osmoregulation, or uncharacterized membrane proteins. Two transposon mutants of interest in the GraRS two-component system and a putative inositol monophosphatase were confirmed in a flow cell biofilm model, genetically complemented, and further verified in a community-associated methicillin-resistant S. aureus (CA-MRSA isolate. Collectively, our screen for biofilm defective mutants identified novel loci involved in S. aureus biofilm formation and underscored the importance of extracellular protease activity and autolysis in biofilm development.

Dynamic interactions of neutrophils and biofilms

Directory of Open Access Journals (Sweden)

Josefine Hirschfeld

2014-12-01

Full Text Available Background: The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms. Objective/design: In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed. Results/conclusion: Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

Induction of Biofilm Formation in the Betaproteobacterium Burkholderia unamae CK43B Exposed to Exogenous Indole and Gallic Acid

Science.gov (United States)

Kim, Dongyeop; Sitepu, Irnayuli R.

2013-01-01

Burkholderia unamae CK43B, a member of the Betaproteobacteria that was isolated from the rhizosphere of a Shorea balangeran sapling in a tropical peat swamp forest, produces neither indole nor extracellular polymeric substances associated with biofilm formation. When cultured in a modified Winogradsky's medium supplemented with up to 1.7 mM indole, B. unamae CK43B maintains its planktonic state by cell swelling and effectively degrades exogenous indole. However, in medium supplemented with 1.7 mM exogenous indole and 1.0 mM gallic acid, B. unamae CK43B produced extracellular polymeric substances and formed a biofilm. The concentration indicated above of gallic acid alone had no effect on either the growth or the differentiation of B. unamae CK43B cells above a certain concentration threshold, whereas it inhibited indole degradation by B. unamae CK43B to 3-hydroxyindoxyl. In addition, coculture of B. unamae CK43B with indole-producing Escherichia coli in nutrient-rich Luria-Bertani medium supplemented with 1.0 mM gallic acid led to the formation of mixed cell aggregates. The viability and active growth of B. unamae CK43B cells in a coculture system with Escherichia coli were evidenced by fluorescence in situ hybridization. Our data thus suggest that indole facilitates intergenus communication between indole-producing gammaproteobacteria and some indole-degrading bacteria, particularly in gallic acid-rich environments. PMID:23747701

Poly-γ-Glutamic Acids Contribute to Biofilm Formation and Plant Root Colonization in Selected Environmental Isolates of Bacillus subtilis

Science.gov (United States)

Yu, Yiyang; Yan, Fang; Chen, Yun; Jin, Christopher; Guo, Jian-Hua; Chai, Yunrong

2016-01-01

Bacillus subtilis is long known to produce poly-γ-glutamic acids (γ-PGA) as one of the major secreted polymeric substances. In B. subtilis, the regulation of γ-PGA production and its physiological role are still unclear. B. subtilis is also capable of forming structurally complex multicellular communities, or biofilms, in which an extracellular matrix consisting of secreted proteins and polysaccharides holds individual cells together. Biofilms were shown to facilitate B. subtilis–plant interactions. In this study, we show that different environmental isolates of B. subtilis, all capable of forming biofilms, vary significantly in γ-PGA production. This is possibly due to differential regulation of γ-PGA biosynthesis genes. In many of those environmental isolates, γ-PGA seems to contribute to robustness and complex morphology of the colony biofilms, suggesting a role of γ-PGA in biofilm formation. Our evidence further shows that in selected B. subtilis strains, γ-PGA also plays a role in root colonization by the bacteria, pinpointing a possible function of γ-PGA in B. subtilis–plant interactions. Finally, we found that several pathways co-regulate both γ-PGA biosynthesis genes and genes for the biofilm matrix in B. subtilis, but in an opposing fashion. We discussed potential biological significance of that. PMID:27891125

Biofilm structures (EPS and bacterial communities) in drinking water distribution systems are conditioned by hydraulics and influence discolouration.

Science.gov (United States)

Fish, K; Osborn, A M; Boxall, J B

2017-09-01

High-quality drinking water from treatment works is degraded during transport to customer taps through the Drinking Water Distribution System (DWDS). Interactions occurring at the pipe wall-water interface are central to this degradation and are often dominated by complex microbial biofilms that are not well understood. This study uses novel application of confocal microscopy techniques to quantify the composition of extracellular polymeric substances (EPS) and cells of DWDS biofilms together with concurrent evaluation of the bacterial community. An internationally unique, full-scale, experimental DWDS facility was used to investigate the impact of three different hydraulic patterns upon biofilms and subsequently assess their response to increases in shear stress, linking biofilms to water quality impacts such as discolouration. Greater flow variation during growth was associated with increased cell quantity but was inversely related to EPS-to-cell volume ratios and bacterial diversity. Discolouration was caused and EPS was mobilised during flushing of all conditions. Ultimately, biofilms developed under low-varied flow conditions had lowest amounts of biomass, the greatest EPS volumes per cell and the lowest discolouration response. This research shows that the interactions between hydraulics and biofilm physical and community structures are complex but critical to managing biofilms within ageing DWDS infrastructure to limit water quality degradation and protect public health. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

The role of microbial-produced extracellular polymeric matrix in the formation and survival of biological soil crusts

Science.gov (United States)

Rossi, Federico; Adessi, Alessandra; De Philippis, Roberto

2016-04-01

Biological soil crusts (BSCs) are complex communities commonly constituting organo-mineral layers in arid and semiarid environment having a major influence on these ecosystems (Belnap and Lange, 2001). They have high tolerance towards a-biotic stresses and fluctuations in moisture, illumination, salinity and nutrients. The plasticity exhibited by BSCs is hugely contributed by the presence of the extracellular polymeric matrix (EPM) that is synthesized by crustal organisms, notably cyanobacteria and microalgae. This polysaccharidic net plays key roles in biofilm relations with the surrounding constrained environment. Notably, EPM concurs in coping with water scarcity, freezing and salt stress; increases biolayers stability against erosion, and is involved in nutrient provision (Rossi and De Philippis, 2015). We conducted several investigations in a research area located in the Inner Mongolian desert (Inner Mongolia, China) where BSCs were induced over different sites through inoculation-based techniques performed in different years. Our studies were aimed at determining the role of EPM in BSC development and survival in such a hyper-arid system. This presentation will report the results concerning the role of EPM in water capture from non-rainfall sources, water maintenance at the topsoil, and in water infiltrability, the latter being a factor with important ecological implications. In additions we investigated the role of the matrix as a source of carbon for the crustal heterotrophs. Furthermore, EPM was extracted with methods optimized in our lab, aiming at removing tightly bound fractions and loosely bound fractions from BSCs having different ages. The fractions were analyzed in terms of monosaccharidic composition, and molecular weight (MW) distribution. We show how the relative amounts of uronic acids increase in the EPM with the age of the crusts, implying advantages for the community-water relations. In addition, we observed significant differences in MW

Investigation of Aspergillus fumigatus biofilm formation by various “omics” approaches

Science.gov (United States)

Muszkieta, Laetitia; Beauvais, Anne; Pähtz, Vera; Gibbons, John G.; Anton Leberre, Véronique; Beau, Rémi; Shibuya, Kazutoshi; Rokas, Antonis; Francois, Jean M.; Kniemeyer, Olaf; Brakhage, Axel A.; Latgé, Jean P.

2013-01-01

In the lung, Aspergillus fumigatus usually forms a dense colony of filaments embedded in a polymeric extracellular matrix called biofilm (BF). This extracellular matrix embeds and glues hyphae together and protects the fungus from an outside hostile environment. This extracellular matrix is absent in fungal colonies grown under classical liquid shake conditions (PL), which were historically used to understand A. fumigatus pathobiology. Recent works have shown that the fungus in this aerial grown BF-like state exhibits reduced susceptibility to antifungal drugs and undergoes major metabolic changes that are thought to be associated to virulence. These differences in pathological and physiological characteristics between BF and liquid shake conditions suggest that the PL condition is a poor in vitro disease model. In the laboratory, A. fumigatus mycelium embedded by the extracellular matrix can be produced in vitro in aerial condition using an agar-based medium. To provide a global and accurate understanding of A. fumigatus in vitro BF growth, we utilized microarray, RNA-sequencing, and proteomic analysis to compare the global gene and protein expression profiles of A. fumigatus grown under BF and PL conditions. In this review, we will present the different signatures obtained with these three “omics” methods. We will discuss the advantages and limitations of each method and their complementarity. PMID:23407341

Efficacy of a marine bacterial nuclease against biofilm forming microorganisms isolated from chronic rhinosinusitis.

Directory of Open Access Journals (Sweden)

Robert C Shields

Full Text Available BACKGROUND: The persistent colonization of paranasal sinus mucosa by microbial biofilms is a major factor in the pathogenesis of chronic rhinosinusitis (CRS. Control of microorganisms within biofilms is hampered by the presence of viscous extracellular polymers of host or microbial origin, including nucleic acids. The aim of this study was to investigate the role of extracellular DNA in biofilm formation by bacteria associated with CRS. METHODS/PRINCIPAL FINDINGS: Obstructive mucin was collected from patients during functional endoscopic sinus surgery. Examination of the mucous by transmission electron microscopy revealed an acellular matrix punctuated occasionally with host cells in varying states of degradation. Bacteria were observed in biofilms on mucosal biopsies, and between two and six different species were isolated from each of 20 different patient samples. In total, 16 different bacterial genera were isolated, of which the most commonly identified organisms were coagulase-negative staphylococci, Staphylococcus aureus and α-haemolytic streptococci. Twenty-four fresh clinical isolates were selected for investigation of biofilm formation in vitro using a microplate model system. Biofilms formed by 14 strains, including all 9 extracellular nuclease-producing bacteria, were significantly disrupted by treatment with a novel bacterial deoxyribonuclease, NucB, isolated from a marine strain of Bacillus licheniformis. Extracellular biofilm matrix was observed in untreated samples but not in those treated with NucB and extracellular DNA was purified from in vitro biofilms. CONCLUSION/SIGNIFICANCE: Our data demonstrate that bacteria associated with CRS form robust biofilms which can be reduced by treatment with matrix-degrading enzymes such as NucB. The dispersal of bacterial biofilms with NucB may offer an additional therapeutic target for CRS sufferers.

The possible role of bacterial signal molecules N-acyl homoserine lactones in the formation of diatom-biofilm (Cylindrotheca sp.)

International Nuclear Information System (INIS)

Yang, Cuiyun; Fang, Shengtao; Chen, Dehui; Wang, Jianhua; Liu, Fanghua; Xia, Chuanhai

2016-01-01

Bacterial quorum sensing signal molecules N-acyl homoserine lactones (AHLs) (C10-HSL, 3-OXO-C10-HSL and 3-OH-C10-HSL) as possible chemical cues were employed to investigate the role in the formation of fouling diatom-biofilm (Cylindrotheca sp.). Results showed that AHLs promoted Chlorophyll a (Chl.a) and extracellular polymeric substance (EPS) contents in the diatom-biofilm. In the presence of AHLs-inhibitor 3, 4-Dibromo-2(5)H-furanone, which was used to avoid the possible interference of AHLs from bacteria, AHLs also increased the Chl.a and EPS contents. Scanning electron microscope and confocal laser scanning microscope analysis further demonstrated that AHLs promoted the formation of the diatom-biofilm. Non-invasive micro-test technique showed that AHLs promoted Ca 2+ efflux in Cylindrotheca sp., which implied that Ca 2+ might be correlated with AHLs-induced positive effect on the formation of diatom-biofilm. This study provides direct evidences that AHLs play an important role in developing the diatom-biofilm and AHLs-inhibitors might be promising active agents in marine antifouling. - Highlights: •AHLs effectively increase Chl.a and EPS contents in diatom-biofilm. •SEM and CLSM further demonstrate that AHLs promote the formation of diatom-biofilm. •AHLs trigger algal cellular Ca 2+ efflux. •AHLs-inhibitors might be promising active agents in marine antifouling.

In situ biosensing of the nanomechanical property and electrochemical spectroscopy of Streptococcus mutans-containing biofilms

Science.gov (United States)

Haochih Liu, Bernard; Li, Kun-Lin; Kang, Kai-Li; Huang, Wen-Ke; Liao, Jiunn-Der

2013-07-01

This work presents in situ biosensing approaches to study the nanomechanical and electrochemical behaviour of Streptococcus mutans biofilms under different cultivation conditions and microenvironments. The surface characteristics and sub-surface electrochemistry of the cell wall of S. mutans were measured by atomic force microscopy (AFM) based techniques to monitor the in situ biophysical status of biofilms under common anti-pathogenic procedures such as ultraviolet (UV) radiation and alcohol treatment. The AFM nanoindentation suggested a positive correlation between nanomechanical strength and the level of UV radiation of S. mutans; scanning impedance spectroscopy of dehydrated biofilms revealed reduced electrical resistance that is distinctive from that of living biofilms, which can be explained by the discharge of cytoplasm after alcohol treatment. Furthermore, the localized elastic moduli of four regions of the biofilm were studied: septum (Z-ring), cell wall, the interconnecting area between two cells and extracellular polymeric substance (EPS) area. The results indicated that cell walls exhibit the highest elastic modulus, followed by Z-ring, interconnect and EPS. Our approach provides an effective alternative for the characterization of the viability of living cells without the use of biochemical labelling tools such as fluorescence dyeing, and does not rely on surface binding or immobilization for detection. These AFM-based techniques can be very promising approaches when the conventional methods fall short.

In situ biosensing of the nanomechanical property and electrochemical spectroscopy of Streptococcus mutans-containing biofilms

International Nuclear Information System (INIS)

Liu, Bernard Haochih; Li, Kun-Lin; Kang, Kai-Li; Huang, Wen-Ke; Liao, Jiunn-Der

2013-01-01

This work presents in situ biosensing approaches to study the nanomechanical and electrochemical behaviour of Streptococcus mutans biofilms under different cultivation conditions and microenvironments. The surface characteristics and sub-surface electrochemistry of the cell wall of S. mutans were measured by atomic force microscopy (AFM) based techniques to monitor the in situ biophysical status of biofilms under common anti-pathogenic procedures such as ultraviolet (UV) radiation and alcohol treatment. The AFM nanoindentation suggested a positive correlation between nanomechanical strength and the level of UV radiation of S. mutans; scanning impedance spectroscopy of dehydrated biofilms revealed reduced electrical resistance that is distinctive from that of living biofilms, which can be explained by the discharge of cytoplasm after alcohol treatment. Furthermore, the localized elastic moduli of four regions of the biofilm were studied: septum (Z-ring), cell wall, the interconnecting area between two cells and extracellular polymeric substance (EPS) area. The results indicated that cell walls exhibit the highest elastic modulus, followed by Z-ring, interconnect and EPS. Our approach provides an effective alternative for the characterization of the viability of living cells without the use of biochemical labelling tools such as fluorescence dyeing, and does not rely on surface binding or immobilization for detection. These AFM-based techniques can be very promising approaches when the conventional methods fall short. (paper)

Combination of cupric ion with hydroxylamine and hydrogen peroxide for the control of bacterial biofilms on RO membranes.

Science.gov (United States)

Lee, Hye-Jin; Kim, Hyung-Eun; Lee, Changha

2017-03-01

Combinations of Cu(II) with hydroxylamine (HA) and hydrogen peroxide (H 2 O 2 ) (i.e., Cu(II)/HA, Cu(II)/H 2 O 2 , and Cu(II)/HA/H 2 O 2 systems) were investigated for the control of P. aeruginosa biofilms on reverse osmosis (RO) membranes. These Cu(II)-based disinfection systems effectively inactivated P. aeruginosa cells, exhibiting different behaviors depending on the state of bacterial cells (planktonic or biofilm) and the condition of biofilm growth and treatment (normal or pressurized condition). The Cu(II)/HA and Cu(II)/HA/H 2 O 2 systems were the most effective reagents for the inactivation of planktonic cells. However, these systems were not effective in inactivating cells in biofilms on the RO membranes possibly due to the interactions of Cu(I) with extracellular polymeric substances (EPS), where biofilms were grown and treated in center for disease control (CDC) reactors. Different from the results using CDC reactors, in a pressurized cross-flow RO filtration unit, the Cu(II)/HA/H 2 O 2 treatment significantly inactivated biofilm cells formed on the RO membranes, successfully recovering the permeate flux reduced by the biofouling. The pretreatment of feed solutions by Cu(II)/HA and Cu(II)/HA/H 2 O 2 systems (applied before the biofilm formation) effectively mitigated the permeate flux decline by preventing the biofilm growth on the RO membranes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Iron on DNA Release and Biofilm Development by Pseudomonas Aeruginosa

DEFF Research Database (Denmark)

Yang, Liang; Barken, Kim Bundvig; Skindersø, Mette Elena

2007-01-01

Extracellular DNA is one of the major matrix components in Pseudomonas aeruginosa biofilms. It functions as an intercellular connector and plays a role in stabilization of the biofilms. Evidence that DNA release in P. aeruginosa PAO1 biofilms is controlled by the las-rhl and pqs quorum-sensing sy......Extracellular DNA is one of the major matrix components in Pseudomonas aeruginosa biofilms. It functions as an intercellular connector and plays a role in stabilization of the biofilms. Evidence that DNA release in P. aeruginosa PAO1 biofilms is controlled by the las-rhl and pqs quorum......-sensing systems has been previously presented. This paper provides evidence that DNA release in P. aeruginosa PAO1 biofilms is also under iron regulation. Experiments involving cultivation of P. aeruginosa in microtitre trays suggested that pqs expression, DNA release and biofilm formation were favoured in media...

Transcriptomic and proteomic analyses of Desulfovibrio vulgaris biofilms: carbon and energy flow contribute to the distinct biofilm growth state.

Science.gov (United States)

Clark, Melinda E; He, Zhili; Redding, Alyssa M; Joachimiak, Marcin P; Keasling, Jay D; Zhou, Jizhong Z; Arkin, Adam P; Mukhopadhyay, Aindrila; Fields, Matthew W

2012-04-16

Desulfovibrio vulgaris Hildenborough is a sulfate-reducing bacterium (SRB) that is intensively studied in the context of metal corrosion and heavy-metal bioremediation, and SRB populations are commonly observed in pipe and subsurface environments as surface-associated populations. In order to elucidate physiological changes associated with biofilm growth at both the transcript and protein level, transcriptomic and proteomic analyses were done on mature biofilm cells and compared to both batch and reactor planktonic populations. The biofilms were cultivated with lactate and sulfate in a continuously fed biofilm reactor, and compared to both batch and reactor planktonic populations. The functional genomic analysis demonstrated that biofilm cells were different compared to planktonic cells, and the majority of altered abundances for genes and proteins were annotated as hypothetical (unknown function), energy conservation, amino acid metabolism, and signal transduction. Genes and proteins that showed similar trends in detected levels were particularly involved in energy conservation such as increases in an annotated ech hydrogenase, formate dehydrogenase, pyruvate:ferredoxin oxidoreductase, and rnf oxidoreductase, and the biofilm cells had elevated formate dehydrogenase activity. Several other hydrogenases and formate dehydrogenases also showed an increased protein level, while decreased transcript and protein levels were observed for putative coo hydrogenase as well as a lactate permease and hyp hydrogenases for biofilm cells. Genes annotated for amino acid synthesis and nitrogen utilization were also predominant changers within the biofilm state. Ribosomal transcripts and proteins were notably decreased within the biofilm cells compared to exponential-phase cells but were not as low as levels observed in planktonic, stationary-phase cells. Several putative, extracellular proteins (DVU1012, 1545) were also detected in the extracellular fraction from biofilm cells

Antibiotic polymeric nanoparticles for biofilm-associated infection therapy.

Science.gov (United States)

Cheow, Wean Sin; Hadinoto, Kunn

2014-01-01

Polymeric nanoparticles are highly attractive as drug delivery vehicles due to their high structural integrity, stability during storage, ease of preparation and functionalization, and controlled release capability. Similarly, lipid-polymer hybrid nanoparticles, which retain the benefits of polymeric nanoparticles plus the enhanced biocompatibility and prolonged circulation time owed to the lipids, have recently emerged as a superior alternative to polymeric nanoparticles. Drug nanoparticle complex prepared by electrostatic interaction of oppositely charged drug and polyelectrolytes represents another type of polymeric nanoparticle. This chapter details the preparation, characterization, and antibiofilm efficacy testing of antibiotic-loaded polymeric and hybrid nanoparticles and antibiotic nanoparticle complex.

Visualizing the dental biofilm matrix by means of fluorescence lectin-binding analysis

DEFF Research Database (Denmark)

Tawakoli, Pune Nina; Neu, Thomas R; Busck, Mette Marie

2017-01-01

lectins to visualize and quantify extracellular glycoconjugates in dental biofilms. Lectin binding was screened on pooled supragingival biofilm samples collected from 76 subjects using confocal microscopy. FLBA was then performed with 10 selected lectins on biofilms grown in situ for 48 h in the absence......The extracellular matrix is a poorly studied, yet important component of dental biofilms. Fluorescence lectin-binding analysis (FLBA) is a powerful tool to characterize glycoconjugates in the biofilm matrix. This study aimed to systematically investigate the ability of 75 fluorescently labeled......-biofilms: Aleuria aurantia (AAL), Calystega sepiem (Calsepa), Lycopersicon esculentum (LEA), Morniga-G (MNA-G) and Helix pomatia (HPA). No significant correlation between the binding of specific lectins and bacterial composition was found. Fluorescently labeled lectins enable the visualization of glycoconjugates...

Antibiotic resistance in Pseudomonas aeruginosa biofilms: towards the development of novel anti-biofilm therapies.

Science.gov (United States)

Taylor, Patrick K; Yeung, Amy T Y; Hancock, Robert E W

2014-12-10

The growth of bacteria as structured aggregates termed biofilms leads to their protection from harsh environmental conditions such as physical and chemical stresses, shearing forces, and limited nutrient availability. Because of this highly adapted ability to survive adverse environmental conditions, bacterial biofilms are recalcitrant to antibiotic therapies and immune clearance. This is particularly problematic in hospital settings where biofilms are a frequent cause of chronic and device-related infections and constitute a significant burden on the health-care system. The major therapeutic strategy against infections is the use of antibiotics, which, due to adaptive resistance, are often insufficient to clear biofilm infections. Thus, novel biofilm-specific therapies are required. Specific features of biofilm development, such as surface adherence, extracellular matrix formation, quorum sensing, and highly regulated biofilm maturation and dispersal are currently being studied as targets to be exploited in the development of novel biofilm-specific treatments. Using Pseudomonas aeruginosa for illustrative purposes, this review highlights the antibiotic resistance mechanisms of biofilms, and discusses current research into novel biofilm-specific therapies. Copyright © 2014 Elsevier B.V. All rights reserved.

A cathelicidin-2-derived peptide effectively impairs Staphylococcus epidermidis biofilms

NARCIS (Netherlands)

Molhoek, E.M.; van Dijk, A.; Veldhuizen, E.J.A.; Haagsman, H.P.; Bikker, F.J.

2011-01-01

Staphylococcus epidermidis is a major cause of nosocomial infections owing to its ability to form biofilms on the surface of medical devices. Biofilms are surface-adhered bacterial communities. In mature biofilms these communities are encased in an extracellular matrix composed of bacterial

The virulence regulator PrfA promotes biofilm formation by Listeria monocytogenes.

Science.gov (United States)

Lemon, Katherine P; Freitag, Nancy E; Kolter, Roberto

2010-08-01

Listeria monocytogenes is a food-borne facultative intracellular pathogen. It is widespread in the environment and has several distinct life-styles. The key transcriptional activator PrfA positively regulates L. monocytogenes virulence genes to mediate the transition from extracellular, flagellum-propelled cell to intracellular pathogen. Here we report the first evidence that PrfA also has a significant positive impact on extracellular biofilm formation. Mutants lacking prfA were defective in surface-adhered biofilm formation. The DeltaprfA mutant exhibited wild-type flagellar motility, and its biofilm defect occurred after initial surface adhesion. We also observed that mutations that led to the constitutive expression of PrfA-dependent virulence genes had a minimal impact on biofilm formation. Furthermore, biofilm development was enhanced in a mutant encoding a PrfA protein variant unable to fully transition from the extracellular form to the virulent, intracellular activity conformation. These results indicate that PrfA positively regulates biofilm formation and suggest that PrfA has a global role in modulating the life-style of L. monocytogenes. The requirement of PrfA for optimal biofilm formation may provide selective pressure to maintain this critical virulence regulator when L. monocytogenes is outside host cells in the environment.

To be or not to be planktonic? Self-inhibition of biofilm development.

Science.gov (United States)

Nagar, Elad; Schwarz, Rakefet

2015-05-01

The transition between planktonic growth and biofilm formation represents a tightly regulated developmental shift that has substantial impact on cell fate. Here, we highlight different mechanisms through which bacteria limit their own biofilm development. The mechanisms involved in these self-inhibition processes include: (i) regulation by secreted small molecules, which govern intricate signalling cascades that eventually decrease biofilm development, (ii) extracellular polysaccharides capable of modifying the physicochemical properties of the substratum and (iii) extracellular DNA that masks an adhesive structure. These mechanisms, which rely on substances produced by the bacterium and released into the extracellular milieu, suggest regulation at the communal level. In addition, we provide specific examples of environmental cues (e.g. blue light or glucose level) that trigger a cellular response reducing biofilm development. All together, we describe a diverse array of mechanisms underlying self-inhibition of biofilm development in different bacteria and discuss possible advantages of these processes. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

New Technologies for Studying Biofilms

Science.gov (United States)

FRANKLIN, MICHAEL J.; CHANG, CONNIE; AKIYAMA, TATSUYA; BOTHNER, BRIAN

2016-01-01

Bacteria have traditionally been studied as single-cell organisms. In laboratory settings, aerobic bacteria are usually cultured in aerated flasks, where the cells are considered essentially homogenous. However, in many natural environments, bacteria and other microorganisms grow in mixed communities, often associated with surfaces. Biofilms are comprised of surface-associated microorganisms, their extracellular matrix material, and environmental chemicals that have adsorbed to the bacteria or their matrix material. While this definition of a biofilm is fairly simple, biofilms are complex and dynamic. Our understanding of the activities of individual biofilm cells and whole biofilm systems has developed rapidly, due in part to advances in molecular, analytical, and imaging tools and the miniaturization of tools designed to characterize biofilms at the enzyme level, cellular level, and systems level. PMID:26350329

Pattern formation in Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Parsek, Matthew R.; Tolker-Nielsen, Tim

2008-01-01

Bacteria are capable of forming elaborate multicellular communities called biofilms. Pattern formation in biofilms depends on cell proliferation and cellular migration in response to the available nutrients and other external cues, as well as on self-generated intercellular signal molecules...... and the production of an extracellular matrix that serves as a structural 'scaffolding' for the biofilm cells. Pattern formation in biofilms allows cells to position themselves favorably within nutrient gradients and enables buildup and maintenance of physiologically distinct subpopulations, which facilitates...... survival of one or more subpopulations upon environmental insult, and therefore plays an important role in the innate tolerance displayed by biofilms toward adverse conditions....

Extracellular Polymeric Substances Govern the Surface Charge of Biogenic Elemental Selenium Nanoparticles

KAUST Repository

Jain, Rohan

2015-02-03

© 2014 American Chemical Society. The origin of the organic layer covering colloidal biogenic elemental selenium nanoparticles (BioSeNPs) is not known, particularly in the case when they are synthesized by complex microbial communities. This study investigated the presence of extracellular polymeric substances (EPS) on BioSeNPs. The role of EPS in capping the extracellularly available BioSeNPs was also examined. Fourier transform infrared (FT-IR) spectroscopy and colorimetric measurements confirmed the presence of functional groups characteristic of proteins and carbohydrates on the BioSeNPs, suggesting the presence of EPS. Chemical synthesis of elemental selenium nanoparticles in the presence of EPS, extracted from selenite fed anaerobic granular sludge, yielded stable colloidal spherical selenium nanoparticles. Furthermore, extracted EPS, BioSeNPs, and chemically synthesized EPS-capped selenium nanoparticles had similar surface properties, as shown by ζ-potential versus pH profiles and isoelectric point measurements. This study shows that the EPS of anaerobic granular sludge form the organic layer present on the BioSeNPs synthesized by these granules. The EPS also govern the surface charge of these BioSeNPs, thereby contributing to their colloidal properties, hence affecting their fate in the environment and the efficiency of bioremediation technologies.

Raman microspectroscopy, surface-enhanced Raman scattering microspectroscopy, and stable-isotope Raman microspectroscopy for biofilm characterization.

Science.gov (United States)

Ivleva, Natalia P; Kubryk, Patrick; Niessner, Reinhard

2017-07-01

Biofilms represent the predominant form of microbial life on our planet. These aggregates of microorganisms, which are embedded in a matrix formed by extracellular polymeric substances, may colonize nearly all interfaces. Detailed knowledge of microorganisms enclosed in biofilms as well as of the chemical composition, structure, and functions of the complex biofilm matrix and their changes at different stages of the biofilm formation and under various physical and chemical conditions is relevant in different fields. Important research topics include the development and improvement of antibiotics and medical devices and the optimization of biocides, antifouling strategies, and biological wastewater treatment. Raman microspectroscopy is a capable and nondestructive tool that can provide detailed two-dimensional and three-dimensional chemical information about biofilm constituents with the spatial resolution of an optical microscope and without interference from water. However, the sensitivity of Raman microspectroscopy is rather limited, which hampers the applicability of Raman microspectroscopy especially at low biomass concentrations. Fortunately, the resonance Raman effect as well as surface-enhanced Raman scattering can help to overcome this drawback. Furthermore, the combination of Raman microspectroscopy with other microscopic techniques, mass spectrometry techniques, or particularly with stable-isotope techniques can provide comprehensive information on monospecies and multispecies biofilms. Here, an overview of different Raman microspectroscopic techniques, including resonance Raman microspectroscopy and surface-enhanced Raman scattering microspectroscopy, for in situ detection, visualization, identification, and chemical characterization of biofilms is given, and the main feasibilities and limitations of these techniques in biofilm research are presented. Future possibilities of and challenges for Raman microspectroscopy alone and in combination with other

Strategies for combating bacterial biofilms: A focus on anti-biofilm agents and their mechanisms of action

Science.gov (United States)

Roy, Ranita; Tiwari, Monalisa; Donelli, Gianfranco; Tiwari, Vishvanath

2018-01-01

ABSTRACT Biofilm refers to the complex, sessile communities of microbes found either attached to a surface or buried firmly in an extracellular matrix as aggregates. The biofilm matrix surrounding bacteria makes them tolerant to harsh conditions and resistant to antibacterial treatments. Moreover, the biofilms are responsible for causing a broad range of chronic diseases and due to the emergence of antibiotic resistance in bacteria it has really become difficult to treat them with efficacy. Furthermore, the antibiotics available till date are ineffective for treating these biofilm related infections due to their higher values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), which may result in in-vivo toxicity. Hence, it is critically important to design or screen anti-biofilm molecules that can effectively minimize and eradicate biofilm related infections. In the present article, we have highlighted the mechanism of biofilm formation with reference to different models and various methods used for biofilm detection. A major focus has been put on various anti-biofilm molecules discovered or tested till date which may include herbal active compounds, chelating agents, peptide antibiotics, lantibiotics and synthetic chemical compounds along with their structures, mechanism of action and their respective MICs, MBCs, minimum biofilm inhibitory concentrations (MBICs) as well as the half maximal inhibitory concentration (IC50) values available in the literature so far. Different mode of action of anti biofilm molecules addressed here are inhibition via interference in the quorum sensing pathways, adhesion mechanism, disruption of extracellular DNA, protein, lipopolysaccharides, exopolysaccharides and secondary messengers involved in various signaling pathways. From this study, we conclude that the molecules considered here might be used to treat biofilm-associated infections after significant structural modifications, thereby

Biofilm exopolymers control microbialite formation at thermal springs discharging into the alkaline Pyramid Lake, Nevada, USA

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Arp, Gernot; Thiel, Volker; Reimer, Andreas; Michaelis, Walter; Reitner, Joachim

1999-07-01

Calcium carbonate precipitation and microbialite formation at highly supersaturated mixing zones of thermal spring waters and alkaline lake water have been investigated at Pyramid Lake, Nevada. Without precipitation, pure mixing should lead to a nearly 100-fold supersaturation at 40°C. Physicochemical precipitation is modified or even inhibited by the properties of biofilms, dependent on the extent of biofilm development and the current precipitation rate. Mucus substances (extracellular polymeric substances, EPS, e.g., of cyanobacteria) serve as effective Ca 2+-buffers, thus preventing seed crystal nucleation even in a highly supersaturated macroenvironment. Carbonate is then preferentially precipitated in mucus-free areas such as empty diatom tests or voids. After the buffer capacity of the EPS is surpassed, precipitation is observed at the margins of mucus areas. Hydrocarbon biomarkers extracted from (1) a calcifying Phormidium-biofilm, (2) the stromatolitic carbonate below, and (3) a fossil `tufa' of the Pleistocene pinnacles, indicate that the cyanobacterial primary producers have been subject to significant temporal changes in their species distribution. Accordingly, the species composition of cyanobacterial biofilms does not appear to be relevant for the formation of microbial carbonates in Pyramid Lake. The results demonstrate the crucial influence of mucus substances on carbonate precipitation in highly supersaturated natural environments.

The clinical impact of bacterial biofilms

DEFF Research Database (Denmark)

Høiby, Niels; Ciofu, Oana; Johansen, Helle Krogh

2011-01-01

Bacteria survive in nature by forming biofilms on surfaces and probably most, if not all, bacteria (and fungi) are capable of forming biofilms. A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and extracellular DNA....... Bacterial biofilms are resistant to antibiotics, disinfectant chemicals and to phagocytosis and other components of the innate and adaptive inflammatory defense system of the body. It is known, for example, that persistence of staphylococcal infections related to foreign bodies is due to biofilm formation....... Likewise, chronic Pseudomonas aeruginosa lung infections in cystic fibrosis patients are caused by biofilm growing mucoid strains. Gradients of nutrients and oxygen exist from the top to the bottom of biofilms and the bacterial cells located in nutrient poor areas have decreased metabolic activity...

Thermodynamics of binding interactions between extracellular polymeric substances and heavy metals by isothermal titration microcalorimetry.

Science.gov (United States)

Yan, Peng; Xia, Jia-Shuai; Chen, You-Peng; Liu, Zhi-Ping; Guo, Jin-Song; Shen, Yu; Zhang, Cheng-Cheng; Wang, Jing

2017-05-01

Extracellular polymeric substances (EPS) play a crucial role in heavy metal bio-adsorption using activated sludge, but the interaction mechanism between heavy metals and EPS remains unclear. Isothermal titration calorimetry was employed to illuminate the mechanism in this study. The results indicate that binding between heavy metals and EPS is spontaneous and driven mainly by enthalpy change. Extracellular proteins in EPS are major participants in the binding process. Environmental conditions have significant impact on the adsorption performance. Divalent and trivalent cations severely impeded the binding of heavy metal ions to EPS. Electrostatic interaction mainly attributed to competition between divalent cations and heavy metal ions; trivalent cations directly competed with heavy metal ions for EPS binding sites. Trivalent cations were more competitive than divalent cations for heavy metal ion binding because they formed complexing bonds. This study facilitates a better understanding about the interaction between heavy metals and EPS in wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Extracellular polymeric substances from copper-tolerance Sinorhizobium meliloti immobilize Cu{sup 2+}

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Hou, Wenjie; Ma, Zhanqiang; Sun, Liangliang; Han, Mengsha; Lu, Jianjun; Li, Zhenxiu; Mohamad, Osama Abdalla; Wei, Gehong, E-mail: weigehong@nwsuaf.edu.cn

2013-10-15

Highlights: • EPS produced by Sinorhizobium meliloti CCNWSX0020 restricts uptake of Cu{sup 2+}. • We focused on the EPS, which is divided into three main parts. • LB-EPS played a more important role than S-EPS and TB-EPS in Cu{sup 2+} immobilization. • Proteins and carbohydrates were the main extracellular compounds which had functional groups such as carboxyl (-COOH), hydroxyl (-OH), and amide (N-H), primarily involved in metal ion binding. -- Abstract: The copper tolerance gene of wild-type heavy metal-tolerance Sinorhizobium meliloti CCNWSX0020 was mutated by transposon Tn5-a. The mutant was sensitive up to 1.4 mM Cu{sup 2+}. Production, components, surface morphology, and functional groups of extracellular polymeric substances (EPS) of the wild-type strains were compared with sensitive mutant in immobilization of Cu{sup 2+}. EPS produced by S. meliloti CCNWSX0020 restricts uptake of Cu{sup 2+}. The cell wall EPS were categorized based on the compactness and fastness: soluble EPS (S-EPS), loosely bound EPS (LB-EPS), and tightly bound EPS (TB-EPS). LB-EPS played a more important role than S-EPS and TB-EPS in Cu{sup 2+} immobilization. Scanning electron microscopy (SEM) analysis LB-EPS had rough surface and many honeycomb pores, making them conducive to copper entry; therefore, they may play a role as a microbial protective barrier. Fourier transform-infrared (FT-IR) analysis further confirm that proteins and carbohydrates were the main extracellular compounds which had functional groups such as carboxyl (-COOH), hydroxyl (-OH), and amide (N-H), primarily involved in metal ion binding.

Progressive biogeochemical transformation of placer gold particles drives compositional changes in associated biofilm communities.

Science.gov (United States)

Rea, Maria Angelica; Standish, Christopher D; Shuster, Jeremiah; Bissett, Andrew; Reith, Frank

2018-05-03

Biofilms on placer gold (Au)-particle surfaces drive Au solubilization and re-concentration thereby progressively transforming the particles. Gold solubilization induces Au-toxicity; however, Au-detoxifying community members ameliorates Au-toxicity by precipitating soluble Au to metallic Au. We hypothesize that Au-dissolution and re-concentration (precipitation) places selective pressures on associated microbial communities, leading to compositional changes and subsequent Au-particle transformation. We analyzed Au-particles from eight United Kingdom sites using next generation sequencing, electron microscopy and micro-analyses. Gold particles contained biofilms composed of prokaryotic cells and extracellular polymeric substances intermixed with (bio)minerals. Across all sites communities were dominated by Proteobacteria (689, 97% Operational Taxonomic Units, 59.3% of total reads), with β-Proteobacteria being the most abundant. A wide range of Au-morphotypes including nanoparticles, micro-crystals, sheet-like Au and secondary rims, indicated that dissolution and re-precipitation occurred, and from this transformation indices were calculated. Multivariate statistical analyses showed a significant relationship between the extent of Au-particle transformation and biofilm community composition, with putative metal-resistant Au-cycling taxa linked to progressive Au transformation. These included the genera Pseudomonas, Leptothrix and Acinetobacter. Additionally, putative exoelectrogenic genera Rhodoferax and Geobacter were highly abundant. In conclusion, biogeochemical Au-cycling and Au-particle transformation occurred at all sites and exerted a strong influence on biofilm community composition.

The Exopolysaccharide Matrix: A Virulence Determinant of Cariogenic Biofilm

OpenAIRE

Koo, H.; Falsetta, M.L.; Klein, M.I.

2013-01-01

Many infectious diseases in humans are caused or exacerbated by biofilms. Dental caries is a prime example of a biofilm-dependent disease, resulting from interactions of microorganisms, host factors, and diet (sugars), which modulate the dynamic formation of biofilms on tooth surfaces. All biofilms have a microbial-derived extracellular matrix as an essential constituent. The exopolysaccharides formed through interactions between sucrose- (and starch-) and Streptococcus mutans-derived exoenzy...

Extracellular matrix formation enhances the ability of Streptococcus pneumoniae to cause invasive disease.

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Claudia Trappetti

Full Text Available During infection, pneumococci exist mainly in sessile biofilms rather than in planktonic form, except during sepsis. However, relatively little is known about how biofilms contribute to pneumococcal pathogenesis. Here, we carried out a biofilm assay on opaque and transparent variants of a clinical serotype 19F strain WCH159. After 4 days incubation, scanning electron microscopy revealed that opaque biofilm bacteria produced an extracellular matrix, whereas the transparent variant did not. The opaque biofilm-derived bacteria translocated from the nasopharynx to the lungs and brain of mice, and showed 100-fold greater in vitro adherence to A549 cells than transparent bacteria. Microarray analysis of planktonic and sessile bacteria from transparent and opaque variants showed differential gene expression in two operons: the lic operon, which is involved in choline uptake, and in the two-component system, ciaRH. Mutants of these genes did not form an extracellular matrix, could not translocate from the nasopharynx to the lungs or the brain, and adhered poorly to A549 cells. We conclude that only the opaque phenotype is able to form extracellular matrix, and that the lic operon and ciaRH contribute to this process. We propose that during infection, extracellular matrix formation enhances the ability of pneumococci to cause invasive disease.

Candida Biofilms: Development, Architecture, and Resistance

Science.gov (United States)

CHANDRA, JYOTSNA; MUKHERJEE, PRANAB K.

2015-01-01

Intravascular device–related infections are often associated with biofilms (microbial communities encased within a polysaccharide-rich extracellular matrix) formed by pathogens on the surfaces of these devices. Candida species are the most common fungi isolated from catheter-, denture-, and voice prosthesis–associated infections and also are commonly isolated from contact lens–related infections (e.g., fungal keratitis). These biofilms exhibit decreased susceptibility to most antimicrobial agents, which contributes to the persistence of infection. Recent technological advances have facilitated the development of novel approaches to investigate the formation of biofilms and identify specific markers for biofilms. These studies have provided extensive knowledge of the effect of different variables, including growth time, nutrients, and physiological conditions, on biofilm formation, morphology, and architecture. In this article, we will focus on fungal biofilms (mainly Candida biofilms) and provide an update on the development, architecture, and resistance mechanisms of biofilms. PMID:26350306

Cross-feeding and interkingdom communication in dual-species biofilms of Streptococcus mutans and Candida albicans

Science.gov (United States)

Sztajer, Helena; Szafranski, Szymon P; Tomasch, Jürgen; Reck, Michael; Nimtz, Manfred; Rohde, Manfred; Wagner-Döbler, Irene

2014-01-01

Polymicrobial biofilms are of large medical importance, but relatively little is known about the role of interspecies interactions for their physiology and virulence. Here, we studied two human pathogens co-occuring in the oral cavity, the opportunistic fungus Candida albicans and the caries-promoting bacterium Streptococcus mutans. Dual-species biofilms reached higher biomass and cell numbers than mono-species biofilms, and the production of extracellular polymeric substances (EPSs) by S. mutans was strongly suppressed, which was confirmed by scanning electron microscopy, gas chromatography–mass spectrometry and transcriptome analysis. To detect interkingdom communication, C. albicans was co-cultivated with a strain of S. mutans carrying a transcriptional fusion between a green fluorescent protein-encoding gene and the promoter for sigX, the alternative sigma factor of S. mutans, which is induced by quorum sensing signals. Strong induction of sigX was observed in dual-species biofilms, but not in single-species biofilms. Conditioned media from mixed biofilms but not from C. albicans or S. mutans cultivated alone activated sigX in the reporter strain. Deletion of comS encoding the synthesis of the sigX-inducing peptide precursor abolished this activity, whereas deletion of comC encoding the competence-stimulating peptide precursor had no effect. Transcriptome analysis of S. mutans confirmed induction of comS, sigX, bacteriocins and the downstream late competence genes, including fratricins, in dual-species biofilms. We show here for the first time the stimulation of the complete quorum sensing system of S. mutans by a species from another kingdom, namely the fungus C. albicans, resulting in fundamentally changed virulence properties of the caries pathogen. PMID:24824668

Growth of Pseudomonas taiwanensis VLB120∆C biofilms in the presence of n-butanol.

Science.gov (United States)

Halan, Babu; Vassilev, Igor; Lang, Karsten; Schmid, Andreas; Buehler, Katja

2017-07-01

Biocatalytic processes often encounter problems due to toxic reactants and products, which reduce biocatalyst viability. Thus, robust organisms capable of tolerating or adapting towards such compounds are of high importance. This study systematically investigated the physiological response of Pseudomonas taiwanensis VLB120∆C biofilms when exposed to n-butanol, one of the potential next generation biofuels as well as a toxic substance using microscopic and biochemical methods. Initially P. taiwanensis VLB120∆C biofilms did not show any observable growth in the presence of 3% butanol. Prolonged cultivation of 10 days led to biofilm adaptation, glucose and oxygen uptake doubled and consequently it was possible to quantify biomass. Complementing the medium with yeast extract and presumably reducing the metabolic burden caused by butanol exposure further increased the biomass yield. In course of cultivation cells reduced their size in the presence of n-butanol which results in an enlarged surface-to-volume ratio and thus increased nutrient uptake. Finally, biofilm enhanced its extracellular polymeric substances (EPS) production when exposed to n-butanol. The predominant response of these biofilms under n-butanol stress are higher energy demand, increased biomass yield upon medium complements, larger surface-to-volume ratio and enhanced EPS production. Although we observed a distinct increase in biomass in the presence of 3% butanol it was not possible to cultivate P. taiwanensis VLB120∆C biofilms at higher n-butanol concentrations. Thereby this study shows that biofilms are not per se tolerant against solvents, and need to adapt to toxic n-butanol concentrations. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

In situ characterization and analysis of Salmonella biofilm formation under meat processing environments using a combined microscopic and spectroscopic approach.

Science.gov (United States)

Wang, Huhu; Ding, Shijie; Wang, Guangyu; Xu, Xinglian; Zhou, Guanghong

2013-11-01

Salmonella biofilm on food-contact surfaces present on food processing facilities may serve as a source of cross-contamination. In our work, biofilm formation by multi-strains of meat-borne Salmonella incubated at 20 °C, as well as the composition and distribution of extracellular polymeric substances (EPS), were investigated in situ by combining confocal laser scanning microscopy (CLSM), scanning electron microscope (SEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy. A standard laboratory culture medium (tryptic soy broth, TSB) was used and compared with an actual meat substrate (meat thawing-loss broth, MTLB). The results indicated that Salmonella grown in both media were able to form biofilms on stainless steel surfaces via building a three-dimensional structure with multilayers of cells. Although the number of biofilm cells grown in MTLB was less than that in TSB, the cell numbers in MTLB was adequate to form a steady and mature biofilm. Salmonella grown in MTLB showed "cloud-shaped" morphology in the mature biofilm, whereas when grown in TSB appeared "reticular-shaped". The ATR-FTIR and Raman analysis revealed a completely different chemical composition between biofilms and the corresponding planktonic cells, and some important differences in biofilms grown in MTLB and in TSB. Importantly, our findings suggested that the progress towards a mature Salmonella biofilm on stainless steel surfaces may be associated with the production of the EPS matrix, mainly consisting of polysaccharides and proteins, which may serve as useful markers of biofilm formation. Our work indicated that a combination of these non-destructive techniques provided new insights into the formation of Salmonella biofilm matrix. © 2013.

Enhanced Biotransformation of Fluoranthene by Intertidally Derived Cunninghamella elegans under Biofilm-Based and Niche-Mimicking Conditions

Science.gov (United States)

Mitra, Sayani; Pramanik, Arnab; Banerjee, Srijoni; Haldar, Saubhik; Gachhui, Ratan

2013-01-01

The aims of the investigation were to ascertain if surface attachment of Cunninghamella elegans and niche intertidal conditions provided in a bioreactor influenced biotransformation of fluoranthene by C. elegans. A newly designed polymethylmethacrylate (PMMA) conico-cylindrical flask (CCF) holding eight equidistantly spaced rectangular strips mounted radially on a circular disc allowed comparison of fluoranthene biotransformation between CCFs with a hydrophobic surface (PMMA-CCF) and a hydrophilic glass surface (GS-CCF) and a 500-ml Erlenmeyer flask (EF). Fluoranthene biotransformation was higher by 22-fold, biofilm growth was higher by 3-fold, and cytochrome P450 gene expression was higher by 2.1-fold when C. elegans was cultivated with 2% inoculum as biofilm culture in PMMA-CCF compared to planktonic culture in EF. Biotransformation was enhanced by 7-fold with 10% inoculum. The temporal pattern of biofilm progression based on three-channel fluorescence detection by confocal laser scanning microscopy demonstrated well-developed, stable biofilm with greater colocalization of fluoranthene within extracellular polymeric substances and filaments of the biofilm grown on PMMA in contrast to a glass surface. A bioreactor with discs rotating at 2 revolutions per day affording 6-hourly emersion and immersion mimicked the niche intertidal habitat of C. elegans and supported biofilm formation and transformation of fluoranthene. The amount of transformed metabolite was 3.5-fold, biofilm growth was 3-fold, and cytochrome P450 gene expression was 1.9-fold higher in the process mimicking the intertidal conditions than in a submerged process without disc rotation. In the CCF and reactor, where biofilm formation was comparatively greater, higher concentration of exopolysaccharides allowed increased mobilization of fluoranthene within the biofilm with consequential higher gene expression leading to enhanced volumetric productivity. PMID:24038685

Production of gold nanoparticles by electrode-respiring Geobacter sulfurreducens biofilms

Energy Technology Data Exchange (ETDEWEB)

Tanzil, Abid H.; Sultana, Sujala T.; Saunders, Steven R.; Dohnalkova, Alice C.; Shi, Liang; Davenport, Emily; Ha, Phuc; Beyenal, Haluk

2016-12-01

Current chemical syntheses of nanoparticles (NP) has had limited success due to the relatively high environmental cost caused by the use of harsh chemicals requiring necessary purification and size-selective fractionation. Therefore, biological approaches have received recent attention for their potential to overcome these obstacles as a benign synthetic approach. The intrinsic nature of biomolecules present in microorganisms has intrigued researchers to design bottom-up approaches to biosynthesize metal nanoparticles using microorganisms. Most of the literature work has focused on NP synthesis using planktonic cells while the use of biofilms are limited. The goal of this work was to synthesize gold nanoparticles (AuNPs) using electrode respiring Geobacter sulfurreducens biofilms. We found that most of the AuNPs are generated in the extracellular matrix of Geobacter biofilms with an average particle size of 20 nm. The formation of AuNPs was verified using TEM, FTIR and EDX. We also found that the extracellular substances extracted from electrode respiring G. sulfurreducens biofilms can reduce Au3+ to AuNPs. It appears that reducing sugars were involved in bioreduction and synthesis of AuNPs and amine groups acted as the major biomolecules involved in binding. This is first demonstration of AuNPs formation from the extracellular matrix of electrode respiring biofilms.

Biofilm characteristics and evaluation of the sanitation procedures of thermophilic Aeribacillus pallidus E334 biofilms.

Science.gov (United States)

Kilic, Tugba; Karaca, Basar; Ozel, Beste Piril; Ozcan, Birgul; Cokmus, Cumhur; Coleri Cihan, Arzu

2017-04-01

The ability of Aeribacillus pallidus E334 to produce pellicle and form a biofilm was studied. Optimal biofilm formation occurred at 60 °C, pH 7.5 and 1.5% NaCl. Extra polymeric substances (EPS) were composed of proteins and eDNA (21.4 kb). E334 formed biofilm on many surfaces, but mostly preferred polypropylene and glass. Using CLSM analysis, the network-like structure of the EPS was observed. The A. pallidus biofilm had a novel eDNA content. DNaseI susceptibility (86.8% removal) of eDNA revealed its importance in mature biofilms, but the purified eDNA was resistant to DNaseI, probably due to its extended folding outside the matrix. Among 15 cleaning agents, biofilms could be removed with alkaline protease and sodium dodecyl sulphate (SDS). The removal of cells from polypropylene and biomass on glass was achieved with combined SDS/alkaline protease treatment. Strong A. pallidus biofilms could cause risks for industrial processes and abiotic surfaces must be taken into consideration in terms of sanitation procedures.

Neutrophil extracellular traps and bacterial biofilms in middle ear effusion of children with recurrent acute otitis media--a potential treatment target.

Directory of Open Access Journals (Sweden)

Ruth B Thornton

Full Text Available BACKGROUND: Bacteria persist within biofilms on the middle ear mucosa of children with recurrent and chronic otitis media however the mechanisms by which these develop remain to be elucidated. Biopsies can be difficult to obtain from children and their small size limits analysis. METHODS: In this study we aimed to investigate biofilm presence in middle ear effusion (MEE from children with recurrent acute otitis media (rAOM and to determine if these may represent infectious reservoirs similarly to those on the mucosa. We examined this through culture, viability staining and fluorescent in situ hybridisation (FISH to determine bacterial species present. Most MEEs had live bacteria present using viability staining (32/36 and all effusions had bacteria present using the universal FISH probe (26/26. Of these, 70% contained 2 or more otopathogenic species. Extensive DNA stranding was also present. This DNA was largely host derived, representing neutrophil extracellular traps (NETs within which live bacteria in biofilm formations were present. When treated with the recombinant human deoxyribonuclease 1, Dornase alfa, these strands were observed to fragment. CONCLUSIONS: Bacterial biofilms, composed of multiple live otopathogenic species can be demonstrated in the MEEs of children with rAOM and that these contain extensive DNA stranding from NETs. The NETs contribute to the viscosity of the effusion, potentially contributing to its failure to clear as well as biofilm development. Our data indicates that Dornase alfa can fragment these strands and may play a role in future chronic OM treatment.

Biocorrosion: towards understanding interactions between biofilms and metals.

Science.gov (United States)

Beech, Iwona B; Sunner, Jan

2004-06-01

The term microbially influenced corrosion, or biocorrosion, refers to the accelerated deterioration of metals owing to the presence of biofilms on their surfaces. The detailed mechanisms of biocorrosion are still poorly understood. Recent investigations into biocorrosion have focused on the influence of biomineralization processes taking place on metallic surfaces and the impact of extracellular enzymes, active within the biofilm matrix, on electrochemical reactions at the biofilm-metal interface.

Relative contributions of norspermidine synthesis and signaling pathways to the regulation of Vibrio cholerae biofilm formation.

Directory of Open Access Journals (Sweden)

Caitlin K Wotanis

Full Text Available The polyamine norspermidine is one of the major polyamines synthesized by Vibrionales and has also been found in various aquatic organisms. Norspermidine is among the environmental signals that positively regulate Vibrio cholerae biofilm formation. The NspS/MbaA signaling complex detects extracellular norspermidine and mediates the response to this polyamine. Norspermidine binding to the NspS periplasmic binding protein is thought to inhibit the phosphodiesterase activity of MbaA, increasing levels of the biofilm-promoting second messenger cyclic diguanylate monophosphate, thus enhancing biofilm formation. V. cholerae can also synthesize norspermidine using the enzyme NspC as well as import it from the environment. Deletion of the nspC gene was shown to reduce accumulation of bacteria in biofilms, leading to the conclusion that intracellular norspermidine is also a positive regulator of biofilm formation. Because V. cholerae uses norspermidine to synthesize the siderophore vibriobactin it is possible that intracellular norspermidine is required to obtain sufficient amounts of iron, which is also necessary for robust biofilm formation. The objective of this study was to assess the relative contributions of intracellular and extracellular norspermidine to the regulation of biofilm formation in V. cholerae. We show the biofilm defect of norspermidine synthesis mutants does not result from an inability to produce vibriobactin as vibriobactin synthesis mutants do not have diminished biofilm forming abilities. Furthermore, our work shows that extracellular, but not intracellular norspermidine, is mainly responsible for promoting biofilm formation. We establish that the NspS/MbaA signaling complex is the dominant mediator of biofilm formation in response to extracellular norspermidine, rather than norspermidine synthesized by NspC or imported into the cell.

Potential coupling effects of ammonia-oxidizing and anaerobic ammonium-oxidizing bacteria on completely autotrophic nitrogen removal over nitrite biofilm formation induced by the second messenger cyclic diguanylate.

Science.gov (United States)

Wang, Chao; Liu, Sitong; Xu, Xiaochen; Zhao, Chuanqi; Yang, Fenglin; Wang, Dong

2017-05-01

The objective of this study was to investigate the influence of extracellular polymeric substance (EPS) on the coupling effects between ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing (anammox) bacteria for the completely autotrophic nitrogen removal over nitrite (CANON) biofilm formation in a moving bed biofilm reactor (MBBR). Analysis of the quantity of EPS and cyclic diguanylate (c-di-GMP) confirmed that the contents of polysaccharides and c-di-GMP were correlated in the AOB sludge, anammox sludge, and CANON biofilm. The anammox sludge secreted more EPS (especially polysaccharides) than AOB with a markedly higher c-di-GMP content, which could be used by the bacteria to regulate the synthesis of exopolysaccharides that are ultimately used as a fixation matrix, for the adhesion of biomass. Indeed, increased intracellular c-di-GMP concentrations in the anammox sludge enhanced the regulation of polysaccharides to promote the adhesion of AOB and formation of the CANON biofilm. Overall, the results of this study provide new comprehensive information regarding the coupling effects of AOB and anammox bacteria for the nitrogen removal process.

Fractional, biodegradable and spectral characteristics of extracted and fractionated sludge extracellular polymeric substances.

Science.gov (United States)

Wei, Liang-Liang; Wang, Kun; Zhao, Qing-Liang; Jiang, Jun-Qiu; Kong, Xiang-Juan; Lee, Duu-Jong

2012-09-15

Correlation between fractional, biodegradable and spectral characteristics of sludge extracellular polymeric substances (EPS) by different protocols has not been well established. This work extracted sludge EPS using alkaline extractants (NH₄OH and formaldehyde + NaOH) and physical protocols (ultrasonication, heating at 80 °C or cation exchange resin (CER)) and then fractionated the extracts using XAD-8/XAD-4 resins. The alkaline extractants yielded more sludge EPS than the physical protocols. However, the physical protocols extracted principally the hydrophilic components which were readily biodegradable by microorganisms. The alkaline extractants dissolved additional humic-like substances from sludge solids which were refractory in nature. Different extraction protocols preferably extracted EPS with distinct fractional, biodegradable and spectral characteristics which could be applied in specific usages. Copyright © 2012 Elsevier Ltd. All rights reserved.

IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION

Energy Technology Data Exchange (ETDEWEB)

Leschine, Susan

2009-10-31

colonizes and degrades insoluble substrates. Major accomplishments of the project include: • Development of media containing dialysis tubing (described by the manufacturer as “regenerated cellulose”) as sole carbon and energy source and a nutritive surface for the growth of cellulolytic bacteria, and development of various microscopic methods to image biofilms on dialysis tubing. • Demonstration that cultures of C. phytofermentans, an obligate anaerobe, C. uda, a facultative aerobe, and T. fusca, a filamentous aerobe, formed microbial communities on the surface of dialysis tubing, which possessed architectural features and functional characteristics typical of biofilms. • Demonstration that biofilm formation on the nutritive surface, cellulose, involves a complex developmental processes, including colonization of dialysis tubing, formation of cell clusters attached to the nutritive surface, cell morphological changes, formation of complex structures embedded in extracellular polymeric matrices, and dispersal of biofilm communities as the nutritive surface is degraded. • Determination of surface specificity and regulatory aspects of biofilm formation by C. phytofermentans, C. uda, and T. fusca. • Demonstration that biofilm formation by T. fusca forms an integral part of the life cycle of this filamentous cellulolytic bacterium, including studies on the role of mycelial pellet formation in the T. fusca life cycle and a comparison of mycelial pellets to surface-attached T. fusca biofilms. • Characterization of T. fusca biofilm EPS, including demonstration of a functional role for EPS constituents. • Correlation of T. fusca developmental life cycle and cellulase gene expression.

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques

International Nuclear Information System (INIS)

Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.; Mehta, Hardeep S.; Ewing, R. James; Ewing, Thomas; Mueller, Karl T.; Beyenal, Haluk

2014-01-01

In order to fully understand electrochemically active biofilms and the limitations to their scale-up in industrial biofilm reactors, a complete picture of the microenvironments inside the biofilm is needed. Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for non-invasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live electrochemically active biofilms. Here, we introduce a novel biofilm microreactor system that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radiofrequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system, we grew Geobacter sulfurreducens biofilms. NMR was used to investigate growth media flow velocities, which were compared to simulated laminar flow, and electron donor concentrations inside the biofilms. We use Monte Carlo error analysis to estimate standard deviations of the electron donor concentration measurements within the biofilm. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms

Multispecies Biofilms Transform Selenium Oxyanions into Elemental Selenium Particles: Studies Using Combined Synchrotron X-ray Fluorescence Imaging and Scanning Transmission X-ray Microscopy

Energy Technology Data Exchange (ETDEWEB)

Yang, Soo In; George, Graham N.; Lawrence, John R.; Kaminskyj, Susan G. W.; Dynes, James J.; Lai, Barry; Pickering, Ingrid J.

2016-10-04

Selenium (Se) is an element of growing environmental concern, because low aqueous concentrations can lead to biomagnification through the aquatic food web. Biofilms, naturally occurring microbial consortia, play numerous important roles in the environment, especially in biogeochemical cycling of toxic elements in aquatic systems. The complexity of naturally forming multispecies biofilms presents challenges for characterization because conventional microscopic techniques require chemical and physical modifications of the sample. Here, multispecies biofilms biotransforming selenium oxyanions were characterized using X-ray fluorescence imaging (XFI) and scanning transmission X-ray microscopy (STXM). These complementary synchrotron techniques required minimal sample preparation and were applied correlatively to the same biofilm areas. Sub-micrometer XFI showed distributions of Se and endogenous metals, while Se K-edge X-ray absorption spectroscopy indicated the presence of elemental Se (Se0). Nanoscale carbon K-edge STXM revealed the distributions of microbial cells, extracellular polymeric substances (EPS), and lipids using the protein, saccharide, and lipid signatures, respectively, together with highly localized Se0 using the Se LIII edge. Transmission electron microscopy showed the electron-dense particle diameter to be 50–700 nm, suggesting Se0 nanoparticles. The intimate association of Se0 particles with protein and polysaccharide biofilm components has implications for the bioavailability of selenium in the environment.

A dual role of extracellular DNA during biofilm formation of Neisseria meningitidis

DEFF Research Database (Denmark)

Lappann, M.; Claus, H.; van Alen, T.

2010-01-01

formation, whereas biofilm formation of cc with low point prevalence (ST-8 cc and ST-11 cc) was eDNA-independent. For initial biofilm formation, a ST-32 cc type strain, but not a ST-11 type strain, utilized eDNA. The release of eDNA was mediated by lytic transglycosylase and cytoplasmic N......-acetylmuramyl-l-alanine amidase genes. In late biofilms, outer membrane phospholipase A-dependent autolysis, which was observed in most cc, but not in ST-8 and ST-11 strains, was required for shear force resistance of microcolonies. Taken together, N. meningitidis evolved two different biofilm formation strategies, an e....... On the contrary, spreaders (ST-11 and ST-8 cc) are unable to use eDNA for biofilm formation and might compensate for poor colonization properties by high transmission rates....

SarA is a negative regulator of Staphylococcus epidermidis biofilm formation

DEFF Research Database (Denmark)

Martin, Christer; Heinze, C.; Busch, M.

2012-01-01

Biofilm formation is essential for Staphylococcus epidermidis pathogenicity in implant-associated infections. Nonetheless, large proportions of invasive S. epidermidis isolates fail to show accumulative biofilm growth in vitro. We here tested the hypothesis that this apparent paradox is related...... virulence. Genetic analysis revealed that inactivation of sarA induced biofilm formation via over-expression of the giant 1 MDa extracellular matrix binding protein (Embp), serving as an intercellular adhesin. In addition to Embp, increased extracellular DNA (eDNA) release significantly contributed...... to biofilm formation in mutant 1585ΔsarA. Increased eDNA amounts indirectly resulted from up-regulation of metalloprotease SepA, leading to boosted processing of major autolysin AtlE, in turn inducing augmented autolysis and release of chromosomal DNA. Hence, this study identifies sarA as a negative...

From biofilm ecology to reactors: a focused review

DEFF Research Database (Denmark)

Boltz, Joshua P.; Smets, Barth F.; Rittmann, Bruce E.

2017-01-01

the following three topics: (1) biofilm ecology, (2) biofilm reactor technology and design, and (3) biofilm modeling. In so doing, it addresses the processes occurring in the biofilm, and how these affect and are affected by the broader biofilm system. The symphonic application of a suite of biological methods...... on the performance of various systems, but they can also be used beneficially for the treatment of water (defined herein as potable water, municipal and industrial wastewater, fresh/brackish/salt water bodies, groundwater) as well as in water stream-based biological resource recovery systems. This review addresses...... polymeric substance matrix are somewhat known, but their exact composition and role in the microbial conversion kinetics and biochemical transformations are still to be resolved. Biofilm grown microorganisms may contribute to increased metabolism of micro-pollutants. Several types of biofilm reactors have...

Metagenomic Sequencing of Marine Periphyton: Taxonomic and Functional Insights into Biofilm Communities

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Kemal eSanli

2015-10-01

Full Text Available Periphyton communities are complex phototrophic, multispecies biofilms that develop on surfaces in aquatic environments. These communities harbor a large diversity of organisms comprising viruses, bacteria, algae, fungi, protozoans and metazoans. However, thus far the total biodiversity of periphyton has not been described. In this study, we use metagenomics to characterize periphyton communities from the marine environment of the Swedish west coast. Although we found approximately ten times more eukaryotic rRNA marker gene sequences compared to prokaryotic, the whole metagenome-based similarity searches showed that bacteria constitute the most abundant phyla in these biofilms. We show that marine periphyton encompass a range of heterotrophic and phototrophic organisms. Heterotrophic bacteria, including the majority of proteobacterial clades and Bacteroidetes, and eukaryotic macro-invertebrates were found to dominate periphyton. The phototrophic groups comprise Cyanobacteria and the alpha-proteobacterial genus Roseobacter, followed by different micro- and macro-algae. We also assess the metabolic pathways that predispose these communities to an attached lifestyle. Functional indicators of the biofilm form of life in periphyton involve genes coding for enzymes that catalyze the production and degradation of extracellular polymeric substances, mainly in the form of complex sugars such as starch and glycogen-like meshes together with chitin. Genes for 278 different transporter proteins were detected in the metagenome, constituting the most abundant protein complexes. Finally, genes encoding enzymes that participate in anaerobic pathways, such as denitrification and methanogenesis, were detected suggesting the presence of anaerobic or low-oxygen micro-zones within the biofilms.

Optimization of Cultural Conditions for Production of Extracellular Polymeric Substances (EPS) by Serpentine Rhizobacterium Cupriavidus pauculus KPS 201

OpenAIRE

Arundhati Pal; A. K. Paul

2013-01-01

Extracellular polymeric substances (EPS) are complex biopolymers produced by a wide array of microorganisms for protection against dessication, aggregation, adhesion, and expression of virulence. Growth associated production of EPS by Ni-resistant Cupriavidus pauculus KPS 201 was determined in batch culture using sodium gluconate as the sole carbon source. The optimum pH and temperature for EPS production were 6.5 and 25°C, respectively. Optimal EPS yield (118 μg/mL) was attained at 0.35% Na-...

Biofilm inhibitors that target amyloid proteins.

Science.gov (United States)

Romero, Diego; Sanabria-Valentín, Edgardo; Vlamakis, Hera; Kolter, Roberto

2013-01-24

Bacteria establish stable communities, known as biofilms, that are resistant to antimicrobials. Biofilm robustness is due to the presence of an extracellular matrix, which for several species-among them Bacillus subtilis-includes amyloid-like protein fibers. In this work, we show that B. subtilis biofilms can be a simple and reliable tool for screening of molecules with antiamyloid activity. We identified two molecules, AA-861 and parthenolide, which efficiently inhibited biofilms by preventing the formation of amyloid-like fibers. Parthenolide also disrupted pre-established biofilms. These molecules also impeded the formation of biofilms of other bacterial species that secrete amyloid proteins, such as Bacillus cereus and Escherichia coli. Furthermore, the identified molecules decreased the conversion of the yeast protein New1 to the prion state in a heterologous host, indicating the broad range of activity of the molecules. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterisation of the physical composition and microbial community structure of biofilms within a model full-scale drinking water distribution system.

Science.gov (United States)

Fish, Katherine E; Collins, Richard; Green, Nicola H; Sharpe, Rebecca L; Douterelo, Isabel; Osborn, A Mark; Boxall, Joby B

2015-01-01

Within drinking water distribution systems (DWDS), microorganisms form multi-species biofilms on internal pipe surfaces. A matrix of extracellular polymeric substances (EPS) is produced by the attached community and provides structure and stability for the biofilm. If the EPS adhesive strength deteriorates or is overcome by external shear forces, biofilm is mobilised into the water potentially leading to degradation of water quality. However, little is known about the EPS within DWDS biofilms or how this is influenced by community composition or environmental parameters, because of the complications in obtaining biofilm samples and the difficulties in analysing EPS. Additionally, although biofilms may contain various microbial groups, research commonly focuses solely upon bacteria. This research applies an EPS analysis method based upon fluorescent confocal laser scanning microscopy (CLSM) in combination with digital image analysis (DIA), to concurrently characterize cells and EPS (carbohydrates and proteins) within drinking water biofilms from a full-scale DWDS experimental pipe loop facility with representative hydraulic conditions. Application of the EPS analysis method, alongside DNA fingerprinting of bacterial, archaeal and fungal communities, was demonstrated for biofilms sampled from different positions around the pipeline, after 28 days growth within the DWDS experimental facility. The volume of EPS was 4.9 times greater than that of the cells within biofilms, with carbohydrates present as the dominant component. Additionally, the greatest proportion of EPS was located above that of the cells. Fungi and archaea were established as important components of the biofilm community, although bacteria were more diverse. Moreover, biofilms from different positions were similar with respect to community structure and the quantity, composition and three-dimensional distribution of cells and EPS, indicating that active colonisation of the pipe wall is an important

Characterisation of the Physical Composition and Microbial Community Structure of Biofilms within a Model Full-Scale Drinking Water Distribution System

Science.gov (United States)

Fish, Katherine E.; Collins, Richard; Green, Nicola H.; Sharpe, Rebecca L.; Douterelo, Isabel; Osborn, A. Mark; Boxall, Joby B.

2015-01-01

Within drinking water distribution systems (DWDS), microorganisms form multi-species biofilms on internal pipe surfaces. A matrix of extracellular polymeric substances (EPS) is produced by the attached community and provides structure and stability for the biofilm. If the EPS adhesive strength deteriorates or is overcome by external shear forces, biofilm is mobilised into the water potentially leading to degradation of water quality. However, little is known about the EPS within DWDS biofilms or how this is influenced by community composition or environmental parameters, because of the complications in obtaining biofilm samples and the difficulties in analysing EPS. Additionally, although biofilms may contain various microbial groups, research commonly focuses solely upon bacteria. This research applies an EPS analysis method based upon fluorescent confocal laser scanning microscopy (CLSM) in combination with digital image analysis (DIA), to concurrently characterize cells and EPS (carbohydrates and proteins) within drinking water biofilms from a full-scale DWDS experimental pipe loop facility with representative hydraulic conditions. Application of the EPS analysis method, alongside DNA fingerprinting of bacterial, archaeal and fungal communities, was demonstrated for biofilms sampled from different positions around the pipeline, after 28 days growth within the DWDS experimental facility. The volume of EPS was 4.9 times greater than that of the cells within biofilms, with carbohydrates present as the dominant component. Additionally, the greatest proportion of EPS was located above that of the cells. Fungi and archaea were established as important components of the biofilm community, although bacteria were more diverse. Moreover, biofilms from different positions were similar with respect to community structure and the quantity, composition and three-dimensional distribution of cells and EPS, indicating that active colonisation of the pipe wall is an important

NEW METHODOLOGIES FOR BIOFILMS CONTROL IN FOOD INDUSTRY

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Pavol Bajzík

2010-07-01

Full Text Available The complete removal of biofilms on food  equipment surfaces  is essential to ensure food safety and quality. However, cells in biofilms exhibit greater resistance against the action of sanitizers and other antimicrobial agents compared to their free living counterparts, making them much more difficult to remove. They can be a significant source of post - processing contamination and could potentially harbor pathogens in food processing platns. The biotechnology sector is just beginning to tackle the problem of biofilms by developing antimicrobial agents with novel mechanisms of action. Some studies seek to prevent biofilm formation, others aim to develop antimicrobial agents to treat existing biofilms, and still others are trying to disrupt the polymeric ties that bind the biofilms together. doi:10.5219/17

Pseudomonas aeruginosa Biofilm, a Programmed Bacterial Life for Fitness.

Science.gov (United States)

Lee, Keehoon; Yoon, Sang Sun

2017-06-28

A biofilm is a community of microbes that typically inhabit on surfaces and are encased in an extracellular matrix. Biofilms display very dissimilar characteristics to their planktonic counterparts. Biofilms are ubiquitous in the environment and influence our lives tremendously in both positive and negative ways. Pseudomonas aeruginosa is a bacterium known to produce robust biofilms. P. aeruginosa biofilms cause severe problems in immunocompromised patients, including those with cystic fibrosis or wound infection. Moreover, the unique biofilm properties further complicate the eradication of the biofilm infection, leading to the development of chronic infections. In this review, we discuss the history of biofilm research and general characteristics of bacterial biofilms. Then, distinct features pertaining to each stage of P. aeruginosa biofilm development are highlighted. Furthermore, infections caused by biofilms on their own or in association with other bacterial species ( i.e. , multispecies biofilms) are discussed in detail.

Sticking together: building a biofilm the Bacillus subtilis way.

Science.gov (United States)

Vlamakis, Hera; Chai, Yunrong; Beauregard, Pascale; Losick, Richard; Kolter, Roberto

2013-03-01

Biofilms are ubiquitous communities of tightly associated bacteria encased in an extracellular matrix. Bacillus subtilis has long served as a robust model organism to examine the molecular mechanisms of biofilm formation, and a number of studies have revealed that this process is regulated by several integrated pathways. In this Review, we focus on the molecular mechanisms that control B. subtilis biofilm assembly, and then briefly summarize the current state of knowledge regarding biofilm disassembly. We also discuss recent progress that has expanded our understanding of B. subtilis biofilm formation on plant roots, which are a natural habitat for this soil bacterium.

Characterization of the Vibrio cholerae extracellular matrix: a top-down solid-state NMR approach.

Science.gov (United States)

Reichhardt, Courtney; Fong, Jiunn C N; Yildiz, Fitnat; Cegelski, Lynette

2015-01-01

Bacterial biofilms are communities of bacterial cells surrounded by a self-secreted extracellular matrix. Biofilm formation by Vibrio cholerae, the human pathogen responsible for cholera, contributes to its environmental survival and infectivity. Important genetic and molecular requirements have been identified for V. cholerae biofilm formation, yet a compositional accounting of these parts in the intact biofilm or extracellular matrix has not been described. As insoluble and non-crystalline assemblies, determinations of biofilm composition pose a challenge to conventional biochemical and biophysical analyses. The V. cholerae extracellular matrix composition is particularly complex with several proteins, complex polysaccharides, and other biomolecules having been identified as matrix parts. We developed a new top-down solid-state NMR approach to spectroscopically assign and quantify the carbon pools of the intact V. cholerae extracellular matrix using ¹³C CPMAS and ¹³C{(¹⁵N}, ¹⁵N{³¹P}, and ¹³C{³¹P}REDOR. General sugar, lipid, and amino acid pools were first profiled and then further annotated and quantified as specific carbon types, including carbonyls, amides, glycyl carbons, and anomerics. In addition, ¹⁵N profiling revealed a large amine pool relative to amide contributions, reflecting the prevalence of molecular modifications with free amine groups. Our top-down approach could be implemented immediately to examine the extracellular matrix from mutant strains that might alter polysaccharide production or lipid release beyond the cell surface; or to monitor changes that may accompany environmental variations and stressors such as altered nutrient composition, oxidative stress or antibiotics. More generally, our analysis has demonstrated that solid-state NMR is a valuable tool to characterize complex biofilm systems. Copyright © 2014. Published by Elsevier B.V.

Modeling Substrate Utilization, Metabolite Production, and Uranium Immobilization in Shewanella oneidensis Biofilms

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Ryan S. Renslow

2017-06-01

Full Text Available In this study, we developed a two-dimensional mathematical model to predict substrate utilization and metabolite production rates in Shewanella oneidensis MR-1 biofilm in the presence and absence of uranium (U. In our model, lactate and fumarate are used as the electron donor and the electron acceptor, respectively. The model includes the production of extracellular polymeric substances (EPS. The EPS bound to the cell surface and distributed in the biofilm were considered bound EPS (bEPS and loosely associated EPS (laEPS, respectively. COMSOL® Multiphysics finite element analysis software was used to solve the model numerically (model file provided in the Supplementary Material. The input variables of the model were the lactate, fumarate, cell, and EPS concentrations, half saturation constant for fumarate, and diffusion coefficients of the substrates and metabolites. To estimate unknown parameters and calibrate the model, we used a custom designed biofilm reactor placed inside a nuclear magnetic resonance (NMR microimaging and spectroscopy system and measured substrate utilization and metabolite production rates. From these data we estimated the yield coefficients, maximum substrate utilization rate, half saturation constant for lactate, stoichiometric ratio of fumarate and acetate to lactate and stoichiometric ratio of succinate to fumarate. These parameters are critical to predicting the activity of biofilms and are not available in the literature. Lastly, the model was used to predict uranium immobilization in S. oneidensis MR-1 biofilms by considering reduction and adsorption processes in the cells and in the EPS. We found that the majority of immobilization was due to cells, and that EPS was less efficient at immobilizing U. Furthermore, most of the immobilization occurred within the top 10 μm of the biofilm. To the best of our knowledge, this research is one of the first biofilm immobilization mathematical models based on experimental

Density of founder cells affects spatial pattern formation and cooperation in Bacillus subtilis biofilms

NARCIS (Netherlands)

van Gestel, Jordi; Weissing, Franz J.; Kuipers, Oscar P.; Kovacs, Akos T.

2014-01-01

In nature, most bacteria live in surface-attached sedentary communities known as biofilms. Biofilms are often studied with respect to bacterial interactions. Many cells inhabiting biofilms are assumed to express 'cooperative traits', like the secretion of extracellular polysaccharides (EPS). These

Biofilms of vaginal Lactobacillus in vitro test.

Science.gov (United States)

Wei, Xiao-Yu; Zhang, Rui; Xiao, Bing-Bing; Liao, Qin-Ping

2017-01-01

This paper focuses on biofilms of Lactobacillus spp. - a type of normal flora isolated from healthy human vaginas of women of childbearing age; thereupon, it broadens the research scope of investigation of vaginal normal flora. The static slide culture method was adopted to foster biofilms, marked by specific fluorescence staining. Laser scanning confocal and scanning electron microscopy were used to observe the microstructure of the biofilms. Photographs taken from the microstructure were analysed to calculate the density of the biofilms. The body of Lactobacillus spp., though red, turned yellow when interacting with the green extracellular polysaccharides. The structure of the biofilm and aquaporin within the biofilm were imaged. Lactobacillus density increases over time. This study provides convincing evidence that Lactobacillus can form biofilms and grow over time in vitro. This finding establishes an important and necessary condition for selecting proper strains for the pharmaceutics of vaginal ecology.

A vibrating membrane bioreactor (VMBR): Macromolecular transmission-influence of extracellular polymeric substances

DEFF Research Database (Denmark)

Beier, Søren; Jonsson, Gunnar Eigil

2009-01-01

The vibrating membrane bioreactor (VMBR) system facilitates the possibility of conducting a separation of macromolecules (BSA) from larger biological components (yeast cells) with a relatively high and stable macromolecular transmission at sub-critical flux. This is not possible to achieve...... for a static non-vibrating membrane module. A BSA transmission of 74% has been measured in the separation of 4g/L BSA from 8 g/L dry weight yeast cells in suspension at sub-critical flux (20L/(m(2) h)). However, this transmission is lower than the 85% BSA transmission measured for at pure 4g/L BSA solution....... This can be ascribed to the presence of extracellular polymeric substances (EPS) from the yeast cells. The initial fouling rate for constant sub-critical flux filtration of unwashed yeast cells is 3-4 times larger than for washed yeast cells (18(mbar/h)/5(mbar/h)). At sub-critical flux, an EPS transmission...

Identification of Bicarbonate as a Trigger and Genes Involved with Extracellular DNA Export in Mycobacterial Biofilms

Directory of Open Access Journals (Sweden)

Sasha J. Rose

2016-12-01

Full Text Available Extracellular DNA (eDNA is an integral biofilm matrix component of numerous pathogens, including nontuberculous mycobacteria (NTM. Cell lysis is the source of eDNA in certain bacteria, but the source of eDNA remains unidentified for NTM, as well as for other eDNA-containing bacterial species. In this study, conditions affecting eDNA export were examined, and genes involved with the eDNA export mechanism were identified. After a method for monitoring eDNA in real time in undisturbed biofilms was established, different conditions affecting eDNA were investigated. Bicarbonate positively influenced eDNA export in a pH-independent manner in Mycobacterium avium, M. abscessus, and M. chelonae. The surface-exposed proteome of M. avium in eDNA-containing biofilms revealed abundant carbonic anhydrases. Chemical inhibition of carbonic anhydrases with ethoxzolamide significantly reduced eDNA export. An unbiased transposon mutant library screen for eDNA export in M. avium identified many severely eDNA-attenuated mutants, including one not expressing a unique FtsK/SpoIIIE-like DNA-transporting pore, two with inactivation of carbonic anhydrases, and nine with inactivation of genes belonging to a unique genomic region, as well as numerous mutants involved in metabolism and energy production. Complementation of nine mutants that included the FtsK/SpoIIIE and carbonic anhydrase significantly restored eDNA export. Interestingly, several attenuated eDNA mutants have mutations in genes encoding proteins that were found with the surface proteomics, and many more mutations are localized in operons potentially encoding surface proteins. Collectively, our data strengthen the evidence of eDNA export being an active mechanism that is activated by the bacterium responding to bicarbonate.

A Phytoanticipin Derivative, Sodium Houttuyfonate, Induces in Vitro Synergistic Effects with Levofloxacin against Biofilm Formation by Pseudomonas aeruginosa

Directory of Open Access Journals (Sweden)

Jing Shao

2012-09-01

Full Text Available Antibiotic resistance has become the main deadly factor in infections, as bacteria can protect themselves by hiding in a self-constructed biofilm. Consequently, more attention is being paid to the search for “non-antibiotic drugs” to solve this problem. Phytoanticipins, the natural antibiotics from plants, could be a suitable alternative, but few works on this aspect have been reported. In this study, a preliminary study on the synergy between sodium houttuyfonate (SH and levofloxacin (LFX against the biofilm formation of Pseudomonas aeruginosa was performed. The minimal inhibitory concentrations (MIC of LFX and SH, anti-biofilm formation and synergistic effect on Pseudomonas aeruginosa, and quantification of alginate were determined by the microdilution method, crystal violet (CV assay, checkerboard method, and hydroxybiphenyl colorimetry. The biofilm morphology of Pseudomonas aeruginosa was observed by fluorescence microscope and scanning electric microscope (SEM. The results showed that: (i LFX and SH had an obvious synergistic effect against Pseudomonas aeruginosa with MIC values of 0.25 μg/mL and 128 μg/mL, respectively; (ii ½ × MIC SH combined with 2 × MIC LFX could suppress the biofilm formation of Pseudomonas aeruginosa effectively, with up to 73% inhibition; (iii the concentration of alginate decreased dramatically by a maximum of 92% after treatment with the combination of antibiotics; and (iv more dead cells by fluorescence microscope and more removal of extracellular polymeric structure (EPS by SEM were observed after the combined treatment of LFX and SH. Our experiments demonstrate the promising future of this potent antimicrobial agent against biofilm-associated infections.

Plasticity of Candida albicans Biofilms

Science.gov (United States)

Daniels, Karla J.

2016-01-01

SUMMARY Candida albicans, the most pervasive fungal pathogen that colonizes humans, forms biofilms that are architecturally complex. They consist of a basal yeast cell polylayer and an upper region of hyphae encapsulated in extracellular matrix. However, biofilms formed in vitro vary as a result of the different conditions employed in models, the methods used to assess biofilm formation, strain differences, and, in a most dramatic fashion, the configuration of the mating type locus (MTL). Therefore, integrating data from different studies can lead to problems of interpretation if such variability is not taken into account. Here we review the conditions and factors that cause biofilm variation, with the goal of engendering awareness that more attention must be paid to the strains employed, the methods used to assess biofilm development, every aspect of the model employed, and the configuration of the MTL locus. We end by posing a set of questions that may be asked in comparing the results of different studies and developing protocols for new ones. This review should engender the notion that not all biofilms are created equal. PMID:27250770

The Interface between Fungal Biofilms and Innate Immunity

Directory of Open Access Journals (Sweden)

John F. Kernien

2018-01-01

Full Text Available Fungal biofilms are communities of adherent cells surrounded by an extracellular matrix. These biofilms are commonly found during infection caused by a variety of fungal pathogens. Clinically, biofilm infections can be extremely difficult to eradicate due to their resistance to antifungals and host defenses. Biofilm formation can protect fungal pathogens from many aspects of the innate immune system, including killing by neutrophils and monocytes. Altered immune recognition during this phase of growth is also evident by changes in the cytokine profiles of monocytes and macrophages exposed to biofilm. In this manuscript, we review the host response to fungal biofilms, focusing on how these structures are recognized by the innate immune system. Biofilms formed by Candida, Aspergillus, and Cryptococcus have received the most attention and are highlighted. We describe common themes involved in the resilience of fungal biofilms to host immunity and give examples of biofilm defenses that are pathogen-specific.

Host Proteins Determine MRSA Biofilm Structure and Integrity

DEFF Research Database (Denmark)

Dreier, Cindy; Nielsen, Astrid; Jørgensen, Nis Pedersen

Human extracellular matrix (hECM) proteins aids the initial attachment and initiation of an infection, by specific binding to bacterial cell surface proteins. However, the importance of hECM proteins in structure, integrity and antibiotic resilience of a biofilm is unknown. This study aims...... to determine how specific hECM proteins affect S. aureus USA300 JE2 biofilms. Biofilms were grown in the presence of synovial fluid from rheumatoid arteritis patients to mimic in vivo conditions, where bacteria incorporate hECM proteins into the biofilm matrix. Difference in biofilm structure, with and without...... addition of hECM to growth media, was visualized by confocal laser scanning microscopy. Two enzymatic degradation experiments were used to study biofilm matrix composition and importance of hECM proteins: enzymatic removal of specific hECM proteins from growth media, before biofilm formation, and enzymatic...

Understanding, Monitoring, and Controlling Biofilm Growth in Drinking Water Distribution Systems.

Science.gov (United States)

Liu, Sanly; Gunawan, Cindy; Barraud, Nicolas; Rice, Scott A; Harry, Elizabeth J; Amal, Rose

2016-09-06

In drinking water distribution systems (DWDS), biofilms are the predominant mode of microbial growth, with the presence of extracellular polymeric substance (EPS) protecting the biomass from environmental and shear stresses. Biofilm formation poses a significant problem to the drinking water industry as a potential source of bacterial contamination, including pathogens, and, in many cases, also affecting the taste and odor of drinking water and promoting the corrosion of pipes. This article critically reviews important research findings on biofilm growth in DWDS, examining the factors affecting their formation and characteristics as well as the various technologies to characterize and monitor and, ultimately, to control their growth. Research indicates that temperature fluctuations potentially affect not only the initial bacteria-to-surface attachment but also the growth rates of biofilms. For the latter, the effect is unique for each type of biofilm-forming bacteria; ammonia-oxidizing bacteria, for example, grow more-developed biofilms at a typical summer temperature of 22 °C compared to 12 °C in fall, and the opposite occurs for the pathogenic Vibrio cholerae. Recent investigations have found the formation of thinner yet denser biofilms under high and turbulent flow regimes of drinking water, in comparison to the more porous and loosely attached biofilms at low flow rates. Furthermore, in addition to the rather well-known tendency of significant biofilm growth on corrosion-prone metal pipes, research efforts also found leaching of growth-promoting organic compounds from the increasingly popular use of polymer-based pipes. Knowledge of the unique microbial members of drinking water biofilms and, importantly, the influence of water characteristics and operational conditions on their growth can be applied to optimize various operational parameters to minimize biofilm accumulation. More-detailed characterizations of the biofilm population size and structure are now

Molecular Characterisation and Co-cultivation of Bacterial Biofilm Communities Associated with the Mat-Forming Diatom Didymosphenia geminata.

Science.gov (United States)

Brandes, Josephin; Kuhajek, Jeanne M; Goodwin, Eric; Wood, Susanna A

2016-10-01

Didymosphenia geminata (Lyngbye) M. Schmidt is a stalked freshwater diatom that is expanding its range globally. In some rivers, D. geminata forms thick and expansive polysaccharide-dominated mats. Like other stalked diatoms, D. geminata cells attach to the substratum with a pad of adhesive extracellular polymeric substance. Research on D. geminata and other diatoms suggests that bacterial biofilm composition may contribute to successful attachment. The aim of this study was to investigate the composition and role of bacterial biofilm communities in D. geminata attachment and survival. Bacterial biofilms were collected at four sites in the main stem of a river (containing D. geminata) and in four tributaries (free of D. geminata). Samples were characterised using automated rRNA intergenic spacer analysis and high-throughput sequencing (HTS). Mat-associated bacteria were isolated and their effect on the early establishment of D. geminata cells assessed using co-culturing experiments. ARISA and HTS data showed differences in bacterial communities between samples with and without D. geminata at two of the four sites. Samples with D. geminata had a higher relative abundance of Sphingobacteria (p geminata reduced survival (p geminata. Attachment was enhanced by Micrococcus sp. and Pseudomonas sp. (p geminata, and may partly explain observed distribution patterns.

Sticking together: building a biofilm the Bacillus subtilis way

Science.gov (United States)

Vlamakis, Hera; Chai, Yunrong; Beauregard, Pascale; Losick, Richard; Kolter, Roberto

2014-01-01

Preface Biofilms are ubiquitous communities of tightly associated bacteria encased in an extracellular matrix. Bacillus subtilis has long-served as a robust model organism to examine the molecular mechanisms of biofilm formation and a number of studies have revealed that this process is subject to a number of integrated regulatory pathways. In this Review, we focus on the molecular mechanisms controlling biofilm assembly and briefly summarize the current state of knowledge regarding their disassembly. We also discuss recent progress that has expanded our understanding of biofilm formation on plant roots, which are a natural habitat for this soil bacterium. PMID:23353768

Biofilms and planktonic cells of Deinococcus geothermalis in extreme environments

Science.gov (United States)

Panitz, Corinna; Reitz, Guenther; Rabbow, Elke; Rettberg, Petra; Flemming, Hans-Curt; Wingender, Jost; Froesler, Jan

In addition to the several extreme environments on Earth, Space can be considered as just another exceptional environment with a unique mixture of stress factors comprising UV radiation, vacuum, desiccation, temperature, ionizing radiation and microgravity. Life that processes in these environments can depend on the life forms and their state of living. The question is whether there are different strategies for individual microorganisms compared to communities of the same organisms to cope with the different factors of their surroundings. Comparative studies of the survi-val of these communities called biofilms and planktonic cell samples of Deinococcus geothermalis stand at the focal point of the presented investigations. A biofilm is a structured community of microorganisms that live encapsulated in a matrix of extracellular polymeric substances on a surface. Microorganisms living in a biofilm usually have significantly different properties to cooperate than individually living microorganisms of the same species. An advantage of the biofilm is increased resistance to various chemical and physical effects, while the dense extracellular matrix and the outer layer of the cells protect the interior of the microbial consortium. The space experiment BOSS (Biofilm organisms surfing Space) as part the ESA experimental unit EXPOSE R-2 with a planned launch date in July 2014 will be subsequently mounted on the Russian Svesda module outside the ISS. An international team of scientists coordinated by Dr. P. Rettberg will investigate the hypothesis whether microorganisms organized as biofilm outmatch the same microorganisms exposed individually in the long-term survival of the harsh environmental conditions as they occur in space and on Mars. Another protective function in the samples could be dust par-ticles for instance Mars regolith simulant contained inside the biofilms or mixed with the planktonic cells, as additional shelter especially against the extraterrestrial UV

The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus.

Directory of Open Access Journals (Sweden)

Jin Hwan Park

2015-09-01

Full Text Available A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3',5'-cyclic diguanylic acid (c-di-GMP and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose.

New approaches to combat Porphyromonas gingivalis biofilms

Science.gov (United States)

Gerits, Evelien; Verstraeten, Natalie; Michiels, Jan

2017-01-01

ABSTRACT In nature, bacteria predominantly reside in structured, surface-attached communities embedded in a self-produced, extracellular matrix. These so-called biofilms play an important role in the development and pathogenesis of many infections, as they are difficult to eradicate due to their resistance to antimicrobials and host defense mechanisms. This review focusses on the biofilm-forming periodontal bacterium Porphyromonas gingivalis. Current knowledge on the virulence mechanisms underlying P. gingivalis biofilm formation is presented. In addition, oral infectious diseases in which P. gingivalis plays a key role are described, and an overview of conventional and new therapies for combating P. gingivalis biofilms is given. More insight into this intriguing pathogen might direct the development of better strategies to combat oral infections. PMID:28473880

Controlled assembly of silver nano-fluid in Heliotropium crispum extract: A potent anti-biofilm and bactericidal formulation

Science.gov (United States)

Khan, Faria; Hashmi, Muhammad Uzair; Khalid, Nauman; Hayat, Muhammad Qasim; Ikram, Aamer; Janjua, Hussnain A.

2016-11-01

The study describes the optimized method for silver nanoparticle (AgNPs) synthesis using Heliotropium crispum (HC) plant extract. Optimization of physicochemical parameters resulted in stable and rapidly assembled AgNPs. FTIR results suggest presence of plant phytochemicals that helped in the reduction, stabilization and capping of AgNPs. The assembled Ag nano-composites displayed the peak surface plasmon resonance (SPR) around 428 nm. The presence of uniquely assembled Ag-biomolecule composites, cap and stabilize nanoparticles in aqueous plant suspension. Spherical, uniform-shaped AgNPs with low poly-dispersion and average particle size of 42 nm and was determined through dynamic light scattering (DLS) and scanning election microscopy (SEM) which present robust interaction with microbes. The study also evaluates the antimicrobial and anti-biofilm properties of biologically synthesized AgNPs on clinical isolates of MRSA, Pseudomonas aeruginosa and Acinetobacter baumannii. Minimum inhibitory concentration (0.5 mg mL-1) of nanoparticles that presented bactericidal effect was made through inhibition assays on bacterial strains. The concentration which presented potent bactericidal response was then evaluated through growth inhibition in liquid medium for anti-biofilm studies at 2.0 mg mL-1. HC-Ag nanoparticles mediated anti-biofilm effects on Pseudomonas aeruginosa was revealed through SEM. Complete breakdown of biofilm's extracellular polymeric substances resulted after incubation with AgNPs. Peptidoglycan cell wall destruction was also revealed on planktonic bacterial images after 24 h of incubation.

Membrane fouling related to microbial community and extracellular polymeric substances at different temperatures.

Science.gov (United States)

Gao, Da-Wen; Wen, Zhi-Dan; Li, Bao; Liang, Hong

2013-09-01

An anoxic-aerobic membrane bioreactor was established to investigate the role of microorganisms and microbial metabolites in membrane fouling at different temperatures. The results showed that the membrane fouling cycle at 303, 293, and 283 K were 30, 29, and 5.5 days, respectively. Polysaccharides dominated the extracellular polymeric substances (EPS) and soluble microbial products (SMP) at 303 and 293 K, instead, proteins was the predominant composition of metabolites at 283 K. The correlation coefficient (r(2)) was calculated to identify the relationship between temperature (T), filtration resistance (R) and compositions of EPS and SMP. In biocake, the EPS polysaccharides (EPSc) was the most correlative factor to temperature (T) and filtration resistance (R); in mixed liquor, the ratio of SMP polysaccharides to proteins (SMPc/p) was the most correlative factor. The microbial community structure and the dominant species was the major reason causing the change of EPS and SMP composition. Copyright © 2013 Elsevier Ltd. All rights reserved.

Anti-biofilm formation of a novel stainless steel against Staphylococcus aureus.

Science.gov (United States)

Nan, Li; Yang, Ke; Ren, Guogang

2015-06-01

Staphylococcus aureus (S. aureus) is a bacterium frequently found proliferating on metal surfaces such as stainless steels used in healthcare and food processing facilities. Past research has shown that a novel Cu-bearing 304 type stainless steel (304CuSS) exhibits excellent antibacterial ability (i.e. against S. aureus) in a short time period (24h.). This work was dedicated to investigate the 304CuSS's inhibition ability towards the S. aureus biofilm formation for an extended period of 7days after incubation. It was found that the antibacterial rate of the 304CuSS against sessile bacterial cells reached over 99.9% in comparison with the 304SS. The thickness and sizes of the biofilms on the 304SS surfaces increased markedly with period of contact, and thus expected higher risk of bio-contamination, indicated by the changes of surface free energy between biofilm and the steel surfaces. The results demonstrated that the 304CuSS exhibited strong inhibition on the growth and adherence of the biofilms. The surface free energy of the 304CuSS after contact with sessile bacterial cells was much lower than that of the 304SS towards the same culture times. The continuously dissolved Cu(2+) ions well demonstrated the dissolution ability of Cu-rich precipitates after exposure to S. aureus solution, from 3.1ppm (2days) to 4.5ppm (7days). For this to occur, a hypothesis mechanism might be established for 304CuSS in which the Cu(2+) ions were released from Cu-rich phases that bond with extracellular polymeric substances (EPS) of the microorganisms. And these inhibited the activities of cell protein/enzymes and effectively prevented planktonic bacterial cells attaching to the 304CuSS metal surface. Copyright © 2015. Published by Elsevier B.V.

Anti-biofilm formation of a novel stainless steel against Staphylococcus aureus

International Nuclear Information System (INIS)

Nan, Li; Yang, Ke; Ren, Guogang

2015-01-01

Staphylococcus aureus (S. aureus) is a bacterium frequently found proliferating on metal surfaces such as stainless steels used in healthcare and food processing facilities. Past research has shown that a novel Cu-bearing 304 type stainless steel (304CuSS) exhibits excellent antibacterial ability (i.e. against S. aureus) in a short time period (24 h.). This work was dedicated to investigate the 304CuSS's inhibition ability towards the S. aureus biofilm formation for an extended period of 7 days after incubation. It was found that the antibacterial rate of the 304CuSS against sessile bacterial cells reached over 99.9% in comparison with the 304SS. The thickness and sizes of the biofilms on the 304SS surfaces increased markedly with period of contact, and thus expected higher risk of bio-contamination, indicated by the changes of surface free energy between biofilm and the steel surfaces. The results demonstrated that the 304CuSS exhibited strong inhibition on the growth and adherence of the biofilms. The surface free energy of the 304CuSS after contact with sessile bacterial cells was much lower than that of the 304SS towards the same culture times. The continuously dissolved Cu 2+ ions well demonstrated the dissolution ability of Cu-rich precipitates after exposure to S. aureus solution, from 3.1 ppm (2 days) to 4.5 ppm (7 days). For this to occur, a hypothesis mechanism might be established for 304CuSS in which the Cu 2+ ions were released from Cu-rich phases that bond with extracellular polymeric substances (EPS) of the microorganisms. And these inhibited the activities of cell protein/enzymes and effectively prevented planktonic bacterial cells attaching to the 304CuSS metal surface

Anti-biofilm formation of a novel stainless steel against Staphylococcus aureus

Energy Technology Data Exchange (ETDEWEB)

Nan, Li; Yang, Ke [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Ren, Guogang, E-mail: g.g.ren@herts.ac.uk [University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)

2015-06-01

Staphylococcus aureus (S. aureus) is a bacterium frequently found proliferating on metal surfaces such as stainless steels used in healthcare and food processing facilities. Past research has shown that a novel Cu-bearing 304 type stainless steel (304CuSS) exhibits excellent antibacterial ability (i.e. against S. aureus) in a short time period (24 h.). This work was dedicated to investigate the 304CuSS's inhibition ability towards the S. aureus biofilm formation for an extended period of 7 days after incubation. It was found that the antibacterial rate of the 304CuSS against sessile bacterial cells reached over 99.9% in comparison with the 304SS. The thickness and sizes of the biofilms on the 304SS surfaces increased markedly with period of contact, and thus expected higher risk of bio-contamination, indicated by the changes of surface free energy between biofilm and the steel surfaces. The results demonstrated that the 304CuSS exhibited strong inhibition on the growth and adherence of the biofilms. The surface free energy of the 304CuSS after contact with sessile bacterial cells was much lower than that of the 304SS towards the same culture times. The continuously dissolved Cu{sup 2+} ions well demonstrated the dissolution ability of Cu-rich precipitates after exposure to S. aureus solution, from 3.1 ppm (2 days) to 4.5 ppm (7 days). For this to occur, a hypothesis mechanism might be established for 304CuSS in which the Cu{sup 2+} ions were released from Cu-rich phases that bond with extracellular polymeric substances (EPS) of the microorganisms. And these inhibited the activities of cell protein/enzymes and effectively prevented planktonic bacterial cells attaching to the 304CuSS metal surface.

Crenarchaeal biofilm formation under extreme conditions.

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Andrea Koerdt

Full Text Available BACKGROUND: Biofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments. METHODOLOGY: We have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitre plate assay adapted to high temperatures to determine how pH and temperature influence biofilm formation in these organisms. Biofilm analysis by confocal laser scanning microscopy demonstrated that the three strains form very different communities ranging from simple carpet-like structures in S. solfataricus to high density tower-like structures in S. acidocaldarius in static systems. Lectin staining indicated that all three strains produced extracellular polysaccharides containing glucose, galactose, mannose and N-acetylglucosamine once biofilm formation was initiated. While flagella mutants had no phenotype in two days old static biofilms of S. solfataricus, a UV-induced pili deletion mutant showed decreased attachment of cells. CONCLUSION: The study gives first insights into formation and development of crenarchaeal biofilms in extreme environments.

A Candida biofilm-induced pathway for matrix glucan delivery: implications for drug resistance.

Directory of Open Access Journals (Sweden)

Heather T Taff

Full Text Available Extracellular polysaccharides are key constituents of the biofilm matrix of many microorganisms. One critical carbohydrate component of Candida albicans biofilms, β-1,3 glucan, has been linked to biofilm protection from antifungal agents. In this study, we identify three glucan modification enzymes that function to deliver glucan from the cell to the extracellular matrix. These enzymes include two predicted glucan transferases and an exo-glucanase, encoded by BGL2, PHR1, and XOG1, respectively. We show that the enzymes are crucial for both delivery of β-1,3 glucan to the biofilm matrix and for accumulation of mature matrix biomass. The enzymes do not appear to impact cell wall glucan content of biofilm cells, nor are they necessary for filamentation or biofilm formation. We demonstrate that mutants lacking these genes exhibit enhanced susceptibility to the commonly used antifungal, fluconazole, during biofilm growth only. Transcriptional analysis and biofilm phenotypes of strains with multiple mutations suggest that these enzymes act in a complementary fashion to distribute matrix downstream of the primary β-1,3 glucan synthase encoded by FKS1. Furthermore, our observations suggest that this matrix delivery pathway works independently from the C. albicans ZAP1 matrix formation regulatory pathway. These glucan modification enzymes appear to play a biofilm-specific role in mediating the delivery and organization of mature biofilm matrix. We propose that the discovery of inhibitors for these enzymes would provide promising anti-biofilm therapeutics.

An update on Pseudomonas aeruginosa biofilm formation, tolerance, and dispersal

DEFF Research Database (Denmark)

Harmsen, Morten; Yang, Liang; Pamp, Sünje Johanna

2010-01-01

We review the recent advances in the understanding of the Pseudomonas aeruginosa biofilm lifestyle from studies using in vitro laboratory setups such as flow chambers and microtiter trays. Recent work sheds light on the role of nutrients, motility, and quorum sensing in structure formation in P....... aeruginosa biofilms. The second messenger, c-di-GMP, is established as an important regulator of the synthesis of polysaccharide and protein components of the biofilm matrix. Extracellular DNA is shown to be an essential component of the biofilm matrix. It has become apparent that biofilm formation involves...... interactions between different subpopulations. The molecular mechanisms underlying the tolerance of biofilm bacteria to antimicrobial agents are beginning to be unraveled, and new knowledge has been obtained regarding the environmental cues and regulatory mechanisms involved in biofilm dispersal....

Nonleachable Imidazolium-Incorporated Composite for Disruption of Bacterial Clustering, Exopolysaccharide-Matrix Assembly, and Enhanced Biofilm Removal.

Science.gov (United States)

Hwang, Geelsu; Koltisko, Bernard; Jin, Xiaoming; Koo, Hyun

2017-11-08

Surface-grown bacteria and production of an extracellular polymeric matrix modulate the assembly of highly cohesive and firmly attached biofilms, making them difficult to remove from solid surfaces. Inhibition of cell growth and inactivation of matrix-producing bacteria can impair biofilm formation and facilitate removal. Here, we developed a novel nonleachable antibacterial composite with potent antibiofilm activity by directly incorporating polymerizable imidazolium-containing resin (antibacterial resin with carbonate linkage; ABR-C) into a methacrylate-based scaffold (ABR-modified composite; ABR-MC) using an efficient yet simplified chemistry. Low-dose inclusion of imidazolium moiety (∼2 wt %) resulted in bioactivity with minimal cytotoxicity without compromising mechanical integrity of the restorative material. The antibiofilm properties of ABR-MC were assessed using an exopolysaccharide-matrix-producing (EPS-matrix-producing) oral pathogen (Streptococcus mutans) in an experimental biofilm model. Using high-resolution confocal fluorescence imaging and biophysical methods, we observed remarkable disruption of bacterial accumulation and defective 3D matrix structure on the surface of ABR-MC. Specifically, the antibacterial composite impaired the ability of S. mutans to form organized bacterial clusters on the surface, resulting in altered biofilm architecture with sparse cell accumulation and reduced amounts of EPS matrix (versus control composite). Biofilm topology analyses on the control composite revealed a highly organized and weblike EPS structure that tethers the bacterial clusters to each other and to the surface, forming a highly cohesive unit. In contrast, such a structured matrix was absent on the surface of ABR-MC with mostly sparse and amorphous EPS, indicating disruption in the biofilm physical stability. Consistent with lack of structural organization, the defective biofilm on the surface of ABR-MC was readily detached when subjected to low shear

Anti-Biofilm Compounds Derived from Marine Sponges

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Christian Melander

2011-10-01

Full Text Available Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks havoc on shipping, utilities, and offshore industry. Within a host environment, they are insensitive to antiseptics and basic host immune responses. It is estimated that up to 80% of all microbial infections are biofilm-based. Biofilm infections of indwelling medical devices are of particular concern, since once the device is colonized, infection is almost impossible to eliminate. Given the prominence of biofilms in infectious diseases, there is a notable effort towards developing small, synthetically available molecules that will modulate bacterial biofilm development and maintenance. Here, we highlight the development of small molecules that inhibit and/or disperse bacterial biofilms specifically through non-microbicidal mechanisms. Importantly, we discuss several sets of compounds derived from marine sponges that we are developing in our labs to address the persistent biofilm problem. We will discuss: discovery/synthesis of natural products and their analogues—including our marine sponge-derived compounds and initial adjuvant activity and toxicological screening of our novel anti-biofilm compounds.

Biofilms in Infections of the Eye

Directory of Open Access Journals (Sweden)

Paulo J. M. Bispo

2015-03-01

Full Text Available The ability to form biofilms in a variety of environments is a common trait of bacteria, and may represent one of the earliest defenses against predation. Biofilms are multicellular communities usually held together by a polymeric matrix, ranging from capsular material to cell lysate. In a structure that imposes diffusion limits, environmental microgradients arise to which individual bacteria adapt their physiologies, resulting in the gamut of physiological diversity. Additionally, the proximity of cells within the biofilm creates the opportunity for coordinated behaviors through cell–cell communication using diffusible signals, the most well documented being quorum sensing. Biofilms form on abiotic or biotic surfaces, and because of that are associated with a large proportion of human infections. Biofilm formation imposes a limitation on the uses and design of ocular devices, such as intraocular lenses, posterior contact lenses, scleral buckles, conjunctival plugs, lacrimal intubation devices and orbital implants. In the absence of abiotic materials, biofilms have been observed on the capsule, and in the corneal stroma. As the evidence for the involvement of microbial biofilms in many ocular infections has become compelling, developing new strategies to prevent their formation or to eradicate them at the site of infection, has become a priority.

Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54

NARCIS (Netherlands)

Hayrapetyan, Hasmik

2017-01-01

Biofilms are surface-associated communities of microbial cells embedded in a matrix of extracellular polymers. It is generally accepted that the biofilm growth mode represents the most common lifestyle of microorganisms. Next to beneficial biofilms used in biotechnology applications, undesired

Competitive adsorption of heavy metal by extracellular polymeric substances (EPS) extracted from sulfate reducing bacteria.

Science.gov (United States)

Wang, Jin; Li, Qing; Li, Ming-Ming; Chen, Tian-Hu; Zhou, Yue-Fei; Yue, Zheng-Bo

2014-07-01

Competitive adsorption of heavy metals by extracellular polymeric substances (EPS) extracted from Desulfovibrio desulfuricans was investigated. Chemical analysis showed that different EPS compositions had different capacities for the adsorption of heavy metals which was investigated using Cu(2+) and Zn(2+). Batch adsorption tests indicated that EPS had a higher combined ability with Zn(2+) than Cu(2+). This was confirmed and explained by Fourier transform infrared (FTIR) and excitation-emission matrix (EEM) spectroscopy analysis. FTIR analysis showed that both polysaccharides and protein combined with Zn(2+) while only protein combined with Cu(2+). EEM spectra further revealed that tryptophan-like substances were the main compositions reacted with the heavy metals. Moreover, Zn(2+) had a higher fluorescence quenching ability than Cu(2+). Copyright © 2014 Elsevier Ltd. All rights reserved.

Biofilm population dynamics in a trickle-bed bioreactor used for the biodegradation of aromatic hydrocarbons from waste gas under transient conditions.

Science.gov (United States)

Hekmat, D; Feuchtinger, A; Stephan, M; Vortmeyer, D

2004-04-01

The dynamics of a multispecies biofilm population in a laboratory-scale trickle-bed bioreactor for the treatment of waste gas was examined. The model pollutant was a VOC-mixture of polyalkylated benzenes called Solvesso 100. Fluorescence in-situ hybridization (FISH) was applied in order to characterise the population composition. The bioreactor was operated under transient conditions by applying pollutant concentration shifts and a starvation phase. Only about 10% of the biofilm mass were cells, the rest consisted of extracellular polymeric substances (EPS). The average fraction of Solvesso 100-degrading cells during pollutant supply periods was less than 10%. About 60% of the cells were saprophytes and about 30% were inactive cells. During pollutant concentration shift experiments, the bioreactor performance adapted within a few hours. The biofilm population exhibited a dependency upon the direction of the shifts. The population reacted within days after a shift-down and within weeks after a shift-up. The pollutant-degraders reacted significantly faster compared to the other cells. During the long-term starvation phase, a shift of the population composition took place. However, this change of composition as well as the degree of metabolic activity was completely reversible. A direct correlation between the biodegradation rate of the bioreactor and the number of pollutant-degrading cells present in the biofilm could not be obtained due to insufficient experimental evidence.

Pseudomonas aeruginosa Psl Exopolysaccharide Interacts with the Antimicrobial Peptide LG21

Directory of Open Access Journals (Sweden)

Joyce Seow Fong Chin

2017-09-01

Full Text Available Biofilm formation by opportunistic pathogens serves as one of the major causes of chronic and persistent infections. Bacterial cells in the biofilms are embedded in their self-generated protective extracellular polymeric substances (EPS, which include exopolysaccharides, large adhesin proteins and extracellular DNA. In this study, we identified an antimicrobial peptide (AMP LG21 that is able to interact specifically with the Psl exopolysaccharide of Pseudomonas aeruginosa, thus it can be used as a diagnostic tool for P. aeruginosa biofilms. Molecular dynamics simulation analysis showed that residues numbered from 15 to 21 (WKRKRFG in LG21 are involved in interacting with Psl. Our study indicates that host immune systems might detect and interact with microbial biofilms through AMPs. Engineering biofilm EPS-targeting AMPs might provide novel strategies for biofilm detection and treatment.

Pseudomonas biofilm matrix composition and niche biology

Science.gov (United States)

Mann, Ethan E.; Wozniak, Daniel J.

2014-01-01

Biofilms are a predominant form of growth for bacteria in the environment and in the clinic. Critical for biofilm development are adherence, proliferation, and dispersion phases. Each of these stages includes reinforcement by, or modulation of, the extracellular matrix. Pseudomonas aeruginosa has been a model organism for the study of biofilm formation. Additionally, other Pseudomonas species utilize biofilm formation during plant colonization and environmental persistence. Pseudomonads produce several biofilm matrix molecules, including polysaccharides, nucleic acids, and proteins. Accessory matrix components shown to aid biofilm formation and adaptability under varying conditions are also produced by pseudomonads. Adaptation facilitated by biofilm formation allows for selection of genetic variants with unique and distinguishable colony morphology. Examples include rugose small-colony variants and wrinkly spreaders (WS), which over produce Psl/Pel or cellulose, respectively, and mucoid bacteria that over produce alginate. The well-documented emergence of these variants suggests that pseudomonads take advantage of matrix-building subpopulations conferring specific benefits for the entire population. This review will focus on various polysaccharides as well as additional Pseudomonas biofilm matrix components. Discussions will center on structure–function relationships, regulation, and the role of individual matrix molecules in niche biology. PMID:22212072

Streptococcus mutans Extracellular DNA Is Upregulated during Growth in Biofilms, Actively Released via Membrane Vesicles, and Influenced by Components of the Protein Secretion Machinery

Science.gov (United States)

Liao, Sumei; Klein, Marlise I.; Heim, Kyle P.; Fan, Yuwei; Bitoun, Jacob P.; Ahn, San-Joon; Burne, Robert A.; Koo, Hyun; Brady, L. Jeannine

2014-01-01

Streptococcus mutans, a major etiological agent of human dental caries, lives primarily on the tooth surface in biofilms. Limited information is available concerning the extracellular DNA (eDNA) as a scaffolding matrix in S. mutans biofilms. This study demonstrates that S. mutans produces eDNA by multiple avenues, including lysis-independent membrane vesicles. Unlike eDNAs from cell lysis that were abundant and mainly concentrated around broken cells or cell debris with floating open ends, eDNAs produced via the lysis-independent pathway appeared scattered but in a structured network under scanning electron microscopy. Compared to eDNA production of planktonic cultures, eDNA production in 5- and 24-h biofilms was increased by >3- and >1.6-fold, respectively. The addition of DNase I to growth medium significantly reduced biofilm formation. In an in vitro adherence assay, added chromosomal DNA alone had a limited effect on S. mutans adherence to saliva-coated hydroxylapatite beads, but in conjunction with glucans synthesized using purified glucosyltransferase B, the adherence was significantly enhanced. Deletion of sortase A, the transpeptidase that covalently couples multiple surface-associated proteins to the cell wall peptidoglycan, significantly reduced eDNA in both planktonic and biofilm cultures. Sortase A deficiency did not have a significant effect on membrane vesicle production; however, the protein profile of the mutant membrane vesicles was significantly altered, including reduction of adhesin P1 and glucan-binding proteins B and C. Relative to the wild type, deficiency of protein secretion and membrane protein insertion machinery components, including Ffh, YidC1, and YidC2, also caused significant reductions in eDNA. PMID:24748612

Nanostructured coatings for controlling bacterial biofilms and antibiotic resistance

OpenAIRE

Ivanova, Kristina Dimitrova

2017-01-01

The accelerated emergence of drug resistant bacteria is one of the most serious problems in healthcare and the difficulties in finding new antibiotics make it even more challenging. To overcome the action of antibiotics bacteria develop effective resistance mechanisms including the formation of biofilms. Biofilms are bacterial communities of cells embedded in a self-produced polymeric matrix commonly found on medical devices such as indwelling catheters. When pathogens adopt this mode of grow...

A Bacillus subtilis Sensor Kinase Involved in Triggering Biofilm Formation on the Roots of Tomato Plants

Science.gov (United States)

Chen, Yun; Cao, Shugeng; Chai, Yunrong; Clardy, Jon; Kolter, Roberto; Guo, Jian-hua; Losick, Richard

2012-01-01

SUMMARY The soil bacterium Bacillus subtilis is widely used in agriculture as a biocontrol agent able to protect plants from a variety of pathogens. Protection is thought to involve the formation of bacterial communities - biofilms - on the roots of the plants. Here we used confocal microscopy to visualize biofilms on the surface of the roots of tomato seedlings and demonstrated that biofilm formation requires genes governing the production of the extracellular matrix that holds cells together. We further show that biofilm formation was dependent on the sensor histidine kinase KinD and in particular on an extracellular CACHE domain implicated in small molecule sensing. Finally, we report that exudates of tomato roots strongly stimulated biofilm formation ex planta and that an abundant small molecule in the exudates, l-malic acid, was able to stimulate biofilm formation at high concentrations in a manner that depended on the KinD CACHE domain. We propose that small signaling molecules released by the roots of tomato plants are directly or indirectly recognized by KinD, triggering biofilm formation. PMID:22716461

Stabilizing Effects of Bacterial Biofilms: EPS Penetration and Redistribution of Bed Stability Down the Sediment Profile

Science.gov (United States)

Chen, X. D.; Zhang, C. K.; Zhou, Z.; Gong, Z.; Zhou, J. J.; Tao, J. F.; Paterson, D. M.; Feng, Q.

2017-12-01

Biofilms, consisting of microorganisms and their secreted extracellular polymeric substances (EPSs), serve as "ecosystem engineers" stabilizing sedimentary environments. Natural sediment bed provides an excellent substratum for biofilm growth. The porous structure and rich nutrients allow the EPS matrix to spread deeper into the bed. A series of laboratory-controlled experiments were conducted to investigate sediment colonization of Bacillus subtilis and the penetration of EPS into the sediment bed with incubation time. In addition to EPS accumulation on the bed surface, EPS also penetrated downward. However, EPS distribution developed strong vertical heterogeneity with a much higher content in the surface layer than in the bottom layer. Scanning electron microscope images of vertical layers also displayed different micromorphological properties of sediment-EPS matrix. In addition, colloidal and bound EPSs exhibited distinctive distribution patterns. After the full incubation, the biosedimentary beds were eroded to test the variation of bed stability induced by biological effects. This research provides an important reference for the prediction of sediment transport and hence deepens the understanding of the biologically mediated sediment system and broadens the scope of the burgeoning research field of "biomorphodynamics."

The Pseudomonas aeruginosa PSL polysaccharide is a social but noncheatable trait in biofilms

DEFF Research Database (Denmark)

Irie, Yasuhiko; Roberts, Aled E.L.; Kragh, Kasper N.

2017-01-01

Extracellular polysaccharides are compounds secreted by microorganisms into the surrounding environment, and they are important for surface attachment and maintaining structural integrity within biofilms. The social nature of many extracellular polysaccharides remains unclear, and it has been sug...

Biological synthesis of nanoparticles in biofilms.

Science.gov (United States)

Tanzil, Abid H; Sultana, Sujala T; Saunders, Steven R; Shi, Liang; Marsili, Enrico; Beyenal, Haluk

2016-12-01

The biological synthesis of nanoparticles (NPs) by bacteria and biofilms via extracellular redox reactions has received attention because of the minimization of harmful chemicals, low cost, and ease of culturing and downstream processing. Bioreduction mechanisms vary across bacteria and growth conditions, which leads to various sizes and shapes of biosynthesized NPs. NP synthesis in biofilms offers additional advantages, such as higher biomass concentrations and larger surface areas, which can lead to more efficient and scalable biosynthesis. Although biofilms have been used to produce NPs, the mechanistic details of NP formation are not well understood. In this review, we identify three critical areas of research and development needed to advance our understanding of NP production by biofilms: 1) synthesis, 2) mechanism and 3) stabilization. Advancement in these areas could result in the biosynthesis of NPs that are suitable for practical applications, especially in drug delivery and biocatalysis. Specifically, the current status of methods and mechanisms of nanoparticle synthesis and surface stabilization using planktonic bacteria and biofilms is discussed. We conclude that the use of biofilms to synthesize and stabilize NPs is underappreciated and could provide a new direction in biofilm-based NP production. Copyright © 2016 Elsevier Inc. All rights reserved.

Functional bacterial amyloid increases Pseudomonas biofilm hydrophobicity and stiffness

DEFF Research Database (Denmark)

Zeng, Guanghong; Vad, Brian S; Dueholm, Morten S

2015-01-01

The success of Pseudomonas species as opportunistic pathogens derives in great part from their ability to form stable biofilms that offer protection against chemical and mechanical attack. The extracellular matrix of biofilms contains numerous biomolecules, and it has recently been discovered...... that in Pseudomonas one of the components includes β-sheet rich amyloid fibrils (functional amyloid) produced by the fap operon. However, the role of the functional amyloid within the biofilm has not yet been investigated in detail. Here we investigate how the fap-based amyloid produced by Pseudomonas affects biofilm...... hydrophobicity and mechanical properties. Using atomic force microscopy imaging and force spectroscopy, we show that the amyloid renders individual cells more resistant to drying and alters their interactions with hydrophobic probes. Importantly, amyloid makes Pseudomonas more hydrophobic and increases biofilm...

A Biofilm Matrix-Associated Protease Inhibitor Protects Pseudomonas aeruginosa from Proteolytic Attack.

Science.gov (United States)

Tseng, Boo Shan; Reichhardt, Courtney; Merrihew, Gennifer E; Araujo-Hernandez, Sophia A; Harrison, Joe J; MacCoss, Michael J; Parsek, Matthew R

2018-04-10

Pseudomonas aeruginosa produces an extracellular biofilm matrix that consists of nucleic acids, exopolysaccharides, lipid vesicles, and proteins. In general, the protein component of the biofilm matrix is poorly defined and understudied relative to the other major matrix constituents. While matrix proteins have been suggested to provide many functions to the biofilm, only proteins that play a structural role have been characterized thus far. Here we identify proteins enriched in the matrix of P. aeruginosa biofilms. We then focused on a candidate matrix protein, the serine protease inhibitor ecotin (PA2755). This protein is able to inhibit neutrophil elastase, a bactericidal enzyme produced by the host immune system during P. aeruginosa biofilm infections. We show that ecotin binds to the key biofilm matrix exopolysaccharide Psl and that it can inhibit neutrophil elastase when associated with Psl. Finally, we show that ecotin protects both planktonic and biofilm P. aeruginosa cells from neutrophil elastase-mediated killing. This may represent a novel mechanism of protection for biofilms to increase their tolerance against the innate immune response. IMPORTANCE Proteins associated with the extracellular matrix of bacterial aggregates called biofilms have long been suggested to provide many important functions to the community. To date, however, only proteins that provide structural roles have been described, and few matrix-associated proteins have been identified. We developed a method to identify matrix proteins and characterized one. We show that this protein, when associated with the biofilm matrix, can inhibit a bactericidal enzyme produced by the immune system during infection and protect biofilm cells from death induced by the enzyme. This may represent a novel mechanism of protection for biofilms, further increasing their tolerance against the immune response. Together, our results are the first to show a nonstructural function for a confirmed matrix

Competitive Interactions in Mixed-Species Biofilms Containing the Marine Bacterium Pseudoalteromonas tunicata

Science.gov (United States)

Rao, Dhana; Webb, Jeremy S.; Kjelleberg, Staffan

2005-01-01

Pseudoalteromonas tunicata is a biofilm-forming marine bacterium that is often found in association with the surface of eukaryotic organisms. It produces a range of extracellular inhibitory compounds, including an antibacterial protein (AlpP) thought to be beneficial for P. tunicata during competition for space and nutrients on surfaces. As part of our studies on the interactions between P. tunicata and the epiphytic bacterial community on the marine plant Ulva lactuca, we investigated the hypothesis that P. tunicata is a superior competitor compared with other bacteria isolated from the plant. A number of U. lactuca bacterial isolates were (i) identified by 16S rRNA gene sequencing, (ii) characterized for the production of or sensitivity to extracellular antibacterial proteins, and (iii) labeled with a fluorescent color tag (either the red fluorescent protein DsRed or green fluorescent protein). We then grew single- and mixed-species bacterial biofilms containing P. tunicata in glass flow cell reactors. In pure culture, all the marine isolates formed biofilms containing microcolony structures within 72 h. However, in mixed-species biofilms, P. tunicata removed the competing strain unless its competitor was relatively insensitive to AlpP (Pseudoalteromonas gracilis) or produced strong inhibitory activity against P. tunicata (Roseobacter gallaeciensis). Moreover, biofilm studies conducted with an AlpP− mutant of P. tunicata indicated that the mutant was less competitive when it was introduced into preestablished biofilms, suggesting that AlpP has a role during competitive biofilm formation. When single-species biofilms were allowed to form microcolonies before the introduction of a competitor, these microcolonies coexisted with P. tunicata for extended periods of time before they were removed. Two marine bacteria (R. gallaeciensis and P. tunicata) were superior competitors in this study. Our data suggest that this dominance can be attributed to the ability of

Inhibition of Nitzschia ovalis biofilm settlement by a bacterial bioactive compound through alteration of EPS and epiphytic bacteria

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Claudia D. Infante

2018-05-01

Full Text Available Background: Marine ecosystems contain benthic microalgae and bacterial species that are capable of secreting extracellular polymeric substances (EPS, suggesting that settlement of these microorganisms can occur on submerged surfaces, a key part of the first stage of biofouling. Currently, anti-fouling treatments that help control this phenomenon involve the use of biocides or antifouling paints that contain heavy metals, which over a long period of exposure can spread to the environment. The bacterium Alteromonas sp. Ni1-LEM has an inhibitory effect on the adhesion of Nitzschia ovalis, an abundant diatom found on submerged surfaces. Results: We evaluated the effect of the bioactive compound secreted by this bacterium on the EPS of biofilms and associated epiphytic bacteria. Three methods of EPS extraction were evaluated to determine the most appropriate and efficient methodology based on the presence of soluble EPS and the total protein and carbohydrate concentrations. Microalgae were cultured with the bacterial compound to evaluate its effect on EPS secretion and variations in its protein and carbohydrate concentrations. An effect of the bacterial supernatant on EPS was observed by assessing biofilm formation and changes in the concentration of proteins and carbohydrates present in the biofilm. Conclusions: These results indicate that a possible mechanism for regulating biofouling could be through alteration of biofilm EPS and alteration of the epiphytic bacterial community associated with the microalga.How to cite: Infante, C.D., Castillo, F., Pérez, V., et al. Inhibition of Nitzschia ovalis biofilm settlement by a bacterial bioactive compound through alteration of EPS and epiphytic bacteria. Electron J Biotechnol 2018;33 https://doi.org/10.1016/j.ejbt.2018.03.002. Keywords: Anti-fouling, Benthic microalgae, Biofilm, Biofouling, Epiphytic bacterial community, EPS, Marine ecosystems, Metagenomic, Nitzschia ovalis, Settlement inhibition

Sexual Biofilm Formation in Candida tropicalis Opaque Cells

Science.gov (United States)

Jones, Stephen K.; Hirakawa, Matthew P.; Bennett, Richard J.

2014-01-01

Summary Candida albicans and Candida tropicalis are opportunistic fungal pathogens that can transition between white and opaque phenotypic states. White and opaque cells differ both morphologically and in their responses to environmental signals. In C. albicans, opaque cells respond to sexual pheromones by undergoing conjugation, while white cells are induced by pheromones to form sexual biofilms. Here, we show that sexual biofilm formation also occurs in C. tropicalis but, unlike C. albicans, biofilms are formed exclusively by opaque cells. C. tropicalis biofilm formation was dependent on the pheromone receptors Ste2 and Ste3, confirming the role of pheromone signaling in sexual biofilm development. Structural analysis of C. tropicalis sexual biofilms revealed stratified communities consisting of a basal layer of yeast cells and an upper layer of filamentous cells, together with an extracellular matrix. Transcriptional profiling showed that genes involved in pheromone signaling and conjugation were upregulated in sexual biofilms. Furthermore, FGR23, which encodes an agglutinin-like protein, was found to enhance both mating and sexual biofilm formation. Together, these studies reveal that C. tropicalis opaque cells form sexual biofilms with a complex architecture, and suggest a conserved role for sexual agglutinins in mediating mating, cell cohesion and biofilm formation. PMID:24612417

Extracellular DNA formation during biofilm development by freshwater bacteria

DEFF Research Database (Denmark)

Tang, Lone; Schramm, Andreas; Revsbech, Niels Peter

2011-01-01

a transient peak at 6 hours, and in Rheinheimera the concentration peaked at 12 hours and remained high. Interestingly, the Rheinheimera biofilm dispersed immediately after the eDNA concentration peaked. The antimicrobial effect of eDNA was tested in growth experiments, and Rheinheimera was strongly affected...

Formation of extracellular polymeric substances from acidogenic sludge in H2-producing process.

Science.gov (United States)

Sheng, Guo-Ping; Yu, Han-Qing

2007-02-01

In this study, the formation of extracellular polymeric substances (EPS) and surface characteristics of an acidogenic sludge in anaerobic H(2)-producing process was investigated. Results show that carbohydrates, proteins, and humic substances were the dominant components in bound EPS (BEPS), while in soluble EPS (SEPS), carbohydrates were the main component. The total content of BEPS initially increased but then kept almost unchanged during fermentation from 25 to 35 h; after that, it slightly decreased. The total content of SEPS increased to 172.5 +/- 0.05 mg C g(-1) volatile suspended solid with the time that increased to 23.5 h, and then rapidly decreased until 43 h; thereafter, it kept almost unchanged. The SEPS had good correlations with the specific H(2) production rate, substrate degradation rate, and specific aqueous products formation rate, but the BEPS seemed to have no such correlations with these specific rates. Results also confirm that part of EPS could be utilized by the H(2)-producing sludge. As the substrate was in short supply, the EPS would be hydrolyzed to sever as carbon and energy source.

Species-independent attraction to biofilms through electrical signaling

Science.gov (United States)

Humphries, Jacqueline; Xiong, Liyang; Liu, Jintao; Prindle, Arthur; Yuan, Fang; Arjes, Heidi A.; Tsimring, Lev; Süel, Gürol M.

2017-01-01

Summary Bacteria residing within biofilm communities can coordinate their behavior through cell-to-cell signaling. However, it remains unclear if these signals can also influence the behavior of distant cells that are not part of the community. Using a microfluidic approach, we find that potassium ion channel-mediated electrical signaling generated by a Bacillus subtilis biofilm can attract distant cells. Integration of experiments and mathematical modeling indicates that extracellular potassium emitted from the biofilm alters the membrane potential of distant cells, thereby directing their motility. This electrically-mediated attraction appears to be a generic mechanism that enables cross-species interactions, as Pseudomonas aeruginosa cells also become attracted to the electrical signal released by the B. subtilis biofilm. Cells within a biofilm community can thus not only coordinate their own behavior, but also influence the behavior of diverse bacteria at a distance through long-range electrical signaling. PMID:28086091

Acoustically excited encapsulated microbubbles and mitigation of biofouling

KAUST Repository

Qamar, Adnan

2017-08-31

Provided herein is a universally applicable biofouling mitigation technology using acoustically excited encapsulated microbubbles that disrupt biofilm or biofilm formation. For example, a method of reducing biofilm formation or removing biofilm in a membrane filtration system is provided in which a feed solution comprising encapsulated microbubbles is provided to the membrane under conditions that allow the encapsulated microbubbles to embed in a biofilm. Sonication of the embedded, encapsulated microbubbles disrupts the biofilm. Thus, provided herein is a membrane filtration system for performing the methods and encapsulated microbubbles specifically selected for binding to extracellular polymeric substances (EFS) in a biofilm.

Antifungal and Anti-Biofilm Activity of Essential Oil Active Components against Cryptococcus neoformans and Cryptococcus laurentii

Directory of Open Access Journals (Sweden)

Poonam Kumari

2017-11-01

Full Text Available Cryptococcosis is an emerging and recalcitrant systemic infection occurring in immunocompromised patients. This invasive fungal infection is difficult to treat due to the ability of Cryptococcus neoformans and Cryptococcus laurentii to form biofilms resistant to standard antifungal treatment. The toxicity concern of these drugs has stimulated the search for natural therapeutic alternatives. Essential oil and their active components (EO-ACs have shown to possess the variety of biological and pharmacological properties. In the present investigation the effect of six (EO-ACs sourced from Oregano oil (Carvacrol, Cinnamon oil (Cinnamaldehyde, Lemongrass oil (Citral, Clove oil (Eugenol, Peppermint oil (Menthol and Thyme oil (thymol against three infectious forms; planktonic cells, biofilm formation and preformed biofilm of C. neoformans and C. laurentii were evaluated as compared to standard drugs. Data showed that antibiofilm activity of the tested EO-ACs were in the order: thymol>carvacrol>citral>eugenol=cinnamaldehyde>menthol respectively. The three most potent EO-ACs, thymol, carvacrol, and citral showed excellent antibiofilm activity at a much lower concentration against C. laurentii in comparison to C. neoformans indicating the resistant nature of the latter. Effect of the potent EO-ACs on the biofilm morphology was visualized using scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM, which revealed the absence of extracellular polymeric matrix (EPM, reduction in cellular density and alteration in the surface morphology of biofilm cells. Further, to realize the efficacy of the EO-ACs in terms of human safety, cytotoxicity assays and co-culture model were evaluated. Thymol and carvacrol as compared to citral were the most efficient in terms of human safety in keratinocyte- Cryptococcus sp. co-culture infection model suggesting that these two can be further exploited as cost-effective and non-toxic anti

A comparison of five extraction methods for extracellular polymeric ...

African Journals Online (AJOL)

Two physical methods (centrifugation and ultrasonication) and 3 chemical methods (extraction with EDTA, extraction with formaldehyde, and extraction with formaldehyde plus NaOH) for extraction of EPS from alga-bacteria biofilm were assessed. Pretreatment with ultrasound at low intensity doubled the EPS yield without ...

Grappling archaea: ultrastructural analyses of an uncultivated, cold-loving archaeon and its biofilm

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Alexandra ePerras

2014-08-01

Full Text Available Similarly to Bacteria, Archaea are microorganisms that interact with their surrounding environment in a versatile manner. To date, interactions based on cellular structure and surface appendages have mainly been documented using model systems of cultivable archaea under laboratory conditions. Here, we report on the microbial interactions and ultrastructural features of the uncultivated SM1 Euryarchaeon, which is highly dominant in its biotope. Therefore, biofilm samples taken from the Sippenauer Moor, Germany, were investigated via transmission electron microscopy (TEM; negative staining, thin-sectioning and scanning electron microscopy (SEM in order to elucidate the fine structures of the microbial cells and the biofilm itself. The biofilm consisted of small archaeal cocci (0.6 µm diameter, arranged in a regular pattern (1.2-2.0 µm distance from cell to cell, whereas each archaeon was connected to 6 other archaea on average. Extracellular polymeric substances (EPS were limited to the close vicinity of the archaeal cells, and specific cell surface appendages (hami, Moissl et al., 2005 protruded beyond the EPS matrix enabling microbial interaction by cell-cell contacts among the archaea and between archaea and bacteria. All analyzed hami revealed their previously described architecture of nano-grappling hooks and barb-wire basal structures. Considering the archaeal cell walls, the SM1 Euryarchaea exhibited a double-membrane, which has rarely been reported for members of this phylogenetic domain. Based on these findings, the current generalized picture on archaeal cell walls needs to be revisited, as archaeal cell structures are more complex and sophisticated than previously assumed, particularly when looking into the uncultivated majority.

Magnesium limitation is an environmental trigger of the Pseudomonas aeruginosa biofilm lifestyle.

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Heidi Mulcahy

Full Text Available Biofilm formation is a conserved strategy for long-term bacterial survival in nature and during infections. Biofilms are multicellular aggregates of cells enmeshed in an extracellular matrix. The RetS, GacS and LadS sensors control the switch from a planktonic to a biofilm mode of growth in Pseudomonas aeruginosa. Here we detail our approach to identify environmental triggers of biofilm formation by investigating environmental conditions that repress expression of the biofilm repressor RetS. Mg(2+ limitation repressed the expression of retS leading to increased aggregation, exopolysaccharide (EPS production and biofilm formation. Repression of retS expression under Mg(2+ limitation corresponded with induced expression of the GacA-controlled small regulatory RNAs rsmZ and rsmY and the EPS biosynthesis operons pel and psl. We recently demonstrated that extracellular DNA sequesters Mg(2+ cations and activates the cation-sensing PhoPQ two-component system, which leads to increased antimicrobial peptide resistance in biofilms. Here we show that exogenous DNA and EDTA, through their ability to chelate Mg(2+, promoted biofilm formation. The repression of retS in low Mg(2+ was directly controlled by PhoPQ. PhoP also directly controlled expression of rsmZ but not rsmY suggesting that PhoPQ controls the equilibrium of the small regulatory RNAs and thus fine-tunes the expression of genes in the RetS pathway. In summary, Mg(2+ limitation is a biologically relevant environmental condition and the first bonafide environmental signal identified that results in transcriptional repression of retS and promotes P. aeruginosa biofilm formation.

A major protein component of the Bacillus subtilis biofilm matrix.

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Branda, Steven S; Chu, Frances; Kearns, Daniel B; Losick, Richard; Kolter, Roberto

2006-02-01

Microbes construct structurally complex multicellular communities (biofilms) through production of an extracellular matrix. Here we present evidence from scanning electron microscopy showing that a wild strain of the Gram positive bacterium Bacillus subtilis builds such a matrix. Genetic, biochemical and cytological evidence indicates that the matrix is composed predominantly of a protein component, TasA, and an exopolysaccharide component. The absence of TasA or the exopolysaccharide resulted in a residual matrix, while the absence of both components led to complete failure to form complex multicellular communities. Extracellular complementation experiments revealed that a functional matrix can be assembled even when TasA and the exopolysaccharide are produced by different cells, reinforcing the view that the components contribute to matrix formation in an extracellular manner. Having defined the major components of the biofilm matrix and the control of their synthesis by the global regulator SinR, we present a working model for how B. subtilis switches between nomadic and sedentary lifestyles.

AHL signaling molecules with a large acyl chain enhance biofilm formation on sulfur and metal sulfides by the bioleaching bacterium Acidithiobacillus ferrooxidans.

Science.gov (United States)

González, Alex; Bellenberg, Sören; Mamani, Sigde; Ruiz, Lina; Echeverría, Alex; Soulère, Laurent; Doutheau, Alain; Demergasso, Cecilia; Sand, Wolfgang; Queneau, Yves; Vera, Mario; Guiliani, Nicolas

2013-04-01

Biofilm formation plays a pivotal role in bioleaching activities of bacteria in both industrial and natural environments. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium Acidithiobacillus ferrooxidans on sulfur and pyrite surfaces by using Quorum Sensing molecules of the N-acylhomoserine lactone type (AHLs). Our results revealed that AHL-signaling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of A. ferrooxidans cells to these substrates. In addition, Card-Fish experiments demonstrated that C14-AHL improved the adhesion of indigenous A. ferrooxidans cells from a mixed bioleaching community to pyrite. Finally, we demonstrated that this improvement of cell adhesion is correlated with an increased production of extracellular polymeric substances. Our results open up a promising means to develop new strategies for the improvement of bioleaching efficiency and metal recovery, which could also be used to control environmental damage caused by acid mine/rock drainage.

Novel application for the prevention and treatment of Staphylococcus aureus biofilm formation

Science.gov (United States)

Traba, Christian

Formation of bacterial biofilms at solid-liquid interfaces creates numerous problems in both industrial and biomedical sciences. In this dissertation, the application of plasma from two very different facets was studied. In part one, the susceptibility of pre-formed Staphylococcus aureus biofilms on biomaterials to different plasmas was investigated. It was found that the distinct chemical/physical properties of plasmas generated from oxygen, nitrogen, and argon all demonstrated very potent but very different anti-biofilm mechanisms of action. An in depth analysis of these results show: 1) different reactive species produced in each plasma demonstrate specific activity, and 2) the commonly associated etching effect could be manipulated and even controlled, depending on experimental conditions and the discharge gas. These studies provide insights into the anti-biofilm mechanisms of plasma as well as the effects of different reactive species on biofilm inactivation. Under experimental parameters, bacterial cells in Staphylococcus aureus biofilms were killed (>99.9%) by plasmas within minutes of exposure and no bacteria nor biofilm re-growth from discharge gas treated biofilms was observed throughout the life-span of the re-growth experiment. The decontamination ability of plasmas for the treatment of biofilm related infections on biomedical materials was confirmed and novel applications involving the use of low power argon and oxygen for the treatment of biofilm contaminated biomaterials and indwelling devices is proposed. The second facet of this dissertation explores the interaction between biofilm forming Staphylococcus aureus bacteria on different antibacterial/anti-biofilm surfaces. The antibiotic-free anti-fouling surfaces constructed in this study were generated from the plasma-assisted graft polymerization technique. These sophisticated surfaces were stable, biocompatible and capable of preventing biofilm formation on biomaterials and medical devices. Under

Analysis of extracellular polymeric substances (EPS) and ciprofloxacin-degrading microbial community in the combined Fe-C micro-electrolysis-UBAF process for the elimination of high-level ciprofloxacin.

Science.gov (United States)

Zhang, Longlong; Yue, Qinyan; Yang, Kunlun; Zhao, Pin; Gao, Baoyu

2018-02-01

Extracellular polymeric substances (EPS) and ciprofloxacin-degrading microbial community in the combined Fe-C micro-electrolysis and up-flow biological aerated filter (UBAF) process for the treatment of high-level ciprofloxacin (CIP) were analyzed. The research demonstrated a great potential of Fe-C micro-electrolysis-UBAF for the elimination of high-level CIP. Above 90% of CIP removal was achieved through the combined process at 100 mg L -1 of CIP loading. In UBAF, the pollutants were mainly removed at 0-70 cm heights. Three-dimensional fluorescence spectrum (3D-EEM) was used to characterize the chemical structural of loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) extracted from biofilm sample in UBAF. The results showed that the protein-like substances in LB-EPS and TB-EPS had no clear change in the study. Nevertheless, an obvious release of polysaccharides in EPSs was observed during long-term exposure to CIP, which was considered as a protective response of microbial to CIP toxic. The high-throughput sequencing results revealed that the biodiversity of bacteria community became increasingly rich with gradual ciprofloxacin biodegradation in UBAF. The ciprofloxacin-degrading microbial community was mainly dominated by Proteobacteria and Bacteroidetes. Microorganisms from genera Dechloromonas, Brevundimonas, Flavobacterium, Sphingopyxis and Bosea might take a major role in ciprofloxacin degradation. This study provides deep theoretical guidance for real CIP wastewater treatment. Copyright © 2017. Published by Elsevier Ltd.

Microbial extracellular polymeric substances in marine biogeochemical processes

Digital Repository Service at National Institute of Oceanography (India)

Bhaskar, P.V.; Bhosle, N.B.

and are found in free dissolved form, colloids, discreet partcles like TEP and/or associated with particulate matter, including cell aggregates, detritus, biofilms, microbial mats, etc. The chemical composition of EPS is influenced by various factors... of EPS in marine waters. Hence, various aspects of EPS di- cussed hereafter indicate bacterial and/or phyto origin unless specified. Characteristics of EPS Microorganisms grow in free planktonic state16,17 or are ata- ched to surfaces (natural...

Highly active bidirectional electron transfer by a self-assembled electroactive reduced-graphene-oxide-hybridized biofilm.

Science.gov (United States)

Yong, Yang-Chun; Yu, Yang-Yang; Zhang, Xinhai; Song, Hao

2014-04-22

Low extracellular electron transfer performance is often a bottleneck in developing high-performance bioelectrochemical systems. Herein, we show that the self-assembly of graphene oxide and Shewanella oneidensis MR-1 formed an electroactive, reduced-graphene-oxide-hybridized, three-dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact-based extracellular electron transfer. This 3D electroactive biofilm delivered a 25-fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74-fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of environmental and nutritional factors and sua gene on in vitro biofilm formation of Streptococcus uberis isolates.

Science.gov (United States)

Moliva, Melina Vanesa; Cerioli, Florencia; Reinoso, Elina Beatriz

2017-06-01

The pathogenesis of Streptococcus uberis is attributed to a combination of extracellular factors and properties such as adherence and biofilm formation. The aim of this work was to evaluate the influence of different factors, additives and bovine milk compounds on S. uberis biofilm formation, as the presence of the sua gene by PCR. Additionally, extracellular DNA and the effect of DNaseI were evaluated in the biofilms yielded. Optimal biofilm development was observed when the pH was adjusted to 7.0 and 37 °C. Additives as glucose and lactose reduced biofilm formation as bovine milk compounds tested. PCR assay showed that not all the isolates yielded sua gene. Extrachromosomal ADN was found in cell-free supernatants, suggesting that DNA released spontaneously to the medium. The results contribute to a better understanding of the factors involved in biofilm production of this important pathogen associated with mastitis in order to promote the design of new therapeutic approaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distinct SagA from hospital-associated clade A1 Enterococcus faecium strains contributes to biofilm formation

NARCIS (Netherlands)

F.L. Paganelli; M. de Been; J.C. Braat (Johanna); T.A. Hoogenboezem (Thomas); C. Vink (Cornelis); J. Bayjanov; M.R.C. Rogers; J. Huebner; M.J.M. Bonten (Marc); R.J.L. Willems (Rob); H.L. Leavis

2015-01-01

textabstractEnterococcus faecium is an important nosocomial pathogen causing biofilm-mediated infections. Elucidation of E. faecium biofilm pathogenesis is pivotal for the development of new strategies to treat these infections. In several bacteria, extracellular DNA (eDNA) and proteins act as

The Effect of Novel Heterocyclic Compounds on Cryptococcal Biofilm

Science.gov (United States)

Korem, Maya; Kagan, Sarah

2017-01-01

Biofilm formation by microorganisms depends on their communication by quorum sensing, which is mediated by small diffusible signaling molecules that accumulate in the extracellular environment. During human infection, the pathogenic yeast Cryptococcus neoformans can form biofilm on medical devices, which protects the organism and increases its resistance to antifungal agents. The aim of this study was to test two novel heterocyclic compounds, S-8 (thiazolidinedione derivative, TZD) and NA-8 (succinimide derivative, SI), for their anti-biofilm activity against strains of Cryptococcus neoformans and Cryptococcus gattii. Biofilms were formed in a defined medium in 96-well polystyrene plates and 8-well micro-slides. The effect of sub-inhibitory concentrations of S-8 and NA-8 on biofilm formation was measured after 48 h by a metabolic reduction assay and by confocal laser microscopy analysis using fluorescent staining. The formation and development of cryptococcal biofilms was inhibited significantly by these compounds in concentrations below the minimum inhibitory concentration (MIC) values. These compounds may have a potential role in preventing fungal biofilm development on indwelling medical devices or even as a therapeutic measure after the establishment of biofilm. PMID:29371559

A 3D Hydrodynamic Model for Heterogeneous Biofilms with Antimicrobial Persistence

Science.gov (United States)

2014-01-01

David A. Weitz, and Michael P. Brenner. Osmotic spreading of bacillus subtilis biofilms driven by an extracellular matrix. PNAS, 2012. [38] Zhiya...Currently, the environmental impact of biocide or side-effect of antibiotics have become common concerns, which makes the derivation of an optimal...biofilms to penetration of antibiotics . To our best knowledge, there has yet been a mathematical model which takes into account both the hydrodynamic

Improved PVDF membrane performance by doping extracellular polymeric substances of activated sludge.

Science.gov (United States)

Guan, Yan-Fang; Huang, Bao-Cheng; Qian, Chen; Wang, Long-Fei; Yu, Han-Qing

2017-04-15

Polyvinylidene fluoride (PVDF) membrane has been widely applied in water and wastewater treatment because of its high mechanical strength, thermal stability and chemical resistance. However, the hydrophobic nature of PVDF membrane makes it readily fouled, substantially reducing water flux and overall membrane rejection ability. In this work, an in-situ blending modifier, i.e., extracellular polymeric substances (EPS) from activated sludge, was used to enhance the anti-fouling ability of PVDF membrane. Results indicate that the pure water flux of the membrane and its anti-fouling performance were substantially improved by blending 8% EPS into the membrane. By introducing EPS, the membrane hydrophilicity was increased and the cross section morphology was changed when it interacted with polyvinl pyrrolidone, resulting in the formation of large cavities below the finger-like pores. In addition, the fraction of pores with a size of 100-500 nm increased, which was also beneficial to improving membrane performance. Surface thermodynamic calculations indicate the EPS-functionalized membrane had a higher cohesion free energy, implying its good pollutant rejection and anti-fouling ability. This work provides a simple, efficient and cost-effective method to improve membrane performance and also extends the applications of EPS. Copyright © 2017 Elsevier Ltd. All rights reserved.

LC/IRMS analysis: A powerful technique to trace carbon flow in microphytobenthic communities in intertidal sediments

NARCIS (Netherlands)

Moerdijk-Poortvliet, T.C.W.; Stal, L.J.; Boschker, H.T.S.

2014-01-01

Microphytobenthic communities are important for primary production in intertidal marine sediments. Extracellular polymeric substances (EPS), comprising polysaccharides and proteins, play a key role in the structure and functioning of microphytobenthic biofilms and allow interactions between the

Assessment and characterization of biofilm formation among human isolates of Streptococcus dysgalactiae subsp. equisimilis.

Science.gov (United States)

Genteluci, Gabrielle Limeira; Silva, Ligia Guedes; Souza, Maria Clara; Glatthardt, Thaís; de Mattos, Marcos Corrêa; Ejzemberg, Regina; Alviano, Celuta Sales; Figueiredo, Agnes Marie Sá; Ferreira-Carvalho, Bernadete Teixeira

2015-12-01

The capacity to form biofilm is considered a protective mechanism that allows the bacteria to survive and proliferate in hostile environments, facilitating the maintenance of the infectious process. Recently, biofilm has become a topic of interest in the study of the human pathogen group A Streptococcus (GAS). Although GAS has not been associated with infection on medical implants, the presence of microcolonies embedded in an extracellular matrix on infected tissues has been reported. Despite the similarity between GAS and Streptococcus dysgalactiae subspecies equisimilis (SDSE), there are no studies in the literature describing the production of biofilm by SDSE. In this work, we assessed and characterized biofilm development among SDSE human isolates of group C. The in vitro data showed that 59.3% of the 118 isolates tested were able to form acid-induced biofilm on glass, and 28% formed it on polystyrene surfaces. More importantly, biofilm was also formed in a foreign body model in mice. The biofilm structure was analyzed by confocal laser scanning microscopy, transmission electron microscopy, and scanning electron microscopy. Long fibrillar-like structures were observed by scanning electron microscopy. Additionally, the expression of a pilus associated gene of SDSE was increased for in vitro sessile cells compared with planktonics, and when sessile cells were collected from biofilms formed in the animal model compared with that of in vitro model. Results obtained from the immunofluorescence microscopy indicated the biofilm was immunogenic. Our data also suggested a role for proteins, exopolysaccharide and extracellular DNA in the formation and accumulation of biofilm by SDSE. Copyright © 2015 Elsevier GmbH. All rights reserved.

Relevant Role of Fibronectin-Binding Proteins in Staphylococcus aureus Biofilm-Associated Foreign-Body Infections▿ †

Science.gov (United States)

Vergara-Irigaray, Marta; Valle, Jaione; Merino, Nekane; Latasa, Cristina; García, Begoña; Ruiz de los Mozos, Igor; Solano, Cristina; Toledo-Arana, Alejandro; Penadés, José R.; Lasa, Iñigo

2009-01-01

Staphylococcus aureus can establish chronic infections on implanted medical devices due to its capacity to form biofilms. Analysis of the factors that assemble cells into a biofilm has revealed the occurrence of strains that produce either a polysaccharide intercellular adhesin/poly-N-acetylglucosamine (PIA/PNAG) exopolysaccharide- or a protein-dependent biofilm. Examination of the influence of matrix nature on the biofilm capacities of embedded bacteria has remained elusive, because a natural strain that readily converts between a polysaccharide- and a protein-based biofilm has not been studied. Here, we have investigated the clinical methicillin (meticillin)-resistant Staphylococcus aureus strain 132, which is able to alternate between a proteinaceous and an exopolysaccharidic biofilm matrix, depending on environmental conditions. Systematic disruption of each member of the LPXTG surface protein family identified fibronectin-binding proteins (FnBPs) as components of a proteinaceous biofilm formed in Trypticase soy broth-glucose, whereas a PIA/PNAG-dependent biofilm was produced under osmotic stress conditions. The induction of FnBP levels due to a spontaneous agr deficiency present in strain 132 and the activation of a LexA-dependent SOS response or FnBP overexpression from a multicopy plasmid enhanced biofilm development, suggesting a direct relationship between the FnBP levels and the strength of the multicellular phenotype. Scanning electron microscopy revealed that cells growing in the FnBP-mediated biofilm formed highly dense aggregates without any detectable extracellular matrix, whereas cells in a PIA/PNAG-dependent biofilm were embedded in an abundant extracellular material. Finally, studies of the contribution of each type of biofilm matrix to subcutaneous catheter colonization revealed that an FnBP mutant displayed a significantly lower capacity to develop biofilm on implanted catheters than the isogenic PIA/PNAG-deficient mutant. PMID:19581398

Dynamic Dispersal of Surface Layer Biofilm Induced by Nanosized TiO2 Based on Surface Plasmon Resonance and Waveguide.

Science.gov (United States)

Zhang, Peng; Guo, Jin-Song; Yan, Peng; Chen, You-Peng; Wang, Wei; Dai, You-Zhi; Fang, Fang; Wang, Gui-Xue; Shen, Yu

2018-05-01

Pollutant degradation is present mainly in the surface layer of biofilms, and the surface layer is the most vulnerable to impairment by toxic pollutants. In this work, the effects of nanosized TiO 2 (n-TiO 2 ) on the average thicknesses of Bacillus subtilis biofilm and on bacterial attachment on different surfaces were investigated. The binding mechanism of n-TiO 2 to the cell surface was also probed. The results revealed that n-TiO 2 caused biofilm dispersal and the thicknesses decreased by 2.0 to 2.6 μm after several hours of exposure. The attachment abilities of bacteria with extracellular polymeric substances (EPS) on hydrophilic surfaces were significantly reduced by 31% and 81% under 10 and 100 mg/liter of n-TiO 2 , respectively, whereas those of bacteria without EPS were significantly reduced by 43% and 87%, respectively. The attachment abilities of bacteria with and without EPS on hydrophobic surfaces were significantly reduced by 50% and 56%, respectively, under 100 mg/liter of n-TiO 2 The results demonstrated that biofilm dispersal can be attributed to the changes in the cell surface structure and the reduction of microbial attachment ability. IMPORTANCE Nanoparticles can penetrate into the outer layer of biofilm in a relatively short period and can bind onto EPS and bacterial surfaces. The current work probed the effects of nanosized TiO 2 (n-TiO 2 ) on biofilm thickness, bacterial migration, and surface properties of the cell in the early stage using the surface plasmon resonance waveguide mode. The results demonstrated that n-TiO 2 decreased the adhesive ability of both cell and EPS and induced bacterial migration and biofilm detachment in several hours. The decreased adhesive ability of microbes and EPS worked against microbial aggregation, reducing the effluent quality in the biological wastewater treatment process. Copyright © 2018 American Society for Microbiology.

Capillary isoelectric focusing--useful tool for detection of the biofilm formation in Staphylococcus epidermidis.

Science.gov (United States)

Ruzicka, Filip; Horka, Marie; Hola, Veronika; Votava, Miroslav

2007-03-01

The biofilm formation is an important factor of S. epidermidis virulence. Biofilm-positive strains might be clinically more important than biofilm-negative ones. Unlike biofilm-negative staphylococci, biofilm-positive staphylococci are surrounded with an extracellular polysaccharide substance. The presence of this substance on the surface can affect physico-chemical properties of the bacterial cell, including surface charge. 73 S. epidermidis strains were examined for the presence of ica operon, for the ability to form biofilm by Christensen test tube method and for the production of slime by Congo red agar method. Isoelectric points (pI) of these strains were determined by means of Capillary Isoelectric Focusing. The biofilm negative strains focused near pI value 2.3, while the pI values of the biofilm positive strains were near 2.6. Isoelectric point is a useful criterion for the differentiation between biofilm-positive and biofilm-negative S. epidermidis strains.

Set potential regulation reveals additional oxidation peaks of Geobacter sulfurreducens anodic biofilms

KAUST Repository

Zhu, Xiuping

2012-08-01

Higher current densities produced in microbial fuel cells and other bioelectrochemical systems are associated with the presence of various Geobacter species. A number of electron transfer components are involved in extracellular electron transfer by the model exoelectrogen, Geobacter sulfurreducens. It has previously been shown that 5 main oxidation peaks can be identified in cyclic voltammetry scans. It is shown here that 7 separate oxidation peaks emerged over relatively long periods of time when a larger range of set potentials was used to acclimate electroactive biofilms. The potentials of oxidation peaks obtained with G. sulfurreducens biofilms acclimated at 0.60 V (vs. Ag/AgCl) were different from those that developed at - 0.46 V, and both of their peaks were different from those obtained for biofilms incubated at - 0.30 V, 0 V, and 0.30 V. These results expand the known range of potentials for which G. sulfurreducens produces identifiable oxidation peaks that could be important for extracellular electron transfer. © 2012 Elsevier B.V.

Glutathione-Disrupted Biofilms of Clinical Pseudomonas aeruginosa Strains Exhibit an Enhanced Antibiotic Effect and a Novel Biofilm Transcriptome

Science.gov (United States)

Das, Theerthankar; Ibugo, Amaye; Buckle, Edwina; Manefield, Mike; Manos, Jim

2016-01-01

Pseudomonas aeruginosa infections result in high morbidity and mortality rates for individuals with cystic fibrosis (CF), with premature death often occurring. These infections are complicated by the formation of biofilms in the sputum. Antibiotic therapy is stymied by antibiotic resistance of the biofilm matrix, making novel antibiofilm strategies highly desirable. Within P. aeruginosa biofilms, the redox factor pyocyanin enhances biofilm integrity by intercalating with extracellular DNA. The antioxidant glutathione (GSH) reacts with pyocyanin, disrupting intercalation. This study investigated GSH disruption by assaying the physiological effects of GSH and DNase I on biofilms of clinical CF isolates grown in CF artificial sputum medium (ASMDM+). Confocal scanning laser microscopy showed that 2 mM GSH, alone or combined with DNase I, significantly disrupted immature (24-h) biofilms of Australian epidemic strain (AES) isogens AES-1R and AES-1M. GSH alone greatly disrupted mature (72-h) AES-1R biofilms, resulting in significant differential expression of 587 genes, as indicated by RNA-sequencing (RNA-seq) analysis. Upregulated systems included cyclic diguanylate and pyoverdine biosynthesis, the type VI secretion system, nitrate metabolism, and translational machinery. Biofilm disruption with GSH revealed a cellular physiology distinct from those of mature and dispersed biofilms. RNA-seq results were validated by biochemical and quantitative PCR assays. Biofilms of a range of CF isolates disrupted with GSH and DNase I were significantly more susceptible to ciprofloxacin, and increased antibiotic effectiveness was achieved by increasing the GSH concentration. This study demonstrated that GSH, alone or with DNase I, represents an effective antibiofilm treatment when combined with appropriate antibiotics, pending in vivo studies. PMID:27161630

Pneumococci in biofilms are non-invasive: implications on nasopharyngeal colonization

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Ryan Paul Gilley

2014-11-01

Full Text Available Streptococcus pneumoniae (the pneumococcus is an opportunistic pathogen that colonizes the human nasopharynx asymptomatically. Invasive pneumococcal disease develops following bacterial aspiration into the lungs. Pneumococci within the nasopharynx exist as biofilms, a growth phenotype characterized by surface attachment, encasement within an extracellular matrix, and antimicrobial resistance. Experimental evidence indicates that biofilm pneumococci are attenuated versus their planktonic counterpart. Biofilm pneumococci failed to cause invasive disease in experimentally challenged mice and in vitro were shown to be non-invasive despite being hyper-adhesive. This attenuated phenotype corresponds with observations that biofilm pneumococci elicit significantly less cytokine and chemokine production from host cells than their planktonic counterparts. Microarray and proteomic studies show that pneumococci within biofilms have decreased metabolism, less capsular polysaccharide, and reduced production of the pore-forming toxin pneumolysin. Biofilm pneumococci are predominately in the transparent phenotype, which has elevated cell wall phosphorylcholine, an adhesin subject to C-reactive protein mediated opsonization. Herein, we review these changes in virulence, interpret their impact on colonization and transmission, and discuss the notion that non-invasive biofilms are principal lifestyle of S. pneumoniae.

Biofilm Formation Characteristics of Pseudomonas lundensis Isolated from Meat.

Science.gov (United States)

Liu, Yong-Ji; Xie, Jing; Zhao, Li-Jun; Qian, Yun-Fang; Zhao, Yong; Liu, Xiao

2015-12-01

Biofilms formations of spoilage and pathogenic bacteria on food or food contact surfaces have attracted increasing attention. These events may lead to a higher risk of food spoilage and foodborne disease transmission. While Pseudomonas lundensis is one of the most important bacteria that cause spoilage in chilled meat, its capability for biofilm formation has been seldom reported. Here, we investigated biofilm formation characteristics of P. lundensis mainly by using crystal violet staining, and confocal laser scanning microscopy (CLSM). The swarming and swimming motility, biofilm formation in different temperatures (30, 10, and 4 °C) and the protease activity of the target strain were also assessed. The results showed that P. lundensis showed a typical surface-associated motility and was quite capable of forming biofilms in different temperatures (30, 10, and 4 °C). The strain began to adhere to the contact surfaces and form biofilms early in the 4 to 6 h. The biofilms began to be formed in massive amounts after 12 h at 30 °C, and the extracellular polysaccharides increased as the biofilm structure developed. Compared with at 30 °C, more biofilms were formed at 4 and 10 °C even by a low bacterial density. The protease activity in the biofilm was significantly correlated with the biofilm formation. Moreover, the protease activity in biofilm was significantly higher than that of the corresponding planktonic cultures after cultured 12 h at 30 °C. © 2015 Institute of Food Technologists®

The biofilm matrix destabilizers, EDTA and DNaseI, enhance the susceptibility of nontypeable Hemophilus influenzae biofilms to treatment with ampicillin and ciprofloxacin.

Science.gov (United States)

Cavaliere, Rosalia; Ball, Jessica L; Turnbull, Lynne; Whitchurch, Cynthia B

2014-08-01

Nontypeable Hemophilus influenzae (NTHi) is a Gram-negative bacterial pathogen that causes chronic biofilm infections of the ears and airways. The biofilm matrix provides structural integrity to the biofilm and protects biofilm cells from antibiotic exposure by reducing penetration of antimicrobial compounds into the biofilm. Extracellular DNA (eDNA) has been found to be a major matrix component of biofilms formed by many species of Gram-positive and Gram-negative bacteria, including NTHi. Interestingly, the cation chelator ethylenediaminetetra-acetic acid (EDTA) has been shown to reduce the matrix strength of biofilms of several bacterial species as well as to have bactericidal activity against various pathogens. EDTA exerts its antimicrobial activity by chelating divalent cations necessary for growth and membrane stability and by destabilizing the matrix thus enhancing the detachment of bacterial cells from the biofilm. In this study, we have explored the role of divalent cations in NTHi biofilm development and stability. We have utilized in vitro static and continuous flow models of biofilm development by NTHi to demonstrate that magnesium cations enhance biofilm formation by NTHi. We found that the divalent cation chelator EDTA is effective at both preventing NTHi biofilm formation and at treating established NTHi biofilms. Furthermore, we found that the matrix destablilizers EDTA and DNaseI increase the susceptibility of NTHi biofilms to ampicillin and ciprofloxacin. Our observations indicate that DNaseI and EDTA enhance the efficacy of antibiotic treatment of NTHi biofilms. These observations may lead to new strategies that will improve the treatment options available to patients with chronic NTHi infections. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Seasonal variations of the composition of microbial biofilms in sandy tidal flats: Focus of fatty acids, pigments and exopolymers

Science.gov (United States)

Passarelli, Claire; Meziane, Tarik; Thiney, Najet; Boeuf, Dominique; Jesus, Bruno; Ruivo, Mickael; Jeanthon, Christian; Hubas, Cédric

2015-02-01

Biofilms, or microbial mats, are common associations of microorganisms in tidal flats; they generally consist of a large diversity of organisms embedded in a matrix of Extracellular Polymeric Substances (EPS). These molecules are mainly composed of carbohydrates and proteins, but their detailed monomer compositions and seasonal variations are currently unknown. Yet this composition determines the numerous roles of biofilms in these systems. This study investigated the changes in composition of carbohydrates in intertidal microbial mats over a year to decipher seasonal variations in biofilms and in varying hydrodynamic conditions. This work also aimed to assess how these compositions are related to microbial assemblages. In this context, natural biofilms whose development was influenced or not by artificial structures mimicking polychaete tubes were sampled monthly for over a year in intertidal flats of the Chausey archipelago. Biofilms were compared through the analysis of their fatty acid and pigment contents, and the monosaccharide composition of their EPS carbohydrates. Carbohydrates from both colloidal and bound EPS contained mainly glucose and, to a lower extent, galactose and mannose but they showed significant differences in their detailed monosaccharide compositions. These two fractions displayed different seasonal evolution, even if glucose accumulated in both fractions in summer; bound EPS only were affected by artificial biogenic structures. Sediment composition in fatty acids and pigments showed that microbial communities were dominated by diatoms and heterotrophic bacteria. Their relative proportions, as well as those of other groups like cryptophytes, changed between times and treatments. The changes in EPS composition were not fully explained by modifications of microbial assemblages but also depended on the processes taking place in sediments and on environmental conditions. These variations of EPS compositions are likely to alter different

Visualization of capsular polysaccharide induction in Acidithiobacillus ferrooxidans

NARCIS (Netherlands)

Bellenberg, S.; Leon Morales, C.F.; Sand, W.; Vera, M.

2012-01-01

Extracellular Polymeric Substances (EPS) are of fundamental importance for attachment to metal sulfides, biofilm formation and leaching efficiency of Acidithiobacillus ferrooxidans. In this work we have visualized the capsular polysaccharides (CPS) of A. ferrooxidans ATCC 23270 using the

Impact of Mycobacterium ulcerans biofilm on transmissibility to ecological niches and Buruli ulcer pathogenesis.

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Laurent Marsollier

2007-05-01

Full Text Available The role of biofilms in the pathogenesis of mycobacterial diseases remains largely unknown. Mycobacterium ulcerans, the etiological agent of Buruli ulcer, a disfiguring disease in humans, adopts a biofilm-like structure in vitro and in vivo, displaying an abundant extracellular matrix (ECM that harbors vesicles. The composition and structure of the ECM differs from that of the classical matrix found in other bacterial biofilms. More than 80 proteins are present within this extracellular compartment and appear to be involved in stress responses, respiration, and intermediary metabolism. In addition to a large amount of carbohydrates and lipids, ECM is the reservoir of the polyketide toxin mycolactone, the sole virulence factor of M. ulcerans identified to date, and purified vesicles extracted from ECM are highly cytotoxic. ECM confers to the mycobacterium increased resistance to antimicrobial agents, and enhances colonization of insect vectors and mammalian hosts. The results of this study support a model whereby biofilm changes confer selective advantages to M. ulcerans in colonizing various ecological niches successfully, with repercussions for Buruli ulcer pathogenesis.

Involvement of NADH Oxidase in Biofilm Formation in Streptococcus sanguinis.

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Xiuchun Ge

Full Text Available Biofilms play important roles in microbial communities and are related to infectious diseases. Here, we report direct evidence that a bacterial nox gene encoding NADH oxidase is involved in biofilm formation. A dramatic reduction in biofilm formation was observed in a Streptococcus sanguinis nox mutant under anaerobic conditions without any decrease in growth. The membrane fluidity of the mutant bacterial cells was found to be decreased and the fatty acid composition altered, with increased palmitic acid and decreased stearic acid and vaccenic acid. Extracellular DNA of the mutant was reduced in abundance and bacterial competence was suppressed. Gene expression analysis in the mutant identified two genes with altered expression, gtfP and Idh, which were found to be related to biofilm formation through examination of their deletion mutants. NADH oxidase-related metabolic pathways were analyzed, further clarifying the function of this enzyme in biofilm formation.

Role of bacterial efflux pumps in biofilm formation.

Science.gov (United States)

Alav, Ilyas; Sutton, J Mark; Rahman, Khondaker Miraz

2018-02-28

Efflux pumps are widely implicated in antibiotic resistance because they can extrude the majority of clinically relevant antibiotics from within cells to the extracellular environment. However, there is increasing evidence from many studies to suggest that the pumps also play a role in biofilm formation. These studies have involved investigating the effects of efflux pump gene mutagenesis and efflux pump inhibitors on biofilm formation, and measuring the levels of efflux pump gene expression in biofilms. In particular, several key pathogenic species associated with increasing multidrug resistance, such as Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, have been investigated, whilst other studies have focused on Salmonella enterica serovar Typhimurium as a model organism and problematic pathogen. Studies have shown that efflux pumps, including AcrAB-TolC of E. coli, MexAB-OprM of P. aeruginosa, AdeFGH of A. baumannii and AcrD of S. enterica, play important roles in biofilm formation. The substrates for such pumps, and whether changes in their efflux activity affect biofilm formation directly or indirectly, remain to be determined. By understanding the roles that efflux pumps play in biofilm formation, novel therapeutic strategies can be developed to inhibit their function, to help disrupt biofilms and improve the treatment of infections. This review will discuss and evaluate the evidence for the roles of efflux pumps in biofilm formation and the potential approaches to overcome the increasing problem of biofilm-based infections.

Evaluation of Two Surface Sampling Methods for Microbiological and Chemical Analyses To Assess the Presence of Biofilms in Food Companies.

Science.gov (United States)

Maes, Sharon; Huu, Son Nguyen; Heyndrickx, Marc; Weyenberg, Stephanie van; Steenackers, Hans; Verplaetse, Alex; Vackier, Thijs; Sampers, Imca; Raes, Katleen; Reu, Koen De

2017-12-01

Biofilms are an important source of contamination in food companies, yet the composition of biofilms in practice is still mostly unknown. The chemical and microbiological characterization of surface samples taken after cleaning and disinfection is very important to distinguish free-living bacteria from the attached bacteria in biofilms. In this study, sampling methods that are potentially useful for both chemical and microbiological analyses of surface samples were evaluated. In the manufacturing facilities of eight Belgian food companies, surfaces were sampled after cleaning and disinfection using two sampling methods: the scraper-flocked swab method and the sponge stick method. Microbiological and chemical analyses were performed on these samples to evaluate the suitability of the sampling methods for the quantification of extracellular polymeric substance components and microorganisms originating from biofilms in these facilities. The scraper-flocked swab method was most suitable for chemical analyses of the samples because the material in these swabs did not interfere with determination of the chemical components. For microbiological enumerations, the sponge stick method was slightly but not significantly more effective than the scraper-flocked swab method. In all but one of the facilities, at least 20% of the sampled surfaces had more than 10 2 CFU/100 cm 2 . Proteins were found in 20% of the chemically analyzed surface samples, and carbohydrates and uronic acids were found in 15 and 8% of the samples, respectively. When chemical and microbiological results were combined, 17% of the sampled surfaces were contaminated with both microorganisms and at least one of the analyzed chemical components; thus, these surfaces were characterized as carrying biofilm. Overall, microbiological contamination in the food industry is highly variable by food sector and even within a facility at various sampling points and sampling times.

Mixed species biofilms of Fusobacterium necrophorum and Porphyromonas levii impair the oxidative response of bovine neutrophils in vitro.

Science.gov (United States)

Lockhart, Joey S; Buret, Andre G; Ceri, Howard; Storey, Douglas G; Anderson, Stefanie J; Morck, Douglas W

2017-10-01

Biofilms composed of anaerobic bacteria can result in persistent infections and chronic inflammation. Host immune cells have difficulties clearing biofilm-related infections and this can result in tissue damage. Neutrophils are a vital component of the innate immune system and help clear biofilms. The comparative neutrophilic response to biofilms versus planktonic bacteria remains incompletely understood, particularly in the context of mixed infections. The objective of this study was to generate mixed species anaerobic bacterial biofilms composed of two opportunistic pathogens, Fusobacterium necrophorum and Porphyromonas levii, and evaluate neutrophil responses to extracellular fractions from both biofilms and planktonic cell co-cultures of the same bacteria. Purified bovine neutrophils exposed to culture supernatants from mixed species planktonic bacteria showed elevated oxidative activity compared to neutrophils exposed to biofilms composed of the same bacteria. Bacterial lipopolysaccharide plays a significant role in the stimulation of neutrophils; biofilms produced substantially more lipopolysaccharide than planktonic bacteria under these experimental conditions. Removal of lipopolysaccharide significantly reduced neutrophil oxidative response to culture supernatants of planktonic bacteria. Oxidative responses to LPS-removed biofilm supernatants and LPS-removed planktonic cell supernatants were similar. The limited neutrophil response to biofilm bacteria observed in this study supports the reduced ability of the innate immune system to eradicate biofilm-associated infections. Lipopolysaccharide is likely important in neutrophil response; however, the presence of other extracellular, immune modifying molecules in the bacterial media also appears to be important in altering neutrophil function. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction of Toxic Metals and Radionuclides

Energy Technology Data Exchange (ETDEWEB)

Judy D. Wall

2011-06-09

Our findings demonstrated that D. vulgaris surface-adhered populations produce extracellular structures, and that that the cells have altered carbon and energy flux compared to planktonic cells. Biofilms did not have greatly increased carbohydrate accumulation. Interestingly genes present on the native plasmid found in D. vulgaris Hildenborough were necessary for wild type biofilm formation. In addition, extracellular appendages dependent on functions or proteins encoded by flaG or fliA also contributed to biofilm formation. Studies with SRB biofilms have indicated that the reduction and precipitation of metals can occur within the biofilm matrix; however, little work has been done to elucidate the physiological state of surface-adhered cells during metal reduction (Cr6+, U6+) and how this process is affected by nutrient feed levels (i.e., the stimulant).

Amyloid fibers provide structural integrity to Bacillus subtilis biofilms.

Science.gov (United States)

Romero, Diego; Aguilar, Claudio; Losick, Richard; Kolter, Roberto

2010-02-02

Bacillus subtilis forms biofilms whose constituent cells are held together by an extracellular matrix. Previous studies have shown that the protein TasA and an exopolysaccharide are the main components of the matrix. Given the importance of TasA in biofilm formation, we characterized the physicochemical properties of this protein. We report that purified TasA forms fibers of variable length and 10-15 nm in width. Biochemical analyses, in combination with the use of specific dyes and microscopic analyses, indicate that TasA forms amyloid fibers. Consistent with this hypothesis, TasA fibers required harsh treatments (e.g., formic acid) to be depolymerized. When added to a culture of a tasA mutant, purified TasA restored wild-type biofilm morphology, indicating that the purified protein retained biological activity. We propose that TasA forms amyloid fibers that bind cells together in the biofilm.

Enhancement of sludge reduction and methane production by removing extracellular polymeric substances from waste activated sludge.

Science.gov (United States)

Nguyen, Minh Tuan; Mohd Yasin, Nazlina Haiza; Miyazaki, Toshiki; Maeda, Toshinari

2014-12-01

The management of waste activated sludge (WAS) recycling is a concern that affects the development of the future low-carbon society, particularly sludge reduction and biomass utilization. In this study, we investigated the effect of removing extracellular polymeric substances (EPS), which play important roles in the adhesion and flocculation of WAS, on increased sludge disintegration, thereby enhancing sludge reduction and methane production by anaerobic digestion. EPS removal from WAS by ethylenediaminetetraacetic acid (EDTA) significantly enhanced sludge reduction, i.e., 49 ± 5% compared with 27 ± 1% of the control at the end the digestion process. Methane production was also improved in WAS without EPS by 8881 ± 109 CH4 μmol g(-1) dry-weight of sludge. Microbial activity was determined by denaturing gradient gel electrophoresis and real-time polymerase chain reaction, which showed that the hydrolysis and acetogenesis stages were enhanced by pretreatment with 2% EDTA, with a larger methanogenic community and better methane production. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamic Membrane Formation in Anaerobic Dynamic Membrane Bioreactors: Role of Extracellular Polymeric Substances.

Directory of Open Access Journals (Sweden)

Hongguang Yu

Full Text Available Dynamic membrane (DM formation in dynamic membrane bioreactors plays an important role in achieving efficient solid-liquid separation. In order to study the contribution of extracellular polymeric substances (EPS to DM formation in anaerobic dynamic membrane bioreactor (AnDMBR processes, EPS extraction from and re-addition to bulk sludge were carried out in short-term filtration tests. DM formation behaviors could be well simulated by cake filtration model, and sludge with EPS re-addition showed the highest resistance coefficient, followed by sludge after EPS extraction. The DM layers exhibited a higher resistance and a lower porosity for the sludge sample after EPS extraction and for the sludge with EPS re-addition. Particle size of sludge flocs decreased after EPS extraction, and changed little with EPS re-addition, which was confirmed by interaction energy analysis. Further investigations by confocal laser scanning microscopy (CLSM analysis and batch tests suggested that the removal of in-situ EPS stimulated release of soluble EPS, and re-added EPS were present as soluble EPS rather than bound EPS, which thus improved the formation of DM. The present work revealed the role of EPS in anaerobic DM formation, and could facilitate the operation of AnDMBR processes.

Calcium carbonate formation on mica supported extracellular polymeric substance produced by Rhodococcus opacus

Energy Technology Data Exchange (ETDEWEB)

Szcześ, Aleksandra, E-mail: aszczes@poczta.umcs.lublin.pl [Department of Physical Chemistry – Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Skłodowska University, Lublin 20-031 (Poland); Czemierska, Magdalena; Jarosz-Wilkołazka, Anna [Department of Biochemistry, Maria Curie-Skłodowska University, Lublin 20-031 (Poland)

2016-10-15

Extracellular polymeric substance (EPS) extracted from Rhodococcus opacus bacterial strain was used as a matrix for calcium carbonate precipitation using the vapour diffusion method. The total exopolymer and water-soluble exopolymer fraction of different concentrations were spread on the mica surface by the spin-coating method. The obtained layers were characterized using the atomic force microscopy measurement and XPS analysis. The effects of polymer concentration, initial pH of calcium chloride solution and precipitation time on the obtained crystals properties were investigated. Raman spectroscopy and scanning electron microscopy were used to characterize the precipitated minerals. It was found that the type of precipitated CaCO{sub 3} polymorph and the crystal size depend on the kind of EPS fraction. The obtained results indicates that the water soluble fraction favours vaterite dissolution and calcite growth, whereas the total EPS stabilizes vaterite and this effect is stronger at basic pH. It seems to be due to different contents of the functional group of EPS fractions. - Highlights: • CaCO{sub 3} crystal size and polymorph can be controlled by EPS substance obtained from R. opacus. • The water soluble fraction favours vaterite dissolution and calcite growth. • The total EPS stabilizes vaterite. • This effect is stronger at basic pH.

Calcium carbonate formation on mica supported extracellular polymeric substance produced by Rhodococcus opacus

International Nuclear Information System (INIS)

Szcześ, Aleksandra; Czemierska, Magdalena; Jarosz-Wilkołazka, Anna

2016-01-01

Extracellular polymeric substance (EPS) extracted from Rhodococcus opacus bacterial strain was used as a matrix for calcium carbonate precipitation using the vapour diffusion method. The total exopolymer and water-soluble exopolymer fraction of different concentrations were spread on the mica surface by the spin-coating method. The obtained layers were characterized using the atomic force microscopy measurement and XPS analysis. The effects of polymer concentration, initial pH of calcium chloride solution and precipitation time on the obtained crystals properties were investigated. Raman spectroscopy and scanning electron microscopy were used to characterize the precipitated minerals. It was found that the type of precipitated CaCO 3 polymorph and the crystal size depend on the kind of EPS fraction. The obtained results indicates that the water soluble fraction favours vaterite dissolution and calcite growth, whereas the total EPS stabilizes vaterite and this effect is stronger at basic pH. It seems to be due to different contents of the functional group of EPS fractions. - Highlights: • CaCO 3 crystal size and polymorph can be controlled by EPS substance obtained from R. opacus. • The water soluble fraction favours vaterite dissolution and calcite growth. • The total EPS stabilizes vaterite. • This effect is stronger at basic pH.

Dynamic energy budget approach to evaluate antibiotic effects on biofilms

Science.gov (United States)

Birnir, Bjorn; Carpio, Ana; Cebrián, Elena; Vidal, Perfecto

2018-01-01

Quantifying the action of antibiotics on biofilms is essential to devise therapies against chronic infections. Biofilms are bacterial communities attached to moist surfaces, sheltered from external aggressions by a polymeric matrix. Coupling a dynamic energy budget based description of cell metabolism to surrounding concentration fields, we are able to approximate survival curves measured for different antibiotics. We reproduce numerically stratified distributions of cell types within the biofilm and introduce ways to incorporate different resistance mechanisms. Qualitative predictions follow that are in agreement with experimental observations, such as higher survival rates of cells close to the substratum when employing antibiotics targeting active cells or enhanced polymer production when antibiotics are administered. The current computational model enables validation and hypothesis testing when developing therapies.

Competitive adsorption of heavy metals by extracellular polymeric substances extracted from Klebsiella sp. J1.

Science.gov (United States)

Yang, Jixian; Wei, Wei; Pi, Shanshan; Ma, Fang; Li, Ang; Wu, Dan; Xing, Jie

2015-11-01

The adsorption of Cu(2+) and Zn(2+) by extracellular polymeric substances (EPS) extracted from Klebsiella sp. J1 and competitive adsorption mechanism were investigated. Equilibrium adsorption capacities of Cu(2+) (1.77mMg(-1)) on Klebsiella sp. J1 EPS were higher than those of Zn(2+) (1.36mMg(-1)) in single systems. The competitive Langmuir and Langmuir-Freundlich isotherm models were proven to be effective in describing the experimental data of binary component system. The three dimensional sorption surfaces of binary component system demonstrated that the presence of Cu(2+) more significantly decreased the sorption of Zn(2+), but the sorption of Cu(2+) was not disturbed by the presence of Zn(2+). FTIR and EEM results revealed the adsorption sites of Cu(2+) entirely overlapped with those of Zn(2+). Cu(2+) and Zn(2+) showed competitive adsorption in binary systems, and Cu(2+) was preferentially adsorbed because of the stronger complexation ability of the protein-like substances in Klebsiella sp. J1 EPS. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biofilms associated with poultry processing equipment.

Science.gov (United States)

Lindsay, D; Geornaras, I; von Holy, A

1996-01-01

Aerobic and Gram-negative bacteria were enumerated on non-metallic surfaces and stainless steel test pieces attached to equipment surfaces by swabbing and a mechanical dislodging procedure, respectively, in a South African grade B poultry processing plant. Changes in bacterial numbers were also monitored over time on metal test pieces. The highest bacterial counts were obtained from non-metallic surfaces such as rubber fingered pluckers and plastic defeathering curtains which exceeded the highest counts found on the metal surfaces by at least 1 log CFU cm-2. Gram-negative bacterial counts on all non-metallic surface types were at least 2 log CFU cm-2 lower than corresponding aerobic plate counts. On metal surfaces, the highest microbial numbers were obtained after 14 days exposure, with aerobic plate counts ranging from 3.57 log CFU cm-2 to 5.13 log CFU cm-2, and Gram-negative counts from 0.70 log CFU cm-2 to 3.31 log CFU cm-2. Scanning electron microscopy confirmed the presence of bacterial cells on non-metallic and metallic surfaces associated with poultry processing. Rubber 'fingers', plastic curtains, conveyor belt material and stainless steel test surfaces placed on the scald tank overflow and several chutes revealed extensive and often confluent bacterial biofilms. Extracellular polymeric substances, but few bacterial cells were visible on test pieces placed on evisceration equipment, spinchiller blades and the spinchiller outlet.

In situ detection and characterization of potable water biofilms on materials by microscopic, spectroscopic and electrochemistry methods

Energy Technology Data Exchange (ETDEWEB)

Gamby, Jean [Universite Pierre et Marie Curie - Paris 6, CNRS-UPR 15, Laboratoire Interfaces et Systemes Electrochimiques, 4 Place Jussieu, Case Courrier 133, 75252 Paris Cedex 05 (France)], E-mail: jean.gamby@upmc.fr; Pailleret, Alain [Universite Pierre et Marie Curie - Paris 6, CNRS-UPR 15, Laboratoire Interfaces et Systemes Electrochimiques, 4 Place Jussieu, Case Courrier 133, 75252 Paris Cedex 05 (France); Clodic, Carol Boucher; Pradier, Claire-Marie [Universite Pierre et Marie Curie - Paris 6, CNRS-UMR 7609, Laboratoire de Reactivite de Surface, 4 Place Jussieu, Case Courrier 178, 75252 Paris Cedex 05 (France); Tribollet, Bernard [Universite Pierre et Marie Curie - Paris 6, CNRS-UPR 15, Laboratoire Interfaces et Systemes Electrochimiques, 4 Place Jussieu, Case Courrier 133, 75252 Paris Cedex 05 (France)

2008-12-01

We studied biofilm formation on stainless steel occurring in a drinking water distribution system which operated in parallel at 20 and 37 deg. C, in order to focus on the effect of temperature rather than on other operational and water quality parameters. A surface conditioning step was followed as a function of time on this material until adhesion of bacterial colonies by using microscopic methods: scanning electron microscopy (SEM) and atomic force microscopy (AFM); a spectroscopic method: polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and an electrochemical method: rotating disk electrode (RDE). Correlations between surface analysis, the duration of immersion of the sample and the influence of temperature have been identified clearly before bacterial adhesion. In cold water, these results showed an initial conditioning step of surface occurring during the first 8 days, with detection of superficial acidic functions grafted on surface, until adsorption of proteins. After 12 days, formation of independent bacteria microcolonies, reaching 2-3 {mu}m in length was observed. In tepid water, the first step was reduced to 2 days during which carbonates, acidic functions, and proteins were detected. After 90 days, the biofilm entered in a stable population state, which appeared as a bacteria rich film, including possibly Legionella. The spatial variation of the biofilm was limited as deduced from the thickness determination (about 4 {mu}m for 3-month period), using a RDE. The combination of these different techniques confirms successive steps for biofilm formation on stainless steel in a tap water. Then, we scrutinized the external near environment of bacteria including extracellular polymeric substances (EPS) and then further characterize the morphology of dominant bacteria (shape, size, flagellum) on gold substrate by AFM in air.

In situ detection and characterization of potable water biofilms on materials by microscopic, spectroscopic and electrochemistry methods

International Nuclear Information System (INIS)

Gamby, Jean; Pailleret, Alain; Clodic, Carol Boucher; Pradier, Claire-Marie; Tribollet, Bernard

2008-01-01

We studied biofilm formation on stainless steel occurring in a drinking water distribution system which operated in parallel at 20 and 37 deg. C, in order to focus on the effect of temperature rather than on other operational and water quality parameters. A surface conditioning step was followed as a function of time on this material until adhesion of bacterial colonies by using microscopic methods: scanning electron microscopy (SEM) and atomic force microscopy (AFM); a spectroscopic method: polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and an electrochemical method: rotating disk electrode (RDE). Correlations between surface analysis, the duration of immersion of the sample and the influence of temperature have been identified clearly before bacterial adhesion. In cold water, these results showed an initial conditioning step of surface occurring during the first 8 days, with detection of superficial acidic functions grafted on surface, until adsorption of proteins. After 12 days, formation of independent bacteria microcolonies, reaching 2-3 μm in length was observed. In tepid water, the first step was reduced to 2 days during which carbonates, acidic functions, and proteins were detected. After 90 days, the biofilm entered in a stable population state, which appeared as a bacteria rich film, including possibly Legionella. The spatial variation of the biofilm was limited as deduced from the thickness determination (about 4 μm for 3-month period), using a RDE. The combination of these different techniques confirms successive steps for biofilm formation on stainless steel in a tap water. Then, we scrutinized the external near environment of bacteria including extracellular polymeric substances (EPS) and then further characterize the morphology of dominant bacteria (shape, size, flagellum) on gold substrate by AFM in air

An individual-based model for biofilm formation at liquid surfaces.

Science.gov (United States)

Ardré, Maxime; Henry, Hervé; Douarche, Carine; Plapp, Mathis

2015-12-10

The bacterium Bacillus subtilis frequently forms biofilms at the interface between the culture medium and the air. We present a mathematical model that couples a description of bacteria as individual discrete objects to the standard advection-diffusion equations for the environment. The model takes into account two different bacterial phenotypes. In the motile state, bacteria swim and perform a run-and-tumble motion that is biased toward regions of high oxygen concentration (aerotaxis). In the matrix-producer state they excrete extracellular polymers, which allows them to connect to other bacteria and to form a biofilm. Bacteria are also advected by the fluid, and can trigger bioconvection. Numerical simulations of the model reproduce all the stages of biofilm formation observed in laboratory experiments. Finally, we study the influence of various model parameters on the dynamics and morphology of biofilms.

Drosophila melanogaster as an animal model for the study of Pseudomonas aeruginosa biofilm infections in vivo.

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Heidi Mulcahy

2011-10-01

Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen capable of causing both acute and chronic infections in susceptible hosts. Chronic P. aeruginosa infections are thought to be caused by bacterial biofilms. Biofilms are highly structured, multicellular, microbial communities encased in an extracellular matrix that enable long-term survival in the host. The aim of this research was to develop an animal model that would allow an in vivo study of P. aeruginosa biofilm infections in a Drosophila melanogaster host. At 24 h post oral infection of Drosophila, P. aeruginosa biofilms localized to and were visualized in dissected Drosophila crops. These biofilms had a characteristic aggregate structure and an extracellular matrix composed of DNA and exopolysaccharide. P. aeruginosa cells recovered from in vivo grown biofilms had increased antibiotic resistance relative to planktonically grown cells. In vivo, biofilm formation was dependent on expression of the pel exopolysaccharide genes, as a pelB::lux mutant failed to form biofilms. The pelB::lux mutant was significantly more virulent than PAO1, while a hyperbiofilm strain (PAZHI3 demonstrated significantly less virulence than PAO1, as indicated by survival of infected flies at day 14 postinfection. Biofilm formation, by strains PAO1 and PAZHI3, in the crop was associated with induction of diptericin, cecropin A1 and drosomycin antimicrobial peptide gene expression 24 h postinfection. In contrast, infection with the non-biofilm forming strain pelB::lux resulted in decreased AMP gene expression in the fly. In summary, these results provide novel insights into host-pathogen interactions during P. aeruginosa oral infection of Drosophila and highlight the use of Drosophila as an infection model that permits the study of P. aeruginosa biofilms in vivo.

Biofilm Formation Derived from Ambient Air and the Characteristics of Apparatus

International Nuclear Information System (INIS)

Kanematsu, H; Kougo, H; Kuroda, D; Itho, H; Ogino, Y; Yamamoto, Y

2013-01-01

Biofilm is a kind of thin film on solidified matters, being derived from bacteria. Generally, planktonic bacteria float in aqueous environments, soil or air, most of which can be regarded as oligotrophic environments. Since they have to survive by instinct, they seek for nutrients that would exist on materials surfaces as organic matters. Therefore, bacteria attach materials surfaces reversibly. The attachment and detachment repeat for a while and finally, they attach on them irreversibly and the number of bacteria on them increases. At a threshold number, bacteria produce polymeric matters at the same time by quorum sensing mechanism and the biofilm produces on material surfaces. The biofilm produced in that way generally contains water (more than 80%), EPS (Exopolymeric Substance) and bacteria themselves. And they might bring about many industrial problems, fouling, corrosion etc. Therefore, it is very important for us to control and prevent the biofilm formation properly. However, it is generally very hard to produce biofilm experimentally and constantly in ambient atmosphere on labo scale. The authors invented an apparatus where biofilm could form on specimen's surfaces from house germs in the ambient air. In this experiment, we investigated the basic characteristics of the apparatus, reproducibility, the change of biofilm with experimental time, the quality change of water for biofilm formation and their significance for biofilm research.

Methicillin-Resistant Staphylococcus aureus Biofilms and Their Influence on Bacterial Adhesion and Cohesion

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Khulood Hamid Dakheel

2016-01-01

Full Text Available Twenty-five methicillin-resistant Staphylococcus aureus (MRSA isolates were characterized by staphylococcal protein A gene typing and the ability to form biofilms. The presence of exopolysaccharides, proteins, and extracellular DNA and RNA in biofilms was assessed by a dispersal assay. In addition, cell adhesion to surfaces and cell cohesion were evaluated using the packed-bead method and mechanical disruption, respectively. The predominant genotype was spa type t127 (22 out of 25 isolates; the majority of isolates were categorized as moderate biofilm producers. Twelve isolates displayed PIA-independent biofilm formation, while the remaining 13 isolates were PIA-dependent. Both groups showed strong dispersal in response to RNase and DNase digestion followed by proteinase K treatment. PIA-dependent biofilms showed variable dispersal after sodium metaperiodate treatment, whereas PIA-independent biofilms showed enhanced biofilm formation. There was no correlation between the extent of biofilm formation or biofilm components and the adhesion or cohesion abilities of the bacteria, but the efficiency of adherence to glass beads increased after biofilm depletion. In conclusion, nucleic acids and proteins formed the main components of the MRSA clone t127 biofilm matrix, and there seems to be an association between adhesion and cohesion in the biofilms tested.

Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction of Toxic Metals and Radionuclides. Final report

International Nuclear Information System (INIS)

Wall, Judy D.

2011-01-01

Our findings demonstrated that D. vulgaris surface-adhered populations produce extracellular structures, and that the cells have altered carbon and energy flux compared to planktonic cells. Biofilms did not have greatly increased carbohydrate accumulation. Interestingly genes present on the native plasmid found in D. vulgaris Hildenborough were necessary for wild type biofilm formation. In addition, extracellular appendages dependent on functions or proteins encoded by flaG or fliA also contributed to biofilm formation. Studies with SRB biofilms have indicated that the reduction and precipitation of metals can occur within the biofilm matrix; however, little work has been done to elucidate the physiological state of surface-adhered cells during metal reduction (Cr6+, U6+) and how this process is affected by nutrient feed levels (i.e., the stimulant).

Spore formation and toxin production in Clostridium difficile biofilms.

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Semenyuk, Ekaterina G; Laning, Michelle L; Foley, Jennifer; Johnston, Pehga F; Knight, Katherine L; Gerding, Dale N; Driks, Adam

2014-01-01

The ability to grow as a biofilm can facilitate survival of bacteria in the environment and promote infection. To better characterize biofilm formation in the pathogen Clostridium difficile, we established a colony biofilm culture method for this organism on a polycarbonate filter, and analyzed the matrix and the cells in biofilms from a variety of clinical isolates over several days of biofilm culture. We found that biofilms readily formed in all strains analyzed, and that spores were abundant within about 6 days. We also found that extracellular DNA (eDNA), polysaccharide and protein was readily detected in the matrix of all strains, including the major toxins A and/or B, in toxigenic strains. All the strains we analyzed formed spores. Apart from strains 630 and VPI10463, which sporulated in the biofilm at relatively low frequencies, the frequencies of biofilm sporulation varied between 46 and 65%, suggesting that variations in sporulation levels among strains is unlikely to be a major factor in variation in the severity of disease. Spores in biofilms also had reduced germination efficiency compared to spores obtained by a conventional sporulation protocol. Transmission electron microscopy revealed that in 3 day-old biofilms, the outermost structure of the spore is a lightly staining coat. However, after 6 days, material that resembles cell debris in the matrix surrounds the spore, and darkly staining granules are closely associated with the spores surface. In 14 day-old biofilms, relatively few spores are surrounded by the apparent cell debris, and the surface-associated granules are present at higher density at the coat surface. Finally, we showed that biofilm cells possess 100-fold greater resistance to the antibiotic metronidazole then do cells cultured in liquid media. Taken together, our data suggest that C. difficile cells and spores in biofilms have specialized properties that may facilitate infection.

Spore formation and toxin production in Clostridium difficile biofilms.

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Ekaterina G Semenyuk

Full Text Available The ability to grow as a biofilm can facilitate survival of bacteria in the environment and promote infection. To better characterize biofilm formation in the pathogen Clostridium difficile, we established a colony biofilm culture method for this organism on a polycarbonate filter, and analyzed the matrix and the cells in biofilms from a variety of clinical isolates over several days of biofilm culture. We found that biofilms readily formed in all strains analyzed, and that spores were abundant within about 6 days. We also found that extracellular DNA (eDNA, polysaccharide and protein was readily detected in the matrix of all strains, including the major toxins A and/or B, in toxigenic strains. All the strains we analyzed formed spores. Apart from strains 630 and VPI10463, which sporulated in the biofilm at relatively low frequencies, the frequencies of biofilm sporulation varied between 46 and 65%, suggesting that variations in sporulation levels among strains is unlikely to be a major factor in variation in the severity of disease. Spores in biofilms also had reduced germination efficiency compared to spores obtained by a conventional sporulation protocol. Transmission electron microscopy revealed that in 3 day-old biofilms, the outermost structure of the spore is a lightly staining coat. However, after 6 days, material that resembles cell debris in the matrix surrounds the spore, and darkly staining granules are closely associated with the spores surface. In 14 day-old biofilms, relatively few spores are surrounded by the apparent cell debris, and the surface-associated granules are present at higher density at the coat surface. Finally, we showed that biofilm cells possess 100-fold greater resistance to the antibiotic metronidazole then do cells cultured in liquid media. Taken together, our data suggest that C. difficile cells and spores in biofilms have specialized properties that may facilitate infection.

Nanotechnology-based drug delivery systems for control of microbial biofilms: a review.

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Dos Santos Ramos, Matheus Aparecido; Da Silva, Patrícia Bento; Spósito, Larissa; De Toledo, Luciani Gaspar; Bonifácio, Bruna Vidal; Rodero, Camila Fernanda; Dos Santos, Karen Cristina; Chorilli, Marlus; Bauab, Taís Maria

2018-01-01

Since the dawn of civilization, it has been understood that pathogenic microorganisms cause infectious conditions in humans, which at times, may prove fatal. Among the different virulent properties of microorganisms is their ability to form biofilms, which has been directly related to the development of chronic infections with increased disease severity. A problem in the elimination of such complex structures (biofilms) is resistance to the drugs that are currently used in clinical practice, and therefore, it becomes imperative to search for new compounds that have anti-biofilm activity. In this context, nanotechnology provides secure platforms for targeted delivery of drugs to treat numerous microbial infections that are caused by biofilms. Among the many applications of such nanotechnology-based drug delivery systems is their ability to enhance the bioactive potential of therapeutic agents. The present study reports the use of important nanoparticles, such as liposomes, microemulsions, cyclodextrins, solid lipid nanoparticles, polymeric nanoparticles, and metallic nanoparticles, in controlling microbial biofilms by targeted drug delivery. Such utilization of these nanosystems has led to a better understanding of their applications and their role in combating biofilms.

Proteomic profiling of Bacillus licheniformis reveals a stress response mechanism in the synthesis of extracellular polymeric flocculants.

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Yu, Wencheng; Chen, Zhen; Shen, Liang; Wang, Yuanpeng; Li, Qingbiao; Yan, Shan; Zhong, Chuan-Jian; He, Ning

2016-04-01

Some bioflocculants composed of extracellular polymeric substances are produced under peculiar conditions. Bacillus licheniformis CGMCC2876 is a microorganism that secretes both extracellular polysaccharides (EPS) and poly-gamma-glutamic acid (γ-PGA) under stress conditions. In this work, SWATH acquisition LC-MS/MS method was adopted for differential proteomic analysis of B. licheniformis, aiming at determining the bacterial stress mechanism. Compared with LB culture, 190 differentially expressed proteins were identified in B. licheniformis CGMCC2876 cultivated in EPS culture, including 117 up-regulated and 73 down-regulated proteins. In γ-PGA culture, 151 differentially expressed proteins, 89 up-regulated and 62 down-regulated, were found in the cells. Up-regulated proteins involved in amino acid biosynthesis were found to account for 43% and 41% of the proteomes in EPS and γ-PGA cultivated cells, respectively. Additionally, a series of proteins associated with amino acid degradation were found to be repressed under EPS and γ-PGA culture conditions. Transcriptional profiling via the qPCR detection of selected genes verified the proteomic analysis. Analysis of free amino acids in the bacterial cells further suggested the presence of amino acid starvation conditions. EPS or γ-PGA was synthesized to alleviate the effect of amino acid limitation in B. licheniformis. This study identified a stress response mechanism in the synthesis of macromolecules in B. licheniformis, providing potential culture strategies to improve the production of two promising bioflocculants. © 2015 Wiley Periodicals, Inc.

Minocycline Inhibits Candida albicans Budded-to-Hyphal-Form Transition and Biofilm Formation.

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Kurakado, Sanae; Takatori, Kazuhiko; Sugita, Takashi

2017-09-25

Candida albicans frequently causes bloodstream infections; its budded-to-hyphalform transition (BHT) and biofilm formation are major contributors to virulence. During an analysis of antibacterial compounds that inhibit C. albicans BHT, we found that the tetracycline derivative minocycline inhibited BHT and subsequent biofilm formation. Minocycline decreased expression of hypha-specific genes HWP1 and ECE1, and adhesion factor gene ALS3 of C. albicans. In addition, minocycline decreased cell surface hydrophobicity and the extracellular β-glucan level in biofilms. Minocycline has been widely used for catheter antibiotic lock therapy to prevent bacterial infection; this compound may also be prophylactically effective against Candida infection.

Silver nanoparticles impede the biofilm formation by Pseudomonas aeruginosa and Staphylococcus epidermidis.

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Kalishwaralal, Kalimuthu; BarathManiKanth, Selvaraj; Pandian, Sureshbabu Ram Kumar; Deepak, Venkataraman; Gurunathan, Sangiliyandi

2010-09-01

Biofilms are ensued due to bacteria that attach to surfaces and aggregate in a hydrated polymeric matrix. Formation of these sessile communities and their inherent resistance to anti-microbial agents are the source of many relentless and chronic bacterial infections. Such biofilms are responsible play a major role in development of ocular related infectious diseases in human namely microbial keratitis. Different approaches have been used for preventing biofilm related infections in health care settings. Many of these methods have their own demerits that include chemical based complications; emergent antibiotic resistant strains, etc. silver nanoparticles are renowned for their influential anti-microbial activity. Hence the present study over the biologically synthesized silver nanoparticles, exhibited a potential anti-biofilm activity that was tested in vitro on biofilms formed by Pseudomonas aeruginosa and Staphylococcus epidermidis during 24-h treatment. Treating these organisms with silver nanoparticles resulted in more than 95% inhibition in biofilm formation. The inhibition was known to be invariable of the species tested. As a result this study demonstrates the futuristic application of silver nanoparticles in treating microbial keratitis based on its potential anti-biofilm activity. Copyright 2010 Elsevier B.V. All rights reserved.

Extracellular DNA metabolism in Haloferax volcanii

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Scott eChimileski

2014-02-01

Full Text Available Extracellular DNA is found in all environments and is a dynamic component of the micro-bial ecosystem. Microbial cells produce and interact with extracellular DNA through many endogenous mechanisms. Extracellular DNA is processed and internalized for use as genetic information and as a major source of macronutrients, and plays several key roles within prokaryotic biofilms. Hypersaline sites contain some of the highest extracellular DNA con-centrations measured in nature–a potential rich source of carbon, nitrogen and phosphorus for halophilic microorganisms. We conducted DNA growth studies for the halophilic archaeon Haloferax volcanii DS2 and show that this model Halobacteriales strain is capable of using exogenous double-stranded DNA as a nutrient. Further experiments with varying medium composition, DNA concentration and DNA types revealed that DNA is utilized primarily as a phosphorus source, that growth on DNA is concentration-dependent and that DNA isolated from different sources is metabolized selectively, with a bias against highly divergent methylated DNA sources. Additionally, fluorescence microscopy experiments showed that labeled DNA colocalized with Haloferax volcanii cells. The gene Hvo_1477 was also identified using a comparative genomic approach as a factor likely to be involved in extracellular DNA processing at the cell surface, and deletion of Hvo_1477 created an H. volcanii strain deficient in its ability to grow on extracellular DNA. Widespread distribution of Hvo_1477 homologs in archaea suggests metabolism of extracellular DNA may be of broad ecological and physiological relevance in this domain of life.

Diffusion Retardation by Binding of Tobramycin in an Alginate Biofilm Model

DEFF Research Database (Denmark)

Cao, Bao; Christophersen, Lars; Kolpen, Mette

2016-01-01

Microbial cells embedded in a self-produced extracellular biofilm matrix cause chronic infections, e. g. by Pseudomonas aeruginosa in the lungs of cystic fibrosis patients. The antibiotic killing of bacteria in biofilms is generally known to be reduced by 100–1000 times relative to planktonic...... bacteria. This makes such infections difficult to treat. We have therefore proposed that biofilms can be regarded as an independent compartment with distinct pharmacokinetics. To elucidate this pharmacokinetics we have measured the penetration of the tobramycin into seaweed alginate beads which serve...... to be uniformly distributed throughout the volume of the alginate bead. The power-law appears to be a consequence of binding to a multitude of different binding sites. In a diffusion model these results are shown to produce pronounced retardation of the penetration of tobramycin into the biofilm. This filtering...

Application of Raman Spectroscopy to the Biooxidation Analysis of Sulfide Minerals

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J. V. García-Meza

2012-01-01

Full Text Available We report the application of confocal laser scanning microscopy CLSM and Raman spectroscopy on the (biochemical oxidation of pyrite and chalcopyrite, in order to understand how surface sulfur species (S2−/S0 affects biofilm evolution during mineral colonization by Acidithiobacillus thiooxidans. We found that cells attachment occurs as cells clusters and monolayered biofilms within the first 12 h. Longer times resulted in the formation of micro- and macrocolonies with variable cell density and higher epifluorescence signal of the extracellular polymeric substances (EPS, indicating double dynamic activity of A. thiooxidans: sulfur biooxidation and biofilm formation. Raman spectra indicated S2−/S0 consumption modification during biofilm evolution. Hence, cell density increase was primarily associated with the presence of S0; the presence of refractory sulfur species on the mineral surfaces does not to affect biofilm evolution. The EPS of the biofilms was mainly composed of extracellular hydrophobic compounds (vr. gr. lipids and a minor content of hydrophilic exopolysaccharides, suggesting a hydrophobic interaction between attached cells and the altered pyrite and chalcopyrite.

Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products.

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Duan, Liang; Tian, Zhiyong; Song, Yonghui; Jiang, Wei; Tian, Yuan; Li, Shan

2015-01-01

The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.

Identification of biofilm-associated cluster (bac in Pseudomonas aeruginosa involved in biofilm formation and virulence.

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Camille Macé

Full Text Available Biofilms are prevalent in diseases caused by Pseudomonas aeruginosa, an opportunistic and nosocomial pathogen. By a proteomic approach, we previously identified a hypothetical protein of P. aeruginosa (coded by the gene pA3731 that was accumulated by biofilm cells. We report here that a Delta pA3731 mutant is highly biofilm-defective as compared with the wild-type strain. Using a mouse model of lung infection, we show that the mutation also induces a defect in bacterial growth during the acute phase of infection and an attenuation of the virulence. The pA3731 gene is found to control positively the ability to swarm and to produce extracellular rhamnolipids, and belongs to a cluster of 4 genes (pA3729-pA3732 not previously described in P. aeruginosa. Though the protein PA3731 has a predicted secondary structure similar to that of the Phage Shock Protein, some obvious differences are observed compared to already described psp systems, e.g., this unknown cluster is monocistronic and no homology is found between the other proteins constituting this locus and psp proteins. As E. coli PspA, the amount of the protein PA3731 is enlarged by an osmotic shock, however, not affected by a heat shock. We consequently named this locus bac for biofilm-associated cluster.

Characterization of mixed-culture biofilms established in microbial fuel cells

International Nuclear Information System (INIS)

Yang, Suling; Du, Fangzhou; Liu, Hong

2012-01-01

For the successful operation of a microbial fuel cell, it is important to characterize the biofilm on the anode. The behavior of MFCs during initial biofilm growth and characterization of anodic biofilm were studied using two-chamber MFCs with activated sludge as inoculum. After three times' replacement of the anodic growth medium, the biofilms were well developed, and a maximum closed circuit potential of 0.41 V and 0.37 V (1000 Ω resistor) was achieved using acetate and glucose, respectively. Electron microscopy revealed that there were rod-shaped cells 0.2–0.3 μm wide by 1.5–2.5 μm long in the anode biofilm in the acetate-fed MFC, and these cells were mainly arranged by monolayer. The biofilm in the glucose-fed MFC was made of cocci-shaped cells in chains and a thick matrix. Both using acetate and glucose, the anodic bacterial communities were different than those of the activated sludge. Cyclic voltammograms suggested that extracellular electron transfer in these MFCs was accomplished mainly by the biofilms on the anode and not by bacteria-produced mediators. -- Highlights: ► The mixed-culture biofilms established in MFCs were characterized. ► The possible electron transfer mechanism was presented. ► In these MFCs the anodic area should be much larger.

Prophage spontaneous activation promotes DNA release enhancing biofilm formation in Streptococcus pneumoniae.

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Margarida Carrolo

Full Text Available Streptococcus pneumoniae (pneumococcus is able to form biofilms in vivo and previous studies propose that pneumococcal biofilms play a relevant role both in colonization and infection. Additionally, pneumococci recovered from human infections are characterized by a high prevalence of lysogenic bacteriophages (phages residing quiescently in their host chromosome. We investigated a possible link between lysogeny and biofilm formation. Considering that extracellular DNA (eDNA is a key factor in the biofilm matrix, we reasoned that prophage spontaneous activation with the consequent bacterial host lysis could provide a source of eDNA, enhancing pneumococcal biofilm development. Monitoring biofilm growth of lysogenic and non-lysogenic pneumococcal strains indicated that phage-infected bacteria are more proficient at forming biofilms, that is their biofilms are characterized by a higher biomass and cell viability. The presence of phage particles throughout the lysogenic strains biofilm development implicated prophage spontaneous induction in this effect. Analysis of lysogens deficient for phage lysin and the bacterial major autolysin revealed that the absence of either lytic activity impaired biofilm development and the addition of DNA restored the ability of mutant strains to form robust biofilms. These findings establish that limited phage-mediated host lysis of a fraction of the bacterial population, due to spontaneous phage induction, constitutes an important source of eDNA for the S. pneumoniae biofilm matrix and that this localized release of eDNA favors biofilm formation by the remaining bacterial population.

Screening of biofilm formation by beneficial vaginal lactobacilli and influence of culture media components.

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Terraf, M C Leccese; Juárez Tomás, M S; Nader-Macías, M E F; Silva, C

2012-12-01

To assess the ability of vaginal lactobacilli to form biofilm under different culture conditions and to determine the relationship between their growth and the capability of biofilm formation by selected strains. Fifteen Lactobacillus strains from human vagina were tested for biofilm formation by crystal violet staining. Only Lactobacillus rhamnosus Centro de Referencia para Lactobacilos Culture Collection (CRL) 1332, Lact. reuteri CRL 1324 and Lact. delbrueckii CRL 1510 were able to grow and form biofilm in culture media without Tween 80. However, Lact. gasseri CRL 1263 (a non-biofilm-forming strain) did not grow in these media. Scanning electron microscopy showed that Lact. rhamnosus CRL 1332 and Lact. reuteri CRL 1324 formed a highly structured biofilm, but only Lact. reuteri CRL 1324 showed a high amount of extracellular material in medium without Tween. Biofilm formation was significantly influenced by the strain, culture medium, inoculum concentration, microbial growth and chemical nature of the support used for the assay. The results allow the selection of biofilm-forming vaginal Lactobacillus strains and the conditions and factors that affect this phenomenon. © 2012 The Society for Applied Microbiology.

Conservation and Divergence in the Candida Species Biofilm Matrix Mannan-Glucan Complex Structure, Function, and Genetic Control.