The fungal pathogen Candida albicans is a leading cause of device-associated and other nosocomial infections. The traits of biofilm formation and invasion into an underlying surface are important for Candida to cause disease. In this dissertation, I describe my work, which reveals a novel role for glycerol in C. albicans biofilm formation and hyphal invasion. Through genomewide expression profiling it was observed that glycerol biosynthetic genes were highly upregulated in biofilms relative to the planktonic (suspension) cultures. Consistent with this observation, cells in a biofilm also accumulated higher amounts of glycerol then non-biofilm cells. In order to study the impact of glycerol on biofilm formation I made a deletion mutant, rhr2Δ/Δ, in the gene encoding glycerol-3-phosphatase. Under in vitro conditions, the rhr2Δ/Δ mutant has reduced biofilm biomass and reduced adherence to silicone. The mutant is also severely defective in biofilm formation in the rat venous catheter model of biofilm
Biofilm formation on medical devices is a common cause of implant failure, especially regarding implants that breach the epithelial tissue, so-called transcutaneous implants. Nanotechnology and the development of new nanomaterials have given the opportunity to design nanotextured implant surfaces. Such surfaces have been studied using various in vitro methods showing that nanosized features strongly benefit bone cell growth. However, little is known on how nanostructured features affect biofilm formation. The aim of this study was therefore to examine the shape- and chemical-dependent effect of a nanostructured hydroxyapatite (HA) coating on the degree of Staphylococcus epidermidis biofilm formation. Three different types of nanosized HA particles having different shapes and calcium to phosphate ratios were compared to uncoated turned titanium using safranin stain in a biofilm assay and confocal laser scanning microscopy (CLSM) for assessment of biofilm biomass and bacterial volume, ...
Biofilm-associated infections are hard to treat because of their high antibiotic resistance and the presence of a very persistent subpopulation of bacteria. The second messenger molecule cyclic di-guanosine monophosphate (c-di-GMP) plays a very important role in this biofilm physiology. Here, we evaluated the role of YddV, an enzyme with a c-di-GMP synthesis function, in the formation and maturation of Escherichia coli biofilms. Our results suggest that YddV stimulates biofilm growth via its role in the production of c-di-GMP and this likely by influencing the production of matrix (e.g. poly-N-acetylglucosamine (PGA)). However, lowering the YddV expression did not alter the biofilm formation since there was no significant difference between the biofilm phenotypes of WT E. coli and YddV-knockout bacteria. Additionally, YddV expression had no significant influence on the amount of persister cells within the biofilm population, questioning the use of YddV as therapeutic target. (C) 2016 Published ...
Biofilms have been implicated as an important reservoir for pathogens and commensal enteric bacteria such as Escherichia coli in natural and engineered water systems. However, the processes that regulate the survival of E. coli in aquatic biofilms have not been thoroughly studied. We examined the effects of hydrodynamic shear and nutrient concentrations on E. coli colonization of pre-established Pseudomonas aeruginosa biofilms, co-inoculation of E. coli and P. aeruginosa biofilms, and P. aeruginosa colonization of pre-established E. coli biofilms. In nutritionally-limited R2A medium, E. coli dominated biofilms when co-inoculated with P. aeruginosa, and successfully colonized and overgrew pre-established P. aeruginosa biofilms. In more enriched media, P. aeruginosa formed larger clusters, but E. coli still extensively overgrew and colonized the interior of P. aeruginosa clusters. In mono-culture, E. coli formed sparse and discontinuous biofilms. After P. aeruginosa was introduced to these biofilms, E.
Staphylococcus aureus extracellular DNA (eDNA) plays a crucial role in the structural stability of biofilms during bacterial colonization; on the contrary, host immune responses can be induced by bacterial eDNA. Previously, we observed production of S. aureus thermonuclease during the early stages of biofilm formation in a mammalian cell culture medium. Using a fluorescence resonance energy transfer (FRET)-based assay, we detected thermonuclease activity of S. aureus biofilms grown in Iscoves modified Dulbeccos medium (IMDM) earlier than that of widely studied biofilms grown in tryptic soy broth (TSB). The thermonuclease found was Nuc1, confirmed by mass spectrometry and competitive Luminex assay. These results indicate that biofilm development in IMDM may not rely on eDNA for structural stability. A bacterial viability assay in combination with wheat germ agglutinin (WGA) staining confirmed the accumulation of dead cells and eDNA in biofilms grown in TSB. However, in biofilms grown in IMDM, ...
Biofilms are ubiquitous in aquatic environments. Biofilms have been shown to attract and harbor pathogens such as P. aeruginosa and Legionella pneumophila in premise plumbing system. The fact that biofilms can protect attached bacterial cells from disinfectants raises rudimentary questions regarding interactions of bacterial cells with biofilm surfaces. Consequently, the main objectives of this study were to: 1) investigate the mechanisms that govern E. coli S17, E. coli 14f and Legionella cells adhesion on clean PVC, copper and biofilms; 2) examine the role of disinfectants on biofilms structure and subsequent effect on bacterial adhesion. Mechanisms of three strains of bacteria attachment on biofilms grown on PVC and copper surfaces were investigated. Biofilms were grown in CDC reactors using different types of feed water such as groundwater, monochloramine-treated groundwater, dechlorinated tap water and tap water. Biofilm physical structure was characterized at micro- and meso-scales using ...
In the majority of cases, the surface-associated multicellular communities found in a wide variety of natural and pathogenic ecosystems are formed in the presence of multiple diverse species and genetically distinct strains. In recent years, well-controlled in vitro biofilm model systems have revealed a diversity of molecular mechanisms contributing to development and maturation of single-species biofilms. The mechanisms underlying the biofilm development in the presence of these multispecies consortia are expected to involve even higher degrees of complexity; however, our understanding of mixed-species biofilms is hampered by the limited number of model systems that have been applied to date. The goal of this study was to test the capacity of a simple in vitro model to reveal factors contributing to the formation of more complex biofilm communities. The suitability of this approach to high-throughput analyses was demonstrated with a systematic survey of a large collection of E. coli isolates ...
Microtiter plate-based bacterial biofilm assay is frequently used to study bacterial biofilm development and growth. While this assay is simple and relatively high-throughput, it frequently shows difficulty in establishing robust biofilm attachment in the wells. We report that the consistency of bacterial biofilm a
The oral microbial ecology is comprised of hundreds of bacterial species that co-exist as multispecies biofilms throughout a range of ecological niches in the oral cavity. However, little is known concerning the interactions of these complex biofilms with host cells. Objective: This study used a novel model of multispecies bacterial biofilms to stimulate oral epithelial cells and profile select cytokines and chemokines that contribute to the local inflammatory environment in the periodontium. Method: Three multispecies biofilms comprising Streptococcus gordonii/S. oralis/S. sanguinis, Sg/Fusobacterium nucleatum/Porphyromonas gingivalis and Sg/Actinomyces naeslundii/Fn were grown for 3 days on rigid gas permeable contact lens pre-coated with 1% fetal bovine serum. OKF4 oral epithelial cells were cultured in 48 well plates at 105 cells/well, which were challenged with the biofilms for 24 hrs. Controls included incubation of the epithelial cells alone or overlaid with contact lens alone. A profile ...
Cells in bacterial biofilms are often less susceptible to host immune responses and antibiotics than cells grown in suspension (18). Biofilms may also provide a protective environment for pathogens, which, when released from the biofilm, may result in contamination of drinking water and medical fluids in delivery devices such as dialysis machines, venous catheters, dental water lines, and airway ventilators. Life-threatening infection caused by Pseudomonas aeruginosa in cystic fibrosis patients is a well-known example (8). Since biofilm formation in itself can be considered a virulence factor, it is important to understand the mechanisms which influence biofilm accumulation, structure, and behavior. Both hydrodynamics and cell signaling have been found to influence the structure of P. aeruginosa PAO1 biofilms. Stoodley et al. (27) reported that, under conditions of low-shear laminar flow, the biofilm consisted of a monolayer of cells with mound-shaped circular microcolonies but under high-shear, ...
S. aureus is a frequent etiological agent of biofilm infections on indwelling devices and orthopedic implants (9, 36), and recent reports by our group and others have demonstrated that biofilms can skew the immune response to favor anti-inflammatory and profibrotic pathways, which likely contribute to biofilm persistence (17, 18). To overcome this immune deviation and provide a novel treatment strategy for biofilm infections, we augmented antimicrobial activity through the local administration of classically activated M1 MΦs or treatment with the CD88 agonist EP67, which invokes MΦ proinflammatory responses. Early administration of M1-activated MΦs or EP67 limited biofilm formation, and treatment of established biofilm infections with M1-activated MΦs also significantly reduced catheter-associated biofilm burdens. Based on this evidence, we have identified a novel therapeutic strategy to limit S. aureus catheter-associated biofilm infections by targeting MΦ activation, which may extend to ...
Fluorescently labelled latex microbeads were used to study the interaction of particles with Pseudomonas aeruginosa biofilms in a continuous flow annular reactor. Beads were readily distinguished and enumerated in both intact and disaggregated biofilm samples. The fraction of beads that attached to biofilm during a 24 h period ranged from 0.001 to 0.01 and was proportional to biofilm cell carbon and to the standard deviation of biofilm thickness. Microbeads added to biofilm of steady state thickness (30 μm) were observed to be located throughout the entire biofilm depth in 24 h. Many of the microbeads that attached to biofilm shortly after bacterial inoculation (thickness of 2 μm) remained near the substratum as cells grew past and covered them. Microbeads were observed near the biofilm-substratum interface for up to 5 days after bead addition. Beads formed aggregates on biofilms, but not in bulk water. Beads captured by biofilm remained in the reactor system longer than beads that never ...
S. mutans UA159 and its derivative mutant strain luxS- [54] were incubated in Brain Heart Infusion Broth (BHI, Difco Labs, Detroit, USA) at 37°C in 95% air/5% CO2 (v/v), with the addition of erythromycin (10 μg/ml) in the case of the luxS- strain. Cultures of S. mutans were diluted 1:50, inoculated into fresh BHI media and grown in polystyrene tubes for 24 h (37°C, 95% air/5% CO2 (v/v)) for planktonic culture generation. The biofilm of luxS- was grown in BHI with addition of erythromycin (10 μg/ml) in 20-mm diameter, 15-mm deep sterile polystyrene multidishes (NUNCLON-143982, Roskilde, Denmark), as described previously [14].. As biofilm thickness plays a crucial role in mature biofilm development, we generated biofilms of wild-type bacteria under controlled nutrition flow and controlled biofilm depth conditions, by using the constant depth film fermentor (CDFF) [55]. The rotating turntable in the CDFF contained 15 polytetrafluoroethylene (PTFE) pans, rotated under PTFE scraper bars that ...
It is clear from many investigations that biofilm-associated cells display high-level tolerance to many antibiotics and other antimicrobial agents, creating considerable problems in removing biofilms from both abiotic and biotic surfaces in various settings, including in patients with infections (6). However, it is less clear if antibiotic tolerance is a shared feature of all biofilm-associated cells or if this property is associated with only parts of the biofilm populations. It is also not clear whether the biofilm-associated antibiotic tolerance is a direct consequence of the biofilm lifestyle per se or whether indirect induction of tolerance occurs in ways similar to what may even be the case for planktonic cells grown under special conditions. In order to obtain a more direct identification of the survivors after antibiotic treatment of biofilms, it is necessary to visualize them in situ. In the present context, we found it particularly interesting to investigate whether the stalk- and ...
A key problem in understanding major transitions in evolution is the evolution of cooperation: how are mutants that exploit the benefits of cooperation without paying the costs (cheats) suppressed within populations? Biofilms, which display properties of both single cell and multicellular organisms, provide an excellent model system to address this question. Biofilms exhibit grouped population structure - they exist primarily as dense aggregates of cells called microcolonies. We aim to test the hypothesis that cell-grouping displayed by microcolonies in bacterial biofilms provides a mechanism to suppress cheats within the biofilm population. We are using the co-operative trait of siderophore production (an extracellular iron-chelating molecule) within Pseudomonas aeruginosa biofilms to investigate cooperation in biofilms. Under iron-limited conditions, production of siderophores enhanced wild type growth, but microcolonies containing GFP-tagged, pyoverdin-mutant cheats developed poorly. In ...
Introduction: The discovery of new antimicrobials derived from plants could aid in the management of biofilm-associated infections, including denture-induced stomatitis (DS). DS is an oral infection caused by Candida biofilms on the surfaces of poorly cleansed dentures. Effective treatment of DS requires the use of an appropriate denture cleanser and preferably one that exhibits antimicrobial properties. Objective: This study aimed to evaluate the anti-Candida and anti-biofilm efficacy of two essential plant oils from Cymbopogon winterianus (citronella) and Cinnamon cassia (cinnamon). Materials and methods: Minimum Inhibitory Concentrations (MICs) and Minimum Fungicidal Concentrations (MFCs) were determined by broth microdilution, whilst anti-biofilm activity was measured against mature (cultured for 72 h) biofilms on acrylic surfaces. Candida cell viability was assessed immediately (0 h) after treatment (T0) and 48 h after biofilm re-growth (T48). Biofilm structure was determined using Scanning ...
The third chapter aimed to study the role of persisters in determining the spatial and temporal pattern of biofilm formation following antibiotic treatment. A key feature of biofilms thought to play a role in antimicrobial tolerance is their ability to develop discrete, differentiated microcolony structures during colonization of a surface - these foci within biofilms are highly recalcitrant towards antimicrobials yet the factors that determine their differentiation and growth are poorly understood. This chapter therefore aimed to study the role of persisters in the initiation of microcolony foci and in mediating regrowth of biofilms. In this work, biofilm initiation was studied under a variety of conditions including with or without exposure to lethal or sub-lethal antibiotic challenge and as expected persister cell populations were able to generate significantly more biomass than in biofilms formed from non-persister populations. Dual labelling experiments were also carried out, where mixed ...
Neisseria gonorrhoeae has been shown to form biofilms during cervical infection. Thus, biofilm formation may play an important role in the infection of women. The ability of N. gonorrhoeae to form membrane blebs is crucial to biofilm formation. Blebs contain DNA and outer membrane structures, which have been shown to be major constituents of the biofilm matrix. The organism expresses a DNA thermonuclease that is involved in remodeling of the biofilm matrix. Comparison of the transcriptional profiles of gonococcal biofilms and planktonic runoff indicate that genes involved in anaerobic metabolism and oxidative stress tolerance are more highly expressed in biofilm. The expression of aniA, ccp, and norB, which encode nitrite reductase, cytochrome c peroxidase, and nitric oxide reductase respectively, is required for mature biofilm formation over glass and human cervical cells. In addition, anaerobic respiration occurs in the substratum of gonococcal biofilms and disruption of the norB gene required ...
Oral candidosis is common in patients with diabetes mellitus, as yeasts, particularly Candida albicans, have the propensity to colonise, form biofilms and release hydrolytic enzymes which cause inflammation. This study aimed to investigate these characteristics in isolates from three groups of patients with type 1 diabetes: individuals with better controlled diabetes (BCD; a parts per thousand yen6 , 8%), individuals with poorly controlled diabetes (PCD; a parts per thousand yen8%) and non-diabetics (ND; HbA(1c) , 5.9%). The biomass (Bm), phospholipase (P-z), haemolysin (H-z) and proteinase (Pr-z) were assessed using a microtitre biofilm assay and agar-based hydrolytic enzyme assays. Biofilm formation was significantly increased in the PCD group compared to ND and BCD groups (P , 0.05). No significant differences in P-z levels were observed between groups, whereas both H-z and Pr-z were significantly greater in the diabetes groups than in the healthy control group (P , 0.05). Statistically ...
Barsoukov E. and J.R. Macdonald (eds). 2005. Impedance Spectroscopy: Theory, Experiment and Applications, 2nded. John Wiley & Sons, Inc., Hoboken, NJ, USA.. Ben-Yoav H., A. Freemanb, M. Sternheimc and Y. Shacham-Dia-manda. 2011. An electrochemical impedance model for integrated bacterial biofilms. Electrochim. Acta. 56:7780-7786.. Bjarnsholt T., K. Kirketerp-Møller, P.Ø. Jensen, K.G. Madsen, R. Phipps, K. Krogfelt, N. Høibyand and M. Givskov. 2008. Why chronic wounds will not heal: a novel hypothesis. Wound Rep. Reg. 16:2-10.. Dominguez-Benetton X., S. Sevda, K. Vanbroekhovena. and D. Panta. 2012. The accurate use of impedance analysis for thestudy of microbial electrochemical systems. Chem. Soc. Rev. 41:7228-7246.. Flemming H., J. Wingender and U. Szewczyk (eds). 2008. Biofilm Highlights. Springer Series on Biofilm Vol. 5. Springer-Verlag, Berlin, Heidelberg.. Ge Y., T. Deng and X. Zheng. 2008. Dynamic monitoring of changes in endothelial cell-substrate adhesiveness during leukocyte adhesion ...
Alexandru Mihai Grumezescu*, Carmen Mariana Chifiriuc: Prevention of Microbial Biofilms - the Contribution of Micro and Nanostructured Materials, Current Medicinal Chemistry, accepted, 2014.. EDITORIAL. Microbial biofilms are associated with drastically enhanced resistance to most of the antimicrobial agents and with frequent treatment failures, generating the search for novel strategies which can eradicate infections by preventing the persistent colonization of the hospital environment, medical devices or human tissues. Some of the current approaches for fighting biofilms are represented by the development of novel biomaterials with increased resistance to microbial colonization and by the improvement of the current therapeutic solutions with the aid of nano(bio)technology. This special issues includes papers describing the applications of nanotechnology and biomaterials science for the development of improved drug delivery systems and nanostructured surfaces for the prevention and treatment of ...
Staphylococcus aureus (S. aureus) is a gram positive pathogen known to cause multiple infectious diseases for both animal and humans, and is responsible for community-associated and nosocomial infections. S. aureus possess the ability to form biofilms, which have a profound ability to adapt and thrive in undesirable conditions as well as resist antibiotic treatment. Recent studies suggest that polymorphonuclear leukocytes are able to attack S. aureus biofilms, thus implying the innate immune system indeed has mechanisms to respond to S. aureus biofilms. We determined if shear affected both the structure of the biofilm as well as the number on PMNs adhering to the S. aureus biofilm, and quantify where these cells adhere with respect to the biofilm. We conclude that shear does not have a significant effect on the number of cells adhering, but affects the depth of penetration in a maturing S. aureus biofilm ...
Biofilm Eradication and Preventions presents the basics of biofilm formation on medical devices, diseases related to this formation, and approaches pharmaceutical researchers need to take to limit this problem. Split into three parts, the first deals with the development and characterization of biofilm on the surfaces of implanted or inserted medical devices. Questions as to why biofilms form over medical device surfaces and what triggers biofilm formation are addressed. In the second section, the author discusses biofilm-mediated chronic infections occurred in various organs (eyes, mouth, wounds) and pharmaceutical and drug delivery knowledge gained from research in these area. The third part explores pharmaceutical approaches like lipid-and polymer-based drug delivery carriers for eradicating biofilm on device-related infections. In addition, this section also explores the topic of novel small molecule (like iron and its complexes/metal chelators) and a quorum-sensing inhibitors to control ...
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Gregory Anderson, biology department at IUPUI, will present Molecular Insights into Bacterial Biofilm Formation in the Cystic Fibrosis Lung. Read more about Anderson at https://science.iupui.edu/people/anderson-gregory .
Biofilms can develop on almost any surface exposed to an aqueous environment. The biofilm systems that result can be used beneficially, as exemplified by fixed-film wastewater treatment processes (for example, trickling filters and rotating biological contactors). In addition, biofilms play a major positive role in stream purification processes. However, biofilms can be quite troublesome in certain engineering systems. In water distribution systems and heat transfer equipment, for example, biofilms can cause substantial energy losses resulting from increased fluid frictional resistance and increased heat transfer resistance. The significance of biofilm development on various processes is summarized ...
Biofilms have been found to be involved in large percentages of all infections in the body. Chronic sinusitis patients undergoing surgery present with biofilms most of the time. The NIH estimates that 80% of all human infections have biofilm involvment. Other infectious processes in which biofilms have been implicated include common problems such as urinary tract infections, catheter infections, middle-ear infections, endocarditis, infections in cystic fibrosis, and infections of permanent indwelling devices such as joint prostheses and heart valves. More recently it has been noted that bacterial biofilms may impair cutaneous wound healing and reduce topical antibacterial efficiency in healing or treating infected skin wounds. Biofilms can also be formed on the inert surfaces of implanted devices such as catheters, prosthetic cardiac valves and intrauterine devices ...
In science-fiction movies, force fields always come in handy when the good guys need protection from hostile aliens or bug-eyed monsters.. Of course, these miraculous devices dont really exist. But some of Earths simplest life forms protect themselves using a similar principle.. Many one-celled organisms secrete protein complexes called biofilms that serve as slimy barriers to the outside world.. Usually, biofilms dont pose any threat to human health. But theres increasing evidence that links them to antibiotic-resistant bacterial infections.. A recent study in the Journal of the American Medical Association suggests biofilms may help some middle-ear infections resist treatment efforts.. The study involved twenty-six children who suffered recurring bouts of otitis media [oh-TIGHT-iss MEE-dee-uh], one of the most common childhood ailments.. Researchers wanted to know if biofilms were protecting the bacteria that cause these infections. So they analyzed tissue samples collected from the middle ...
Fungal biofilms were more resistant to antimicrobial agents than planktonic cells. Four distinct growth phases in relation to antifungal susceptibility were examined. Our results demonstrated that all three strains became increasingly resistant to antifungal agents throughout morphological differentiation, which was consistent with the report by Imamura et al., 10 showing that Fusarium biofilms exhibited reduced susceptibility to lens care solutions in a time-dependent manner. Moreover, our results showed that the mature biofilms were intrinsically resistant to the azole antifungal drugs (FLU, VRC, and ITC). Multiple mechanisms have been proposed for the increased resistance of biofilms to antifungal agents. Our results indicate that ECM increased and a network of hyphal structures formed throughout the incubation time. The architecture of biofilms and the presence of ECM might reduce the diffusion of antifungal drugs, and they may be responsible for the increased resistance of biofilms to ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
Organized within biofilm communities, bacteria exhibit resistance towards a broad spectrum of antibiotics. Thus, one might argue that bacteria isolated from biofilm-associated chronic infections should be subjected to resistance profiling under biofilm growth conditions. Various test systems have been developed to determine the biofilm-associated resistance; however, it is not clear to what extent the in vitro results reflect the situation in vivo, and whether the biofilm-resistance profile should guide clinicians in their treatment choice. To address this issue, we used confocal microscopy in combination with live/dead staining, and profiled biofilm-associated resistance of a large number (,130) of clinical Pseudomonas aeruginosa isolates from overall 15 cystic fibrosis patients. Our results demonstrate that in addition to a general non-responsiveness of bacteria when grown under biofilm conditions, there is an isolate-specific and antibiotic-specific biofilm-resistance profile. This individual ...
During infection, fungi frequently transition to a biofilm lifestyle, proliferating as communities of surface-adherent aggregates of cells. Phenotypically, cells in a biofilm are distinct from free-floating cells. Their high tolerance of antifungals and ability to withstand host defenses are two characteristics that foster resilience. Biofilm infections are particularly difficult to eradicate, and most available antifungals have minimal activity. Therefore, the discovery of novel compounds and innovative strategies to treat fungal biofilms is of great interest. Although many fungi have been observed to form biofilms, the most well-studied is Candida albicans. Animal models have been developed to simulate common Candida device-associated infections, including those involving vascular catheters, dentures, urinary catheters, and subcutaneous implants. Models have also reproduced the most common mucosal biofilm infections: oropharyngeal and vaginal candidiasis. These models incorporate the ...
Bacterial biofilms have been documented on middle ear mucosa, tonsils, and cholesteatoma. We hypothesize that bacterial biofilms are present in mucosa of patients with chronic sinusitis. We believe that frontal sinus stents may serve as a reservoir f
The structural organization of four microbial communities was analysed by a novel computer program, COMSTAT, which comprises ten features for quantifying three-dimensional biofilm image stacks. Monospecies biofilms of each of the four bacteria, Pseudomonas putida, P. aureofaciens, P. fluorescens and P. aeruginosa, tagged with the green fluorescent protein (GFP) were grown in flow chambers with a defined minimal medium as substrate. Analysis by the COMSTAT program of four variables describing biofilm structure - mean thickness, roughness, substratum coverage and surface to volume ratio - showed that the four Pseudomonas strains represent different modes of biofilm growth. P. putida had a unique developmental pattern starting with single cells on the substratum growing into micro-colonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a
... presents carefully refereed volumes on selected topics on this field of research. All volumes reflect the latest findings and developments. Once anchored to a surface, biofilm microorganisms carry out a ...
The presence or absence of virulence factors in pathogenic aetiological agent of a disease is an important variable that decides the course of the illness itself. The enzymes and toxins produced by bacteria or the ability of bacteria to produce biofilm help microorganisms survive in infected tissues either through direct impact on host stromal cells or by affecting host defence mechanisms [18]. In our experiment, most of the analysed isolates of Streptococcus spp. demonstrated an ability to produce biofilm (over 70%), many of which represented strains forming a weak structure. Such high abundance in this group can be explained by the fact that determinations in strains were made after a 24-h incubation period. Moliva et al. [19] recently showed that strains of S. uberis begin to form biofilm structure as early as after 2 h of incubation, but mature biofilm is not formed until after 48 h. It is possible that the relatively longer incubation of isolates in our study influenced the results. ...
A main characteristic associated with microbial biofilms is their increased resistance to antimicrobial chemotherapies. However, at present very little is known about the phenotypic changes that occur during the transition from the planktonic to the biofilm mode of growth. Candida albicans biofilms …
Objective: To assess the volume of biofilm attached on composite materials of multi-species oral microcosms derived from children with a history of Early Childhood Caries. Method: Plaque and saliva samples were collected from multiple pediatric patients (n=8). After saliva coating (filtered sterilized) with matched donors, plaque microcosms were incubated on material circular coupons of Z100 and LS (3M ESPE) and hydroxyapatite. The disks were placed in a CDC based biofilm reactor system for 72 hours with sucrose pulsing occurring 4 times daily. After removal from reactor, biofilms were stained and incubated for 2 hours with FilmTracer SYPRO Ruby Biofilm Matrix Stain and FilmTracer Calcein Green Cell Viability Stain. A confocal laser scanning microscope (Olympus FluoView 1000) was used to analyze the stained biofilms and to construct 3D images of each sample. Average volume of each biofilm sample was then measured with custom software created in MATLAB. Result: The biofilm reactor system produced ...
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
Dental restorative materials interact with their surrounding oral environment. Interaction factors can be release of toxic components and/or effects on biofilm formation and gingiva. In the end of the nineties, a calcium aluminate cement (CAC) was manufactured as a "bioceramic" alternative to resin composite. Dental ceramics are considered to be chemically stable and not to favour dental biofilm formation. Since the influence of aged, resin-bonded ceramic coverages is not fully investigated and the effect of CAC restorations on the dental biofilm formation and gingival response is unknown, those issues were evaluated in this thesis.. With or without oral hygiene, in clinical trials including cervical surfaces of CAC, and approximal surfaces of a leucite-reinforced bonded ceramic; biofilm growth, presence of caries-associated bacteria, clinical expressions of gingivitis, the amounts of gingival crevicular fluid (GCF) and its levels of IL-1α, IL-1β and IL-1 ra were investigated in comparison ...
Biofilms are adherent communities of bacteria contained within a complex matrix. Although host immune responses to planktonic staphylococcal species have been relatively well-characterized, less is known regarding immunity to staphylococcal biofilms and how they modulate anti-bacterial effector mechanisms when organized in this protective milieu. Previously, staphylococcal biofilms were thought to escape immune recognition on the basis of their chronic and indolent nature. Instead, we have proposed that staphylococcal biofilms skew the host immune response away from a proinflammatory bactericidal phenotype toward an anti-inflammatory, pro-fibrotic response that favors bacterial persistence. This possibility is supported by recent studies from our laboratory using a mouse model of catheter-associated biofilm infection, where S. aureus biofilms led to the accumulation of alternatively activated M2 macrophages that exhibit anti-inflammatory and pro-fibrotic properties. In addition, relatively few
Chronic Pseudomonas aeruginosa biofilm lung infection in cystic fibrosis patients is the best described biofilm infection in medicine. The initial focus can be the paranasal sinuses and then follows repeated colonization and infection of the lungs by aspiration. The matrix of the biofilms is dominated by alginate and the pathogenesis of tissue damage is immune complex-mediated chronic inflammation dominated by polymorphonuclear leukocytes and their products (DNA, oxygen radicals and proteases). The P. aeruginosa biofilm infection can be diagnosed by microscopy of lung tissue, sputum and mucus from the paranasal sinuses, where aggregates of the bacteria are found surrounded by the abundant alginate matrix. Specific PNA-FISH probes can be used to identify P. aeruginosa and other pathogens in situ in the biofilms. Growth of mucoid colonies from the locations mentioned above is also diagnostic for biofilm infection. Rise of specific anti-P. aeruginosa antibodies is likewise diagnostic, IgG in serum ...
Bacterial biofilms are sessile microbial communities that cause serious problems, such as antibiotic resistant chronic infections in humans, and persistent biofouling of engineering facilities. Biofilm formation is initiated by bacterial adhesion to a surface followed by the formation of microcolonies and further development of heterogeneous structures with water channels between cell clusters. The mechanism of biofilm structural heterogeneity and the bacterial genes involve in structural organization are still poorly understood. Nevertheless, once microbes adhere to a surface and form biofilm on it, they are up to 10-1,000 times more resistant to antimicrobial agents than their free-swimming counterparts. It is well accepted that biofilm formation involves multicellular behaviors, associated with major changes in microbial gene expression and protein synthesis. These changes are influenced by many environmental factors such as surface hydrophobicity, topography, chemistry, and charge. To better
Microbial biofilms are a major impediment to the use of indwelling medical devices, generating device-related infections with high morbidity and mortality. Major efforts directed towards preventing and eradicating the biofilm problem face difficulties because biofilms protect themselves very effectively by producing a polysaccharide coating, reducing biofilm sensitivity to antimicrobial agents. Techniques applied to combating biofilms have been primarily chemical. These have met with partial and limited success rates, leading to current trends of eradicating biofilms through physico-mechanical strategies. Here we review the different approaches that have been developed to control biofilm formation and removal, focusing on the utilization of acoustic energy to achieve these objectives.
University of Iowa researchers have succeeded in wiping out established biofilms of Staphylococcus aureus (staph) by hijacking one of the bacterias own regulatory systems. Although the discovery is not ready for clinical application, the findings offer insight into a dispersal mechanism for staph biofilms and might help identify therapeutic targets.. Biofilms are communities of bacteria that grow on moist surfaces, including heart valves, bone and medical implants. Encased in self-produced slime and highly resistant to antibiotic therapy and the bodys own immune defenses, biofilm infections represent a tough and dangerous medical problem. The findings were published in the journal Public Library of Science - Pathogens (PLoS-Pathogens) on April 25.. We have shown that activating the cells communication system, also known as quorum sensing, in established biofilms causes the biofilms to disperse rapidly, said Alexander Horswill, Ph.D., UI assistant professor of microbiology and senior study ...
Biofilms are now considered ubiquitous in the natural world. Bacterial biofilms have been observed to be extremely heterogeneous, both structurally and with regard to the physiology of the bacterial cells within them. The prevailing conceptual model depicts bacterial biofilms as being made up of microcolonies, which serve as the basic unit of the greater biofilm structure. A major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. A number of elements in the process of biofilm formation have been studied as targets for novel drug delivery technologies. The present study aimed to penetrate biofilm by gram positive and gram negative bacteria by in-vitro culture technique, with developed nano emulsion containing photodynamic agents. The results of this study are encouraged and significantly prevent the formation of microcolonies, building blocks of biofilms.
Mucus-invasive bacterial biofilms are identified on the colon mucosa of approximately 50% of colorectal cancer (CRC) patients and approximately 13% of healthy subjects. Here, we test the hypothesis that human colon biofilms comprise microbial communities that are carcinogenic in CRC mouse models. Homogenates of human biofilm-positive colon mucosa were prepared from tumor patients (tumor and paired normal tissues from surgical resections) or biofilm-positive biopsies from healthy individuals undergoing screening colonoscopy; homogenates of biofilm-negative colon biopsies from healthy individuals undergoing screening colonoscopy served as controls. After 12 weeks, biofilm-positive, but not biofilm-negative, human colon mucosal homogenates induced colon tumor formation in 3 mouse colon tumor models (germ-free ApcMinΔ850/+;Il10-/- or ApcMinΔ850/+ and specific pathogen-free ApcMinΔ716/+ mice). Remarkably, biofilm-positive communities from healthy colonoscopy biopsies induced colon inflammation and ...
Most studies of biofilms have focused on single species and on genes that control or are regulated by life on a surface. As more information is uncovered by studies of pure cultures, these data can be applied towards understanding the roles of specific genes in multispecies interactions. This chapter focuses mostly on multi-species interactions among oral bacteria in biofilms: a few single-species biofilms are featured to discuss responses to environmental signals, including signals generated by the occupants within the biofilm. Signals involved in cell-to-cell communication among biofilm cells include acyl homoserine lactones, oligopeptides, and autoinducer-2 (AI-2). Importantly, an optimal concentration of 4,5-dihydroxy-2,3-pentanedione (DPD) was critical for maximal biofilm development. One site where natural multispecies biofilms are unusually accessible is the tooth surface in the human oral cavity. We use a retrievable enamel chip model system that permits us to place three pieces of enamel side
Recent anatomical evidence of a biofilm mode of growth in the airway of CF patients and rigorous biochemical data demonstrating biofilm quorum-sensing signals in the sputum of CF patients support the contention that biofilms are present in the airways of adult patients with CF (10, 13, 16, 18, 26). Autopsy immunohistopathologic studies of lungs from CF patients demonstrate biofilm-like aggregates of P. aeruginosa organisms enclosed by circular profiles of exudate arranged in colonies and, in some cases, adherent to the walls of airways (5). Electron microscopy studies of sputum from CF patients have shown clusters of aggregated P. aeruginosa encased in densely stained matrix, suggesting that small biofilm communities may be recoverable in the sputum of adults with CF (26). Physiologic evidence of a biofilm mode of growth of P. aeruginosa in the lungs of CF patients has also been demonstrated, and the magnitude and chemical profile of intercellular bacterial homoserine lactone signaling molecules ...
inbook{5875afa7-6468-4741-88b2-bd174329b39d, abstract = {,p,This manuscript presents novel approaches to grow and evaluate Streptococcal biofilm formation using the human respiratory pathogen Streptococcus pneumoniae (the pneumococcus) as the main model organism on biological surfaces in vitro and in vivo. Most biofilm models are based on growth on abiotic surfaces, which is relevant for many pathogens whose growth on surfaces or medical devices is a major cause of disease transmission and infections, especially in hospital environments. However, most infections with commensal organisms require biofilm formation on biological surfaces in the host at the site of colonization or infection. In vitro model systems incorporating biological components from the host and taking into account the host environment of the infectious site are not well described. In a series of publications, we have shown that S. pneumoniae form complex biofilms in the nasopharynx of mice and have devised methodology to ...
The aim of this study was to determine the surface physicochemical properties of L. monocytogenes LO28 and to investigate its ability to adhere and to form biofilm on abiotic surfaces at different temperatures and in the log and stationary phases. Stainless steel and PTFE were selected because of their common use in food-processing plants and because they have different physicochemical characteristics (3). The growth temperature and the phase of growth may influence the cell wall composition and thereby modify the surface electrical properties, hydrophobicity, and electron donor or electron acceptor character of the bacteria (13, 36).. The affinity of bacterial cells as determined by the comparison of the two pairs of solvents was higher for the electron acceptor solvent and weaker for the electron donor solvent under all conditions of the study, indicating a strong electron donor nature and a weak electron acceptor nature of the bacteria. Lewis acid-base interactions indicated that the cells ...
Author Summary Both in the wild and in the clinical setting many bacterial species live within surface-attached communities called biofilms. It is still unclear the extent to which the biofilm lifestyle and its associated phenotypes, such as hyper-tolerance to antimicrobial agents, can be attributed to structural characteristics of the biofilm community or to intrinsic biofilm-specific physiological programs. In order to address this longstanding question, we focused on poly-N-acetylglucosamine (PNAG)-based biofilms, a clinically relevant phenotype of many bacterial pathogens, including E. coli. Instead of working in a biofilm-permissive genetic background, in which the timescale of biofilm formation is slow, we applied the functionally active secreted version of the PNAG exo-polysaccharide (sPNAG) to wild-type E. coli cells, generating robust biofilms on the timescale of hours. In this way, we managed to uncouple upstream regulatory processes and matrix preparatory phase of biofilm formation, focusing
Cold-adapted marine bacteria represent an untapped reservoir of chemical-diversity able to synthesize a wide range of bioactive compounds, including antibiofilm molecules. The present research project aims to explore extreme marine environments and to exploit marine-derived biomolecules as a sustainable source of novel antibiofilm compounds. In this work, the antibiofilm activity of total organic extracts derived from cultures of Polar marine bacteria, belonging to Flavobacterium, Pseudoalteromonas, Pseudomonas, Psychrobacter and Psychromonas genera, were evaluated against some pathogenic bacteria, such as Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa. Suitable purification protocols will be developed to purify and characterize the most promising antibiofilm molecules, and their possible clinical applications will be investigated.. ...
Biofilms of S. aureus accumulate cells resistant to the antibiotic rifampicin. We show here that the accumulation of rifampicin resistant mutants (RifR) in biofilms is not equable but rather is a local event, suggesting that the growth of a few locally emerged mutants is responsible for this. Competition assays demonstrated that, compared to wild-type bacteria, the isolated RifR mutants have a growth advantage in biofilms, but not in planktonic culture. To gain insight into the mechanism of the growth advantage, we tested the involvement of the two-component systems (TCS) that sense and respond to environmental changes. We found that a deletion of SrrAB or NreBC has a drastic effect on the growth advantage of RifR mutants, suggesting the importance of oxygen/respiration responses. All six of the RifR isolates tested showed increased resistance to at least one of the common stresses found in the biofilm environment (i.e., oxidative, nitric acid, and organic acid stress). The RifR mutants also had a
Hospital-acquired infections caused by enterococci have increased dramatically since the 1970s. Many nosocomial enterococcal bloodstream infections are associated with medical devices such as central venous catheters. The ability to form biofilm on medical devices is a potential virulence trait that may allow enterococci to cause infections in the expanding population of patients managed with such devices. In this study, the hypothesis that increased ability to form biofilm in vitro is associated with medical-device-related infection in vivo was tested. A microplate assay was employed to assess biofilm-forming characteristics of enterococci in 0.9 % (w/v) sodium chloride, an oligotrophic environment, and BHI, a nutrient-rich environment. Results were compared in isolates from different sources of infection. One hundred and nine enterococcal bloodstream isolates were assayed. Biofilm formation on microplates was demonstrated by all Enterococcus faecalis isolates and 16/38 (42 %) Enterococcus faecium
This resistance is adaptive in that it depends on the biofilm growth state and although many explanations have been provided to explain it, it is likely that changes in gene and/or protein expression in the biofilm state explain why organisms become resistant.. Intriguingly despite this problem, not a single antibiotic has been developed for treating biofilms. We have started to address this using as templates the cationic host defence (antimicrobial) peptides, which are produced by virtually all organisms as a major part of their innate defences against infection. They are a key component of innate immunity and have multiple mechanisms that enable them to deal with infections and inflammation, including selective modulation of innate immunity, activity against bacterial biofilms (the cause of 65% of all human infections) and direct antimicrobial activity. We made the breakthrough observation that human peptide LL-37 was able to inhibit Pseudomonas aeruginosa biofilms at one sixteenth of its MIC ...
Carbon removal strategies have gained popularity in the mitigation of biofouling in water reuse processes, but current biofilm-monitoring practices based on organic-carbon concentrations may not provide an accurate representation of the in situ biofilm problem. This study evaluated a submerged microtiter plate assay for direct and rapid monitoring of biofilm formation by subjecting the plates to a continuous flow of either secondary effluent (SE) or biofilter-treated secondary effluent (BF). This method was very robust, based on a high correlation (R2 = 0.92) between the biomass (given by the A600 in the microtiter plate assay) and the biovolume (determined from independent biofilms developed on glass slides under identical conditions) measurements, and revealed that the biomasses in BF biofilms were consistently lower than those in SE biofilms. The influence of the organic-carbon content on the biofilm community composition and succession was further evaluated using molecular tools. Terminal ...
Methods for treating patients in which damaged tissue or an indwelling prosthetic device or catheter has a bacterial biofilm growing thereon, to at least partially disrupt said biofilm, by administering at least one antibacterial enzyme that is lethal or damaging to the biofilm-forming bacteria in an amount that is effective to at least partially disrupt the biofilm upon contact therewith. Methods for prophylactically treating a patient, and methods for disinfecting or sterilizing a surface ex-vivo to remove a biofilm or prevent biofilm growth are also disclosed, as well as implantable articles susceptible to biofilm growth to which a prophylactic coating of an antibacterial enzyme has been applied.
We investigated the effects of pharmaceuticals and pesticides detected in a Mediterranean river, on fluvial biofilms by translocation experiments performed under controlled conditions. Water was sampled from three sites along a pollution gradient. Biofilms grown in mesocosms containing relatively clean water were translocated to heavily polluted water. Several biofilm descriptors were measured before and after translocations. Fifty-seven pharmaceuticals and sixteen pesticides compounds were detected in river waters. The translocation from less to more polluted site was the most effective. Autotrophic biomass and peptidase increased while phosphatase and photosynthetic efficiency decreased. Multivariate analysis revealed that analgesics and anti-inflammatories significantly affected biofilm responses. Ibuprofen and paracetamol were associated with negative effects on photosynthesis, and with the decrease of the green algae/cyanobacteria ratio, while diclofenac was associated with phosphatase ...
The flow cell biofilm system is an important and widely used tool for the in vitro cultivation and evaluation of bacterial biofilms under hydrodynamic conditions of flow. This paper provides an introduction to the background and use of such systems, accompanied by a detailed guide to the assembly of the apparatus including the description of new modifications which enhance its performance. As such, this is an essential guide for the novice biofilm researcher as well as providing valuable trouble-shooting techniques for even the most experienced laboratories. The adoption of a common and reliable methodology amongst researchers would enable findings to be shared and replicated amongst the biofilm research community, with the overall aim of advancing understanding and management of these complex and widespread bacterial communities.. ...
Biofilms are structurally, phenotypically, and compositionally diverse bacterial communities. Biofilm phenotypes observable by eye are often the result of complex interactions and interconnected chemical, physical, and genetic processes. Quantitative methods of assessing single-cell and population level behaviors tease out some of these intermediating phenomena and identify latent phenotypes. Developments in new quantitative techniques include new genetic tools, in situ chemical sensors, imaging technologies, microfabricated growth environments, population modeling techniques, and spectroscopic and mass spectrometry. These methods have all contributed to recent advances in the understanding of the factors determining bacterial behavior and function within biofilms.In this Research Topic, we aim to highlight groundbreaking work in the development and/or application of quantitative analysis methods to bacterial biofilms, with a focus on those studies resulting in the discovery of new phenomena regulating
The feedback between hydrodynamic flow conditions and biofilm spatial architecture drives competition in P. aeruginosa biofilms, and can explain variation in biofilm production observed among bacteria in natural environments.
Amanda Fuchs investigates the interactions between bacterial biofilms and human macrophages, a type of immune cell. Bacterial biofilms consist of densely packed communities of microbial cells that grow on living or inert surfaces. Biofilms are more resistant to antibiotic treatment and are known to evade the immune system. Bacteria residing within chronic wounds, such as diabetic foot ulcers, often form biofilms and have been shown to cause a significant delay in the healing time and closure of wounds due to excessive inflammation. A macrophage is a type of white blood cell found in most bodily tissues, where they survey the area for foreign substances, microbes and cellular debris. It is speculated that macrophages are primarily responsible for the resolution of inflammation in wounds. Fuchs is studying the metabolites and metabolic pathways involved in the interactions between Pseudomonas aeruginosa biofilms and human macrophages to gain insights into the cellular mechanisms contributing to ...
ePIC (electronic Publication Information Center) is the official repository for publications and presentations of Alfred Wegener Institute for Polar and Marine Research (AWI)
Platelets Enhance Biofilm Formation and Resistance of Endocarditis-Inducing Streptococci on the Injured Heart Valve. Chiau-Jing Jung; Chiou-Yueh Yeh; Chia-Tung Shun; Ron-Bin Hsu; Hung-Wei Cheng; Chi-Shuan Lin; Jean-San Chia // Journal of Infectious Diseases;4/1/2012, Vol. 205 Issue 7, p1066 Infective endocarditis is a typical biofilm-associated infectious disease frequently caused by commensal streptococci, but the contribution of host factors in biofilm formation is unclear. We found that platelets are essential for in vitro biofilm formation by Streptococcus mutans or... ...
FIG. 2. Mature in vivo biofilm formation during model development. Scanning electron micrographs of C. albicans biofilms adherent to the intraluminal surface of catheters showing no difference in biofilm architecture at 7 days postinfection (magnification, ×6,500) (A) and 3 days postinfection (magnification, ×2,500) (B) are shown. ...
Mycobacterium tuberculosis (Mtb) forms biofilms harbouring antibiotic-tolerant bacilli in vitro, but the factors that induce biofilm formation and the nature of the extracellular material that holds the cells together are poorly understood. Here we show that intracellular thiol reductive stress (TRS) induces formation of Mtb biofilms in vitro, which harbour drug-tolerant but metabolically active bacteria with unchanged levels of ATP/ADP, NAD(+)/NADH and NADP(+)/NADPH. The development of these biofilms requires DNA, RNA and protein synthesis. Transcriptional analysis suggests that Mtb modulates only ∼7% of its genes for survival in biofilms. In addition to proteins, lipids and DNA, the extracellular material in these biofilms is primarily composed of polysaccharides, with cellulose being a key component. Our results contribute to a better understanding of the mechanisms underlying Mtb biofilm formation, although the clinical relevance of Mtb biofilms in human tuberculosis remains ...
This work concerns the development of a flat plate perfusion model to study biofilms derived from human tongue biota. The model has been derived from a previous sorbarod model, via a flat plate model (used to study wound organisms), to the model described in this thesis. The specific technical objectives were; 1. To measure biofilm pH in real time, 2. To extend VOC analysis by SIFT-MS to six biofilms in parallel and 3. To enable photodynamic interventions and optical monitoring of bioluminescent and non-bioluminescent organisms. The specific scientific objectives were; 1. To validate the model by comparison of in vivo and in vitro case studies, 2. To characterise the in vivo biofilm ecology and compare with ecology in vitro, 3. To compare existing and novel anti-malodour preparations and biofilm disrupting agents (including D-amino acids) and 4. To assess and aid the development of a novel handheld surface plasmon resonance based device for measuring oral volatile compounds ...
Buy Microbial Biofilms (9780521542128): NHBS - Edited By: Hilary M Lappin-Scott and J William Costerton, Cambridge University Press
Many microbes grow in surface-associated, multicellular communities known as biofilms. These biofilms are the most abundant mode of microbial life outside the ocean.
Pseudomonas aeruginosa is an opportunistic human pathogen that forms biofilm infections in a wide variety of contexts. Biofilms initiate when bacteria attach to a surface, which triggers changes in gene expression leading to the biofilm phenotype. We have previously shown, for the P. aeruginosa lab strain PAO1, that the self-produced polymer Psl is the most dominant adhesive for attachment to the surface but that another self-produced polymer, Pel, controls the geometry of attachment of these rod-shaped bacteriastrains that make Psl but not Pel are permanently attached to the surface but adhere at only one end (tilting up off the surface), whereas wild-type bacteria that make both Psl and Pel are permanently attached and lie down flat with very little or no tilting (Cooley et al 2013 Soft Matter 9 38716). Here we show that the change in attachment geometry reflects a change in the distribution of Psl on the bacterial cell surface. Bacteria that make Psl and Pel have Psl evenly coating the ...
immune Uncategorized Bosutinib, LDHAL6A antibody Bacterial biofilm has been shown to play a role in delaying wound healing of chronic wounds, a major medical problem that results in significant healthcare burden. gradually cleared from your wounds while the presence of (part of the normal mouse pores and skin flora) improved. Scabs from all unhealed wounds contained 107 study of bacterial biofilm reactions to sponsor defenses and the effects of biofilms on sponsor wound healing pathways. It may also be used to test anti-biofilm strategies the treatment of chronic wounds. spp., and [5C7] have been isolated from chronic wounds, even though the wound may not display any medical indications of localized illness. Multiple bacterial varieties, usually two to five varieties, reside concurrently on a single ulcer [7C9]. The chronicity of unhealed wounds is definitely associated with higher proportion of colonization by anaerobic bacteria and greater variety of aerobic varieties [5]. More recent studies ...
At International Conference on Emerging Contaminants (EmCon), 2016, Sidney Mermaid fellow Elena Torresi received an award for Best Student Oral Presentation for her work in the mermaid project. The committee gave this reason for the award: "This study showed the impact of biofilm thickness on the removal of several micropollutants (pharmaceuticals) in Moving Bed Biofilm Reactor (MBBR). Biofilm thickness influenced both microbial activity (nitrification and micropollutant biotransformation) as well as the microbial community. Thicker biofilms were more efficient for the removal of a major number of micropollutants and presented a higher microbial diversity compared to thinner biofilms." ...
In this study, we have begun to examine the complex interactions between two common environmental microorganisms, P.a. and A.t., in planktonic and biofilm growth modes. During exponential growth in dispersed, liquid culture, P.a. dominated A.t. because of a higher growth rate. Within biofilms grown on glass surfaces in the same defined medium, P.a. was also found to numerically dominate the population and to cover adherent A.t., a process requiring motility via flagella and type IV pili. Quorum-sensing mutants displayed an impaired competition phenotype in both liquid and flow-cell biofilm cultures. Motility was found to be important for both species in coculture biofilms. Although A.t. was outnumbered after the rapid-growth phase in both growth formats, its population remained viable, leading to a period of coexistence of these two microbes.. Quorum sensing appears to allow P.a. to achieve a slightly higher growth yield in liquid cocultures. Several quorum-sensing-regulated secreted functions ...
Since the serendipitous discovery of the first antibiotic, the wonder drug penicillin by Alexander Fleming, bacteria over time have slowly developed resistance to most antibiotics through three well coordinated processes. Firstly, bacteria can evolve their genetic makeup to become resistant against antibiotics; Secondly, bacteria can relay the modified antibiotic resistant genes to other bacteria and other species through a process called conjugation. Thirdly, bacteria quickly give up their individuality to become a part of a team to form surface attached multicellular communities known as biofilms. Bacteria residing within biofilms are protected by a layer of slime which renders the bacteria one thousand fold more resistant to the action of antibiotics. Nearly eighty percent of bacterial infections are associated with biofilms and therefore understandably, biofilms are considered as one of the seven most important health issues facing mankind in the 21st century. The focus of research work presented
Staphylococcus aureus, a major nosocomial pathogen, causes a wide variety of infections, from simple abscesses to fatal sepsis, plus toxinoses, such as food poisoning and toxic shock syndrome. S. aureus produces and secretes thirty or more specific pathogenicity factors, including superantigen toxins, hemolytic cytotoxins, tissue-component-degrading enzymes, and surface proteins, that interfere with host defenses. Its pathogenic versatility is compounded by its ability to form biofilms and develop resistance to new antibiotics almost as fast as they are introduced. Research in my lab centres on 2 main themes: 1. Staphylococcal biofilm formation. Biofilms are communities of microorganisms, which develop on surfaces in natural and artificial environments. In medical settings, biofilms are found in association with catheters and prosthetic devices and may constitute an important source of nosocomial infections. Bacterial biofilms display specific biological properties that distinguish them from ...
Research and innovation in recent years has led to a paradigm shift in the bioengineering community regarding biofilms. Rather than focusing on their negative impact in disease and materials fouling, we, and other groups, are re-conceptualizing biofilms as an engineering platform. Our group has developed a novel strategy for producing rationally designed biocatalytic surfaces based on Biofilm Integrated Nanofiber Display (BIND). BIND uses the E. coli curli system to create extracellular functional nanofiber networks. In this work, we used protein capture tags displayed on curli fibers to transform biofilms into biocatalytic surfaces. We wanted to address the issues that currently hinder the applicability of surface displayed enzyme catalysts - although genetically engineered and scalable, the enzymes displayed through genetic fusion to cell surface proteins are often improperly folded and have reduced activity. Our catalytic-BIND platform takes advantage of the scalability of biofilms and ...
Biosignal s anti-biofilm technology is based on a discovery that the eastern Australian seaweed Delisea pulchra produces natural furanones that disable bacterias ability to colonise
Red and green autofluorescence have been observed from dental plaque after excitation by blue light. It has been suggested that this red fluorescence is related to caries and the cariogenic potential of dental plaque. Recently, it was suggested that red fluorescence may be related to gingivitis. Little is known about green fluorescence from biofilms. Therefore, we assessed the dynamics of red and green fluorescence in real-time during biofilm formation. In addition, the fluorescence patterns of biofilm formed from saliva of eight different donors are described under simulated gingivitis and caries conditions. Biofilm formation was analysed for 12 hours under flow conditions in a microfluidic BioFlux flow system with high performance microscopy using a camera to allow live cell imaging. For fluorescence images dedicated excitation and emission filters were used. Both green and red fluorescence were linearly related with the total biomass of the biofilms. All biofilms displayed to some extent ...
At least 78% of chronic wounds have been found to contain a biofilm.. These communities of bacteria attach to the wound bed or each other and are protected by a matrix. Their presence in chronic wounds are linked to delayed wound healing.. Biofilms provide a complex treatment challenge to wound care clinicians because they are tolerant to antimicrobial treatments and the host immune response.. At Smith & Nephew we are leading a pioneering initiative to provide education and practical solutions to this problem in chronic wounds. The Wound Biofilm Expert Panel was formed in late 2015 and it has developed consensus recommendations across the themes of understanding and diagnosing biofilms, and treatment of biofilms. This will provide a strong platform towards a paradigm shift in biofilm treatment of chronic wounds.. Prof Gregory Schultz, University of Florida and chair of the panel stated "…this document will have a tremendous impact helping both researchers and clinicians understand biofilms, ...
What biofilms feed on is just as varied. Certain biofilms even thrive on petroleum oil. Interestingly, the capacity of this kind of biofilm to gobble oil has both a bad and a good side. Oil-eating biofilms can grow in and clog an oil pipeline; they can also be used to clean up an oil spill. ...
In aqueous systems, microbial cells are found as both planktonic (floating) cells and sessile (attached) cells on surfaces. For generations, microbiologists studied microbial cells only in their planktonic state or grown in laboratories as single-species colonies on nutrient media. Todays antibiotics, for example, were developed by testing their efficacy on cells in suspension or grown on agar. The research of recent years has revealed, however, that bacteria preferentially attach to a variety of surfaces, and that bacterial communities exhibit properties, behaviors and survival strategies that far exceed their capabilities as individual bacteria. For instance, microbial biofilms are naturally tolerant of antibiotic doses up to 1,000 times greater than doses that kill planktonic bacteria.. Aggregations of microbes were noticed long before people had the tools to study them in detail. In 1684 Anthony van Leewenhoek remarked on the vast accumulation of microorganisms in dental plaque in a ...
Microbial ecology is revealing the vast diversity of strains and species that coexist in many environments, ranging from free-living communities to the symbionts that compose the human microbiome. In parallel, there is growing evidence of the importance of cooperative phenotypes for the growth and behavior of microbial groups. Here we ask: How does the presence of multiple species affect the evolution of cooperative secretions? We use a computer simulation of spatially structured cellular groups that captures key features of their biology and physical environment. When nutrient competition is strong, we find that the addition of new species can inhibit cooperation by eradicating secreting strains before they can become established. When nutrients are abundant and many species mix in one environment, however, our model predicts that secretor strains of any one species will be surrounded by other species. This social insulation protects secretors from competition with nonsecretors of the same species
My primary research probes the role of structure in early biofilm formation. Using optical tweezers to manipulate cells, we are able to control spatial structure with single-cell precision and observe structure-specific effects during subsequent biofilm growth. My secondary research investigates mechanosensing in surface-associated cells of the bacterium Pseudomonas aeruginosa. Using fluorescent reporters and high-resolution confocal scanning laser microscopy, we can quantify the surface-sensing signaling of cells on various substrates or subjected to various external forces.. ...
Definition, Description and Medical Implications of Biofilms What are biofilms and how to they resist normal treatments for sinusitis such as antibiotics? Biofilms are composed of microbal communities that are attached to an environmental surface. The microorganisms usually encase themselves in an extra-cellular polysaccharide or slime matrix. In other words, biofilms are a collection of bacteria and other microbes that encase themselves in a sort of slime. It is apparently the slime material that protects the bacteria from being destroyed by antibiotics, for example. Biofilms have been shown to play a major part in other medical conditions involving chronic infections, such as cystic fibrosis, Legionnaires Disease, and otitis media, the most common type of acute ear infection in children in the U.S., among others. In addition, they can also form on medical implanted products such as stents, implants, catheters, and other devices. They appear to destroy cilia when present in Sinusitis ...
Quick Link Final Program Meeting Location Hyatt Regency Chicago151 East Wacker DriveChicago, IL Biofilms, surface-associated microbial communiti...
Link to Pubmed [PMID] - 31098293. NPJ Biofilms Microbiomes 2019;5:14. is a major cause of nosocomial infections. Bacterial persistence in the gut is responsible for infection relapse; sporulation and other unidentified mechanisms contribute to this process. Intestinal bile salts cholate and deoxycholate stimulate spore germination, while deoxycholate kills vegetative cells. Here, we report that sub-lethal concentrations of deoxycholate stimulate biofilm formation, which protects . from antimicrobial compounds. The biofilm matrix is composed of extracellular DNA and proteinaceous factors that promote biofilm stability. Transcriptomic analysis indicates that deoxycholate induces metabolic pathways and cell envelope reorganization, and represses toxin and spore production. In support of the transcriptomic analysis, we show that global metabolic regulators and an uncharacterized lipoprotein contribute to deoxycholate-induced biofilm formation. Finally, enhances biofilm formation of by converting ...
The Shrout Research Group investigates "sociomicrobiology" and community actions of bacteria that are important to medicine and the environment. Much of our work researches the development of bacterial biofilms.. Biofilms are surface-associated communities of bacteria. Surprisingly, very few factors that regulate biofilm growth on various surfaces such as human tissue, medical implants, water intake pipes, teeth, soil particles, or even other microorganisms are understood even for "simple" bacteria. We use an interdisciplinary research approach to understand how physical and chemical environmental cues influence biological behavior of biofilms.. Relatedly, our group researches the motility of bacteria on surfaces. Many bacteria, such as the organism Pseudomonas aeruginosa, are capable of controlling their surface motility as an initial step in biofilm development. We are working to understand how bacteria orchestrate their response(s).. ...
ABSTRACT: Biofilms are a serious problem in breweries and beverage bottling plants. Biofilms are associations of various species of bacteria, yeasts, and molds. In contrast to planktonic microorganisms, a layer of extracellular substances protects the cells in biofilms, which makes them much more resistant against cleaning and disinfection solutions. Most biofilm starter organisms, such as acetic acid bacteria (AAB) or Enterobacteriaceae, are considered to not be product spoiling. For this reason, most breweries do not use cultivation media that are designed to detect them. Therefore a biofilm will not be detected until product spoiling organisms colonize it. Additionally, established cultivation media methods such as the NBB-B-AM swab test, according to Prof. Back (1994), do not specify the associated organisms. The composition of the associated organisms is very important for evaluation of the level of maturity and potential product spoiling risk of biofilms in breweries or beverage plants. ...
Bacteria love to colonize surfaces inside your body, but they have a hard time getting past your rugged, salty skin. Surgeries to implant medical devices often give such bacteria the opportunity needed to gain entry into ...
Evaluation of full scale plants show that both fixed bed media and moving bed media can work in IFAS systems, provided that the design and operating conditions account for the differences between the two types of media. With respect to MLSS, the operating conditions of fixed bed and moving bed media systems showed that while fixed bed systems tend to operate at MLSS levels of 3000 to 6000 mg/L, moving bed systems are typically operated at less than 3000 mg/L to reduce the formation of foam in the basin and entrapment at the screens used to retain the media. The two types of media have very different biofilm thickness and specific surface areas. The equations to compute biofilm thickness were modified to account for the effect of type of aeration and the hydrodynamic forces generated, the type of media surface, and the shape of the media. Once these corrections were made, the computations showed that the thicker biofilm in fixed bed media denitrified 25 to 50% of ammonia nitrified in the biofilm ...
species isolated from central venous catheters (CVC). Our results showed that the 41 strong and moderate-biofilm-producing isolates presented a higher MBEC/MIC ratio for vancomycin than the 24 weak-biofilm-producing isolates, illustrating the importance of biofilm production ability and the difficulty in treating biofilm-related infections. The MBEC was significantly higher in moderate-biofilm-producing isolates than in weak-biofilm-producing isolates (p < 0.001) and in strong-biofilm-producing isolates than in weak-biofilm-producing isolates (p = 0.001). The correlation between the MIC and the MBEC was poor. Based on our results, we recommend that bacterial biofilms be suspected in all cases of CVC infection ...
Overview. Bacterial adhesion and subsequent colonization of surfaces are the first steps toward forming biofilms, which are a major concern for implanted medical devices and in many diseases. Biofilms are resistant to innate host defences, mechanical removal and antibiotic treatments. It is therefore important to understand the physiological environment and mechanisms that lead to the spread of bacteria. Experimental conditions of biofilm formation on cardiovascular stents, tubing, different surfaces and in the intestines can easily be studied using Cellixs microfluidic pumps and biochips. The dimensions of the biochips facilitate both high and low shear stress conditions. The microcapillary walls of Cellixs biochips may be pre-coated with proteins of interest to promote adhesion and culture of biofilms under different shear stress conditions. Once the biofilm is cultured, it is then possible to flow different substances (e.g. antibiotics) over the biofilm to investigate detachment. There are ...
The roles of different extracellular polymeric substance (EPS) fractions in microbial communities, such as periphytic biofilms, are unclear. In this study, three EPS fractions extracted from a periphytic biofilm were employed to investigate their ability to affect Fe2O3 nanoparticle (IONP) toxicity. The addi
Research groupsCell biology and Biotechnology Mechanisms of gene regulation and bacterial biofilm development Dr Fernando Govantes. ..
ABSTRACT: A new experiment was developed in which the growth rate of Escherichia coli bacterial colonies (biofilms) were studied under the effect of different flow velocities of growth medium. The phases of the experiment consisted of: i) the creation of the chip (microfabrication), ii) preparation of the bacteria inoculum and iii) the monitoring of their growth. All of the three phases exhibited difficulties, in which the sealing and the air bubbles can be singled out. Despite these problems, the simulation of the bacterial growth under the velocities of 0.02, 0.03, 0.04, 0.05, 0.07 and 0.10 mL/ min were recorded once and the bacterial growth of the 0.02, 0.04 and 0.10 mL/min chips were analyzed by measuring the density of the biofilms observing the grey scale throughout the trial and the statistical analysis in the last image that was recorded. This gave a general idea of what could be expected: high biofilm growth rates at low flows and low growth rate at large velocities. It was also noted ...
An in vitro assay is presented for culturing staphylococcal biofilms and biofilms of nonmotile Gram‐positive bacteria under static conditions in microtiter assay plates, and for the quantification of biofilm growth, using a simple staining procedure that measures amounts of bacterial cells and extracellular matrix
PAN, Xiangliang et al. A comparison of five extraction methods for extracellular polymeric substances (EPS) from biofilm by using three-dimensional excitation-emission matrix (3DEEM) fluorescence spectroscopy. Water SA [online]. 2010, vol.36, n.1, pp.111-116. ISSN 1816-7950.. 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 significant modification of the composition of EPS. Extraction with EDTA or extraction with formaldehyde plus NaOH increased yield by about 1 order of magnitude compared with other methods. However, the protein and polysaccharide content in EPS prepared with EDTA or formaldehyde plus NaOH were low. Two fluorescence peaks belonging to protein-like peaks and 2 fluorescence peaks belonging to humic acid-like ...
A theory for analysis and prediction of spatial and temporal patterns of gene and protein expression within microbial biofilms is derived. The theory integrates phenomena of solute reaction and diffusion, microbial growth, mRNA or protein synthesis, biomass advection, and gene transcript or protein turnover. Case studies illustrate the capacity of the theory to simulate heterogeneous spatial patterns and predict microbial activities in biofilms that are qualitatively different from those of planktonic cells. Specific scenarios analyzed include an inducible GFP or fluorescent protein reporter, a denitrification gene repressed by oxygen, an acid stress response gene, and a quorum sensing circuit. It is shown that the patterns of activity revealed by inducible stable fluorescent proteins or reporter unstable proteins overestimate the region of activity. This is due to advective spreading and finite protein turnover rates. In the cases of a gene induced by either limitation for a metabolic substrate or
The present review will explore the most relevant findings on marine microbial biofilm, with particular attention towards its polysaccharide fraction, namely exopolysaccharide (EPS). EPSs of microbial origin are ubiquitous in nature, possess unique properties and can be isolated from the bacteria living in a variety of habitats, including fresh water or marine environments, extreme environments or different soil ecosystems. These biopolymers have many application in the field of biotechnology. Several studies showed that the biofilm formation is closely related to quorum sensing (QS) systems, which is a mechanism relying on the production of small molecules defined as "autoinducers" that bacteria release in the surrounding environment where they accumulate. In this review, the involvement of microbial chemical communication, by QS mechanism, in the formation of marine biofilm will also be discussed.. ...