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1

Biofilms: A microbial home  

PubMed Central

Microbial biofilms are mainly implicated in etiopathogenesis of caries and periodontal disease. Owing to its properties, these pose great challenges. Continuous and regular disruption of these biofilms is imperative for prevention and management of oral diseases. This essay provides a detailed insight into properties, mechanisms of etiopathogenesis, detection and removal of these microbial biofilms.

Chandki, Rita; Banthia, Priyank; Banthia, Ruchi

2011-01-01

2

Hypothesized origin of microbial life in a prebiotic gel and the transition to a living biofilm and microbial mats.  

PubMed

This article hypothesizes that the origin of the first microbial cell(s) occurred as a series of increasing levels of organization within a prebiotic gel attached to a mineral surface, which made the transition to a biofilm composed of the first cell(s) capable of growth and division. A gel microenvironment attached to a surface for the origin of life, and subsequent living cells offers numerous advantages. These include acting as a water and nutrient trap on a surface, physical protection as well as protection from UV radiation. The prebiotic gel and the living biofilm contained the necessary water, does not impede diffusion of molecules including gases, provides a structured gel microscopic location for biochemical interactions and polymerisation reactions, where the necessary molecules for life need to be present and not limiting. The composition of the first gel environment may have been an oily-water mixture (or the interface between an oily-water mixture) of microscopic dimensions, but large enough for the organization of the first cell(s). The living biofilm then made the evolutionary transition to a microbial mat. PMID:21513895

Trevors, Jack T

2011-04-01

3

Overview of microbial biofilms  

Microsoft Academic Search

As the success of this two-issue special section of the Journal of Industrial Microbiology attests, the study of microbial biofilms is truly burgeoning as the uniqueness and the importance of this mode of growth is increasingly recognized. Because of its universality the biofilm concept impacts virtually all of the subdivisions of Microbiology (including Medical, Dental, Agricultural, Industrial and Environmental) and

JW Costerton

1995-01-01

4

Manipulatiaon of Biofilm Microbial Ecology  

SciTech Connect

The Biofilm mode of growth provides such significant advantages to the members of the consortium that most organisms in important habitats are found in biofilms. The study of factors that allow manipulation of biofilm microbes in the biofilm growth state requires that reproducible biofilms by generated. The most effective monitoring of biofilm formation, succession and desquamation is with on-line monitoring of microbial biofilms with flowcell for direct observation. The biofilm growth state incorporates a second important factor, the heterogeneity in the distribution in time and space of the component members of the biofilm consortium. This heterogeneity is reflected not only in the cellular distribution but in the metabolic activity within a population of cells. Activity and cellular distribution can be mapped in four dimensions with confocal microscopy, and function can be ascertained by genetically manipulated reporter functions for specific genes or by vital stains. The methodology for understanding the microbial ecology of biofilms is now much more readily available and the capacity to manipulate biofilms is becoming an important feature of biotechnology.

Burkhalter, R.; Macnaughton, S.J.; Palmer, R.J.; Smith, C.A.; Whitaker, K.W.; White, D.C.; Zinn, M.; kirkegaard, R.

1998-08-09

5

Manipulation of Biofilm Microbial Ecology  

SciTech Connect

The biofilm mode of growth provides such significant advantages to the members of the consortium that most organisms in important habitats are found in biofilms. The study of factors that allow manipulation of biofilm microbes in the biofilm growth state requires that reproducible biofilms be generated. The most effective monitoring of biofilm formation, succession and desaturation is with on-line monitoring of microbial biofilms with flowcell for direct observation. The biofilm growth state incorporates a second important factor, the heterogeneity in distribution in time and space of the component members of the biofilm consortium. This heterogeneity is reflected not only in the cellular distribution but in the metabolic activity within a population of cells. Activity and cellular distribution can be mapped in four dimensions with confocal microscopy, and function can be ascertained by genetically manipulated reporter functions for specific genes or by vital stains. The methodology for understanding the microbial ecology of biofilms is now much more readily available and the capacity to manipulate biofilms is becoming an important feature of biotechnology.

White, D.C.; Palmer, R.J., Jr.; Zinn, M.; Smith, C.A.; Burkhalter, R.; Macnaughton, S.J.; Whitaker, K.W.; Kirkegaard, R.D.

1998-08-15

6

Microbial biofilm studies of the Environmental Control and Life Support System water recovery test for Space Station Freedom  

NASA Technical Reports Server (NTRS)

Analysis of biofilm accumulation, studies of iodine disinfection of biofilm, and the potential for microbially influenced corrosion in the water recovery test (WRT) are presented. The analysis of WRT components showed the presence of biofilms and organic deposits in selected tubing. Water samples from the WRT contained sulfate-reducing and acid-producing organisms implicated in corrosion processes. Corrosion of an aluminum alloy was accelerated in the presence of these water samples, but stainless steel corrosion rates were not accelerated.

Obenhuber, D. C.; Huff, T. L.; Rodgers, E. B.

1991-01-01

7

Microbial biofilm studies of the environmental control and life support system water recovery test for Space Station Freedom  

NASA Technical Reports Server (NTRS)

NASA is developing a water recovery system (WRS) for Space Station Freedom to reclaim human waste water for reuse by astronauts as hygiene or potable water. A water recovery test (WRT) currently in progress investigates the performance of a prototype of the WRS. Analysis of biofilm accumulation, the potential for microbially influenced corrosion (MIC) in the WRT, and studies of iodine disinfection of biofilm are reported. Analysis of WRT components indicated the presence of organic deposits and biofilms in selected tubing. Water samples for the WRT contained acid-producing and sulfate-reducing organisms implicated in corrosion processes. Corrosion of an aluminum alloy was accelerated in the presence of these water samples; however, stainless steel corrosion rates were not accelerated. Biofilm iodine sensitivity tests using an experimental laboratory scale recycled water system containing a microbial check valve (MCV) demonstrated that an iodine concentration of 1 to 2 mg/L was ineffective in eliminating microbial biofilm. For complete disinfection, an initial concentration of 16 mg/L was required, which was gradually reduced by the MCV over 4 to 8 hours to 1 to 2 mg/L. This treatment may be useful in controlling biofilm formation.

Rodgers, E. B.; Obenhuber, D. C.; Huff, T. L.

1992-01-01

8

Cooperation and conflict in microbial biofilms  

PubMed Central

Biofilms, in which cells attach to surfaces and secrete slime (polymeric substances), are central to microbial life. Biofilms are often thought to require high levels of cooperation because extracellular polymeric substances are a shared resource produced by one cell that can be used by others. Here we examine this hypothesis by using a detailed individual-based simulation of a biofilm to investigate the outcome of evolutionary competitions between strains that differ in their level of polymer production. Our model includes a biochemical description of the carbon fluxes for growth and polymer production, and it explicitly calculates diffusion–reaction effects and the resulting solute gradients in the biofilm. An emergent property of these simple but realistic mechanistic assumptions is a strong evolutionary advantage to extracellular polymer production. Polymer secretion is altruistic to cells above a focal cell: it pushes later generations in their lineage up and out into better oxygen conditions, but it harms others; polymer production suffocates neighboring nonpolymer producers. This property, analogous to vertical growth in plants, suggests that polymer secretion provides a strong competitive advantage to cell lineages within mixed-genotype biofilms: global cooperation is not required. Our model fundamentally changes how biofilms are expected to respond to changing social conditions; the presence of multiple strains in a biofilm should promote rather than inhibit polymer secretion.

Xavier, Joao B.; Foster, Kevin R.

2007-01-01

9

Molecular Survey of Concrete Biofilm Microbial Communities  

EPA Science Inventory

Although several studies have shown that bacteria can deteriorate concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different microbial communities associated with concrete biofilms using 16S rRNA g...

10

Microbial biofilms in intertidal systems: an overview  

NASA Astrophysics Data System (ADS)

Intertidal marine systems are highly dynamic systems which are characterized by periodic fluctuations in environmental parameters. Microbial processes play critical roles in the remineralization of nutrients and primary production in intertidal systems. Many of the geochemical and biological processes which are mediated by microorganisms occur within microenvironments which can be measured over micrometer spatial scales. These processes are localized by cells within a matrix of extracellular polymeric secretions (EPS), collectively called a "microbial biofilm". Recent examinations of intertidal systems by a range of investigators using new approaches show an abundance of biofilm communities. The purpose of this overview is to examine recent information concerning the roles of microbial biofilms in intertidal systems. The microbial biofilm is a common adaptation of natural bacteria and other microorganisms. In the fluctuating environments of intertidal systems, biofilms form protective microenvironments and may structure a range of microbial processes. The EPS matrix of biofilm forms sticky coatings on individual sediment particles and detrital surfaces, which act as a stabilizing anchor to buffer cells and their extracellular processes during the frequent physical stresses (e.g., changes in salinity and temperature, UV irradiation, dessication). EPS is an operational definition designed to encompass a range of large microbially-secreted molecules having widely varying physical and chemical properties, and a range of biological roles. Examinations of EPS using Raman and Fourier-transform infared spectroscopy, and atomic-force microscopy suggest that some EPS gels possess physical and chemical properties which may hasten the development of sharp geochemical gradients, and contribute a protective effect to cells. Biofilm polymers act as a sorptive sponge which binds and concentrates organic molecules and ions close to cells. Concurrently, the EPS appear to localize extracellular enzyme activities of bacteria, and hence contribute to the efficient biomineralization of organics. At larger spatial scales, the copious secretion of specific types of EPS by diatoms on the surfaces of intertidal mudflats may stabilize sediments against resuspension. Biofilms exert important roles in environmental- and public health processes occurring within intertidal systems. The sorptive properties of EPS effectively chelate toxic metals and other contaminants, which then act as an efficient trophic-transfer vehicle for the entry of contaminants into food webs. In the water column, biofilm microenvironments in suspended flocs may form a stabilizing refugia that enhances the survival and propagation of pathogenic (i.e., disease-causing) bacteria entering coastal waters from terrestrial and freshwater sources. The EPS matrix affords microbial cells a tremendous potential for resiliency during periods of stress, and may enhance the overall physiological activities of bacteria. It is emphasized here that the influences of small-scale microbial biofilms must be addressed in understanding larger-scale processes within intertidal systems.

Decho, Alan W.

2000-07-01

11

Microbial Biofilms: from Ecology to Molecular Genetics  

PubMed Central

Biofilms are complex communities of microorganisms attached to surfaces or associated with interfaces. Despite the focus of modern microbiology research on pure culture, planktonic (free-swimming) bacteria, it is now widely recognized that most bacteria found in natural, clinical, and industrial settings persist in association with surfaces. Furthermore, these microbial communities are often composed of multiple species that interact with each other and their environment. The determination of biofilm architecture, particularly the spatial arrangement of microcolonies (clusters of cells) relative to one another, has profound implications for the function of these complex communities. Numerous new experimental approaches and methodologies have been developed in order to explore metabolic interactions, phylogenetic groupings, and competition among members of the biofilm. To complement this broad view of biofilm ecology, individual organisms have been studied using molecular genetics in order to identify the genes required for biofilm development and to dissect the regulatory pathways that control the plankton-to-biofilm transition. These molecular genetic studies have led to the emergence of the concept of biofilm formation as a novel system for the study of bacterial development. The recent explosion in the field of biofilm research has led to exciting progress in the development of new technologies for studying these communities, advanced our understanding of the ecological significance of surface-attached bacteria, and provided new insights into the molecular genetic basis of biofilm development.

Davey, Mary Ellen; O'toole, George A.

2000-01-01

12

Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community  

PubMed Central

Background Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy). Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers). In the Río Tinto (Spain), brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum) and Acidithiobacillus ferrooxidans are abundant. These microorganisms play a critical role in bioleaching processes for industrial (biominery) and environmental applications (acid mine drainage, bioremediation). The aim of this study was to investigate the physiological differences between the free living (planktonic) and the sessile (biofilm associated) lifestyles of Leptospirillum spp. as part of its natural extremely acidophilic community. Results Total RNA extracted from environmental samples was used to determine the composition of the metabolically active members of the microbial community and then to compare the biofilm and planktonic environmental transcriptomes by hybridizing to a genomic microarray of L. ferrooxidans. Genes up-regulated in the filamentous biofilm are involved in cellular functions related to biofilm formation and maintenance, such as: motility and quorum sensing (mqsR, cheAY, fliA, motAB), synthesis of cell wall structures (lnt, murA, murB), specific proteases (clpX/clpP), stress response chaperons (clpB, clpC, grpE-dnaKJ, groESL), etc. Additionally, genes involved in mixed acid fermentation (poxB, ackA) were up-regulated in the biofilm. This result, together with the presence of small organic acids like acetate and formate (1.36 mM and 0.06 mM respectively) in the acidic (pH 1.8) water stream, suggests that either L. ferrooxidans or other member of the microbial community are producing acetate in the acidophilic biofilm under microaerophilic conditions. Conclusions Our results indicate that the acidophilic filaments are dynamic structures in which different mechanisms for biofilm formation/dispersion are operating. Specific transcriptomic fingerprints can be inferred for both planktonic and sessile cells, having the former a more active TCA cycle, while the mixed acid fermentation process dominate in the latter. The excretion of acetate may play a relevant ecological role as a source of electron donor for heterotrophic Fe3+ reducers like some Alphaproteobacteria, Acidobacterium spp. and Sulfobacillus spp., also present in the biofilm. Additionally, acetate may have a negative effect on bioleaching by inhibiting the growth of chemolithotrophic bacteria.

2010-01-01

13

Microbial Biofilms: Persisters, Tolerance and Dosing  

NASA Astrophysics Data System (ADS)

Almost all moist surfaces are colonized by microbial biofilms. Biofilms are implicated in cross-contamination of food products, biofouling, medical implants and various human infections such as dental cavities, ulcerative colitis and chronic respiratory infections. Much of current research is focused on the recalcitrance of biofilms to typical antibiotic and antimicrobial treatments. Although the polymer component of biofilms impedes the penetration of antimicrobials through reaction-diffusion limitation, this does not explain the observed tolerance, it merely delays the action of the agent. Heterogeneities in growth-rate also slow the eradication of the bacteria since most antimicrobials are far less effective for non-growing, or slowly growing bacteria. This also does not fully describe biofilm tolerance, since heterogeneities arr primairly a result of nutrient consumption. In this investigation, we describe the formation of `persister' cells which neither grow nor die in the presence of antibiotics. We propose that the cells are of a different phenotype than typical bacterial cells and the expression of the phenotype is regulated by the growth rate and the antibiotic concentration. We describe several experiments which describe the dynamics of persister cells and which motivate a dosing protocol that calls for periodic dosing of the population. We then introduce a mathematical model, which describes the effect of such a dosing regiment and indicates that the relative dose/withdrawal times are important in determining the effectiveness of such a treatment. A reduced model is introduced and the similar behavior is demonstrated analytically.

Cogan, N. G.

2005-03-01

14

Hypersaline Microbial Systems of Sabkhas: Examples of Life's Survival in  

Microsoft Academic Search

Life and living systems need several important factors to establish themselves and to have a continued tradition. In this article the nature of the borderline situation for microbial life under heavy salt stress is analyzed and discussed using the example of biofilms and microbial mats of sabkha systems of the Red Sea. Important factors ruling such environments are described, and

Wolfgang Elisabeth Krumbein; Anna A. Gorbushina; Elisabeth Holtkamp-Tacken

2004-01-01

15

Biophysical controls on cluster dynamics and architectural differentiation of microbial biofilms in contrasting flow environments.  

PubMed

Ecology, with a traditional focus on plants and animals, seeks to understand the mechanisms underlying structure and dynamics of communities. In microbial ecology, the focus is changing from planktonic communities to attached biofilms that dominate microbial life in numerous systems. Therefore, interest in the structure and function of biofilms is on the rise. Biofilms can form reproducible physical structures (i.e. architecture) at the millimetre-scale, which are central to their functioning. However, the spatial dynamics of the clusters conferring physical structure to biofilms remains often elusive. By experimenting with complex microbial communities forming biofilms in contrasting hydrodynamic microenvironments in stream mesocosms, we show that morphogenesis results in 'ripple-like' and 'star-like' architectures--as they have also been reported from monospecies bacterial biofilms, for instance. To explore the potential contribution of demographic processes to these architectures, we propose a size-structured population model to simulate the dynamics of biofilm growth and cluster size distribution. Our findings establish that basic physical and demographic processes are key forces that shape apparently universal biofilm architectures as they occur in diverse microbial but also in single-species bacterial biofilms. PMID:23879839

Hödl, Iris; Mari, Lorenzo; Bertuzzo, Enrico; Suweis, Samir; Besemer, Katharina; Rinaldo, Andrea; Battin, Tom J

2014-03-01

16

Chitosan Coupling Makes Microbial Biofilms Susceptible to Antibiotics  

PubMed Central

Microbial biofilms, prevalent in nature and inherently resistant to both antimicrobial agents and host defenses, can cause serious problems in the chemical, medical and pharmaceutical industries. Herein we demonstrated that conjugation of an aminoglycoside antibiotic (streptomycin) to chitosan could efficiently damage established biofilms and inhibit biofilm formation. This method was suitable to eradiate biofilms formed by Gram-positive organisms, and it appeared that antibiotic contents, molecular size and positive charges of the conjugate were the key to retain this anti-biofilm activity. Mechanistic insight demonstrated chitosan conjugation rendered streptomycin more accessible into biofilms, thereby available to interact with biofilm bacteria. Thus, this work represent an innovative strategy that antibiotic covalently linked to carbohydrate carriers can overcome antibiotic resistance of microbial biofilms, and might provide a comprehensive solution to combat biofilms in industrial and medical settings.

Zhang, Amin; Mu, Haibo; Zhang, Wuxia; Cui, Guoting; Zhu, Jie; Duan, Jinyou

2013-01-01

17

Microbial biofilm formation and its consequences for the CELSS program  

NASA Technical Reports Server (NTRS)

A major goal of the Controlled Ecology Life Support System (CELSS) program is to provide reliable and efficient life support systems for long-duration space flights. A principal focus of the program is on the growth of higher plants in growth chambers. These crops should be grown without the risk of damage from microbial contamination. While it is unlikely that plant pathogens will pose a risk, there are serious hazards associated with microorganisms carried in the nutrient delivery systems and in the atmosphere of the growth chamber. Our experience in surface microbiology showed that colonization of surfaces with microorganisms is extremely rapid even when the inoculum is small. After initial colonization extensive biofilms accumulate on moist surfaces. These microbial films metabolize actively and slough off continuously to the air and water. During plant growth in the CELSS program, microbial biofilms have the potential to foul sensors and to plug nutrient delivery systems. In addition both metabolic products of microbial growth and degradation products of materials being considered for use as nutrient reservoirs and for delivery are likely sources of chemicals known to adversly affect plant growth.

Mitchell, R.

1994-01-01

18

Experimental studies of charge transport and storage in microbial biofilms  

NASA Astrophysics Data System (ADS)

We discuss results of ac impedance spectroscopy and dc I-V measurements applied to microbial biofilms and demonstrate that the biofilms of Geobacter sulfurreducens that grow on the anodes of microbial fuel cells are electronically conductive, with conductivities comparable to conjugated polymers. To investigate the components conferring the conductivity, we studied novel strains of G. sulfurreducens and mutants deficient in various outer surface components. Strains producing more current, produced biofilms with higher conductivity, demonstrating that conduction is the mechanism for long-range electron transfer through the biofilms. There was a direct correspondence between biofilm conductivity and the abundance of pili, referred to as microbial nanowires. Electrochemical gating suggested that in contrast to conventional redox activated hopping, charge transport is polaron-like. Biofilms also exhibited supercapacitor behavior. The results are being incorporated into a physical model of electron transfer and storage through the biofilms.

Malvankar, Nikhil; Nevin, Kelly; Franks, Ashley; Vargas, Madeline; Inoue, Kengo; Tuominen, Mark; Lovley, Derek

2010-03-01

19

OpinionMicrobial landscapes: new paths to biofilm research  

Microsoft Academic Search

It is the best of times for biofilm research. Systems biology approaches are providing new insights into the genetic regulation of microbial functions, and sophisticated modelling techniques are enabling the prediction of microbial community structures. Yet it is also clear that there is a need for ecological theory to contribute to our understanding of biofilms. Here, we suggest a concept

William T. Sloan; Staffan Kjelleberg; Holger Daims; Ian M. Head; Tom P. Curtis; Leo Eberl; Tom J. Battin

2007-01-01

20

Experimental studies of charge transport and storage in microbial biofilms  

Microsoft Academic Search

We discuss results of ac impedance spectroscopy and dc I-V measurements applied to microbial biofilms and demonstrate that the biofilms of Geobacter sulfurreducens that grow on the anodes of microbial fuel cells are electronically conductive, with conductivities comparable to conjugated polymers. To investigate the components conferring the conductivity, we studied novel strains of G. sulfurreducens and mutants deficient in various

Nikhil Malvankar; Kelly Nevin; Ashley Franks; Madeline Vargas; Kengo Inoue; Mark Tuominen; Derek Lovley

2010-01-01

21

The Biofilm Mode of Life  

Microsoft Academic Search

Recent advances in studies of biofilm systems have generated a wealth of novel informa- tion on multicellular prokaryotic biology and have established models for the formation of biofilms and the biology of their lifecycles. As a prelude to the subsequent chapters in this volume, this introductory article is aimed at identifying the contextual scientific and experimental framework for contemporary biofilm

Staffan Kjelleberg; Michael Givskov

22

Electroactive mixed culture biofilms in microbial bioelectrochemical systems: The role of temperature for biofilm formation and performance  

Microsoft Academic Search

In this paper we investigate the temperature dependence and temperature limits of waste water derived anodic microbial biofilms. We demonstrate that these biofilms are active in a temperature range between 5°C and 45°C. Elevated temperatures during initial biofilm growth not only accelerate the biofilm formation process, they also influence the bioelectrocatalytic performance of these biofilms when measured at identical operation

Sunil A. Patil; Falk Harnisch; Balasaheb Kapadnis; Uwe Schröder

2010-01-01

23

The Role of Microbial Biofilms as Ecosystem Engineers in Streams  

NASA Astrophysics Data System (ADS)

Microbial biofilms growing on and through the surface of streambeds physically alter the interface between the water column and benthic zone and influence the biogeochemistry within the steambed and hyporheic zone. We monitored the development of biofilms within stream-side flumes, and were able to relate changes in biofilm structure to concomitant changes in hydrodynamics, particle deposition, and dissolved organic carbon (DOC) uptake. Biofilm development was assessed by measurements of ash free dry mass, bacterial density, concentrations of chlorophyll a and exopolysaccharides, and confocal microscopy of fluorescent-stained biotic and abiotic assemblages. The microbial biofilms were followed through an initial colonization period, the development of mm-thick mats that included streamers undulating in the current, and the eventual erosion and sloughing of these structural features. As the biofilms matured, hydrologic exchange rate, transient storage capacity, and particle deposition rates increased, reached a plateau, and eventually declined. The uptake of glucose and arabinose, added in nM concentrations to the flumes, showed a preferential uptake of glucose over arabinose. However, as the biofilms grew, the differences between the uptake of these two saccharides declined. This change is consistent with a shift in the rate-limiting step for DOC uptake from internal biofilm processes to greater diffusion-limitation as biofilm thickness, and thus the diffusion barrier, increased. We suggest that microscale processes, which alter biofilm structure, in turn alter large-scale physical and biogeochemical processes, including streamwater/subsurface hydrodynamics and organic matter fluxes.

Battin, T. I.; Battin, T. I.; Kaplan, L. A.; Newbold, J. D.

2001-12-01

24

The biofilm ecology of microbial biofouling, biocide resistance and corrosion  

SciTech Connect

In biotechnological or bioremediation processes it is often the aim to promote biofilm formation, and maintain active, high density biomass. In other situations, biofouling can seriously restrict effective heat transport, membrane processes, and potentate macrofouling with loss of transportation efficiency. In biotechnological or bioremediation processes it is often the aim to promote biofilm formation, and maintain active, high density biomass. In other situations, biofouling can seriously restrict effective heat transport, membrane processes, and potentate macrofouling with loss of transportation efficiency. Heterogeneous distribution of microbes and/or their metabolic activity can promote microbially influenced corrosion (MIC) which is a multibillion dollar problem. Consequently, it is important that biofilm microbial ecology be understood so it can be manipulated rationally. It is usually simple to select organisms that form biofilms by flowing a considerably dilute media over a substratum, and propagating the organisms that attach. To examine the biofilm most expeditiously, the biomass accumulation, desquamation, and metabolic activities need to be monitored on-line and non-destructively. This on-line monitoring becomes even more valuable if the activities can be locally mapped in time and space within the biofilm. Herein the authors describe quantitative measures of microbial biofouling, the ecology of pathogens in drinking water distributions systems, and localization of microbial biofilms and activities with localized MIC.

White, D.C. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology]|[Oak Ridge National Lab., TN (United States). Environmental Science Div.; Kirkegaard, R.D.; Palmer, R.J. Jr.; Flemming, C.A.; Chen, G.; Leung, K.T.; Phiefer, C.B. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology; Arrage, A.A. [Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology]|[Microbial Insights, Inc., Rockford, TN (United States)

1997-06-01

25

Metamorphosis of a Scleractinian Coral in Response to Microbial Biofilms  

PubMed Central

Microorganisms have been reported to induce settlement and metamorphosis in a wide range of marine invertebrate species. However, the primary cue reported for metamorphosis of coral larvae is calcareous coralline algae (CCA). Herein we report the community structure of developing coral reef biofilms and the potential role they play in triggering the metamorphosis of a scleractinian coral. Two-week-old biofilms induced metamorphosis in less than 10% of larvae, whereas metamorphosis increased significantly on older biofilms, with a maximum of 41% occurring on 8-week-old microbial films. There was a significant influence of depth in 4- and 8-week biofilms, with greater levels of metamorphosis occurring in response to shallow-water communities. Importantly, larvae were found to settle and metamorphose in response to microbial biofilms lacking CCA from both shallow and deep treatments, indicating that microorganisms not associated with CCA may play a significant role in coral metamorphosis. A polyphasic approach consisting of scanning electron microscopy, fluorescence in situ hybridization (FISH), and denaturing gradient gel electrophoresis (DGGE) revealed that coral reef biofilms were comprised of complex bacterial and microalgal communities which were distinct at each depth and time. Principal-component analysis of FISH data showed that the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Cytophaga-Flavobacterium of Bacteroidetes had the largest influence on overall community composition. A low abundance of Archaea was detected in almost all biofilms, providing the first report of Archaea associated with coral reef biofilms. No differences in the relative densities of each subdivision of Proteobacteria were observed between slides that induced larval metamorphosis and those that did not. Comparative cluster analysis of bacterial DGGE patterns also revealed that there were clear age and depth distinctions in biofilm community structure; however, no difference was detected in banding profiles between biofilms which induced larval metamorphosis and those where no metamorphosis occurred. This investigation demonstrates that complex microbial communities can induce coral metamorphosis in the absence of CCA.

Webster, Nicole S.; Smith, Luke D.; Heyward, Andrew J.; Watts, Joy E. M.; Webb, Richard I.; Blackall, Linda L.; Negri, Andrew P.

2004-01-01

26

Life Support Systems Microbial Challenges  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the current microbial challenges of environmental control and life support systems. The contents include: 1) Environmental Control and Life Support Systems (ECLSS) What is it?; 2) A Look Inside the International Space Station (ISS); 3) The Complexity of a Water Recycling System; 4) ISS Microbiology Acceptability Limits; 5) Overview of Current Microbial Challenges; 6) In a Perfect World What we Would like to Have; and 7) The Future.

Roman, Monserrate C.

2009-01-01

27

Microbial genomes: Blueprints for life  

SciTech Connect

Complete microbial genome sequences hold the promise of profound new insights into microbial pathogenesis, evolution, diagnostics, and therapeutics. From these insights will come a new foundation for understanding the evolution of single-celled life, as well as the evolution of more complex life forms. This report is an in-depth analysis of scientific issues that provides recommendations and will be widely disseminated to the scientific community, federal agencies, industry and the public.

Relman, David A.; Strauss, Evelyn

2000-12-31

28

Molecular Identification and Biofilm-Forming Ability of Culturable Aquatic Bacteria In Microbial Biofilms Formed in Drinking Water Distribution Networks  

Microsoft Academic Search

Drinking water distribution networks are known to harbor microbial biofilms. The aim of the present work is to (i) identify the culturable bacteria presented in the drinking-water distribution network, (ii) investigate the ability of isolated bacteria to form biofilm under some environmental stress conditions and some eliminating or removing treatments. To achieve it, 57 strains were isolated from biofilm (43

Hesham Elhariry; Youssuf Gherbawy; Bahig El-Deeb; Abdullah Altalhi

2012-01-01

29

Conduction-based modeling of the biofilm anode of a microbial fuel cell  

Microsoft Academic Search

The biofilm of a microbial fuel cell (MFC) experiences biofilm-related (growth and mass transport) and electrochemical (electron conduction and charger- transfer) processes. We developed a dynamic, one-dimen- sional, multi-species model for the biofilm in three steps. First, we formulated the biofilm on the anode as a ''biofilm anode'' with the following two properties: (1) The biofilm has a conductive solid

Andrew Kato Marcus; César I. Torres; Bruce E. Rittmann

2007-01-01

30

Spatial & Temporal Geophysical Monitoring of Microbial Growth and Biofilm Formation  

Microsoft Academic Search

Previous studies have examined the effect of biogenic gases and biomineralization on the acoustic properties of porous media. In this study, we investigated the spatiotemporal effect of microbial growth and biofilm formation on compressional waves and complex conductivity in sand columns. A control column (non-biostimulated) and a biostimulated column were studied in a 2D acoustic scanning apparatus, and a second

C. A. Davis; L. J. Pyrak-Nolte; E. A. Atekwana; D. D. Werkema; M. E. Haugen

2009-01-01

31

Control of Microbial Biofilms in Dental Unit Waterlines.  

National Technical Information Service (NTIS)

The turbulent two-phase flow method has been found to efficiently remove biofilm from DUWLs. A cleaning device was designed, manufactured and installed in dental chairs at Pedodontics Clinic of the UMAB Dental School. The microbial quality of DUWS from un...

M. E. Labib R. Lai R. L. Hensler G. L. Mahon S. A. Weitzel Y. Tabani H. N. Williams

2001-01-01

32

Modelling mechanical characteristics of microbial biofilms by network theory  

PubMed Central

In this contribution, we present a constitutive model to describe the mechanical behaviour of microbial biofilms based on classical approaches in the continuum theory of polymer networks. Although the model is particularly developed for the well-studied biofilms formed by mucoid Pseudomonas aeruginosa strains, it could easily be adapted to other biofilms. The basic assumption behind the model is that the network of extracellular polymeric substances can be described as a superposition of worm-like chain networks, each connected by transient junctions of a certain lifetime. Several models that were applied to biofilms previously are included in the presented approach as special cases, and for small shear strains, the governing equations are those of four parallel Maxwell elements. Rheological data given in the literature are very adequately captured by the proposed model, and the simulated response for a series of compression tests at large strains is in good qualitative agreement with reported experimental behaviour.

Ehret, Alexander E.; Bol, Markus

2013-01-01

33

Modelling mechanical characteristics of microbial biofilms by network theory.  

PubMed

In this contribution, we present a constitutive model to describe the mechanical behaviour of microbial biofilms based on classical approaches in the continuum theory of polymer networks. Although the model is particularly developed for the well-studied biofilms formed by mucoid Pseudomonas aeruginosa strains, it could easily be adapted to other biofilms. The basic assumption behind the model is that the network of extracellular polymeric substances can be described as a superposition of worm-like chain networks, each connected by transient junctions of a certain lifetime. Several models that were applied to biofilms previously are included in the presented approach as special cases, and for small shear strains, the governing equations are those of four parallel Maxwell elements. Rheological data given in the literature are very adequately captured by the proposed model, and the simulated response for a series of compression tests at large strains is in good qualitative agreement with reported experimental behaviour. PMID:23034354

Ehret, Alexander E; Böl, Markus

2012-10-01

34

Life Support Systems Microbial Challenges  

NASA Technical Reports Server (NTRS)

Many microbiological studies were performed during the development of the Space Station Water Recovery and Management System from1990-2009. Studies include assessments of: (1) bulk phase (planktonic) microbial population (2) biofilms, (3) microbially influenced corrosion (4) biofouling treatments. This slide presentation summarizes the studies performed to assess the bulk phase microbial community during the Space Station Water Recovery Tests (WRT) from 1990 to 1998. This report provides an overview of some of the microbiological analyses performed during the Space Station WRT program. These tests not only integrated several technologies with the goal of producing water that met NASA s potable water specifications, but also integrated humans, and therefore human flora into the protocols. At the time these tests were performed, not much was known (or published) about the microbial composition of these types of wastewater. It is important to note that design changes to the WRS have been implemented over the years and results discussed in this report might be directly related to test configurations that were not chosen for the final flight configuration. Results microbiological analyses performed Conclusion from the during the WRT showed that it was possible to recycle water from different sources, including urine, and produce water that can exceed the quality of municipally produced water.

Roman, Monsi C.

2010-01-01

35

Microbial diversity of biofilms in dental unit water systems.  

PubMed

We investigated the microbial diversity of biofilms found in dental unit water systems (DUWS) by three methods. The first was microscopic examination by scanning electron microscopy (SEM), acridine orange staining, and fluorescent in situ hybridization (FISH). Most bacteria present in the biofilm were viable. FISH detected the beta and gamma, but not the alpha, subclasses of Proteobacteria: In the second method, 55 cultivated biofilm isolates were identified with the Biolog system, fatty acid analysis, and 16S ribosomal DNA (rDNA) sequencing. Only 16S identified all 55 isolates, which represented 13 genera. The most common organisms, as shown by analyses of 16S rDNA, belonged to the genera Afipia (28%) and Sphingomonas (16%). The third method was a culture-independent direct amplification and sequencing of 165 subclones from community biofilm 16S rDNA. This method revealed 40 genera: the most common ones included Leptospira (20%), Sphingomonas (14%), Bacillus (7%), Escherichia (6%), Geobacter (5%), and Pseudomonas (5%). Some of these organisms may be opportunistic pathogens. Our results have demonstrated that a biofilm in a health care setting may harbor a vast diversity of organisms. The results also reflect the limitations of culture-based techniques to detect and identify bacteria. Although this is the greatest diversity reported in DUWS biofilms, other genera may have been missed. Using a technique based on jackknife subsampling, we projected that a 25-fold increase in the number of subclones sequenced would approximately double the number of genera observed, reflecting the richness and high diversity of microbial communities in these biofilms. PMID:12788744

Singh, Ruby; Stine, O Colin; Smith, David L; Spitznagel, John K; Labib, Mohamed E; Williams, Henry N

2003-06-01

36

High-throughput metal susceptibility testing of microbial biofilms  

PubMed Central

Background Microbial biofilms exist all over the natural world, a distribution that is paralleled by metal cations and oxyanions. Despite this reality, very few studies have examined how biofilms withstand exposure to these toxic compounds. This article describes a batch culture technique for biofilm and planktonic cell metal susceptibility testing using the MBEC assay. This device is compatible with standard 96-well microtiter plate technology. As part of this method, a two part, metal specific neutralization protocol is summarized. This procedure minimizes residual biological toxicity arising from the carry-over of metals from challenge to recovery media. Neutralization consists of treating cultures with a chemical compound known to react with or to chelate the metal. Treated cultures are plated onto rich agar to allow metal complexes to diffuse into the recovery medium while bacteria remain on top to recover. Two difficulties associated with metal susceptibility testing were the focus of two applications of this technique. First, assays were calibrated to allow comparisons of the susceptibility of different organisms to metals. Second, the effects of exposure time and growth medium composition on the susceptibility of E. coli JM109 biofilms to metals were investigated. Results This high-throughput method generated 96-statistically equivalent biofilms in a single device and thus allowed for comparative and combinatorial experiments of media, microbial strains, exposure times and metals. By adjusting growth conditions, it was possible to examine biofilms of different microorganisms that had similar cell densities. In one example, Pseudomonas aeruginosa ATCC 27853 was up to 80 times more resistant to heavy metalloid oxyanions than Escherichia coli TG1. Further, biofilms were up to 133 times more tolerant to tellurite (TeO32-) than corresponding planktonic cultures. Regardless of the growth medium, the tolerance of biofilm and planktonic cell E. coli JM109 to metals was time-dependent. Conclusion This method results in accurate, easily reproducible comparisons between the susceptibility of planktonic cells and biofilms to metals. Further, it was possible to make direct comparisons of the ability of different microbial strains to withstand metal toxicity. The data presented here also indicate that exposure time is an important variable in metal susceptibility testing of bacteria.

Harrison, Joe J; Turner, Raymond J; Ceri, Howard

2005-01-01

37

Sponge larval settlement cues: the role of microbial biofilms in a warming ocean  

PubMed Central

Microbial biofilms play important roles in initiating settlement of marine invertebrate larvae. Given the importance of habitat selection by the motile larval phase, understanding settlement choices is critical if we are to successfully predict the population dynamics of sessile adults. Marine microbial biofilms show remarkable variability in community composition, often mediated by environmental conditions and biofilm age. To determine if biofilm communities were influenced by the time allowed to establish (age) and/or seawater temperature, we manipulated experimental surfaces to firstly determine biofilm community composition and secondly test larval settlement responses for the abundant coral reef sponge Rhopaloeides odorabile. Microbial profiling of biofilms revealed different communities according to both age and temperature. Biofilm community composition, as a result of both elevated seawater temperature and biofilm age, contributed to settlement for sponge larvae with markedly higher numbers of larvae settling to biofilms developed over longer periods (10?d) and at temperatures 2–6°C above ambient.

Whalan, S.; Webster, N. S.

2014-01-01

38

Microbial biofilm growth on irradiated, spent nuclear fuel cladding  

NASA Astrophysics Data System (ADS)

A fundamental criticism regarding the potential for microbial influenced corrosion in spent nuclear fuel cladding or storage containers concerns whether the required microorganisms can, in fact, survive radiation fields inherent in these materials. This study was performed to unequivocally answer this critique by addressing the potential for biofilm formation, the precursor to microbial-influenced corrosion, in radiation fields representative of spent nuclear fuel storage environments. This study involved the formation of a microbial biofilm on irradiated spent nuclear fuel cladding within a hot cell environment. This was accomplished by introducing 22 species of bacteria, in nutrient-rich media, to test vessels containing irradiated cladding sections and that was then surrounded by radioactive source material. The overall dose rate exceeded 2 Gy/h gamma/beta radiation with the total dose received by some of the bacteria reaching 5 × 10 3 Gy. This study provides evidence for the formation of biofilms on spent-fuel materials, and the implication of microbial influenced corrosion in the storage and permanent deposition of spent nuclear fuel in repository environments.

Bruhn, D. F.; Frank, S. M.; Roberto, F. F.; Pinhero, P. J.; Johnson, S. G.

2009-02-01

39

Molecular survey of concrete sewer biofilm microbial communities.  

PubMed

The microbial composition of concrete biofilms within wastewater collection systems was studied using molecular assays. SSU rDNA clone libraries were generated from 16 concrete surfaces of manholes, a combined sewer overflow, and sections of a corroded sewer pipe. Of the 2457 sequences analyzed, ?-, ?-, ?-, and ?-Proteobacteria represented 15%, 22%, 11%, and 4% of the clones, respectively. ?-Proteobacteria (47%) sequences were more abundant in the pipe crown than any of the other concrete surfaces. While 178 to 493 Operational Taxonomic Units (OTUs) were associated with the different concrete samples, only four sequences were shared among the different clone libraries. Bacteria implicated in concrete corrosion were found in the clone libraries while archaea, fungi, and several bacterial groups were also detected using group-specific assays. The results showed that concrete sewer biofilms are more diverse than previously reported. A more comprehensive molecular database will be needed to better study the dynamics of concrete biofilms. PMID:21981064

Santo Domingo, Jorge W; Revetta, Randy P; Iker, Brandon; Gomez-Alvarez, Vicente; Garcia, Jarissa; Sullivan, John; Weast, James

2011-10-01

40

Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community  

Microsoft Academic Search

BACKGROUND: Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy). Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers). In the Río Tinto (Spain), brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum) and

Mercedes Moreno-Paz; Manuel J Gómez; Aida Arcas; Víctor Parro

2010-01-01

41

Spatial & Temporal Geophysical Monitoring of Microbial Growth and Biofilm Formation  

NASA Astrophysics Data System (ADS)

Previous studies have examined the effect of biogenic gases and biomineralization on the acoustic properties of porous media. In this study, we investigated the spatiotemporal effect of microbial growth and biofilm formation on compressional waves and complex conductivity in sand columns. A control column (non-biostimulated) and a biostimulated column were studied in a 2D acoustic scanning apparatus, and a second set of columns were constructed with Ag-AgCl electrodes for complex conductivity measurements. At the completion of the 29-day experiment, compressional wave amplitudes and arrival times for the control column were observed to be relatively uniform over the scanned 2D region. However, the biostimulated sample exhibited a high degree of spatial variability within the column for both the amplitude and arrival times. Furthermore, portions of the sample exhibited increased attenuation (~ 80%) concurrent with an increase in the arrival times, while other portions exhibited decreased attenuation (~ 45%) and decreased arrival time. The acoustic amplitude and arrival times changed significantly in the biostimulated column between Days 5 and 7 of the experiment and are consistent with a peak in the imaginary conductivity (?”) values. The ?” response corresponds to different stages of biofilm development. That is, we interpret the peak ?” with the maximum biofilm thickness and decreasing ?” due to cell death or detachment. Environmental scanning electron microscope (ESEM) imaging confirmed microbial cell attachment to sand surfaces in the biostimulated columns, showed apparent differences in the morphology of attached biomass between regions of increased and decreased attenuation, and indicated no mineral precipitation or biomineralization. The heterogeneity in the elastic properties arises from the differences in the morphology and structure of attached biofilms. These results suggest that combining acoustic imaging and complex conductivity techniques can provide a powerful tool for assessing microbial growth or biofilm formation and the associated changes in porous media, such as those that occur during bioremediation and microbial enhanced oil recovery. Furthermore, this study suggests microbial growth and biofilm development can yield a detectable geophysical response without biomineralization effects. Acknowledgments: This material is based in part on work supported by the National Science Foundation under Grant No. OCE-0729642, EAR 0722410 (MRI), EAR 0525316, and REU Award # 0552918, and EPA Student Services Contract EP07D000660. LJPN would like to acknowledge support from Geosciences Research Program, Office of Basic Energy Sciences, US Department of Energy (DEFG02-97ER14785 08).

Davis, C. A.; Pyrak-Nolte, L. J.; Atekwana, E. A.; Werkema, D. D.; Haugen, M. E.

2009-12-01

42

Theoretical aspects of antibiotic diffusion into microbial biofilms.  

PubMed Central

Antibiotic penetration into microbial biofilm was investigated theoretically by the solution of mathematical equations describing various combinations of the processes of diffusion, sorption, and reaction. Unsteady material balances on the antibiotic and on a reactive or sorptive biomass constituent, along with associated boundary and initial conditions, constitute the mathematical formulations. Five cases were examined: diffusion of a noninteracting solute; diffusion of a reversibly sorbing, nonreacting solute; diffusion of an irreversibly sorbing, nonreacting solute; diffusion of a stoichiometrically reacting solute; and diffusion of a catalytically reacting solute. A noninteracting solute was predicted to penetrate biofilms of up to 1 mm in thickness relatively quickly, within a matter of seconds or minutes. In the case of a solute that does not sorb or react in the biofilm, therefore, the diffusion barrier is not nearly large enough to account for the reduced susceptibility of biofilms to antibiotics. Reversible and irreversible sorption retards antibiotic penetration. On the basis of data available in the literature at this point, the extent of retardation of antibiotic diffusion due to sorption does not appear to be sufficient to account for reduced biofilm susceptibility. A catalytic (e.g., enzymatic) reaction, provided it is sufficiently rapid, can lead to severe antibiotic penetration failure. For example, calculation of beta-lactam penetration indicated that the reaction-diffusion mechanism may be a viable explanation for failure of certain of these agents to control biofilm infections. The theory presented in this study provides a framework for the design and analysis of experiments to test these mechanisms of reduced biofilm susceptibility to antibiotics.

Stewart, P S

1996-01-01

43

Electroactive mixed culture biofilms in microbial bioelectrochemical systems: the role of temperature for biofilm formation and performance.  

PubMed

In this paper we investigate the temperature dependence and temperature limits of waste water derived anodic microbial biofilms. We demonstrate that these biofilms are active in a temperature range between 5°C and 45°C. Elevated temperatures during initial biofilm growth not only accelerate the biofilm formation process, they also influence the bioelectrocatalytic performance of these biofilms when measured at identical operation temperatures. For example, the time required for biofilm formation decreases from above 40 days at 15°C to 3.5 days at 35°C. Biofilms grown at elevated temperatures are more electrochemically active at these temperatures than those grown at lower incubation temperature. Thus, at 30°C current densities of 520 ?A cm(-2) and 881 ?A cm(-2) are achieved by biofilms grown at 22°C and 35°C, respectively. Vice versa, and of great practical relevance for waste water treatment plants in areas of moderate climate, at low operation temperatures, biofilms grown at lower temperatures outperform those grown at higher temperatures. We further demonstrate that all biofilms possess similar lower (0°C) and upper (50°C) temperature limits--defining the operational limits of a respective microbial fuel cell or microbial biosensor--as well as similar electrochemical electron transfer characteristics. PMID:20630740

Patil, Sunil A; Harnisch, Falk; Kapadnis, Balasaheb; Schröder, Uwe

2010-10-15

44

Acoustic and Electrical Property Changes Due to Microbial Growth and Biofilm Formation in Porous Media  

EPA Science Inventory

A laboratory study was conducted to investigate the effect of microbial growth and biofilm formation on compressional waves, and complex conductivity during stimulated microbial growth. Over the 29 day duration of the experiment, compressional wave amplitudes and arrival times f...

45

Microbial Biofilms and Breast Tissue Expanders  

PubMed Central

We previously developed and validated a vortexing-sonication technique for detection of biofilm bacteria on the surface of explanted prosthetic joints. Herein, we evaluated this technique for diagnosis of infected breast tissue expanders and used it to assess colonization of breast tissue expanders. From April 2008 to December 2011, we studied 328 breast tissue expanders at Mayo Clinic, Rochester, MN, USA. Of seven clinically infected breast tissue expanders, six (85.7%) had positive cultures, one of which grew Propionibacterium species. Fifty-two of 321 breast tissue expanders (16.2%, 95% CI, 12.3–20.7%) without clinical evidence of infection also had positive cultures, 45 growing Propionibacterium species and ten coagulase-negative staphylococci. While vortexing-sonication can detect clinically infected breast tissue expanders, 16 percent of breast tissue expanders appear to be asymptomatically colonized with normal skin flora, most commonly, Propionibacterium species.

Karau, Melissa J.; Greenwood-Quaintance, Kerryl E.; Schmidt, Suzannah M.; Tran, Nho V.; Convery, Phyllis A.; Jacobson, Steven R.; Bite, Uldis; Clay, Ricky P.; Petty, Paul M.; Johnson, Craig H.; Mandrekar, Jayawant; Patel, Robin

2013-01-01

46

Micro-cantilever method for measuring the tensile strength of biofilms and microbial flocs  

Microsoft Academic Search

Cohesive strength is an important factor in determining the structure and function of biofilm systems, and cohesive strength plays a key role in our ability to remove or control biofilms in engineered systems. A micro-mechanical device has been developed to directly measure the tensile strength of biofilms and other microbial aggregates. An important feature of this method is the combination

Eric H Poppele; Raymond M Hozalski

2003-01-01

47

Complex conductivity response to microbial growth and biofilm formation on phenanthrene spiked medium  

Microsoft Academic Search

Several laboratory studies have recently demonstrated the utility of geophysical methods for the investigation of microbial-induced changes over contaminated sites. However, it remains difficult to distinguish the effects due to the new physical properties imparted by microbial processes, to bacterial growth, or to the development of bacterial biofilm. We chose to study the influence of biofilm formation on geophysical response

Remy Albrecht; Jean Christophe Gourry; Marie-Odile Simonnot; Corinne Leyval

2011-01-01

48

Early microbial biofilm formation on marine plastic debris.  

PubMed

An important aspect of the global problem of plastic debris pollution is plastic buoyancy. There is some evidence that buoyancy is influenced by attached biofilms but as yet this is poorly understood. We submerged polyethylene plastic in seawater and sampled weekly for 3 weeks in order to study early stage processes. Microbial biofilms developed rapidly on the plastic and coincided with significant changes in the physicochemical properties of the plastic. Submerged plastic became less hydrophobic and more neutrally buoyant during the experiment. Bacteria readily colonised the plastic but there was no indication that plastic-degrading microorganisms were present. This study contributes to improved understanding of the fate of plastic debris in the marine environment. PMID:21093883

Lobelle, Delphine; Cunliffe, Michael

2011-01-01

49

Biofilms  

PubMed Central

Our understanding of the virulence and pathogenesis of Francisella spp. has significantly advanced in recent years, including a new understanding that this organism can form biofilms. What is known so far about Francisella spp. biofilms is summarized here and future research questions are suggested. The molecular basis of biofilm production has begun to be studied, especially the role of extracellular carbohydrates and capsule, quorum sensing and two-component signaling systems. Further work has explored the contribution of amoebae, pili, outer-membrane vesicles, chitinases, and small molecules such as c-di-GMP to Francisella spp. biofilm formation. A role for Francisella spp. biofilm in feeding mosquito larvae has been suggested. As no strong role in virulence has been found yet, Francisella spp. biofilm formation is most likely a key mechanism for environmental survival and persistence. The significance and importance of Francisella spp.’s biofilm phenotype as a critical aspect of its microbial physiology is being developed. Areas for further studies include the potential role of Francisella spp. biofilms in the infection of mammalian hosts and virulence regulation.

van Hoek, Monique L

2013-01-01

50

Origin of phagotrophic eukaryotes as social cheaters in microbial biofilms  

PubMed Central

Background The origin of eukaryotic cells was one of the most dramatic evolutionary transitions in the history of life. It is generally assumed that eukaryotes evolved later then prokaryotes by the transformation or fusion of prokaryotic lineages. However, as yet there is no consensus regarding the nature of the prokaryotic group(s) ancestral to eukaryotes. Regardless of this, a hardly debatable fundamental novel characteristic of the last eukaryotic common ancestor was the ability to exploit prokaryotic biomass by the ingestion of entire cells, i.e. phagocytosis. The recent advances in our understanding of the social life of prokaryotes may help to explain the origin of this form of total exploitation. Presentation of the hypothesis Here I propose that eukaryotic cells originated in a social environment, a differentiated microbial mat or biofilm that was maintained by the cooperative action of its members. Cooperation was costly (e.g. the production of developmental signals or an extracellular matrix) but yielded benefits that increased the overall fitness of the social group. I propose that eukaryotes originated as selfish cheaters that enjoyed the benefits of social aggregation but did not contribute to it themselves. The cheaters later evolved into predators that lysed other cells and eventually became professional phagotrophs. During several cycles of social aggregation and dispersal the number of cheaters was contained by a chicken game situation, i.e. reproductive success of cheaters was high when they were in low abundance but was reduced when they were over-represented. Radical changes in cell structure, including the loss of the rigid prokaryotic cell wall and the development of endomembranes, allowed the protoeukaryotes to avoid cheater control and to exploit nutrients more efficiently. Cellular changes were buffered by both the social benefits and the protective physico-chemical milieu of the interior of biofilms. Symbiosis with the mitochondial ancestor evolved after phagotrophy as alphaproteobacterial prey developed post-ingestion defence mechanisms to circumvent digestion in the food vacuole. Mitochondrial symbiosis triggered the origin of the nucleus. Cilia evolved last and allowed eukaryotes to predate also on planktonic prey. I will discuss how this scenario may possibly fit into the contrasting phylogenetic frameworks that have been proposed. Testing the hypothesis Some aspects of the hypothesis can be tested experimentally by studying the level of exploitation cheaters can reach in social microbes. It would be interesting to test whether absorption of nutrients from lysed fellow colony members can happen and if cheaters can evolve into predators that actively digest neighbouring cells. Implications of the hypothesis The hypothesis highlights the importance of social exploitation in cell evolution and how a social environment can buffer drastic cellular transformations that would be lethal for planktonic forms. Reviewers This article was reviewed by Eugene V Koonin, Purificación López-García, and Igor Zhulin.

Jekely, Gaspar

2007-01-01

51

Microbial growth and biofilm formation in geologic media is detected with complex conductivity measurements  

NASA Astrophysics Data System (ADS)

Complex conductivity measurements (0.1-1000 Hz) were obtained from biostimulated sand-packed columns to investigate the effect of microbial growth and biofilm formation on the electrical properties of porous media. Microbial growth was verified by direct microbial counts, pH measurements, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the biostimulated columns were coincident with peaks in the microbial cell concentrations extracted from sands. However, the real conductivity component showed no discernible relationship to microbial cell concentration. We suggest that the observed dynamic changes in the imaginary conductivity (??) arise from the growth and attachment of microbial cells and biofilms to sand surfaces. We conclude that complex conductivity techniques, specifically imaginary conductivity measurements are a proxy indicator for microbial growth and biofilm formation in porous media. Our results have implications for microbial enhanced oil recovery, CO2 sequestration, bioremediation, and astrobiology studies.

Davis, Caroline A.; Atekwana, Estella; Atekwana, Eliot; Slater, Lee D.; Rossbach, Silvia; Mormile, Melanie R.

2006-09-01

52

Microbial Communities in Biofilms of an Acid Mine Drainage Site Determined by Phospholipid Analysis  

NASA Astrophysics Data System (ADS)

Phospholipids were extracted to determine the microbial biomass and community structure of biofims from an acid mine drainage (AMD) at the Green Valley coal mine site (GVS) in western Indiana. The distribution of specific biomarkers indicated the presence of a variety of microorganisms. Phototrophic microeukaryotes, which include Euglena mutabilis, algae, and cyanobacteria were the most dominant organisms, as indicated by the presence of polyunsaturated fatty acids. The presence of terminally methyl branched fatty acids suggests the presence of Gram-positive bacteria, and the mid-methyl branched fatty acids indicates the presence of sulfate-reducing bacteria. Fungi appear to also be an important part of the AMD microbial communities as suggested by the presence of 18:2 fatty acid. The acidophilic microeukaryotes Euglena dominated the biofilm microbial communities. These microorganisms appear to play a prominent role in the formation and preservation of stromatolites and in releasing oxygen to the atmosphere by oxygenic photosynthesis. Thus, the AMD environment comprises a host of microorganisms spreading out within the phylogenetic tree of life. Novel insights on the roles of microbial consortia in the formation and preservation of stromatolites and the production of oxygen through photosynthesis in AMD systems may have significance in the understanding of the interaction of Precambrian microbial communities in environments that produced microbially-mediated sedimentary structures and that caused oxygenation of Earth's atmosphere.

Das Gupta, S.; Fang, J.

2008-12-01

53

Tobacco Smoke Mediated Induction of Sinonasal Microbial Biofilms  

PubMed Central

Cigarette smokers and those exposed to second hand smoke are more susceptible to life threatening infection than non-smokers. While much is known about the devastating effect tobacco exposure has on the human body, less is known about the effect of tobacco smoke on the commensal and commonly found pathogenic bacteria of the human respiratory tract, or human respiratory tract microbiome. Chronic rhinosinusitis (CRS) is a common medical complaint, affecting 16% of the US population with an estimated aggregated cost of $6 billion annually. Epidemiologic studies demonstrate a correlation between tobacco smoke exposure and rhinosinusitis. Although a common cause of CRS has not been defined, bacterial presence within the nasal and paranasal sinuses is assumed to be contributory. Here we demonstrate that repetitive tobacco smoke exposure induces biofilm formation in a diverse set of bacteria isolated from the sinonasal cavities of patients with CRS. Additionally, bacteria isolated from patients with tobacco smoke exposure demonstrate robust in vitro biofilm formation when challenged with tobacco smoke compared to those isolated from smoke naïve patients. Lastly, bacteria from smoke exposed patients can revert to a non-biofilm phenotype when grown in the absence of tobacco smoke. These observations support the hypothesis that tobacco exposure induces sinonasal biofilm formation, thereby contributing to the conversion of a transient and medically treatable infection to a persistent and therapeutically recalcitrant condition.

Goldstein-Daruech, Natalia; Cope, Emily K.; Zhao, Ke-Qing; Vukovic, Katarina; Kofonow, Jennifer M.; Doghramji, Laurel; Gonzalez, Bernardo; Chiu, Alexander G.; Kennedy, David W.; Palmer, James N.; Leid, Jeffery G.; Kreindler, James L.; Cohen, Noam A.

2011-01-01

54

Detection of microbial Life in the Subsurface  

NASA Astrophysics Data System (ADS)

In recent years microbial communities were detected, which dwell in rocks, soil and caves deep below the surface of the Earth. This has led to a new view of the diversity of the terrestrial biosphere and of the physico-chemical boundaries for life. Two types of subterranean environments are Permo-Triassic salt sediments and thermal radioactive springs from igneous rocks in the Alps. Viable extremely halophilic archaea were isolated from ancient salt sediments which are estimated to be about 250 million years old (1). Chemotaxonomic and molecular characterization showed that they represent novel species, e. g. Halococcus salifodinae, Hcc. dombrowskiiand Halobacterium noricense. Simulation experiments with artificial halite suggested that these microorganisms probably survived while embedded in fluid inclusions. In the thermal springs, evidence for numerous novel microorganisms was found by 16S rDNA sequencing and probing for some metabolic genes; in addition, scanning electron microscopy of biofilms on the rock surfaces revealed great diversity of morphotypes (2). These communities appear to be active and growing, although their energy and carbon sources are entirely unknown. The characterization of subsurface inhabitants is of astrobiological relevance since extraterrestrial halite has been detected (3) and since microbial life on Mars, if existent, may have retreated into the subsurface. As a long-term goal, a thorough census of terrestrial microorganisms should be taken and their survival potential be determined in view of future missions for the search for extraterrestrial life, including planning precautions against possible forward contamination by space probes. (1) Fendrihan, S., Legat, A., Gruber, C., Pfaffenhuemer, M., Weidler, G., Gerbl, F., Stan-Lotter, H. (2006) Extremely halophilic archaea and the issue of long term microbial survival. Reviews in Environmental Science and Bio/technology 5, 1569-1605. (2) Weidler, G.W., Dornmayr-Pfaffenhuemer, M., Gerbl, F.W., Heinen, W., Stan- Lotter, H. (2007) Communities of Archaea and Bacteria in a subsurface radioactive thermal spring in the Austrian Central Alps and evidence for ammonia oxidizing Crenarchaeota. Appl. Environ. Microbiol. 73, 259-270. (3) Stan-Lotter, H., Radax, C., McGenity, T.J., Legat, A., Pfaffenhuemer, M.,Wieland, H., Gruber, C., Denner, E.B.M. (2004) From Intraterrestrials to Extraterrestrials - Viable haloarchaea in ancient salt deposits. In: Halophilic Microorganisms. Ventosa A. (Ed.), Springer Verlag, Berlin, Heidelberg, New York, pp. 89-102.

Stan-Lotter, H.; Fendrihan, S.; Dornmayr-Pfaffenhuemer, M.; Legat, A.; Gruber, C.; Weidler, G.; Gerbl, F.

2007-08-01

55

Influence of microbial interactions and EPS\\/polysaccharide composition on nutrient removal activity in biofilms formed by strains found in wastewater treatment systems  

Microsoft Academic Search

The study of biofilm function, structure and microbial interactions might help to improve our understanding of biofilm wastewater treatment processes. However, few reports specifically address the influence of interactions within multispecies biofilms on microbial activity and biofilm composition. Thus, the relationship between biofilm formation, denitrification activity, phosphorus removal and the composition of extracellular polymeric substances (EPS), exopolysaccharides and the bacterial

Sofia Andersson; Gunnel Dalhammar; Gunaratna Kuttuva Rajarao

2011-01-01

56

Microbial Biofilms: Their Development and Significance for Medical Device–Related Infections  

Microsoft Academic Search

Microbial adhesion and biofilm formation on medical devices represent a common occurrence that can lead to serious illness and death. The process by which bacteria and yeast colonize open and closed implants is fairly complicated and involves a series of steps commencing with deposition of host substances onto the material. Prevention and treatment of established biofilms with antimicrobial agents are

Marc Habash; Gregor Reid

1999-01-01

57

In situ environment rather than substrate type dictates microbial community structure of biofilms in a cold seep system  

NASA Astrophysics Data System (ADS)

Using microscopic and molecular techniques combined with computational analysis, this study examined the structure and composition of microbial communities in biofilms that formed on different artificial substrates in a brine pool and on a seep vent of a cold seep in the Red Sea to test our hypothesis that initiation of the biofilm formation and spreading mode of microbial structures differs between the cold seep and the other aquatic environments. Biofilms on different substrates at two deployment sites differed morphologically, with the vent biofilms having higher microbial abundance and better structural features than the pool biofilms. Microbes in the pool biofilms were more taxonomically diverse and mainly composed of various sulfate-reducing bacteria whereas the vent biofilms were exclusively dominated by sulfur-oxidizing Thiomicrospira. These results suggest that the redox environments at the deployment sites might have exerted a strong selection on microbes in the biofilms at two sites whereas the types of substrates had limited effects on the biofilm development.

Lee, On On; Wang, Yong; Tian, Renmao; Zhang, Weipeng; Shek, Chun Shum; Bougouffa, Salim; Al-Suwailem, Abdulaziz; Batang, Zenon B.; Xu, Wei; Wang, Guang Chao; Zhang, Xixiang; Lafi, Feras F.; Bajic, Vladmir B.; Qian, Pei-Yuan

2014-01-01

58

Microbial growth and biofilm formation in geologic media is detected with complex conductivity measurements  

Microsoft Academic Search

Complex conductivity measurements (0.1–1000 Hz) were obtained from biostimulated sand-packed columns to investigate the effect of microbial growth and biofilm formation on the electrical properties of porous media. Microbial growth was verified by direct microbial counts, pH measurements, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the biostimulated columns were coincident with peaks in the microbial

Caroline A. Davis; Estella Atekwana; Eliot Atekwana; Lee D. Slater; Silvia Rossbach; Melanie R. Mormile

2006-01-01

59

Microbial community analysis of fresh and old microbial biofilms on Bayon temple sandstone of Angkor Thom, Cambodia.  

PubMed

The temples of Angkor monuments including Angkor Thom and Bayon in Cambodia and surrounding countries were exclusively constructed using sandstone. They are severely threatened by biodeterioration caused by active growth of different microorganisms on the sandstone surfaces, but knowledge on the microbial community and composition of the biofilms on the sandstone is not available from this region. This study investigated the microbial community diversity by examining the fresh and old biofilms of the biodeteriorated bas-relief wall surfaces of the Bayon Temple by analysis of 16S and 18S rRNA gene sequences. The results showed that the retrieved sequences were clustered in 11 bacterial, 11 eukaryotic and two archaeal divisions with disparate communities (Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria; Alveolata, Fungi, Metazoa, Viridiplantae; Crenarchaeote, and Euyarchaeota). A comparison of the microbial communities between the fresh and old biofilms revealed that the bacterial community of old biofilm was very similar to the newly formed fresh biofilm in terms of bacterial composition, but the eukaryotic communities were distinctly different between these two. This information has important implications for understanding the formation process and development of the microbial diversity on the sandstone surfaces, and furthermore to the relationship between the extent of biodeterioration and succession of microbial communities on sandstone in tropic region. PMID:20593173

Lan, Wensheng; Li, Hui; Wang, Wei-Dong; Katayama, Yoko; Gu, Ji-Dong

2010-07-01

60

Microbial Community Analysis of Fresh and Old Microbial Biofilms on Bayon Temple Sandstone of Angkor Thom, Cambodia  

PubMed Central

The temples of Angkor monuments including Angkor Thom and Bayon in Cambodia and surrounding countries were exclusively constructed using sandstone. They are severely threatened by biodeterioration caused by active growth of different microorganisms on the sandstone surfaces, but knowledge on the microbial community and composition of the biofilms on the sandstone is not available from this region. This study investigated the microbial community diversity by examining the fresh and old biofilms of the biodeteriorated bas-relief wall surfaces of the Bayon Temple by analysis of 16S and 18S rRNA gene sequences. The results showed that the retrieved sequences were clustered in 11 bacterial, 11 eukaryotic and two archaeal divisions with disparate communities (Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria; Alveolata, Fungi, Metazoa, Viridiplantae; Crenarchaeote, and Euyarchaeota). A comparison of the microbial communities between the fresh and old biofilms revealed that the bacterial community of old biofilm was very similar to the newly formed fresh biofilm in terms of bacterial composition, but the eukaryotic communities were distinctly different between these two. This information has important implications for understanding the formation process and development of the microbial diversity on the sandstone surfaces, and furthermore to the relationship between the extent of biodeterioration and succession of microbial communities on sandstone in tropic region. Electronic supplementary material The online version of this article (doi:10.1007/s00248-010-9707-5) contains supplementary material, which is available to authorized users.

Lan, Wensheng; Li, Hui; Wang, Wei-Dong; Katayama, Yoko

2010-01-01

61

Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels  

PubMed Central

Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general diversity patterns, despite increased mutation levels at the single-OTU level. Therefore, biofilm communities growing in sunlight exposed substrates are capable of coping with increased mutation rates and appear pre-adapted to levels of ionizing radiation in Chernobyl due to their natural adaptation to periodical desiccation and ambient UV radiation.

Ragon, Marie; Restoux, Gwendal; Moreira, David; M?ller, Anders Pape; Lopez-Garcia, Purificacion

2011-01-01

62

Microbial endolithic biofilms: a means of surviving the harsh conditions of the Antarctic  

NASA Astrophysics Data System (ADS)

Much of the Antarctic continent's microbiota is restricted to endolithic microecosystems which harbour distinct microbial communities as biofilms. The lithic substrate and the microorganisms comprising these films are intimately linked, giving rise to complex mineral-microbe interactions. The Antarctic biofilms analysed in this study were characterised by the presence of extracellular polymer substances. Cyanobacteria appeared as key components of these biofilms in zones where there were no nearby lichen thalli. Fungal cells were the predominant organisms in areas inhabited by epilithic lichens. The combined use of microscopy and molecular techniques enabled the identification of the different biological components of biofilms found in subsurface layers of the lighic substrate. It is proposed that in this extreme environment, the structure of the biofilm may favour the formation of microsites with specific physicochemical conditions that permit the survival of microbial communities.

de Los Ríos, Asunción; Wierzchos, Jacek; Sancho, Leopoldo G.; Grube, Martín; Ascaso, Carmen

2002-11-01

63

Microbial diversity in biofilm infections of the urinary tract with the use of sonication techniques.  

PubMed

Infections of the urinary tract account for >40% of nosocomial infections; most of these are infections in catheterized patients. Bacterial colonization of the urinary tract and catheters causes not only the particular infection but also a number of complications, for example blockage of catheters with crystallic deposits of bacterial origin, generation of gravels and pyelonephritis. Infections of urinary catheters are only rarely single-species infections. The longer a patient is catheterized, the higher the diversity of biofilm microbial communities. The aims of this study were to investigate the microbial diversity on the catheters and to compare the ability to form biofilm among isolated microbial species. The next aim was to discriminate particular causative agents of infections of the urinary tract and their importance as biofilm formers in the microbial community on the urinary catheter. We examined catheters from 535 patients and isolated 1555 strains of microorganisms. Most of the catheters were infected by three or more microorganisms; only 12.5% showed monomicrobial infection. Among the microorganisms isolated from the urinary catheters, there were significant differences in biofilm-forming ability, and we therefore conclude that some microbial species have greater potential to cause a biofilm-based infection, whereas others can be only passive members of the biofilm community. PMID:20602639

Holá, Veronika; Ruzicka, Filip; Horka, Marie

2010-08-01

64

Microbial analysis of anodic biofilm in a microbial fuel cell using slaughterhouse wastewater.  

PubMed

The ability of dual-chambered microbial fuel cell, fed with slaughterhouse wastewater with an anaerobic mixed-sludge as initial source of bacteria, to generate power is investigated. MFC voltage generation across a fixed 100 ? load indicates power generation capability, with power production correlated to changes in anolyte VFA content. A maximum MFC power density of 578 mW/m(2) is obtained for an MFC developed under 100 ? load, compared to a maximum power density of 277 mW/m(2) for an MFC developed under higher resistance (1 M?) control conditions. Voltammetry of the biofilm developed under 100 ? load displays a current-voltage signal indicative of bioelectrocatalytic oxidation of feed at a potential of -0.35 V vs. Ag/AgCl, compared to negligible signals for biofilms developed under control conditions. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA gene fragments reveals that the anodic bacterial communities in reactors operated under 100 ? load result in communities of lower diversity than for the control condition, with Geovibrio ferrireducens dominant in the anodic biofilm community. These results indicate that in MFC reactors, functionally stable electroactive bacteria are enriched under 100 ? load compared to high resistance control conditions, and were able to sustain higher power in MFCs. PMID:22226620

Katuri, Krishna P; Enright, Ann-Marie; O'Flaherty, Vincent; Leech, Dónal

2012-10-01

65

Acoustic and electrical property changes due to microbial growth and biofilm formation in porous media  

Microsoft Academic Search

A laboratory study was conducted to investigate the effect of microbial growth and biofilm formation on compressional waves, and complex conductivity during stimulated microbial growth. Over the 29 day duration of the experiment, compressional wave amplitudes and arrival times for the control (nonbiostimulated) sample were observed to be relatively uniform over the scanned 2-D region. However, the biostimulated sample exhibited

Caroline A. Davis; Laura J. Pyrak-Nolte; Estella A. Atekwana; Douglas D. Werkema; Marisa E. Haugen

2010-01-01

66

Conduction-based modeling of the biofilm anode of a microbial fuel cell.  

PubMed

The biofilm of a microbial fuel cell (MFC) experiences biofilm-related (growth and mass transport) and electrochemical (electron conduction and charger-transfer) processes. We developed a dynamic, one-dimensional, multi-species model for the biofilm in three steps. First, we formulated the biofilm on the anode as a "biofilm anode" with the following two properties: (1) The biofilm has a conductive solid matrix characterized by the biofilm conductivity (kappa(bio)). (2) The biofilm matrix accepts electrons from biofilm bacteria and conducts the electrons to the anode. Second, we derived the Nernst-Monod expression to describe the rate of electron-donor (ED) oxidation. Third, we linked these components using the principles of mass balance and Ohm's law. We then solved the model to study dual limitation in biofilm by the ED concentration and local potential. Our model illustrates that kappa(bio) strongly influences the ED and current fluxes, the type of limitation in biofilm, and the biomass distribution. A larger kappa(bio) increases the ED and current fluxes, and, consequently, the ED mass-transfer resistance becomes significant. A significant gradient in ED concentration, local potential, or both can develop in the biofilm anode, and the biomass actively respires only where ED concentration and local potential are high. When kappa(bio) is relatively large (i.e., > or =10(-3) mS cm(-1)), active biomass can persist up to tens of micrometers away from the anode. Increases in biofilm thickness and accumulation of inert biomass accentuate dual limitation and reduce the current density. These limitations can be alleviated with increases in the specific detachment rate and biofilm density. PMID:17570714

Kato Marcus, Andrew; Torres, César I; Rittmann, Bruce E

2007-12-15

67

Microbial Life-Educational Resources  

NSDL National Science Digital Library

The Marine Biology Laboratory of Woods Hole, Massachusetts and Montana State University are the collaborators on this easily navigable website of educational resources about microbial life. The goal of the site is to provide expert information about microorganisms for K-12 classrooms, university educators, and the general public. They effectively accomplish their goal here, with a host of resources, in formats appropriate for different knowledge levels, in a well-organized manner. For all of the topics covered, three levels of information are provided. Resources such as newspapers, websites, and magazine articles are provided for general learners; journal articles and academic reviews are provided for advanced learners; and activities, assignments, and readings are provided for educators. Interestingly, one of the activities found in the "Teaching Methods" tab on the left side of the homepage, is how to use the Socratic Method with students, with question suggestions, rules of participation, and what to expect from the students. An interesting part of the website is its focus on the microorganisms that live in extreme environments. Visitors can learn about the many types of extremes environments, the extremophiles, and how to teach about extreme environments in K-12 classrooms, by clicking on the "Extreme Environments" tab on the left side of the homepage. The photos of the extreme environments resemble abstract art with their close ups of the microorganisms in their environment. By clicking on the "Online Resources" tab on the left hand side of the homepage, visitors will be taken to a virtual index of their resources, where they can also narrow their view by resource type, subject, environment type, and grade-level. Each category that can be used to narrow results also shows how many entries are available for that category.

68

Complex conductivity response to microbial growth and biofilm formation on phenanthrene spiked medium  

NASA Astrophysics Data System (ADS)

Several laboratory studies have recently demonstrated the utility of geophysical methods for the investigation of microbial-induced changes over contaminated sites. However, it remains difficult to distinguish the effects due to the new physical properties imparted by microbial processes, to bacterial growth, or to the development of bacterial biofilm. We chose to study the influence of biofilm formation on geophysical response using complex conductivity measurements (0.1-1000 Hz) in phenanthrene-contaminated media. Biotic assays were conducted with two phenanthrene (PHE) degrading bacterial strains: Burkholderia sp (NAH1), which produced biofilm and Stenophomonas maltophilia (MATE10), which did not, and an abiotic control. Results showed that bacterial densities for NAH1 and MATE10 strains continuously increased at the same rate during the experiment. However, the complex conductivity signature showed noticeable differences between the two bacteria, with a phase shift of 50 mrad at 4 Hz for NAH1, which produced biofilm. Biofilm volume was quantified by Scanning Confocal Laser Microscopy (SCLM). Significant correlations were established between phase shift decrease and biofilm volume for NAH1 assays. Results suggest that complex conductivity measurements, specifically phase shift, can be a useful indicator of biofilm formation inside the overall signal of microbial activity on contaminated sites.

Albrecht, Remy; Gourry, Jean Christophe; Simonnot, Marie-Odile; Leyval, Corinne

2011-11-01

69

Life in the "plastisphere": microbial communities on plastic marine debris.  

PubMed

Plastics are the most abundant form of marine debris, with global production rising and documented impacts in some marine environments, but the influence of plastic on open ocean ecosystems is poorly understood, particularly for microbial communities. Plastic marine debris (PMD) collected at multiple locations in the North Atlantic was analyzed with scanning electron microscopy (SEM) and next-generation sequencing to characterize the attached microbial communities. We unveiled a diverse microbial community of heterotrophs, autotrophs, predators, and symbionts, a community we refer to as the "Plastisphere". Pits visualized in the PMD surface conformed to bacterial shapes suggesting active hydrolysis of the hydrocarbon polymer. Small-subunit rRNA gene surveys identified several hydrocarbon-degrading bacteria, supporting the possibility that microbes play a role in degrading PMD. Some Plastisphere members may be opportunistic pathogens (the authors, unpublished data) such as specific members of the genus Vibrio that dominated one of our plastic samples. Plastisphere communities are distinct from surrounding surface water, implying that plastic serves as a novel ecological habitat in the open ocean. Plastic has a longer half-life than most natural floating marine substrates, and a hydrophobic surface that promotes microbial colonization and biofilm formation, differing from autochthonous substrates in the upper layers of the ocean. PMID:23745679

Zettler, Erik R; Mincer, Tracy J; Amaral-Zettler, Linda A

2013-07-01

70

Acoustic and electrical property changes due to microbial growth and biofilm formation in porous media  

NASA Astrophysics Data System (ADS)

A laboratory study was conducted to investigate the effect of microbial growth and biofilm formation on compressional waves, and complex conductivity during stimulated microbial growth. Over the 29 day duration of the experiment, compressional wave amplitudes and arrival times for the control (nonbiostimulated) sample were observed to be relatively uniform over the scanned 2-D region. However, the biostimulated sample exhibited a high degree of spatial variability in both the amplitude and arrival times, with portions of the sample exhibiting increased attenuation (˜80%) concurrent with an increase in the arrival times, while other portions exhibited decreased attenuation (˜45%) and decreased arrival times. The acoustic amplitude and arrival times changed significantly in the biostimulated column between days 5 and 7 of the experiment, consistent with a peak in the imaginary conductivity (??) values. The ?? response is interpreted as recording the different stages of biofilm development with peak ?? representing maximum biofilm thickness and decreasing ?? representing cell death or detachment. Environmental scanning electron microscope imaging confirmed microbial cell attachment to sand surfaces and showed apparent differences in the morphology of attached biomass between regions of increased and decreased attenuation. The heterogeneity in the elastic properties arises from the differences in the morphology and structure of attached biofilms. These results suggest that combining acoustic imaging and complex conductivity techniques can provide a powerful tool for assessing microbial growth or biofilm formation and the associated changes in porous media, such as those that occur during bioremediation and microbial enhanced oil recovery.

Davis, Caroline A.; Pyrak-Nolte, Laura J.; Atekwana, Estella A.; Werkema, Douglas D.; Haugen, Marisa E.

2010-09-01

71

Potential Antibacterial Activity of Carvacrol-Loaded Poly(DL-lactide-co-glycolide) (PLGA) Nanoparticles against Microbial Biofilm.  

PubMed

The ability to form biofilms contributes significantly to the pathogenesis of many microbial infections, including a variety of ocular diseases often associated with the biofilm formation on foreign materials. Carvacrol (Car.) is an important component of essential oils and recently has attracted much attention pursuant to its ability to promote microbial biofilm disruption. In the present study Car. has been encapsulated in poly(dl-lactide-co-glycolide (PLGA) nanocapsules in order to obtain a suitable drug delivery system that could represent a starting point for developing new therapeutic strategies against biofilm-associated infections, such as improving the drug effect by associating an antimicrobial agent with a biofilm viscoelasticity modifier. PMID:21954343

Iannitelli, Antonio; Grande, Rossella; Di Stefano, Antonio; Di Giulio, Mara; Sozio, Piera; Bessa, Lucinda Janete; Laserra, Sara; Paolini, Cecilia; Protasi, Feliciano; Cellini, Luigina

2011-01-01

72

Characterization of microbial communities during anode biofilm reformation in a two-chambered microbial electrolysis cell (MEC)  

Microsoft Academic Search

GeoChip (II) and single strand conformation polymorphism (SSCP) were used to characterize anode microbial communities of a microbial electrolysis cell (MEC). Biofilm communities, enriched in a two-chamber MEC (R1, 0.6V applied) having a coulombic efficiency (CE) of 35±4% and a hydrogen yield (YH2) of 31±3%, were used as the inoculum for a new reactor (R2). After three months R2 achieved

Wenzong Liu; Aijie Wang; Dan Sun; Nanqi Ren; Yunqing Zhang; Jizhong Zhou

73

Hypersaline microbial systems of sabkhas: examples of life's survival in "extreme" conditions.  

PubMed

Life and living systems need several important factors to establish themselves and to have a continued tradition. In this article the nature of the borderline situation for microbial life under heavy salt stress is analyzed and discussed using the example of biofilms and microbial mats of sabkha systems of the Red Sea. Important factors ruling such environments are described, and include the following: (1) Microbial life is better suited for survival in extremely changing and only sporadically water-supplied environments than are larger organisms (including humans). (2) Microbial life shows extremely poikilophilic adaptation patterns to conditions that deviate significantly from conditions normal for life processes on Earth today. (3) Microbial life adapts itself to such extremely changing and only ephemerally supportive conditions by the capacity of extreme changes (a) in morphology (pleomorphy), (b) in metabolic patterns (poikilotrophy), (c) in survival strategies (poikilophily), and (d) by trapping and enclosing all necessary sources of energy matter in an inwardly oriented diffusive cycle. All this is achieved without any serious attempt at escaping from the extreme and extremely changing conditions. Furthermore, these salt swamp systems are geophysiological generators of energy and material reservoirs recycled over a geological time scale. Neither energy nor material is wasted for propagation by spore formation. This capacity is summarized as poikilophilic and poikilotroph behavior of biofilm or microbial mat communities in salt and irradiationstressed environmental conditions of the sabkha or salt desert type. We use mainly cyanobacteria as an example, although other bacteria and even eukaryotic fungi may exhibit the same potential of living and surviving under conditions usually not suitable for life on Earth. It may, however, be postulated that such poikilophilic organisms are the true candidates for life support and survival under conditions never recorded on Planet Earth. Mars and some planets of other suns may be good candidates to search for life under conditions normally not thought to be favorable for the maintenance of life. PMID:15684726

Krumbein, Wolfgang Elisabeth; Gorbushina, Anna A; Holtkamp-Tacken, Elisabeth

2004-01-01

74

Evaluation of microbial biofilm communities from an Alberta oil sands tailings pond.  

PubMed

Bitumen extraction from the oil sands of Alberta has resulted in millions of cubic meters of waste stored on-site in tailings ponds. Unique microbial ecology is expected in these ponds, which may be key to their bioremediation potential. We considered that direct culturing of microbes from a tailings sample as biofilms could lead to the recovery of microbial communities that provide good representation of the ecology of the tailings. Culturing of mixed species biofilms in vitro using the Calgary Biofilm Device (CBD) under aerobic, microaerobic, and anaerobic growth conditions was successful both with and without the addition of various growth nutrients. Denaturant gradient gel electrophoresis and 16S rRNA gene pyrotag sequencing revealed that unique mixed biofilm communities were recovered under each incubation condition, with the dominant species belonging to Pseudomonas, Thauera, Hydrogenophaga, Rhodoferax, and Acidovorax. This work used an approach that allowed organisms to grow as a biofilm directly from a sample collected of their environment, and the biofilms cultivated in vitro were representative of the endogenous environmental community. For the first time, representative environmental mixed species biofilms have been isolated and grown under laboratory conditions from an oil sands tailings pond environment and a description of their composition is provided. PMID:22029695

Golby, Susanne; Ceri, Howard; Gieg, Lisa M; Chatterjee, Indranil; Marques, Lyriam L R; Turner, Raymond J

2012-01-01

75

The role of microbial biofilms in deterioration of space station candidate materials.  

PubMed

Formation of microbial biofilms on surfaces of a wide range of materials being considered as candidates for use on the International Space Station was investigated. The materials included a fibre-reinforced polymeric composite, an adhesive sealant, a polyimide insulation foam, teflon cable insulation, titanium, and an aliphatic polyurethane coating. They were exposed to a natural mixed population of bacteria under controlled conditions of temperature and relative humidity (RH). Biofilms formed on the surfaces of the materials at a wide range of temperatures and RHs. The biofilm population was dominated by Pseudomonas aeruginosa, Ochrobactrum anthropi, Alcaligenes denitrificans, Xanthomonas maltophila, and Vibrio harveyi. The biocide, diiodomethyl-p-tolyl sulfone, impregnated in the polyurethane coating, was ineffective against microbial colonization and growth. Degradation of the polyurethane coatings was monitored with electrochemical impedance spectroscopy (EIS). The impedance spectra indicated that microbial degradation of the coating occurred in several stages. The initial decreases in impedance were due to the transport of water and solutes into the polymeric matrices. Further decreases were a result of polymer degradation by microorganisms. Our data showed that these candidate materials for space application are susceptible to biofilm formation and subsequent degradation. Our study suggests that candidate materials for use in space missions need to be carefully evaluated for their susceptibility to microbial biofilm formation and biodegradation. PMID:11541393

Gu, J D; Roman, M; Esselman, T; Mitchell, R

1998-01-01

76

Biopolymer and Water Dynamics in Microbial Biofilm Extracellular Polymeric Substance  

PubMed Central

Nuclear magnetic resonance (NMR) is a noninvasive and nondestructive tool able to access several observable quantities in biofilms such as chemical composition, diffusion, and macroscale structure and transport. Pulsed gradient spin echo (PGSE) NMR techniques were used to measure spectrally resolved biomacromolecular diffusion in biofilm biomass, extending previous research on spectrally resolved diffusion in biofilms. The dominant free water signal was nulled using an inversion recovery modification of the traditional PGSE technique in which the signal from free water is minimized in order to view the spectra of components such as the rotationally mobile carbohydrates, DNA, and proteins. Diffusion data for the major constituents obtained from each of these spectral peaks demonstrate that the biomass of the biofilm contains both a fast and slow diffusion component. The dependence of diffusion on antimicrobial and environmental challenges suggests the polymer molecular dynamics measured by NMR are a sensitive indicator of biofilm function.

Hornemann, Jennifer A.; Lysova, Anna A.; Codd, Sarah L.; Seymour, Joseph D.; Busse, Scott C.; Stewart, Philip S.; Brown, Jennifer R.

2008-01-01

77

The study of electrochemically active microbial biofilms on different carbon-based anode materials in microbial fuel cells.  

PubMed

In this communication we show that the achievable maximum current density for mature wastewater-based microbial biofilms is strongly dependent on the electrode material and the operation temperature. On graphite and polycrystalline carbon rods, the catalytic current of about 500 microA cm(-2) (projected surface area) at 30 degrees C was achieved. Carbon fiber veil or carbon-paper based materials, having a large microbially-accessible surface gave a projected current density approximately 40% higher than on graphite rod. In contrast, the biofilm cannot form well on graphite foil. Elevating the temperature from 30 to 40 degrees C increased current density by 80% on graphite rod anodes. Interestingly, the formal potential of the active site (-0.12 V (vs. standard hydrogen electrode (SHE))) is similar to all electrocatalytically active microbial biofilms and to that found for Geobacter sulfurreducens in previous studies. In addition, the real surface area values measured by BET surface area technique cannot provide a reasonable explanation for suitability of an electrode material for the formation of electrochemically active biofilm. PMID:20189793

Liu, Ying; Harnisch, Falk; Fricke, Katja; Schröder, Uwe; Climent, Victor; Feliu, Juan Miguel

2010-05-15

78

Microbial Extremophiles in Aspect of Limits of Life  

NASA Technical Reports Server (NTRS)

During Earth's evolution accompanied by geophysical and climatic changes a number of ecosystems have been formed. These ecosystems differ by the broad variety of physicochemical and biological factors composing our environment. Traditionally, pH and salinity are considered as geochemical extremes, as opposed to the temperature, pressure and radiation that are referred to as physical extremes (Van den Burg, 2003). Life inhabits all possible places on Earth interacting with the environment and within itself (cross species relations). In nature it is very rare when an ecotope is inhabited by a single species. As a rule, most ecosystems contain the functionally related and evolutionarily adjusted communities (consortia and populations). In contrast to the multicellular structure of eukaryotes (tissues, organs, systems of organs, whole organism), the highest organized form of prokaryotic life in nature is the benthic colonization in biofilms and microbial mats. In these complex structures all microbial cells of different species are distributed in space and time according to their functions and to physicochemical gradients that allow more effective system support, self-protection, and energy distribution. In vitro, of course, the most primitive organized structure for bacterial and archaeal cultures is the colony, the size, shape, color, consistency, and other characteristics of which could carry varies specifics on species or subspecies levels. In table 1 all known types of microbial communities are shown (Pikuta et a]., 2005). In deep underground (lithospheric) and deep-sea ecosystems an additional factor - pressure, and irradiation - could also be included in the list of microbial communities. Currently the beststudied ecosystems are: human body (due to the medical importance), and fresh water and marine ecosystems (due to the reason of an environmental safety). For a long time, extremophiles were terra incognita, since the environments with aggressive parameters (compared to the human body temperature, pH, mineralization, and pressure) were considered a priori as a dead zone.

Pikuta, Elena V.; Hoover, Richard B.; Tang, Jane

2007-01-01

79

Unraveling microbial biofilms of importance for food microbiology.  

PubMed

The presence of biofilms is a relevant risk factors in the food industry due to the potential contamination of food products with pathogenic and spoilage microorganisms. The majority of bacteria are able to adhere and to form biofilms, where they can persist and survive for days to weeks or even longer, depending on the microorganism and the environmental conditions. The biological cycle of biofilms includes several developmental phases such as: initial attachment, maturation, maintenance, and dispersal. Bacteria in biofilms are generally well protected against environmental stress, consequently, extremely difficult to eradicate and detect in food industry. In the present manuscript, some techniques and compounds used to control and to prevent the biofilm formation are presented and discussed. Moreover, a number of novel techniques have been recently employed to detect and evaluate bacteria attached to surfaces, including real-time polymerase chain reaction (PCR), DNA microarray and confocal laser scanning microscopy. Better knowledge on the architecture, physiology and molecular signaling in biofilms can contribute for preventing and controlling food-related spoilage and pathogenic bacteria. The present study highlights basic and applied concepts important for understanding the role of biofilms in bacterial survival, persistence and dissemination in food processing environments. PMID:24370864

Winkelströter, Lizziane Kretli; Teixeira, Fernanda Barbosa Dos Reis; Silva, Eliane Pereira; Alves, Virgínia Farias; De Martinis, Elaine Cristina Pereira

2014-07-01

80

Metal concentrations in stream biofilm and sediments and their potential to explain biofilm microbial community structure.  

PubMed

Concentrations of metals associated with sediments have traditionally been analysed to assess the extent of heavy metal contamination in freshwater environments. Stream biofilms present an alternative medium for this assessment which may be more relevant to the risk incurred by stream ecosystems as they are intensively grazed by aquatic organisms at a higher trophic level. Therefore, we investigated zinc, copper and lead concentrations in biofilms and sediments of 23 stream sites variously impacted by urbanisation. Simultaneously, biofilm bacterial and ciliate protozoan community structure was analysed by Automated Ribosomal Intergenic Spacer Analysis and Terminal Restriction Fragment Length Polymorphism, respectively. Statistical analysis revealed that biofilm associated metals explained a greater proportion of the variations observed in bacterial and ciliate communities than did sediment associated-metals. This study suggests that the analysis of metal concentrations in biofilms provide a good assessment of detrimental effects of metal contaminants on aquatic biota. PMID:23202641

Ancion, Pierre-Yves; Lear, Gavin; Dopheide, Andrew; Lewis, Gillian D

2013-02-01

81

Effects of Current Velocity on the Nascent Architecture of Stream Microbial Biofilms  

PubMed Central

Current velocity affected the architecture and dynamics of natural, multiphyla, and cross-trophic level biofilms from a forested piedmont stream. We monitored the development and activity of biofilms in streamside flumes operated under two flow regimes (slow [0.065 m s?1] and fast [0.23 m s?1]) by combined confocal laser scanning microscopy with cryosectioning to observe biofilm structure and composition. Biofilm growth started as bacterial microcolonies embedded in extracellular polymeric substances and transformed into ripple-like structures and ultimately conspicuous quasihexagonal networks. These structures were particularly pronounced in biofilms grown under slow current velocities and were characterized by the prominence of pennate diatoms oriented along their long axes to form the hexagons. Microstructural heterogeneity was dynamic, and biofilms that developed under slower velocities were thicker and had larger surface sinuosity and higher areal densities than their counterparts exposed to higher velocities. Surface sinuosity and biofilm fragmentation increased with thickness, and these changes likely reduced resistance to the mass transfer of solutes from the water column into the biofilms. Nevertheless, estimates of dissolved organic carbon uptake and microbial growth suggested that internal cycling of carbon was more important in thick biofilms grown in slow flow conditions. High-pressure liquid chromatography-pulsed amperometric detection analyses of exopolysaccharides documented a temporal shift in monosaccharide composition as the glucose levels decreased and the levels of rhamnose, galactose, mannose, xylose, and arabinose increased. We attribute this change in chemical composition to the accumulation of diatoms and increased incorporation of detrital particles in mature biofilms.

Battin, Tom J.; Kaplan, Louis A.; Newbold, J. Denis; Cheng, Xianhao; Hansen, Claude

2003-01-01

82

Monitoring of microbial adhesion and biofilm growth using electrochemical impedancemetry  

Microsoft Academic Search

Electrochemical impedance spectroscopy was tested to monitor the cell attachment and the biofilm proliferation in order to\\u000a identify characteristic events induced on the metal surface by Gram-negative (Pseudomonas aeruginosa PAO1) and Gram-positive (Bacillus subtilis) bacteria strains. Electrochemical impedance spectra of AISI 304 electrodes during cell attachment and initial biofilm growth\\u000a for both strains were obtained. It can be observed that

A. Dheilly; I. Linossier; A. Darchen; D. Hadjiev; C. Corbel; V. Alonso

2008-01-01

83

Microbial diversity in biofilms on water distribution pipes of different materials.  

PubMed

The effects of pipe materials on biofilm formation potential (BFP) and microbial communities in biofilms were analyzed. Pipe coupons made of six different materials (CU, copper; CP, chlorinated poly vinyl chloride; PB, polybutylene; PE, polyethylene; SS, stainless steel; ST, steel coated with zinc) were incubated in drinking water, mixed water (inoculated with 10% (v/v) of river water) and drinking water inoculated with Escherichia coli JM109 (E. coli), respectively. The highest BFPs were observed from steel pipes, SS and ST, while CU showed the lowest BFP values. Of the plastic materials, the BFP of CP in drinking water (96 pg ATP/cm(2)) and mixed water (183 pg ATP/cm(2)) were comparable to those of CU, but the other plastic materials, PB and PE, displayed relatively high BFP. The Number of E. coli in the drinking water inoculated with cultures of E. coli strain showed similar trends with BFP values of the pipe coupons incubated in drinking water and mixed water. Molecular analysis of microbial communities indicated the presence of alpha- and beta-proteobacteria, actinobacteria and bacteroidetes in biofilm on the pipe materials. However, the DGGE profile of bacterial 16S rDNA fragments showed significant differences among different materials, suggesting that the pipe materials affect not only BFP but also microbial diversity. Some plastic materials, such as CP, would be suitable for plumbing, particularly for drinking water distribution pipes, due to its low BFP and little microbial diversity in biofilm. PMID:20057102

Yu, J; Kim, D; Lee, T

2010-01-01

84

Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice  

Microsoft Academic Search

Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on

JAMES T. WALKER; DAVID J. BRADSHAW; ALLAN M. BENNETT; MARTIN R. FULFORD; MICHAEL V. MARTIN; PHILIP D. MARSH

2000-01-01

85

Initial development and structure of biofilms on microbial fuel cell anodes  

Microsoft Academic Search

BACKGROUND: Microbial fuel cells (MFCs) rely on electrochemically active bacteria to capture the chemical energy contained in organics and convert it to electrical energy. Bacteria develop biofilms on the MFC electrodes, allowing considerable conversion capacity and opportunities for extracellular electron transfer (EET). The present knowledge on EET is centred around two Gram-negative models, i.e. Shewanella and Geobacter species, as it

Suzanne T Read; Paritam Dutta; Phillip L Bond; Jürg Keller; Korneel Rabaey

2010-01-01

86

Microbial degradation of acetonitrile using a suspended-carrier biofilm process  

Microsoft Academic Search

A microbial process for the destruction of acetonitrile has been developed. Suitable microorganisms were enriched from activated sludge by cultivation with a high selection pressure when acetonitrile was the sole source of carbon and nitrogen. The process is based on cultivating the microorganisms as a biofilm on plastic carriers. These are utilised in a stirred-tank reactor with continuous feeding of

Kristina Håkansson; Bo Mattiasson

2002-01-01

87

The role of microbial biofilms in deterioration of space station candidate materials  

Microsoft Academic Search

Formation of microbial biofilms on surfaces of a wide range of materials being considered as candidates for use on the International Space Station was investigated. The materials included a fibre-reinforced polymeric composite, an adhesive sealant, a polyimide insulation foam, teflon cable insulation, titanium, and an aliphatic polyurethane coating. They were exposed to a natural mixed population of bacteria under controlled

Ji-Dong Gu; Monsi Roman; Thomas Esselman; Ralph Mitchell

1998-01-01

88

Homogeneity and Synchronous Dynamics of Microbial Communities in Particulate Biofilms: from Major Populations to Minor Groups  

PubMed Central

Natural or engineered microbial populations often show variations over time. These variations may be due to environmental fluctuations or intrinsic factors. Thus, studying the dynamics of microbial diversity for different communities living in a spatially homogeneous landscape is of interest. As a model ecosystem, nitrifying biofilm communities were grown in a two litre inverse turbulent bed reactor (ITBR) containing an estimated 200 million small particles (about 150 ?m in diameter). Each particulate biofilm is considered as a distinct community growing in the neighborhood of other similar particles, in a homogeneous and well-controlled environmental context. A molecular approach was adopted to test how microbial community structures might evolve: either in synchrony, converging or diverging. The shape of biofilm was observed by microscopy for each particle. The biomass content was evaluated by quantitative PCR and showed similar values for each particle. The microbial community structure was evaluated by Capillary Electrophoresis-Single Strand Conformation Polymorphism (CE-SSCP) fingerprinting and showed extraordinary homogeneity between particles, even though transitory community structures were observed when reactor operating conditions were modified. This homogeneity was observed for the Bacteria primer set but, more interestingly, was also observed when minor non-nitrifying bacteria making up the biofilm, representing about 5% and 10% of total cells, were targeted.

Gevaudan, Gaelle; Hamelin, Jerome; Dabert, Patrick; Godon, Jean-Jacques; Bernet, Nicolas

2012-01-01

89

Soil microbial growth and biofilm expansion assessment under wastewater infiltration percolation treatment process: column experiments  

Microsoft Academic Search

The current work tackles the problem of soil microbial growth and biofilm expansion assessment in infiltration percolation process in order to optimize the technique design and monitoring. Experiments were conducted on a sand filled PVC column fed at a pulsed rhythm of 8 sequences per day in order to maximize the soil aeration that generates a better oxygen renewal in

Asma Ben Rajeb; Hamadi Kallali; Nadhira Ben Aissa; Olfa Bouzaiene; Salah Jellali; Naceur Jedidi; Abdennaceur Hassen

2009-01-01

90

Microbial extremophiles at the limits of life.  

PubMed

Prokaryotic extremophiles were the first representatives of life on Earth and they are responsible for the genesis of geological structures during the evolution and creation of all currently known ecosystems. Flexibility of the genome probably allowed life to adapt to a wide spectrum of extreme environments. As a result, modern prokaryotic diversity formed in a framework of physico-chemical factors, and it is composed of: thermophilic, psychrophilic, acidophilic, alkaliphilic, halophilic, barophilic, and radioresistant species. This artificial systematics cannot reflect the multiple actions of different environmental factors since one organism could unite characteristics of several extreme-groups. In this review we show the current status of studies in all fields of extremophiles and summarize the limits of life for different species of microbial extremophiles. We also discuss the finding of extremophiles from unusual places such as soils, and briefly review recent studies of microfossils in meteorites in the context of the significance of microbial extremophiles to Astrobiology. PMID:17653987

Pikuta, Elena V; Hoover, Richard B; Tang, Jane

2007-01-01

91

Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs  

PubMed Central

Background Mineralized and permineralized bone is the most common form of fossilization in the vertebrate record. Preservation of gross soft tissues is extremely rare, but recent studies have suggested that primary soft tissues and biomolecules are more commonly preserved within preserved bones than had been presumed. Some of these claims have been challenged, with presentation of evidence suggesting that some of the structures are microbial artifacts, not primary soft tissues. The identification of biomolecules in fossil vertebrate extracts from a specimen of Brachylophosaurus canadensis has shown the interpretation of preserved organic remains as microbial biofilm to be highly unlikely. These discussions also propose a variety of potential mechanisms that would permit the preservation of soft-tissues in vertebrate fossils over geologic time. Methodology/Principal Findings This study experimentally examines the role of microbial biofilms in soft-tissue preservation in vertebrate fossils by quantitatively establishing the growth and morphology of biofilms on extant archosaur bone. These results are microscopically and morphologically compared with soft-tissue extracts from vertebrate fossils from the Hell Creek Formation of southeastern Montana (Latest Maastrichtian) in order to investigate the potential role of microbial biofilms on the preservation of fossil bone and bound organic matter in a variety of taphonomic settings. Based on these analyses, we highlight a mechanism whereby this bound organic matter may be preserved. Conclusions/Significance Results of the study indicate that the crystallization of microbial biofilms on decomposing organic matter within vertebrate bone in early taphonomic stages may contribute to the preservation of primary soft tissues deeper in the bone structure.

Peterson, Joseph E.; Lenczewski, Melissa E.; Scherer, Reed P.

2010-01-01

92

A personal history of research on microbial biofilms and biofilm infections.  

PubMed

The observation of aggregated microorganisms surrounded by a self-produced matrix adhering to surfaces or located in tissues or secretions is as old as microbiology, with both Leeuwenhoek and Pasteur describing the phenomenon. In environmental and technical microbiology, biofilms were already shown 80-90 years ago to be important for biofouling on submerged surfaces, e.g. ships. The concept of biofilm infections and their importance in medicine is, however, < 40 years old and was started by Jendresen's observations of aquired dental pellicles and my own observations of heaps of Pseudomonas aeruginosa cells in sputum and lung tissue from chronically infected cystic fibrosis patients. The term biofilm was introduced into medicine in 1985 by Costerton. In the following decades, it became obvious that biofilm infections are widespread in medicine, and their importance is now generally accepted. PMID:24585728

Høiby, Niels

2014-04-01

93

Microbial biofilm modulation by ultrasound: current concepts and controversies.  

PubMed

Biofilm elimination is often necessary during antimicrobial therapy or industrial medical manufacturing decontamination. In this context, ultrasound treatment has been frequently described in the literature for its antibiofilm effectiveness, but at the same time, various authors have described ultrasound as a formidable enhancer of bacterial viability. This discrepancy has found no solution in the current literature for around 9 years; some works have shown that every time bacteria are exposed to an ultrasonic field, both destruction and stimulation phenomena co-exist. This co-existence proves to have different final effects based on various factors such as: ultrasound frequency and intensity, the bacterial species involved, the material used for ultrasound diffusion, the presence of cavitation effects and the forms of bacterial planktonic or biofilm. The aim of this work is to analyze current concepts regarding ultrasound effect on prokaryotic cells, and in particular ultrasound activity on bacterial biofilm. PMID:23751458

Erriu, Matteo; Blus, Cornelio; Szmukler-Moncler, Serge; Buogo, Silvano; Levi, Raffaello; Barbato, Giulio; Madonnaripa, Daniele; Denotti, Gloria; Piras, Vincenzo; Orrù, Germano

2014-01-01

94

Characterization of microbial communities during anode biofilm reformation in a two-chambered microbial electrolysis cell (MEC).  

PubMed

GeoChip (II) and single strand conformation polymorphism (SSCP) were used to characterize anode microbial communities of a microbial electrolysis cell (MEC). Biofilm communities, enriched in a two-chamber MEC (R1, 0.6 V applied) having a coulombic efficiency (CE) of 35±4% and a hydrogen yield (Y(H?))of 31±3%, were used as the inoculum for a new reactor (R2). After three months R2 achieved stable performance with CE=38±4% and (Y(H?)). Few changes in the predominant populations were observed from R1 to R2. Unlike sludge inoculation process in R1 in the beginning, little further elimination was aroused by community competitions in anode biofilm reformation in R2. Functional genes detection of biofilm indicated that cytochrome genes enriched soon in new reactor R2, and four genera (Desulfovibrio, Rhodopseudomonas, Shewanella and Geobacter) were likely to contribute to exoelectrogenic activity. This work also implied that symbiosis of microbial communities (exoelectrogens and others) contribute to system performance and stability. PMID:21939699

Liu, Wenzong; Wang, Aijie; Sun, Dan; Ren, Nanqi; Zhang, Yunqing; Zhou, Jizhong

2012-02-20

95

Microbial Community Composition and Dynamics of Moving Bed Biofilm Reactor Systems Treating Municipal Sewage  

PubMed Central

Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems.

Turner, Susan J.

2012-01-01

96

Methods for Observing Microbial Biofilms Directly on Leaf Surfaces and Recovering Them for Isolation of Culturable Microorganisms  

PubMed Central

Epifluorescence microscopy, scanning electron microscopy, and confocal laser scanning microscopy were used to observe microbial biofilms directly on leaf surfaces. Biofilms were observed on leaves of all species sampled (spinach, lettuce, Chinese cabbage, celery, leeks, basil, parsley, and broad-leaved endive), although the epifluorescent images were clearest when pale green tissue or cuticle pieces were used. With these techniques, biofilms were observed that were about 20 (mu)m in depth and up to 1 mm in length and that contained copious exopolymeric matrices, diverse morphotypes of microorganisms, and debris. The epifluorescence techniques described here can be used to rapidly determine the abundance and localization of biofilms on leaves. An additional technique was developed to recover individual biofilms or portions of single biofilms from leaves and to disintegrate them for isolation of the culturable microorganisms they contained. Nineteen biofilms from broad-leaved endive, spinach, parsley, and olive leaves were thus isolated and characterized to illustrate the applications of this technique.

Morris, C. E.; Monier, J.; Jacques, M.

1997-01-01

97

Growth dynamic of Naegleria fowleri in a microbial freshwater biofilm.  

PubMed

The presence of pathogenic free-living amoebae (FLA) such as Naegleria fowleri in freshwater environments is a potential public health risk. Although its occurrence in various water sources has been well reported, its presence and associated factors in biofilm remain unknown. In this study, the density of N. fowleri in biofilms spontaneously growing on glass slides fed by raw freshwater were followed at 32 °C and 42 °C for 45 days. The biofilms were collected with their substrata and characterized for their structure, numbered for their bacterial density, thermophilic free-living amoebae, and pathogenic N. fowleri. The cell density of N. fowleri within the biofilms was significantly affected both by the temperature and the nutrient level (bacteria/amoeba ratio). At 32 °C, the density remained constantly low (1-10 N. fowleri/cm(2)) indicating that the amoebae were in a survival state, whereas at 42 °C the density reached 30-900 N. fowleri/cm(2) indicating an active growth phase. The nutrient level, as well, strongly affected the apparent specific growth rate (?) of N. fowleri in the range of 0.03-0.23 h(-1). At 42 °C a hyperbolic relationship was found between ? and the bacteria/amoeba ratio. A ratio of 10(6) to 10(7) bacteria/amoeba was needed to approach the apparent ?(max) value (0.23 h(-1)). Data analysis also showed that a threshold for the nutrient level of close to 10(4) bacteria/amoeba is needed to detect the growth of N. fowleri in freshwater biofilm. This study emphasizes the important role of the temperature and bacteria as prey to promote not only the growth of N. fowleri, but also its survival. PMID:22695355

Goudot, Sébastien; Herbelin, Pascaline; Mathieu, Laurence; Soreau, Sylvie; Banas, Sandrine; Jorand, Frédéric

2012-09-01

98

Characterization of microbial community in an aerobic moving bed biofilm reactor applied for simultaneous nitrification and denitrification  

Microsoft Academic Search

A continuous-flow moving bed biofilm reactor (MBBR) under aerobic conditions was established for simultaneous nitrification\\u000a and denitrification (SND), and microbial communities were investigated by a combination of denaturing gel gradient electrophoresis\\u000a (DGGE) and fluorescence in situ hybridization (FISH). DGGE analysis has revealed more similar microbial community structures\\u000a formed in the biofilms with more similar carbon nitrogen (C\\/N) ratios. FISH analysis

Bo FuXiaoyi; Xiaoyi Liao; Lili Ding; Hongqiang Ren

2010-01-01

99

Biofilms and biofilm reactors. (Latest citations from the Life Sciences Collection database). Published Search  

SciTech Connect

The bibliography contains citations concerning the formation and characterization of biofilms. Biofilms occur in fermentation, wastewater treatment, packed-bed reactors, fluidized-bed reactors, medical prostheses, fouling, biomass reactors, waste supply systems, and other aquatic systems. Topics include microorganism makeup of biofilms, controlling biofilm formation, biological and chemical properties, model studies, kinetic studies, and biofilm identification and detection. (Contains a minimum of 209 citations and includes a subject term index and title list.)

Not Available

1993-05-01

100

Extracellular Polysaccharides in Microbial Biofilm and Their Influence on the Electrophoretic Properties of Microbial Cells  

Microsoft Academic Search

\\u000a The surfaces of biofilm-positive microorganisms are usually covered with biofilm-specific extracellular polysaccharide substances\\u000a that play a key role in a biofilm formation and function [1,2]. The presence of this substance on the surface can affect the physicochemical properties of the bacterial cell, including\\u000a the cell-surface hydrophobicity and surface charge. The differences in the surface charges lead to the different isoelectric

Filip Ruzicka; Marie Horka; Veronika Hola

101

Metagenome analyses of corroded concrete wastewater pipe biofilms reveal a complex microbial system  

PubMed Central

Background Concrete corrosion of wastewater collection systems is a significant cause of deterioration and premature collapse. Failure to adequately address the deteriorating infrastructure networks threatens our environment, public health, and safety. Analysis of whole-metagenome pyrosequencing data and 16S rRNA gene clone libraries was used to determine microbial composition and functional genes associated with biomass harvested from crown (top) and invert (bottom) sections of a corroded wastewater pipe. Results Taxonomic and functional analysis demonstrated that approximately 90% of the total diversity was associated with the phyla Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. The top (TP) and bottom pipe (BP) communities were different in composition, with some of the differences attributed to the abundance of sulfide-oxidizing and sulfate-reducing bacteria. Additionally, human fecal bacteria were more abundant in the BP communities. Among the functional categories, proteins involved in sulfur and nitrogen metabolism showed the most significant differences between biofilms. There was also an enrichment of genes associated with heavy metal resistance, virulence (protein secretion systems) and stress response in the TP biofilm, while a higher number of genes related to motility and chemotaxis were identified in the BP biofilm. Both biofilms contain a high number of genes associated with resistance to antibiotics and toxic compounds subsystems. Conclusions The function potential of wastewater biofilms was highly diverse with level of COG diversity similar to that described for soil. On the basis of the metagenomic data, some factors that may contribute to niche differentiation were pH, aerobic conditions and availability of substrate, such as nitrogen and sulfur. The results from this study will help us better understand the genetic network and functional capability of microbial members of wastewater concrete biofilms.

2012-01-01

102

Microbial Biofilm Voltammetry: Direct Electrochemical Characterization of Catalytic Electrode-Attached Biofilms  

Microsoft Academic Search

While electrochemical characterization of enzymes immobilized on electrodes has become common, there is still a need for reliable quantitative methods for study of electron transfer between living cells and conductive surfaces. This work describes growth of thin (<20 m) Geobacter sulfurreducens biofilms on polished glassy carbon electrodes, using stirred three-electrode anaerobic bioreactors controlled by potentiostats and nonde- structive voltammetry techniques

Enrico Marsili; Janet B. Rollefson; Daniel B. Baron; Raymond M. Hozalski; Daniel R. Bond

2008-01-01

103

Photosynthetic solar cell using nanostructured proton exchange membrane for microbial biofilm prevention.  

PubMed

Unwanted biofilm formation has a detrimental effect on bioelectrical energy harvesting in microbial cells. This issue still needs to be solved for higher power and longer durability and could be resolved with the help of nanoengineering in designing and manufacturing. Here, we demonstrate a photosynthetic solar cell (PSC) that contains a nanostructure to prevent the formation of biofilm by micro-organisms. Nanostructures were fabricated using nanoimprint lithography, where a film heater array system was introduced to precisely control the local wall temperature. To understand the heat and mass transfer phenomena behind the manufacturing and energy harvesting processes of PSC, we carried out a numerical simulation and experimental measurements. It revealed that the nanostructures developed on the proton exchange membrane enable PSC to produce enhanced output power due to the retarded microbial attachment on the Nafion membrane. We anticipate that this strategy can provide a pathway where PSC can ensure more renewable, sustainable, and efficient energy harvesting performance. PMID:24840499

Lee, Dong Hyun; Oh, Hwa Jin; Bai, Seoung Jae; Song, Young Seok

2014-06-24

104

Characteristics of the photosynthesis microbial fuel cell with a Spirulina platensis biofilm.  

PubMed

A novel design of a photosynthetic microbial fuel cell (PMFC) is constructed. It is a membrane-less and mediator-free apparatus with a gilding gold mesh as an anode and a graphite carbon cloth as a cathode. The electrode spacing is 4 cm. Spirulina platensis is aggregated and deposited on the anode to form a thin biofilm. Results show that the chlorophyll (Chl) content of the biofilm attributed the PMFC's electricity performance. The open circuit voltage (OCV) reading of PMFC is proportional to Chl content when the Chl was below 0.5mg. The maximal OCV of PMFC is 0.49 V. When the PMFC was connected to an external resistance of 1 k?, a maximum power density of 10 mW m(-2) was obtained. This designed PMFC yielded competitively high OCV and power density as compared to other microbial fuel cells reported in the literature. PMID:23186678

Lin, Chia-Chi; Wei, Chih-Hsun; Chen, Chih-I; Shieh, Chwen-Jen; Liu, Yung-Chuan

2013-05-01

105

Characterization of microbial biofilms in a thermophilic biogas system by high-throughput metagenome sequencing.  

PubMed

DNAs of two biofilms of a thermophilic two-phase leach-bed biogas reactor fed with rye silage and winter barley straw were sequenced by 454-pyrosequencing technology to assess the biofilm-based microbial community and their genetic potential for anaerobic digestion. The studied biofilms matured on the surface of the substrates in the hydrolysis reactor (HR) and on the packing in the anaerobic filter reactor (AF). The classification of metagenome reads showed Clostridium as most prevalent bacteria in the HR, indicating a predominant role for plant material digestion. Notably, insights into the genetic potential of plant-degrading bacteria were determined as well as further bacterial groups, which may assist Clostridium in carbohydrate degradation. Methanosarcina and Methanothermobacter were determined as most prevalent methanogenic archaea. In consequence, the biofilm-based methanogenesis in this system might be driven by the hydrogenotrophic pathway but also by the aceticlastic methanogenesis depending on metabolite concentrations such as the acetic acid concentration. Moreover, bacteria, which are capable of acetate oxidation in syntrophic interaction with methanogens, were also predicted. Finally, the metagenome analysis unveiled a large number of reads with unidentified microbial origin, indicating that the anaerobic degradation process may also be conducted by up to now unknown species. PMID:22126587

Rademacher, Antje; Zakrzewski, Martha; Schlüter, Andreas; Schönberg, Mandy; Szczepanowski, Rafael; Goesmann, Alexander; Pühler, Alfred; Klocke, Michael

2012-03-01

106

Molecular techniques revealed highly diverse microbial communities in natural marine biofilms on polystyrene dishes for invertebrate larval settlement.  

PubMed

Biofilm microbial communities play an important role in the larval settlement response of marine invertebrates. However, the underlying mechanism has yet to be resolved, mainly because of the uncertainties in characterizing members in the communities using traditional 16S rRNA gene-based molecular methods and in identifying the chemical signals involved. In this study, pyrosequencing was used to characterize the bacterial communities in intertidal and subtidal marine biofilms developed during two seasons. We revealed highly diverse biofilm bacterial communities that varied with season and tidal level. Over 3,000 operational taxonomic units with estimates of up to 8,000 species were recovered in a biofilm sample, which is by far the highest number recorded in subtropical marine biofilms. Nineteen phyla were found, of which Cyanobacteria and Proteobacteria were the most dominant one in the intertidal and subtidal biofilms, respectively. Apart from these, Actinobacteria, Bacteroidetes, and Planctomycetes were the major groups recovered in both intertidal and subtidal biofilms, although their relative abundance varied among samples. Full-length 16S rRNA gene clone libraries were constructed for the four biofilm samples and showed similar bacterial compositions at the phylum level to those revealed by pyrosequencing. Laboratory assays confirmed that cyrids of the barnacle Balanus amphitrite preferred to settle on the intertidal rather than subtidal biofilms. This preference was independent of the biofilm bacterial density or biomass but was probably related to the biofilm community structure, particularly, the Proteobacterial and Cyanobacterial groups. PMID:24402362

Lee, On On; Chung, Hong Chun; Yang, Jiangke; Wang, Yong; Dash, Swagatika; Wang, Hao; Qian, Pei-Yuan

2014-07-01

107

Microbial communities in deep Canadian shield groundwaters—an in situ biofilm experiment  

Microsoft Academic Search

Microbial biofilm communities were cultivated on stainless steel and polypropylene surfaces within brine?filled exploration boreholes in crystalline rocks of the Canadian Shield at Kidd Creek Mine (Timmins, Ontario) and Copper Cliff South Mine (Sudbury, Ontario) at depths of 1402 m and 1219 m, respectively. The calcium?sodium?chloride brines were acidic (pH 3.5–4.8) and had temperatures of 23.4°C to 18.6°C. Direct microscopic

F. Doig; B. Sherwood Lollar; F. G. Ferris

1995-01-01

108

Biofilms.  

PubMed

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. PMID:20519345

López, Daniel; Vlamakis, Hera; Kolter, Roberto

2010-07-01

109

Analysis of microbial community during biofilm development in an anaerobic wastewater treatment reactor.  

PubMed

The formation, structure, and biodiversity of a multispecies anaerobic biofilm inside an Upflow Anaerobic Sludge Bed (UASB) reactor fed with brewery wastewater was examined using complementary microbial ecology methods such us fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), and cloning. The biofilm development can be roughly divided into three stages: an initial attachment phase (0-36 h) characterized by random adhesion of the cells to the surface; a consolidation phase (from 36 h to 2 weeks) defined by the appearance of microcolonies; and maturation phase (from 2 weeks to 2 months). During the consolidation period, proteobacteria with broad metabolic capabilities, mainly represented by members of alpha-Proteobacteria class (Oleomonas, Azospirillum), predominated. Beta-, gamma-, delta- (both syntrophobacteria and sulfate-reducing bacteria) and epsilon- (Arcobacter sp.) Proteobacteria were also noticeable. Archaea first appeared during the consolidation period. A Methanospirillum-like methanogen was detected after 36 h, and this was followed by the detection of Methanosarcina, after 4 days of biofilm development. The mature biofilm displayed a hill and valley topography with cells embedded in a matrix of exopolymers where the spatial distribution of the microorganisms became well-established. Compared to the earlier phases, the biodiversity had greatly increased. Although alpha-Proteobacteria remained as predominant, members of the phyla Firmicutes, Bacteroidete, and Thermotogae were also detected. Within the domain Archaea, the acetoclastic methanogen Methanosaeta concilii become dominant. This study provides insights on the trophic web and the shifts in population during biofilm development in an UASB reactor. PMID:18034358

Fernández, Nuria; Díaz, Emiliano Enrique; Amils, Ricardo; Sanz, José L

2008-07-01

110

Microbial community structure and metabolic property of biofilms in vermifiltration for liquid-state sludge stabilization using PLFA profiles.  

PubMed

To investigate effects of earthworms on microbial community structure and metabolic properties of biofilms in vermifiltration for liquid-state sludge stabilization, a vermifilter (VF) with earthworms and a conventional biofilter (BF) without earthworms were compared. The Shannon index of fungi in VF was 16% higher than that in BF, which indicated earthworm activities significantly enhanced fungi diversity. The ratio of monounsaturated to saturated (mono:sat) PLFAs of VF biofilms was higher than that of BF biofilms, which indicated the physiological and nutritional stress for microbial community in VF was relieved due to the increasing of soluble substances caused by the earthworm ingestion. Further investigation showed that the burrowing action of earthworms promoted the aeration condition and led to aerobic microorganisms were predominant in VF. Those results indicated earthworms improved microbial community structure and metabolic properties of biofilms and thus resulted in the overall optimization of the vermifiltration system for liquid-state sludge stabilization. PMID:24262843

Zhao, Chunhui; Xing, Meiyan; Yang, Jian; Lu, Yongsen; Lv, Baoyi

2014-01-01

111

Evaluation of Sterilox for controlling microbial biofilm contamination of dental water.  

PubMed

The purpose of the investigation was to evaluate the effectiveness of Sterilox, a sterilizing unit that produces a hydrochlorous acid solution that controls microbial contamination as well as reduces biofilms and endotoxin in dental unit waterlines (DUWLs). A total of 15 dental units were used: 10 in the Sterilox group and 5 in the control group (treatment with Bio2000). Distilled water was used as source water. Samples were collected at the baseline, 1-day, and 1, 2, 4, and 8 weeks. A scanning electron microscope was used to evaluate the biofilm in dental tubing before and after the treatment. The content of endotoxin was analyzed using the Chromogenic Limulus Method. The baseline CFU revealed high microbial counts (> 39,000 CFU/mL) in all DUWLs. After the treatment and throughout the study, the Sterilox practically eliminated the CFU in the waterlines, while the control group remained at high CFU counts similar to the baseline values. The differences between the 2 groups were significant (P < .05). The endotoxin analysis of the DUWL samples indicated that the average amount of endotoxin per milliliter increased immediately after the Sterilox shock treatment, indicating the lysis of gram-negative bacteria. Endotoxin content then quickly declined and remained at an acceptable level throughout the study Endotoxin in controls fluctuated in higher levels. It was concluded that Sterilox is effective at controlling microbial contamination and reducing biofilms and endotoxin in DUWLs. PMID:18064783

Zhang, Wu; Onyango, Omari; Lin, Zhi; Lee, Sean S; Li, Yiming

2007-11-01

112

Effect of Coffea canephora aqueous extract on microbial counts in ex vivo oral biofilms: a case study.  

PubMed

In the present study, the ex vivo antimicrobial effect of brewed coffee was tested on oral biofilms. For this, unsweetened and sweetened (10 % sucrose) brewed light-roasted Coffea canephora at 20 % was used in biofilms formed by non-stimulated saliva from three volunteers. After 30 min contact with unsweetened and sweetened brews, the average microorganism count in the biofilms reduced by 15.2 % and 12.4 %, respectively, with no statistical difference among them. We also observed a drop of microorganisms in the biofilms after treatment with sucrose solution at 5 % compared to control (saline) and to sucrose at 1 % and 3 %. In conclusion, Coffea canephora extract reduces the microbial count in oral biofilm, and our data suggest that sucrose concentration in coffee brew can influence its antimicrobial property against the referred biofilm. PMID:22532021

Antonio, Andréa Gonçalves; Iorio, Natália Lopes Pontes; Farah, Adriana; Netto dos Santos, Kátia Regina; Maia, Lucianne Cople

2012-05-01

113

Influence of biofilms on microbial contamination in dental unit water.  

PubMed

Water from dental units (DU), used for cooling and clearing the field of dental operations, is frequently contaminated by microorganisms. Retrograde spread of oral microbes into DU tubuing, contaminated plumbing systems and endogenous DU contamination have been implicated. This study investigated the contribution of DU tubing to this contamination in 11 randomly selected DU. The times required, under standardized conditions, for DU bacterial levels to decrease in response to the flushing caused by DU operation, or increase in response to stagnation caused by shutting down the DU, were measured. The DU tubing was then removed and similarly manipulated. The results showed similar bacterial levels and populations in the DU and their corresponding tubes. Sixteen control samples taken from the connecting plumbing system at distant locations, after periods of stagnation which result in DU bacterial contamination, were negative. This suggests the plumbing, in our system, is not an important factor. Thus, DU can endogenously contaminate the water passing through them; their tubes have the potential to generate similar magnitudes of bacterial contamination to that determined from intact DU. Scanning electron microscopy of the tube lumens showed a biofilm, characterized by microorganisms embedded in an amorphous matrix in all cases. This biofilm could act as a reservoir to facilitate rapid recontamination. Further analysis of the data indicates there could be other contributing factors. PMID:1806595

Whitehouse, R L; Peters, E; Lizotte, J; Lilge, C

1991-10-01

114

Metal Interactions with Microbial Biofilms in Acidic and Neutral pH Environments  

PubMed Central

Microbial biofilms were grown on strips of epoxy-impregnated filter paper submerged at four sites in water contaminated with metals from mine wastes. At two sample stations, the water was acidic (pH 3.1); the other sites were in a lake restored to a near neutral pH level by application of a crushed limestone slurry. During a 17-week study period, planktonic bacterial counts increased from 101 to 103 CFU/ml at all sites. Biofilm counts increased rapidly over the first 5 weeks and then leveled to 104 CFU/cm2 in the neutral pH system and 103 CFU/cm2 at the acidic sites. In each case, the biofilms bound Mn, Fe, Ni, and Cu in excess of the amounts adsorbed by control strips covered with nylon filters (pore size, 0.22 ?m) to exclude microbial growth; Co bound under neutral conditions but not under acidic conditions. Conditional adsorption capacity constants, obtained graphically from the data, showed that biofilm metal uptake at a neutral pH level was enhanced by up to 12 orders of magnitude over acidic conditions. Similarly, adsorption strength values were usually higher at elevated pH levels. In thin sections of the biofilms, encapsulated bacterial cells were commonly found enmeshed together in microcolonies. The extracellular polymers often contained iron oxide precipitates which generated weak electron diffraction patterns with characteristic reflections for ferrihydrite (Fe2O3 · H2O) at d equaling 0.15 and 0.25 nm. At neutral pH levels, these deposits incorporated trace amounts of Si and exhibited a granular morphology, whereas acicular crystalloids containing S developed under acidic conditions. Images

Ferris, F. G.; Schultze, S.; Witten, T. C.; Fyfe, W. S.; Beveridge, T. J.

1989-01-01

115

Different biogeographic patterns of prokaryotes and microbial eukaryotes in epilithic biofilms.  

PubMed

Microbial biogeography studies expend much effort in determining whether environmental selection or stochastic processes related to dispersal are more important in shaping community composition. While both types of factors are possibly influential, it is tacitly assumed that protists, or microbial eukaryotes in general, behave biogeographically as prokaryotes because of their small physical size. However, direct evidence for this in exactly the same environment and at the same phylogenetic depth is lacking. In this study, we compared the structure of both prokaryotic and eukaryotic components of microbial communities forming biofilms on mineral substrates in different geographic locations at the level of small-subunit (SSU) rRNA-based operational taxonomic units (OTUs). These microbial communities are subjected to strong environmental selection and contain significant proportions of extremophilic microorganisms adapted to desiccation and UV radiation. We find that the nature of the substrate as well as climatic variables and geography influences microbial community structure. However, constrained correspondence analyses and distance-decay curves showed that, whereas the substrate type was the most significant factor structuring bacterial communities, geographic location was the most influential factor for microbial eukaryote communities. Biological explanations implying a higher dispersal success for bacteria combined with more mobile lifestyles for predatory protists may underlie these different prokaryote versus microbial eukaryote biogeographic patterns. PMID:22686398

Ragon, Marie; Fontaine, Michaël C; Moreira, David; López-García, Purificación

2012-08-01

116

Biofilm formation at warming temperature: acceleration of microbial colonization and microbial interactive effects  

Microsoft Academic Search

River biofilms that grow on wet benthic surface are mainly composed of bacteria, algae, cyanobacteria and protozoa embedded in a polysaccharide matrix. The effects of increased river water temperature on biofilm formation were investigated. A laboratory experiment was designed employing two temperatures (11.1–13.2°C, night–day; 14.7–16.0°C, night–day) and two nutrient levels (0.054 mg P l, 0.75 mg N l; 0.54 mg

Verónica Díaz Villanueva; Thomas Schwartz; Anna M. Romaní

2010-01-01

117

Waste water derived electroactive microbial biofilms: growth, maintenance, and basic characterization.  

PubMed

The growth of anodic electroactive microbial biofilms from waste water inocula in a fed-batch reactor is demonstrated using a three-electrode setup controlled by a potentiostat. Thereby the use of potentiostats allows an exact adjustment of the electrode potential and ensures reproducible microbial culturing conditions. During growth the current production is monitored using chronoamperometry (CA). Based on these data the maximum current density (jmax) and the coulombic efficiency (CE) are discussed as measures for characterization of the bioelectrocatalytic performance. Cyclic voltammetry (CV), a nondestructive, i.e. noninvasive, method, is used to study the extracellular electron transfer (EET) of electroactive bacteria. CV measurements are performed on anodic biofilm electrodes in the presence of the microbial substrate, i.e. turnover conditions, and in the absence of the substrate, i.e. nonturnover conditions, using different scan rates. Subsequently, data analysis is exemplified and fundamental thermodynamic parameters of the microbial EET are derived and explained: peak potential (Ep), peak current density (jp), formal potential (E(f)) and peak separation (?Ep). Additionally the limits of the method and the state-of the art data analysis are addressed. Thereby this video-article shall provide a guide for the basic experimental steps and the fundamental data analysis. PMID:24430581

Gimkiewicz, Carla; Harnisch, Falk

2013-01-01

118

Waste Water Derived Electroactive Microbial Biofilms: Growth, Maintenance, and Basic Characterization  

PubMed Central

The growth of anodic electroactive microbial biofilms from waste water inocula in a fed-batch reactor is demonstrated using a three-electrode setup controlled by a potentiostat. Thereby the use of potentiostats allows an exact adjustment of the electrode potential and ensures reproducible microbial culturing conditions. During growth the current production is monitored using chronoamperometry (CA). Based on these data the maximum current density (jmax) and the coulombic efficiency (CE) are discussed as measures for characterization of the bioelectrocatalytic performance. Cyclic voltammetry (CV), a nondestructive, i.e. noninvasive, method, is used to study the extracellular electron transfer (EET) of electroactive bacteria. CV measurements are performed on anodic biofilm electrodes in the presence of the microbial substrate, i.e. turnover conditions, and in the absence of the substrate, i.e. nonturnover conditions, using different scan rates. Subsequently, data analysis is exemplified and fundamental thermodynamic parameters of the microbial EET are derived and explained: peak potential (Ep), peak current density (jp), formal potential (Ef) and peak separation (?Ep). Additionally the limits of the method and the state-of the art data analysis are addressed. Thereby this video-article shall provide a guide for the basic experimental steps and the fundamental data analysis.

Gimkiewicz, Carla; Harnisch, Falk

2013-01-01

119

Initial development and structure of biofilms on microbial fuel cell anodes  

PubMed Central

Background Microbial fuel cells (MFCs) rely on electrochemically active bacteria to capture the chemical energy contained in organics and convert it to electrical energy. Bacteria develop biofilms on the MFC electrodes, allowing considerable conversion capacity and opportunities for extracellular electron transfer (EET). The present knowledge on EET is centred around two Gram-negative models, i.e. Shewanella and Geobacter species, as it is believed that Gram-positives cannot perform EET by themselves as the Gram-negatives can. To understand how bacteria form biofilms within MFCs and how their development, structure and viability affects electron transfer, we performed pure and co-culture experiments. Results Biofilm viability was maintained highest nearer the anode during closed circuit operation (current flowing), in contrast to when the anode was in open circuit (soluble electron acceptor) where viability was highest on top of the biofilm, furthest from the anode. Closed circuit anode Pseudomonas aeruginosa biofilms were considerably thinner compared to the open circuit anode (30 ± 3 ?m and 42 ± 3 ?m respectively), which is likely due to the higher energetic gain of soluble electron acceptors used. The two Gram-positive bacteria used only provided a fraction of current produced by the Gram-negative organisms. Power output of co-cultures Gram-positive Enterococcus faecium and either Gram-negative organisms, increased by 30-70% relative to the single cultures. Over time the co-culture biofilms segregated, in particular, Pseudomonas aeruginosa creating towers piercing through a thin, uniform layer of Enterococcus faecium. P. aeruginosa and E. faecium together generated a current of 1.8 ± 0.4 mA while alone they produced 0.9 ± 0.01 and 0.2 ± 0.05 mA respectively. Conclusion We postulate that this segregation may be an essential difference in strategy for electron transfer and substrate capture between the Gram-negative and the Gram-positive bacteria used here.

2010-01-01

120

Microbial Life of North Pacific Oceanic Crust  

NASA Astrophysics Data System (ADS)

Information on the microbiology of the deep subsurface is necessary in order to understand the factors controlling the rate and extent of the microbially catalyzed reactions that influence the geophysical properties of these environments. Drilling into 45-Ma oceanic basaltic crust in a deepwater environment during ODP Leg 200 provided a promising opportunity to explore the abundance, diversity and activity of micro-organisms. The combined use of culture-independent molecular phylogenetic analyses and enrichment culture techniques is an advantageous approach in investigating subsurface microbial ecosystems. Enrichment culture methods allow the evaluation of potential activities and functions. Microbiological investigations revealed few aerobic cultivable, in part hitherto unknown, micro-organisms in deep submarine sediments and basaltic lava flows. 16S rDNA sequencing of isolates from sediment revealed the next relatives to be members of the genera Halomonas, Pseudomonas, and Lactobacillus. Within the Pseudomonadaceae the closest relative is Acinetobacter sp., which was isolated from a deep subsurface environment. The next phylogenetical relatives within the Halomonadaceae are bacteria typically isolated from Soda lakes, which are considered as model of early life conditions. Interestingly, not only sediment bacteria could be obtained in pure culture. Aerobic strains could also be successfully isolated from the massive tholeiitic basalt layer at a depth of 76.16 mbsf (46 m below the sediment/basement contact). These particular isolates are gram-positive with low G+C content of DNA, phylogenetically affiliated to the phylum Firmicutes. The closest neighbors are e.g. a marine Bacillus isolated from the Gulf of Mexico and a low G+C gram-positive bacterium, which belongs to the microbial flora in the deepest sea mud of the Mariana Trench, isolated from a depth of 10,897 m. Based on the similarity values, the isolates represent hitherto undescribed species of the deep biosphere. Molecular microbial diversity is currently determined by cloning und comparative 16S rRNA gene analyses. The first results will also be presented. In summary, the low number of isolates, cultivated under aerobic conditions, is in good agreement with the common opinion that most of the bacteria within the deep biosphere are anaerobic. Thus, studies of microbial community structure in solid geological materials are feasible and constitute further evidence that continuing microbiological activity in the challenging exploration of the deep sub-seafloor biosphere environment is absolutely promising.

Schumann, G.; Koos, R.; Manz, W.; Reitner, J.

2003-12-01

121

Microbial diversity of peri-implant biofilms on implant fixed bar and telescopic double crown attachments.  

PubMed

One of the principal problems in oral implantation is inflammation of peri-implant hard and soft tissues caused by bacterial biofilms. The purpose of the present study was to evaluate the microbial diversity of peri-implant biofilms on 2 different implant-anchored attachment types in vivo. Samples of peri-implant sulcus fluid were collected from 8 patients with implant-supported bar attachments and 8 patients with implant-anchored telescopic double crown attachments. Samples of sulcus fluid of the adjacent teeth were also collected from the partially edentulous patients with implant fixed telescopic double crowns. The mixed amplicons of 16S rRNA fragments of different bacterial origins were separated by use of single-strand conformation polymorphism analysis to identify the predominant bacterial genera. With 3.5 ± 2.1 different predominant bacterial genera in the sulcus fluid surrounding implant-supported bar attachments and 6.3 ± 3.1 different predominant genera in the sulcular fluid of implant-anchored double crown attachments, the differences were not statistically significant (P = .11). The microbial diversity in the sulcus fluid surrounding the remaining dentition was similar to that of the implant fixed telescopic attachments (6.3 ± 2.1). Aside from host response and other individual factors, the microbial diversity of peri-implant biofilms seems to be impaired by cofactors such as the possibility of cleaning the implant-supported supraconstructions and the different plaque-retaining sites. Nevertheless, these differences do not lead to statistically significant differences in the microbial diversity of peri-implant plaques. PMID:21332328

Heuer, Wieland; Kettenring, Andreas; Demling, Anton; Stumpp, Sascha Nico; Gellermann, Eva; Winkel, Andreas; Stiesch, Meike

2013-12-01

122

Assessment of Microbial Diversity in Biofilms Recovered from Endotracheal Tubes Using Culture Dependent and Independent Approaches  

PubMed Central

Ventilator-associated pneumonia (VAP) is a common nosocomial infection in mechanically ventilated patients. Biofilm formation is one of the mechanisms through which the endotracheal tube (ET) facilitates bacterial contamination of the lower airways. In the present study, we analyzed the composition of the ET biofilm flora by means of culture dependent and culture independent (16 S rRNA gene clone libraries and pyrosequencing) approaches. Overall, the microbial diversity was high and members of different phylogenetic lineages were detected (Actinobacteria, beta-Proteobacteria, Candida spp., Clostridia, epsilon-Proteobacteria, Firmicutes, Fusobacteria and gamma-Proteobacteria). Culture dependent analysis, based on the use of selective growth media and conventional microbiological tests, resulted in the identification of typical aerobic nosocomial pathogens which are known to play a role in the development of VAP, e.g. Staphylococcus aureus and Pseudomonas aeruginosa. Other opportunistic pathogens were also identified, including Staphylococcus epidermidis and Kocuria varians. In general, there was little correlation between the results obtained by sequencing 16 S rRNA gene clone libraries and by cultivation. Pyrosequencing of PCR amplified 16 S rRNA genes of four selected samples resulted in the identification of a much wider variety of bacteria. The results from the pyrosequencing analysis suggest that these four samples were dominated by members of the normal oral flora such as Prevotella spp., Peptostreptococcus spp. and lactic acid bacteria. A combination of methods is recommended to obtain a complete picture of the microbial diversity of the ET biofilm.

Vandecandelaere, Ilse; Matthijs, Nele; Van Nieuwerburgh, Filip; Deforce, Dieter; Vosters, Peter; De Bus, Liesbet; Nelis, Hans J.; Depuydt, Pieter; Coenye, Tom

2012-01-01

123

Assessment of microbial diversity in biofilms recovered from endotracheal tubes using culture dependent and independent approaches.  

PubMed

Ventilator-associated pneumonia (VAP) is a common nosocomial infection in mechanically ventilated patients. Biofilm formation is one of the mechanisms through which the endotracheal tube (ET) facilitates bacterial contamination of the lower airways. In the present study, we analyzed the composition of the ET biofilm flora by means of culture dependent and culture independent (16 S rRNA gene clone libraries and pyrosequencing) approaches. Overall, the microbial diversity was high and members of different phylogenetic lineages were detected (Actinobacteria, beta-Proteobacteria, Candida spp., Clostridia, epsilon-Proteobacteria, Firmicutes, Fusobacteria and gamma-Proteobacteria). Culture dependent analysis, based on the use of selective growth media and conventional microbiological tests, resulted in the identification of typical aerobic nosocomial pathogens which are known to play a role in the development of VAP, e.g. Staphylococcus aureus and Pseudomonas aeruginosa. Other opportunistic pathogens were also identified, including Staphylococcus epidermidis and Kocuria varians. In general, there was little correlation between the results obtained by sequencing 16 S rRNA gene clone libraries and by cultivation. Pyrosequencing of PCR amplified 16 S rRNA genes of four selected samples resulted in the identification of a much wider variety of bacteria. The results from the pyrosequencing analysis suggest that these four samples were dominated by members of the normal oral flora such as Prevotella spp., Peptostreptococcus spp. and lactic acid bacteria. A combination of methods is recommended to obtain a complete picture of the microbial diversity of the ET biofilm. PMID:22693635

Vandecandelaere, Ilse; Matthijs, Nele; Van Nieuwerburgh, Filip; Deforce, Dieter; Vosters, Peter; De Bus, Liesbet; Nelis, Hans J; Depuydt, Pieter; Coenye, Tom

2012-01-01

124

Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics.  

PubMed

Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration can bring the rapid and long-term suppression of NOB and the onset of the activity of anaerobic ammonium oxidizing bacteria (AnAOB). Real-time quantitative polymerase chain reaction analyses confirmed that such shift in performance was mirrored by a change in population densities, with a very drastic reduction of the NOB?Nitrospira and Nitrobacter and a 10-fold increase in AnAOB numbers. The study of biofilm sections with relevant 16S rRNA fluorescent probes revealed strongly stratified biofilm structures fostering aerobic ammonium oxidizing bacteria (AOB) in biofilm areas close to the membrane surface (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal. PMID:24112350

Pellicer-Nàcher, Carles; Franck, Stéphanie; Gülay, Arda; Ruscalleda, Maël; Terada, Akihiko; Al-Soud, Waleed Abu; Hansen, Martin Asser; Sørensen, Søren J; Smets, Barth F

2014-01-01

125

Analysis of Structural and Physiological Profiles To Assess the Effects of Cu on Biofilm Microbial Communities  

PubMed Central

We investigated the effects of copper on the structure and physiology of freshwater biofilm microbial communities. For this purpose, biofilms that were grown during 4 weeks in a shallow, slightly polluted ditch were exposed, in aquaria in our laboratory, to a range of copper concentrations (0, 1, 3, and 10 ?M). Denaturing gradient gel electrophoresis (DGGE) revealed changes in the bacterial community in all aquaria. The extent of change was related to the concentration of copper applied, indicating that copper directly or indirectly caused the effects. Concomitantly with these changes in structure, changes in the metabolic potential of the heterotrophic bacterial community were apparent from changes in substrate use profiles as assessed on Biolog plates. The structure of the phototrophic community also changed during the experiment, as observed by microscopic analysis in combination with DGGE analysis of eukaryotic microorganisms and cyanobacteria. However, the extent of community change, as observed by DGGE, was not significantly greater in the copper treatments than in the control. Yet microscopic analysis showed a development toward a greater proportion of cyanobacteria in the treatments with the highest copper concentrations. Furthermore, copper did affect the physiology of the phototrophic community, as evidenced by the fact that a decrease in photosynthetic capacity was detected in the treatment with the highest copper concentration. Therefore, we conclude that copper affected the physiology of the biofilm and had an effect on the structure of the communities composing this biofilm.

Massieux, B.; Boivin, M. E. Y.; van den Ende, F. P.; Langenskiold, J.; Marvan, P.; Barranguet, C.; Admiraal, W.; Laanbroek, H. J.; Zwart, G.

2004-01-01

126

Rhodobacteraceae are the key members of the microbial community of the initial biofilm formed in Eastern Mediterranean coastal seawater.  

PubMed

The formation of biofilms and biofouling is a common feature in aquatic environments. The aim of this study was to identify the primary colonizers of biofilm formed in Eastern Mediterranean Coastal water at different seasons and follow early dynamics of biofilm community development. Pre-treated coastal seawater and biofilm samples were collected from six different sampling events of 2 weeks' duration each during 1 year. The microbial community composition and specific abundance were estimated by 16S rRNA gene clone libraries and fluorescence in situ hybridization-confocal laser scanning microscopy (FISH-CLSM), respectively. The biofilm formed over the course of the year was fairly consistent in terms of community composition and overall abundance with the exception of spring season. Alphaproteobacteria (30-70% of total bacteria), in particular Rhodobacteraceae, were the dominant bacteria in the biofilm, regardless of season, followed by Bacteroidetes (5-35%) and Gammaproteobacteria (6-35%). There was a decrease in relative abundance of Alphaproteobacteria and an increase in the abundance of Bacteroidetes between the initial and 2-week-old biofilm. This observation may aid man-made facilities that have to deal with biofilm formation and help the development of appropriate strategies to control those biofilms. PMID:23551015

Elifantz, Hila; Horn, Gilad; Ayon, Meir; Cohen, Yehuda; Minz, Dror

2013-08-01

127

Identification of Biofilm Matrix-Associated Proteins from an Acid Mine Drainage Microbial Community ? †  

PubMed Central

In microbial communities, extracellular polymeric substances (EPS), also called the extracellular matrix, provide the spatial organization and structural stability during biofilm development. One of the major components of EPS is protein, but it is not clear what specific functions these proteins contribute to the extracellular matrix or to microbial physiology. To investigate this in biofilms from an extremely acidic environment, we used shotgun proteomics analyses to identify proteins associated with EPS in biofilms at two developmental stages, designated DS1 and DS2. The proteome composition of the EPS was significantly different from that of the cell fraction, with more than 80% of the cellular proteins underrepresented or undetectable in EPS. In contrast, predicted periplasmic, outer membrane, and extracellular proteins were overrepresented by 3- to 7-fold in EPS. Also, EPS proteins were more basic by ?2 pH units on average and about half the length. When categorized by predicted function, proteins involved in motility, defense, cell envelope, and unknown functions were enriched in EPS. Chaperones, such as histone-like DNA binding protein and cold shock protein, were overrepresented in EPS. Enzymes, such as protein peptidases, disulfide-isomerases, and those associated with cell wall and polysaccharide metabolism, were also detected. Two of these enzymes, identified as ?-N-acetylhexosaminidase and cellulase, were confirmed in the EPS fraction by enzymatic activity assays. Compared to the differences between EPS and cellular fractions, the relative differences in the EPS proteomes between DS1 and DS2 were smaller and consistent with expected physiological changes during biofilm development.

Jiao, Yongqin; D'haeseleer, Patrik; Dill, Brian D.; Shah, Manesh; VerBerkmoes, Nathan C.; Hettich, Robert L.; Banfield, Jillian F.; Thelen, Michael P.

2011-01-01

128

Microbial Biofilm Formation and Contamination of Dental-Unit Water Systems in General Dental Practice  

PubMed Central

Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 105 CFU · ml?1; in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this “viable by BacLight” fraction produced colonies on agar plates. Legionella pneumophila, Mycobacterium spp., Candida spp., and Pseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci and Fusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered “cleaner” than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.

Walker, James T.; Bradshaw, David J.; Bennett, Allan M.; Fulford, Martin R.; Martin, Michael V.; Marsh, Philip D.

2000-01-01

129

Interactions between microbial biofilms and marine fouling algae: a mini review.  

PubMed

Natural and artificial substrata immersed in the marine environment are typically colonized by microorganisms, which may moderate the settlement/recruitment of algal spores and invertebrate larvae of macrofouling organisms. This mini-review summarizes the major interactions occurring between microbial biofilms and marine fouling algae, including their effects on the settlement, growth and morphology of the adult plants. The roles of chemical compounds that are produced by both bacteria and algae and which drive the interactions are reviewed. The possibility of using such bioactive compounds to control macrofouling will be discussed. PMID:24047430

Mieszkin, Sophie; Callow, Maureen E; Callow, James A

2013-01-01

130

Electricity production and microbial biofilm characterization in cellulose-fed microbial fuel cells  

Microsoft Academic Search

Converting biodegradable materials into electricity, microbial fuel cells (MFCs) present a promising technology for renewable energy production in specific applications. Unlike typical soluble substrates that have been used as electron donors in MFC studies, cellulose is unique because it requires a microbial consortium that can metabolize both an insoluble electron donor (cellulose) and electron acceptor (electrode). In this study, electricity

Z. Ren; L. M. Steinberg; J. M. Regan

2008-01-01

131

Human plasma enhances the expression of Staphylococcal microbial surface components recognizing adhesive matrix molecules promoting biofilm formation and increases antimicrobial tolerance In Vitro  

PubMed Central

Background Microbial biofilms have been associated with the development of chronic human infections and represent a clinical challenge given their increased antimicrobial tolerance. Staphylococcus aureus is a major human pathogen causing a diverse range of diseases, of which biofilms are often involved. Staphylococcal attachment and the formation of biofilms have been shown to be facilitated by host factors that accumulate on surfaces. To better understand how host factors enhance staphylococcal biofilm formation, we evaluated the effect of whole human plasma on biofilm formation in clinical isolates of S. aureus and the expression of seven microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) known to be involved in biofilm formation by quantitative real-time PCR. We also evaluated whether plasma augmented changes in S. aureus biofilm morphology and antimicrobial resistance. Results Exposure of clinical isolates of S. aureus to human plasma (10%) within media, and to a lesser extent when coated onto plates, significantly enhanced biofilm formation in all of the clinical isolates tested. Compared to biofilms grown under non-supplemented conditions, plasma-augmented biofilms displayed significant changes in both the biofilm phenotype and cell morphology as determined by confocal scanning laser microscopy (CLSM) and scanning electron microscopy (SEM), respectively. Exposure of bacteria to plasma resulted in a significant fold-increase in MSCRAMM expression in both a time and isolate-dependent manner. Additionally, plasma-augmented biofilms displayed an increased tolerance to vancomycin compared to biofilms grown in non-supplemented media. Conclusions Collectively, these studies support previous findings demonstrating a role for host factors in biofilm formation and provide further insight into how plasma, a preferred growth medium for staphylococcal biofilm formation enhances as well as augments other intrinsic properties of S. aureus biofilms. Consequently, these findings indicate that incorporation of host factors may be necessary to better replicate in vivo conditions and for the best utility of a clinical biofilm assay to evaluate the process of biofilm formation and treatments.

2014-01-01

132

Role of bacterial adhesion in the microbial ecology of biofilms in cooling tower systems.  

PubMed

The fate of the three heterotrophic biofilm forming bacteria, Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. in pilot scale cooling towers was evaluated both by observing the persistence of each species in the recirculating water and the formation of biofilms on steel coupons placed in each cooling tower water reservoir. Two different cooling tower experiments were performed: a short-term study (6 days) to observe the initial bacterial colonization of the cooling tower, and a long-term study (3 months) to observe the ecological dynamics with repeated introduction of the test strains. An additional set of batch experiments (6 days) was carried out to evaluate the adhesion of each strain to steel surfaces under similar conditions to those found in the cooling tower experiments. Substantial differences were observed in the microbial communities that developed in the batch systems and cooling towers. P. aeruginosa showed a low degree of adherence to steel surfaces both in batch and in the cooling towers, but grew much faster than K. pneumoniae and Flavobacterium in mixed-species biofilms and ultimately became the dominant organism in the closed batch systems. However, the low degree of adherence caused P. aeruginosa to be rapidly washed out of the open cooling tower systems, and Flavobacterium became the dominant microorganism in the cooling towers in both the short-term and long-term experiments. These results indicate that adhesion, retention and growth on solid surfaces play important roles in the bacterial community that develops in cooling tower systems. PMID:19177226

Liu, Yang; Zhang, Wei; Sileika, Tadas; Warta, Richard; Cianciotto, Nicholas P; Packman, Aaron

2009-01-01

133

Community structure of microbial biofilms associated with membrane-based water purification processes as revealed using a polyphasic approach  

Microsoft Academic Search

The microbial communities of membrane biofilms occurring in two full-scale water purification processes employing microfiltration (MF) and reverse osmosis (RO) membranes were characterized using a polyphasic approach that employed bacterial cultivation, 16S rDNA clone library and fluorescence in situ hybridization techniques. All methods showed that the a-Proteobacteria was the largest microbial fraction in the samples, followed by the ?-Proteobacteria. This

C.-L. Chen; W.-T. Liu; M.-L. Chong; M.-T. Wong; S. L. Ong; H. Seah; W. J. Ng

2004-01-01

134

Time-course correlation of biofilm properties and electrochemical performance in single-chamber microbial fuel cells  

Microsoft Academic Search

The relationship between anode microbial characteristics and electrochemical parameters in microbial fuel cells (MFCs) was analyzed by time-course sampling of parallel single-bottle MFCs operated under identical conditions. While voltage stabilized within 4days, anode biofilms continued growing during the six-week operation. Viable cell density increased asymptotically, but membrane-compromised cells accumulated steadily from only 9% of total cells on day 3 to

Zhiyong Ren; Ramaraja P. Ramasamy; Susan Red Cloud-Owen; Hengjing Yan; Matthew M. Mench; John M. Regan

2011-01-01

135

Microbial Diversity and Population Structure of Extremely Acidic Sulfur-Oxidizing Biofilms From Sulfidic Caves  

NASA Astrophysics Data System (ADS)

Extremely acidic (pH 0-1) microbial biofilms called snottites form on the walls of sulfidic caves where gypsum replacement crusts isolate sulfur-oxidizing microorganisms from the buffering action of limestone host rock. We investigated the phylogeny and population structure of snottites from sulfidic caves in central Italy using full cycle rRNA methods. A small subunit rRNA bacterial clone library from a Frasassi cave complex snottite sample contained a single sequence group (>60 clones) similar to Acidithiobacillus thiooxidans. Bacterial and universal rRNA clone libraries from other Frasassi snottites were only slightly more diverse, containing a maximum of 4 bacterial species and probably 2 archaeal species. Fluorescence in situ hybridization (FISH) of snottites from Frasassi and from the much warmer Rio Garrafo cave complex revealed that all of the communities are simple (low-diversity) and dominated by Acidithiobacillus and/or Ferroplasma species, with smaller populations of an Acidimicrobium species, filamentous fungi, and protists. Our results suggest that sulfidic cave snottites will be excellent model microbial ecosystems suited for ecological and metagenomic studies aimed at elucidating geochemical and ecological controls on microbial diversity, and at mapping the spatial history of microbial evolutionary events such as adaptations, recombinations and gene transfers.

Jones, D.; Stoffer, T.; Lyon, E. H.; Macalady, J. L.

2005-12-01

136

Impact of initial biofilm growth on the anode impedance of microbial fuel cells.  

PubMed

Electrochemical impedance spectroscopy (EIS) was used to study the behavior of a microbial fuel cell (MFC) during initial biofilm growth in an acetate-fed, two-chamber MFC system with ferricyanide in the cathode. EIS experiments were performed both on the full cell (between cathode and anode) as well as on individual electrodes. The Nyquist plots of the EIS data were fitted with an equivalent electrical circuit to estimate the contributions of various intrinsic resistances to the overall internal MFC impedance. During initial development of the anode biofilm, the anode polarization resistance was found to decrease by over 70% at open circuit and by over 45% at 27 microA/cm(2), and a simultaneous increase in power density by about 120% was observed. The exchange current density for the bio-electrochemical reaction on the anode was estimated to be in the range of 40-60 nA/cm(2) for an immature biofilm after 5 days of closed circuit operation, which increased to around 182 nA/cm(2) after more than 3 weeks of operation and stable performance in an identical parallel system. The polarization resistance of the anode was 30-40 times higher than that of the ferricyanide cathode for the conditions tested, even with an established biofilm. For a two-chamber MFC system with a Nafion 117 membrane and an inter-electrode spacing of 15 cm, the membrane and electrolyte solution dominate the ohmic resistance and contribute to over 95% of the MFC internal impedance. Detailed EIS analyses provide new insights into the dominant kinetic resistance of the anode bio-electrochemical reaction and its influence on the overall power output of the MFC system, even in the high internal resistance system used in this study. These results suggest that new strategies to address this kinetic constraint of the anode bio-electrochemical reactions are needed to complement the reduction of ohmic resistance in modern designs. PMID:18646217

Ramasamy, Ramaraja P; Ren, Zhiyong; Mench, Matthew M; Regan, John M

2008-09-01

137

A modeling and simulation study of the role of suspended microbial populations in nitrification in a biofilm reactor.  

PubMed

Many biological wastewater treatment processes are based on bacterial biofilms, i.e. layered aggregates of microbial populations deposited on surfaces. Detachment and (re-)attachment leads to an exchange of biomass between the biofilm and the surrounding aqueous phase. Traditionally, mathematical models of biofilm processes do not take the contribution of the suspended, non-attached bacteria into account, implicitly assuming that these are negligible due to the relatively small amount of suspended biomass compared to biofilm biomass. In this paper, we present a model for a nitrifying biofilm reactor that explicitly includes both types of biomass. The model is derived by coupling a reactor mass balance for suspended populations and substrates with a full one-dimensional Wanner-Gujer type biofilm model. The complexity of this model, both with respect to mathematical structure and number of parameters, prevents a rigorous analysis of its dynamics, wherefore we study the model numerically.Our investigations show that suspended biomass needs to be considered explicitly in the model if the interests of the study are the details of the nitrification process and its intermediate steps and compounds. However, suspended biomass may be neglected if the primary interests are the overall reactor performance criteria, such as removal rates. Furthermore, it can be expected that changes in the biofilm area, attachment, detachment, and dilution rates are more likely to affect the variables primarily associated with the second step of nitrification, while the variables associated with the first step tend to be more robust. PMID:24307083

Maši?, Alma; Eberl, Hermann J

2014-01-01

138

Workshop Report: Microbial Research: Progress and Potential NSF Microbial Observatories/Life in Extreme Environments  

NSF Publications Database

Microbial Research: Progress and Potential NSF Microbial Observatory/Life in Extreme Environments Principal Investigators? Workshop Sept. 22-24, 2002, Arlington, VA Mary Ann Moran Department of Marine Sciences University of Georgia Sherry L. Cady Department of Geology Portland State University Table of Contents Executive Summary . 11 Box: Working in the Antarctic . 12 Box: Making Culturing Better .

139

Submersible microbial fuel cell sensor for monitoring microbial activity and BOD in groundwater: Focusing on impact of anodic biofilm on sensor applicability.  

PubMed

A sensor, based on a submersible microbial fuel cell (SUMFC), was developed for in situ monitoring of microbial activity and biochemical oxygen demand (BOD) in groundwater. Presence or absence of a biofilm on the anode was a decisive factor for the applicability of the sensor. Fresh anode was required for application of the sensor for microbial activity measurement, while biofilm-colonized anode was needed for utilizing the sensor for BOD content measurement. The current density of SUMFC sensor equipped with a biofilm-colonized anode showed linear relationship with BOD content, to up to 250?mg/L (?233?±?1?mA/m(2) ), with a response time of <0.67?h. This sensor could, however, not measure microbial activity, as indicated by the indifferent current produced at varying active microorganisms concentration, which was expressed as microbial adenosine-triphosphate (ATP) concentration. On the contrary, the current density (0.6?±?0.1 to 12.4?±?0.1?mA/m(2) ) of the SUMFC sensor equipped with a fresh anode showed linear relationship, with active microorganism concentrations from 0 to 6.52?nmol-ATP/L, while no correlation between the current and BOD was observed. It was found that temperature, pH, conductivity, and inorganic solid content were significantly affecting the sensitivity of the sensor. Lastly, the sensor was tested with real contaminated groundwater, where the microbial activity and BOD content could be detected in <3.1?h. The microbial activity and BOD concentration measured by SUMFC sensor fitted well with the one measured by the standard methods, with deviations ranging from 15% to 22% and 6% to 16%, respectively. The SUMFC sensor provides a new way for in situ and quantitative monitoring contaminants content and biological activity during bioremediation process in variety of anoxic aquifers. Biotechnol. Bioeng. © 2011 Wiley Periodicals, Inc. PMID:21557205

Zhang, Yifeng; Angelidaki, Irini

2011-05-01

140

Enhanced current production by Desulfovibrio desulfuricans biofilm in a mediator-less microbial fuel cell.  

PubMed

In this study, a mediator-less microbial fuel cell (MFC) inoculated with a sulfate-reducing bacterium (SBR), Desulfovibrio desulfuricans, was equipped with bare and surface-treated graphite felt electrodes. Electrochemical treatment of the anode surface facilitated biofilm formation on the electrode, resulting in rapid and enhanced current production. The maximum current density of the treated anode was 233±24.2mA/m(2), which was 41% higher than that of the untreated anode. The electron transfer rate also increased from 2.45±0.04 to 3.0±0.02?mol of electrons/mg of protein·min. Biofilm formation on the treated anode was mainly due to the strong hydrogen or peptide bonds between the amide groups of bacterial materials (including cytochrome c) and carboxyl groups formed on the electrodes. These results provide useful information on direct electron transfer by SRB in a mediator-less MFC through cytochrome c and the effects of the electrochemical treatment of electrodes on MFC performance. PMID:24751374

Kang, Christina S; Eaktasang, Numfon; Kwon, Dae-Young; Kim, Han S

2014-08-01

141

Intermittent contact of fluidized anode particles containing exoelectrogenic biofilms for continuous power generation in microbial fuel cells  

NASA Astrophysics Data System (ADS)

Current generation in a microbial fuel cell can be limited by the amount of anode surface area available for biofilm formation, and slow substrate degradation kinetics. Increasing the anode surface area can increase the amount of biofilm, but performance will improve only if the anode material is located near the cathode to minimize solution internal resistance. Here we demonstrate that biofilms do not have to be in constant contact with the anode to produce current in an MFC. Granular activated carbon particles enriched with exoelectrogenic biofilm are fluidized (by stirring) in the anode chamber of the MFC, resulting in only intermittent contact between the particles and the anode current collector. The maximum power density generated is 951 ± 10 mW m-2, compared to 813 ± 2 mW m-2 for the control without stirring (packed bed), and 525 ± 1 mW m-2 in the absence of GAC particles and without stirring. GAC-biofilm particles demonstrate capacitor-like behavior, but achieve nearly constant discharge conditions due to the large number of particles that contact the current collector. These results provide proof of concept for the development of flowable electrode reactors, where anode biofilms can be electrically charged in a separate storage tank and then rapidly discharged in compact anode chambers.

Liu, Jia; Zhang, Fang; He, Weihua; Zhang, Xiaoyuan; Feng, Yujie; Logan, Bruce E.

142

Scanning Transmission X-Ray, Laser Scanning, and Transmission Electron Microscopy Mapping of the Exopolymeric Matrix of Microbial Biofilms  

PubMed Central

Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provided the highest-resolution structural imaging, CLSM provided detailed compositional information when used in conjunction with molecular probes, and STXM provided compositional mapping of macromolecule distributions without the addition of probes. By examining exactly the same region of a sample with combinations of these techniques (STXM with CLSM and STXM with TEM), we demonstrate that this combination of multimicroscopy analysis can be used to create a detailed correlative map of biofilm structure and composition. We are using these correlative techniques to improve our understanding of the biochemical basis for biofilm organization and to assist studies intended to investigate and optimize biofilms for environmental remediation applications.

Lawrence, J. R.; Swerhone, G. D. W.; Leppard, G. G.; Araki, T.; Zhang, X.; West, M. M.; Hitchcock, A. P.

2003-01-01

143

Microbial Life in a Liquid Asphalt Desert  

NASA Astrophysics Data System (ADS)

Pitch Lake in Trinidad and Tobago is a natural asphalt reservoir nourished by pitch seepage, a form of petroleum that consists of mostly asphaltines, from the surrounding oil-rich region. During upward seepage, pitch mixes with mud and gases under high pressure, and the lighter portion evaporates or is volatilized, which produces a liquid asphalt residue characterized by low water activity, recalcitrant carbon substrates, and noxious chemical compounds. An active microbial community of archaea and bacteria, many of them novel strains (particularly from the new Tar ARC groups), totaling a biomass of up to 107 cells per gram, was found to inhabit the liquid hydrocarbon matrix of Pitch Lake. Geochemical and molecular taxonomic approaches revealed diverse, novel, and deeply branching microbial lineages with the potential to mediate anaerobic hydrocarbon degradation processes in different parts of the asphalt column. In addition, we found markers for archaeal methane metabolism and specific gene sequences affiliated with facultative and obligate anaerobic sulfur- and nitrite-oxidizing bacteria. The microbial diversity at Pitch Lake was found to be unique when compared to microbial communities analyzed at other hydrocarbon-rich environments, which included Rancho Le Brea, a natural asphalt environment in California, USA, and an oil well and a mud volcano in Trinidad and Tobago, among other sites. These results open a window into the microbial ecology and biogeochemistry of recalcitrant hydrocarbon matrices and establish the site as a terrestrial analogue for modeling the biotic potential of hydrocarbon lakes such as those found on Saturn's largest moon Titan.

Schulze-Makuch, Dirk; Haque, Shirin; de Sousa Antonio, Marina Resendes; Ali, Denzil; Hosein, Riad; Song, Young C.; Yang, Jinshu; Zaikova, Elena; Beckles, Denise M.; Guinan, Edward; Lehto, Harry J.; Hallam, Steven J.

2011-04-01

144

Pyrosequencing analysis yields comprehensive assessment of microbial communities in pilot-scale two-stage membrane biofilm reactors.  

PubMed

We studied the microbial community structure of pilot two-stage membrane biofilm reactors (MBfRs) designed to reduce nitrate (NO3(-)) and perchlorate (ClO4(-)) in contaminated groundwater. The groundwater also contained oxygen (O2) and sulfate (SO4(2-)), which became important electron sinks that affected the NO3(-) and ClO4(-) removal rates. Using pyrosequencing, we elucidated how important phylotypes of each "primary" microbial group, i.e., denitrifying bacteria (DB), perchlorate-reducing bacteria (PRB), and sulfate-reducing bacteria (SRB), responded to changes in electron-acceptor loading. UniFrac, principal coordinate analysis (PCoA), and diversity analyses documented that the microbial community of biofilms sampled when the MBfRs had a high acceptor loading were phylogenetically distant from and less diverse than the microbial community of biofilm samples with lower acceptor loadings. Diminished acceptor loading led to SO4(2-) reduction in the lag MBfR, which allowed Desulfovibrionales (an SRB) and Thiothrichales (sulfur-oxidizers) to thrive through S cycling. As a result of this cooperative relationship, they competed effectively with DB/PRB phylotypes such as Xanthomonadales and Rhodobacterales. Thus, pyrosequencing illustrated that while DB, PRB, and SRB responded predictably to changes in acceptor loading, a decrease in total acceptor loading led to important shifts within the "primary" groups, the onset of other members (e.g., Thiothrichales), and overall greater diversity. PMID:24917125

Ontiveros-Valencia, Aura; Tang, Youneng; Zhao, He-Ping; Friese, David; Overstreet, Ryan; Smith, Jennifer; Evans, Patrick; Rittmann, Bruce E; Krajmalnik-Brown, Rosa

2014-07-01

145

Enrichment of anodic biofilm inoculated with anaerobic or aerobic sludge in single chambered air-cathode microbial fuel cells.  

PubMed

Aerobic sludge after anaerobic pretreatment and anaerobic sludge were separately used as inoculum to start up air-cathode single-chamber MFCs. Aerobic sludge-inoculated MFCs arrived at 0.27V with a maximum power density of 5.79Wm(-3), while anaerobic sludge-inoculated MFCs reached 0.21V with 3.66Wm(-3). Microbial analysis with DGGE profiling and high-throughput sequencing indicated that aerobic sludge contained more diverse bacterial populations than anaerobic sludge. Nitrospira species dominated in aerobic sludge, while anaerobic sludge was dominated by Desulfurella and Acidithiobacillus species. Microbial community structure and composition in anodic biofilms enriched, respectively from aerobic and anaerobic sludges tended gradually to be similar. Potentially exoelectrogenic Geobacter and Anaeromusa species, biofilm-forming Zoogloea and Acinetobacter species were abundant in both anodic biofilms. This study indicated that aerobic sludge performed better for MFCs startup, and the enrichment of anodic microbial consortium with different inocula but same substrate resulted in uniformity of functional microbial communities. PMID:24973773

Gao, Chongyang; Wang, Aijie; Wu, Wei-Min; Yin, Yalin; Zhao, Yang-Guo

2014-09-01

146

Shifts in the Microbial Community, Nitrifiers and Denitrifiers in the Biofilm in a Full-scale Rotating Biological Contactor.  

PubMed

The objective of this study was to investigate the microbial community shifts, especially nitrifiers and denitrifiers, in the biofilm of two rotating biological contactor (RBC) trains with different running times along the plug flowpath. The microbial consortia were profiled using multiple approaches, including 454 high-throughput sequencing of the V3-V4 region of 16S rRNA gene, clone libraries, and quantitative polymerase chain reaction (qPCR). The results demonstrated that (1) the overall microbial community at different locations had distinct patterns, that is, there were similar microbial communities at the beginnings of the two RBC trains and completely different populations at the ends of the two RBC trains; (2) nitrifiers, including ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB, Nitrosomonas) and nitrite-oxidizing bacteria (NOB, Nitrospira), increased in relative abundance in the biofilm along the flowpath, whereas denitrifiers (Rhodanobacter, Paracoccus, Thauera, and Azoarcus) markedly decreased; (3) the AOA were subdominant to the AOB in all sampled sections; and (4) strong ecological associations were shown among different bacteria. Overall, the results of this study provided more comprehensive information regarding the biofilm community composition and assemblies in full-scale RBCs. PMID:24936907

Peng, Xingxing; Guo, Feng; Ju, Feng; Zhang, Tong

2014-07-15

147

Development and structure of microbial biofilms in river water studied by confocal laser scanning microscopy  

Microsoft Academic Search

The development of stream biofilms was studied using a rotating annular biofilm reactor system for cultivation and confocal laser scanning microscopy for structural examination. Biofilms were generated by feeding the reactor with raw river water as inoculum and a sole nutrient source. The biofilm developed during 56 days from microcolonies via a thin patchy film into a ridged structure. The

Thomas R Neu; John R Lawrence

1997-01-01

148

Eukaryotic life in biofilms formed in a uranium mine  

PubMed Central

The underground uranium mine Königstein (Saxony, Germany), currently in the process of remediation, represents an underground acid mine drainage (AMD) environment, that is, low pH conditions and high concentrations of heavy metals including uranium, in which eye-catching biofilm formations were observed. During active uranium mining from 1984 to 1990, technical leaching with sulphuric acid was applied underground on-site resulting in a change of the underground mine environment and initiated the formation of AMD and also the growth of AMD-related copious biofilms. Biofilms grow underground in the mine galleries in a depth of 250 m (50 m above sea level) either as stalactite-like slime communities or as acid streamers in the drainage channels. The eukaryotic diversity of these biofilms was analyzed by microscopic investigations and by molecular methods, that is, 18S rDNA PCR, cloning, and sequencing. The biofilm communities of the Königstein environment showed a low eukaryotic biodiversity and consisted of a variety of groups belonging to nine major taxa: ciliates, flagellates, amoebae, heterolobosea, fungi, apicomplexa, stramenopiles, rotifers and arthropoda, and a large number of uncultured eukaryotes, denoted as acidotolerant eukaryotic cluster (AEC). In Königstein, the flagellates Bodo saltans, the stramenopiles Diplophrys archeri, and the phylum of rotifers, class Bdelloidea, were detected for the first time in an AMD environment characterized by high concentrations of uranium. This study shows that not only bacteria and archaea may live in radioactive contaminated environments, but also species of eukaryotes, clearly indicating their potential influence on carbon cycling and metal immobilization within AMD-affected environment.

Zirnstein, Isabel; Arnold, Thuro; Krawczyk-Barsch, Evelyn; Jenk, Ulf; Bernhard, Gert; Roske, Isolde

2012-01-01

149

Microbial life in the deep terrestrial subsurface  

Microsoft Academic Search

The distribution and function of microorganisms is a vital issue in microbial ecology. The US Department of Energy`s Program, ``Microbiology of the Deep Subsurface,`` concentrates on establishing fundamental scientific information about organisms at depth, and the use of these organisms for remediation of contaminants in deep vadose zone and groundwater environments. This investigation effectively extends the Biosphere hundreds of meters

C. B. Fliermans; D. L. Balkwill; R. E. Beeman

1988-01-01

150

Microbial geomorphology: A neglected link between life and landscape  

NASA Astrophysics Data System (ADS)

Whilst recognition is increasing that life and landscapes are intimately related, as evidenced by growing research into ecosystem engineering, biogeomorphology and allied topics, the microbial contribution to such interactions has been relatively neglected. A revolution in environmental microbiology, based on molecular techniques, is now driving a reconsideration of the role of microbial processes in geomorphology at all scales. Recent research illustrates the hitherto unknown microbial diversity present in many extreme geomorphic environments, such as hyperarid deserts, subglacial lakes, hot springs, and much richer microbial life than previously suspected within the soils and sediments that blanket most other landscapes. Such microbial communities have been found to play important geomorphic roles across a wide range of environments, notably in weathering, precipitation of minerals and protecting surfaces from erosion. These geomorphic roles can also be conceptualised as examples of ecosystem engineering, and can pave the way for further plant-geomorphology and zoogeomorphology processes. Three key aspects which emerge from a review of microbial influences on Earth surface processes are a) that microbes play roles on a continuum from full control to passive involvement, b) that complex and widespread communities of microorganisms are involved and c) that microbial activity usually affects several Earth surface processes at once. Examples of the contribution of microbial life to geomorphology over long, medium and short timescales suggest that microorganisms play key geomorphological roles in two major situations; on the cusp between stable states, and in extreme environments where higher plant and animal life is limited and many abiotic processes are also constrained. The dominant link between microbial life and geomorphology appears to take on different forms depending on the timescale under consideration, with a stabilising microbial role apparent over short timescales being replaced by a denudational role over longer timescales. Further research involving microbiologists and geomorphologists is now needed to address three main questions, i.e. under what conditions are microbial and geomorphological processes most closely linked?, what scale issues surround links between microbes and geomorphology? And how do microbiological processes underpin broader biogeomorphological interactions?

Viles, Heather A.

2012-07-01

151

Biofilms  

Microsoft Academic Search

Cell signaling in Escherichia coli biofilms is more important than originally known, in that au toinducer two (AI-2), AI-1 (N-acylhomoserine lactones), indole, hydroxylated indoles, nore pinephrine, and epinephrine are all functional signals in this organism. This gives the bacterium the ability to monitor not only the presence of cells of its own species (through AI-2 and indole) but also the

David Stickler; H. Vlamakis; R. Kolter

1999-01-01

152

Fourier transform-infrared spectroscopic methods for microbial ecology: analysis of bacteria, bacteria-polymer mixtures and biofilms  

NASA Technical Reports Server (NTRS)

Fourier transform-infrared (FT-IR) spectroscopy has been used to rapidly and nondestructively analyze bacteria, bacteria-polymer mixtures, digester samples and microbial biofilms. Diffuse reflectance FT-IR (DRIFT) analysis of freeze-dried, powdered samples offered a means of obtaining structural information. The bacteria examined were divided into two groups. The first group was characterized by a dominant amide I band and the second group of organisms displayed an additional strong carbonyl stretch at approximately 1740 cm-1. The differences illustrated by the subtraction spectra obtained for microbes of the two groups suggest that FT-IR spectroscopy can be utilized to recognize differences in microbial community structure. Calculation of specific band ratios has enabled the composition of bacteria and extracellular or intracellular storage product polymer mixtures to be determined for bacteria-gum arabic (amide I/carbohydrate C-O approximately 1150 cm-1) and bacteria-poly-beta-hydroxybutyrate (amide I/carbonyl approximately 1740 cm-1). The key band ratios correlate with the compositions of the material and provide useful information for the application of FT-IR spectroscopy to environmental biofilm samples and for distinguishing bacteria grown under differing nutrient conditions. DRIFT spectra have been obtained for biofilms produced by Vibrio natriegens on stainless steel disks. Between 48 and 144 h, an increase in bands at approximately 1440 and 1090 cm-1 was seen in FT-IR spectra of the V. natriegens biofilm. DRIFT spectra of mixed culture effluents of anaerobic digesters show differences induced by shifts in input feedstocks. The use of flow-through attenuated total reflectance has permitted in situ real-time changes in biofilm formation to be monitored and provides a powerful tool for understanding the interactions within adherent microbial consortia.

Nichols, P. D.; Henson, J. M.; Guckert, J. B.; Nivens, D. E.; White, D. C.

1985-01-01

153

Regenerable Microbial Check Valve - Life cycle tests results  

NASA Technical Reports Server (NTRS)

Life cycle regeneration testing of the Microbial Check Valve (MCV) that is used on the Shuttle Orbiter to provide microbial control of potable water is currently in progress. Four beds are being challenged with simulated reclaimed waters and repeatedly regenerated. Preliminary results indicate that contaminant systems exhibit unique regeneration periodicities. Cyclic throughput diminishes with increasing cumulative flow. It is considered to be feasible to design a regenerable MCV system which will function without human intervention and with minimal resupply penalty for the 30 year life of the Space Station.

Atwater, James E.; Wheeler, Richard R., Jr.; Olivadoti, J. T.; Sauer, Richard L.; Flanagan, David T.

1992-01-01

154

Microbial life in the deep terrestrial subsurface  

SciTech Connect

The distribution and function of microorganisms is a vital issue in microbial ecology. The US Department of Energy`s Program, ``Microbiology of the Deep Subsurface,`` concentrates on establishing fundamental scientific information about organisms at depth, and the use of these organisms for remediation of contaminants in deep vadose zone and groundwater environments. This investigation effectively extends the Biosphere hundreds of meters into the Geosphere and has implications to a variety of subsurface activities.

Fliermans, C.B. [E.I. DuPont de Nemours and Co., Aiken, SC (United States). Savannah River Lab.; Balkwill, D.L. [Florida State Univ., Tallahassee, FL (United States); Beeman, R.E. [Univ. of Oklahoma, Norman, OK (United States)] [and others

1988-12-31

155

Detection of heavy metals in bacterial biofilms and microbial flocs with the fluorescent complexing agent Newport Green  

Microsoft Academic Search

  The complexing agent Newport Green fluoresces upon binding of nickel, zinc or cobalt. It was used to detect nickel or zinc\\u000a in MOPS buffer, in gel-like matrices, and in natural biofilms and microbial flocs cultivated in the laboratory. The response\\u000a curves for increasing nickel concentrations indicated an equimolar binding capacity of Newport Green for nickel in MOPS buffer,\\u000a whereas zinc

S Wuertz; E Müller; R Spaeth; P Pfleiderer; H-C Flemming

2000-01-01

156

COD removal from expanded granular sludge bed effluent using a moving bed biofilm reactor and their microbial community analysis  

Microsoft Academic Search

The bioreactor performance of a moving bed biofilm reactor (MBBR) as post-treatment of expanded granular sludge bed (EGSB)\\u000a effluent was investigated. Moreover, the microbial communities of the two bioreactors during different operation periods were\\u000a studied. The MBBR was efficient for COD removal with the mean efficiency of 82.4%, and produced an effluent with high and\\u000a stable quality against shock loading

Bo Fu; Xiaoyi Liao; Rui Liang; Lili Ding; Ke Xu; Hongqiang Ren

2011-01-01

157

Nitrogen removal in a single-chamber microbial fuel cell with nitrifying biofilm enriched at the air cathode.  

PubMed

Nitrogen removal is needed in microbial fuel cells (MFCs) for the treatment of most waste streams. Current designs couple biological denitrification with side-stream or combined nitrification sustained by upstream or direct aeration, which negates some of the energy-saving benefits of MFC technology. To achieve simultaneous nitrification and denitrification, without extra energy input for aeration, the air cathode of a single-chamber MFC was pre-enriched with a nitrifying biofilm. Diethylamine-functionalized polymer (DEA) was used as the Pt catalyst binder on the cathode to improve the differential nitrifying biofilm establishment. With pre-enriched nitrifying biofilm, MFCs with the DEA binder had an ammonia removal efficiency of up to 96.8% and a maximum power density of 900 ± 25 mW/m(2), compared to 90.7% and 945 ± 42 mW/m(2) with a Nafion binder. A control with Nafion that lacked nitrifier pre-enrichment removed less ammonia and had lower power production (54.5% initially, 750 mW/m(2)). The nitrifying biofilm MFCs had lower Coulombic efficiencies (up to 27%) than the control reactor (up to 36%). The maximum total nitrogen removal efficiency reached 93.9% for MFCs with the DEA binder. The DEA binder accelerated nitrifier biofilm enrichment on the cathode, and enhanced system stability. These results demonstrated that with proper cathode pre-enrichment it is possible to simultaneously remove organics and ammonia in a single-chamber MFC without supplemental aeration. PMID:22386083

Yan, Hengjing; Saito, Tomonori; Regan, John M

2012-05-01

158

Microbial communities in bulk fluids and biofilms of an oil facility have similar composition but different structure.  

PubMed

The oil-water-gas environments of oil production facilities harbour abundant and diverse microbial communities that can participate in deleterious processes such as biocorrosion. Several molecular methods, including pyrosequencing of 16S rRNA libraries, were used to characterize the microbial communities from an oil production facility on the Alaskan North Slope. The communities in produced water and a sample from a 'pig envelope' were compared in order to identify specific populations or communities associated with biocorrosion. The 'pigs' are used for physical mitigation of pipeline corrosion and fouling and the samples are enriched in surface-associated solids (i.e. paraffins, minerals and biofilm) and coincidentally, microorganisms (over 10(5) -fold). Throughout the oil production facility, bacteria were more abundant (10- to 150-fold) than archaea, with thermophilic members of the phyla Firmicutes (Thermoanaerobacter and Thermacetogenium) and Synergistes (Thermovirga) dominating the community. However, the structure (relative abundances of taxa) of the microbial community in the pig envelope was distinct due to the increased relative abundances of the genera Thermacetogenium and Thermovirga. The data presented here suggest that bulk fluid is representative of the biofilm communities associated with biocorrosion but that certain populations are more abundant in biofilms, which should be the focus of monitoring and mitigation strategies. PMID:21261797

Stevenson, Bradley S; Drilling, Heather S; Lawson, Paul A; Duncan, Kathleen E; Parisi, Victoria A; Suflita, Joseph M

2011-04-01

159

Microbial composition and structure of a rotating biological contactor biofilm treating ammonium-rich wastewater without organic carbon.  

PubMed

High nitrogen losses were observed in a rotating biological contactor (RBC) treating ammonium-rich (up to 500 mg NH4(+)-N/L) but organic-carbon-poor leachate from a hazardous waste landfill in Kölliken, Switzerland. The composition and spatial structure of the microbial community in the biofilm on the RBC was analyzed with specific attention for the presence of aerobic ammonium and nitrite oxidizing bacteria and anaerobic ammonium oxidizers. Anaerobic ammonium oxidation (anammox) involves the oxidation of ammonium with nitrite to N2. First the diversity of the biofilm community was determined from sequencing cloned PCR-amplified 16S rDNA fragments. This revealed the presence of a number of very unusual 16S rDNA sequences, but very few sequences related to known ammonium or nitrite oxidizing bacteria. From analysis of biofilm samples by fluorescence in situ hybridization with known phylogenetic probes and by dot-blot hybridization of the same probes to total RNA purified from biofilm samples, the main groups of microorganisms constituting the biofilm were found to be ammonium-oxidizing bacteria from the Nitrosomonas europaea/eutropha group, anaerobic ammonium-oxidizing bacteria of the "Candidatus Kuenenia stuttgartiensis" type, filamentous bacteria from the phylum Bacteroidetes, and nitrite-oxidizing bacteria from the genus Nitrospira. Aerobic and anaerobic ammonium-oxidizing bacteria were present in similar amounts of around 20 to 30% of the biomass, whereas members of the CFB phylum were present at around 7%. Nitrite oxidizing bacteria were only present in relatively low amounts (less than 5% determined with fluorescence in situ hybridization). Data from 16S rRNA dot-blot and in situ hybridization were not in all cases congruent. FISH analysis of thin-sliced and fixed biofilm samples clearly showed that the aerobic nitrifiers were located at the top of the biofilm in an extremely high density and in alternating clusters. Anammox bacteria were exclusively present in the lower half of the biofilm, whereas CFB-type filamentous bacteria were present throughout the biofilm. The structure and composition of these biofilms correlated very nicely with the proposed physiological functional separations in ammonium conversion. PMID:12704553

Egli, K; Bosshard, F; Werlen, C; Lais, P; Siegrist, H; Zehnder, A J B; Van der Meer, J R

2003-05-01

160

A novel automated waterline cleaning system that facilitates effective and consistent control of microbial biofilm contamination of dental chair unit waterlines: A one-year study  

Microsoft Academic Search

Microbial contamination of dental chair unit (DCU) output water caused by biofilm growth in dental unit waterlines (DUWs) is a universal problem and a potentially significant source of cross-infection. The microbial quality of output water from a Planmeca Compact i DCU equipped with the novel Water Management System (WMS), an integrated and automated DUW cleaning system, was investigated over a

M. J. O’Donnell; A. C. Shore; D. C. Coleman

2006-01-01

161

Modern analogues and the early history of microbial life  

Microsoft Academic Search

Revealing the geological history of microbial life is very challenging. Microbes rarely are preserved with morphological fidelity, and even when they are, morphology is a poor guide to phylogeny and metabolism. Biological studies of environments considered analogous to those of paleobiological interest on the ancient Earth can inform interpretations and suggest new approaches. This paper reviews recent advances in our

Brendan P. Burns; Roberto Anitori; Philip Butterworth; Ruth Henneberger; Falicia Goh; Michelle A. Allen; Raquel Ibañez-Peral; Peter L. Bergquist; Malcolm R. Walter; Brett A. Neilan

2009-01-01

162

Tree of Life: An Introduction to Microbial Phylogeny  

NSDL National Science Digital Library

How do phylogenetic trees help us look more closely at microbial evolution? Explore sequence data and extend your tree thinking to examine possible relationships between the microbes and other life forms. The Biology Workbench provides access to data and tools for investigating these relationships. * read a phylogenetic tree

Beverly Brown (Nazareth College;Biology); Sam Fan (Bradley University;Biology); LeLeng To Isaacs (Goucher College;Biology); Min-Ken Liao (Furman University;Biology)

2006-05-20

163

Preliminary studies on the microbial community structure of membrane-aerated biofilms treating municipal wastewater  

Microsoft Academic Search

Membrane-aerated biofilm reactors (MABRs) support biofilms that receive oxygen and nutrients from opposite sides of the biofilm and thus should behave differently than the activated sludge process. Population modeling predicted the simultaneous presence of aerobic heterotrophs, nitrifying bacteria, denitrifying bacteria, and acetoclastic methanogens in a membrane-supported biofilm. Community analysis by PCR-DGGE demonstrated that a pilot-scale MABR supported a significantly different

Alina C. Cole; John W. Shanahan; Michael J. Semmens; Timothy M. LaPara

2002-01-01

164

A Novel Strategy for Control of Microbial Biofilms through Generation of Biocide at the Biofilm-Surface Interface  

PubMed Central

Biofilms of a mucoid clinical isolate of Pseudomonas aeruginosa (24 h; ca. 10(sup6) CFU/cm(sup2)) were established by immersion of polymer discs in nutrient broth cultures at 37(deg)C. Biofilms exposed for 30 min to various concentrations (0 to 3 mg/ml) of hydrogen peroxide or potassium monopersulfate were rinsed and shaken vigorously in sterile saline to detach loosely associated cells, and the residual viable attached population was quantified by a blot succession method on agar plates. Incorporation of copper and cobalt phthalocyanine catalysts within the polymers significantly enhanced the activity of these oxidizing biocides towards biofilm bacteria by several orders of magnitude. Biofilms established on the control discs resisted treatment with concentrations of either agent of up to 3 mg/ml. Enhancement through incorporation of a catalyst was such that concentrations of potassium monopersulfate of as low as 20 (mu)g/ml gave no recoverable survivors either on the discs or within the washings. Catalysts such as these will promote the formation of active oxygen species from a number of oxidizing agents such as peroxides and persulfates, and it is thought that generation of these at the surface-biofilm interface concentrates the antimicrobial effect to the interfacial cells and generates a diffusion pump which further provides active species to the biofilm matrix. The survivors of low-concentration treatments with these agents were more readily removed from the catalyst-containing discs than from the control discs. This indicated advantages gained in hygienic cleansing of such modified surfaces.

Wood, P.; Jones, M.; Bhakoo, M.; Gilbert, P.

1996-01-01

165

Backwash intensity and frequency impact the microbial community structure and function in a fixed-bed biofilm reactor.  

PubMed

Linkages among bioreactor operation and performance and microbial community structure were investigated for a fixed-bed biofilm system designed to remove perchlorate from drinking water. Perchlorate removal was monitored to evaluate reactor performance during and after the frequency and intensity of the backwash procedure were changed, while the microbial community structure was studied using clone libraries and quantitative PCR targeting the 16S rRNA gene. When backwash frequency was increased from once per month to once per day, perchlorate removal initially deteriorated and then recovered, and the relative abundance of perchlorate-reducing bacteria (PRB) initially increased and then decreased. This apparent discrepancy suggested that bacterial populations other than PRB played an indirect role in perchlorate removal, likely by consuming dissolved oxygen, a competing electron acceptor. When backwash intensity was increased, the reactor gradually lost its ability to remove perchlorate, and concurrently the relative abundance of PRB decreased. The results indicated that changes in reactor operation had a profound impact on reactor performance through altering the microbial community structure. Backwashing is an important yet poorly characterized procedure when operating fixed-bed biofilm reactors. Compared to backwash intensity, changes in backwash frequency exerted less disturbance on the microbial community in the current study. If this finding can be confirmed in future work, backwash frequency may serve as the primary parameter when optimizing backwash procedures. PMID:22258640

Li, Xu; Yuen, Wangki; Morgenroth, Eberhard; Raskin, Lutgarde

2012-11-01

166

[Effect of the biofilm biopolymers on the microbial corrosion rate of the low-carbon steel].  

PubMed

The relationship between exopolymer's specific production, relative carbohydrate and protein content in the biofilm exopolymers of the pure and mixed Thiobacillus thioparus and Stenotrophomonas maltophilia cultures and their corrosion activity was studied. Change of growth model of investigated cultures from plankton to biofilm led to an increase of specific exopolymer's production. In the biofilm formed by T. thioparus and S. maltophilia biofilm on the low-carbon steel surface one could observe an increase of relative protein content in the exopolymer complex in comparison with those in the pure culture. The development of such biofilms stimulatied the 7-fold corrosion activity. PMID:17977451

Borets'ka, M O; Kozlova, I P

2007-01-01

167

Hydrogenophaga electricum sp. nov., isolated from anodic biofilms of an acetate-fed microbial fuel cell.  

PubMed

A Gram-negative, non-spore-forming, rod-shaped bacterial strain, AR20(T), was isolated from anodic biofilms of an acetate-fed microbial fuel cell in Japan and subjected to a polyphasic taxonomic study. Strain AR20(T) grew optimally at pH 7.0-8.0 and 25°C. It contained Q-8 as the predominant ubiquinone and C16:0, summed feature 3 (C16:1?7c and/or iso-C15:02OH), and C18:1?7c as the major fatty acids. The DNA G+C content was 67.1 mol%. A neighbor-joining phylogenetic tree revealed that strain AR20(T) clustered with three type strains of the genus Hydrogenophaga (H. flava, H. bisanensis and H. pseudoflava). Strain AR20(T) exhibited 16S rRNA gene sequence similarity values of 95.8-97.7% to the type strains of the genus Hydrogenophaga. On the basis of phenotypic, chemotaxonomic and phylogenetic data, strain AR20(T) is considered a novel species of the genus Hydrogenophaga, for which the name Hydrogenophaga electricum sp. nov. is proposed. The type strain is AR20(T) (= KCTC 32195(T) = NBRC 109341(T)). PMID:24005175

Kimura, Zen-ichiro; Okabe, Satoshi

2013-01-01

168

Raoultella electrica sp. nov., isolated from anodic biofilms of a glucose-fed microbial fuel cell.  

PubMed

A Gram-stain-negative, non-spore-forming, rod-shaped bacterium, designated strain 1GB(T), was isolated from anodic biofilms of a glucose-fed microbial fuel cell. Strain 1GB(T) was facultatively anaerobic and chemo-organotrophic, having both a respiratory and a fermentative type of metabolism, and utilized a wide variety of sugars as carbon and energy sources. Cells grown aerobically contained Q-8 as the major quinone, but excreted Q-9 and a small amount of Q-10 when cultured with an electrode serving as the sole electron acceptor. The G+C content of the genomic DNA of 1GB(T) was 54.5 mol%. Multilocus sequence typing (MLST) analysis showed that strain 1GB(T) represented a distinct lineage within the genus Raoultella (98.5-99.4?% 16S rRNA gene sequence similarity and 94.0-96.5?% sequence similarity based on the three concatenated housekeeping genes gyrA, rpoB and parC. Strain 1GB(T) exhibited DNA-DNA hybridization relatedness of 7-43?% with type strains of all established species of the genus Raoultella. On the basis of these phenotypic, phylogenetic and genotypic data, the name Raoultella electrica sp. nov. is proposed for strain 1GB(T). The type strain is 1GB(T) (?=?NBRC 109676(T)?=?KCTC 32430(T)). PMID:24449794

Kimura, Zen-Ichiro; Chung, Kyung Mi; Itoh, Hiroaki; Hiraishi, Akira; Okabe, Satoshi

2014-04-01

169

Medical Biofilms  

PubMed Central

For more than two decades, Biotechnology and Bioengineering has documented research focused on natural and engineered microbial biofilms within aquatic and subterranean ecosystems, wastewater and waste-gas treatment systems, marine vessels and structures, and industrial bioprocesses. Compared to suspended culture systems, intentionally engineered biofilms are heterogeneous reaction systems that can increase reactor productivity, system stability, and provide inherent cell: product separation. Unwanted biofilms can create enormous increases in fluid frictional resistances, unacceptable reductions in heat transfer efficiency, product contamination, enhanced material deterioration, and accelerated corrosion. Missing from B&B has been an equivalent research dialogue regarding the basic molecular microbiology, immunology, and biotechnological aspects of medical biofilms. Presented here are the current problems related to medical biofilms; current concepts of biofilm formation, persistence, and interactions with the host immune system; and emerging technologies for controlling medical biofilms.

2009-01-01

170

Time-course correlation of biofilm properties and electrochemical performance in single-chamber microbial fuel cells.  

PubMed

The relationship between anode microbial characteristics and electrochemical parameters in microbial fuel cells (MFCs) was analyzed by time-course sampling of parallel single-bottle MFCs operated under identical conditions. While voltage stabilized within 4days, anode biofilms continued growing during the six-week operation. Viable cell density increased asymptotically, but membrane-compromised cells accumulated steadily from only 9% of total cells on day 3 to 52% at 6weeks. Electrochemical performance followed the viable cell trend, with a positive correlation for power density and an inverse correlation for anode charge transfer resistance. The biofilm architecture shifted from rod-shaped, dispersed cells to more filamentous structures, with the continuous detection of Geobacter sulfurreducens-like 16S rRNA fragments throughout operation and the emergence of a community member related to a known phenazine-producing Pseudomonas species. A drop in cathode open circuit potential between weeks two and three suggested that uncontrolled biofilm growth on the cathode deleteriously affects system performance. PMID:20591659

Ren, Zhiyong; Ramasamy, Ramaraja P; Cloud-Owen, Susan Red; Yan, Hengjing; Mench, Matthew M; Regan, John M

2011-01-01

171

Microbial Ecology of Isolated Life Support Systems  

Microsoft Academic Search

\\u000a Microorganisms are the most widely spread form of living matter – occurring in every climatic region and in every zone of\\u000a water and soil strata. They have a profound role in biogeochemical processes and are crucial for the completion of all biologically\\u000a important material cycles, which support all life on Earth. Microorganisms can enter into varying interactions with human\\u000a population

Lydia A. Somova; Nickolay S. Pechurkin; Mark Nelson; Lawrence K. Wang

172

Microbial diversity in paleolithic caves: a study case on the phototrophic biofilms of the Cave of Bats (Zuheros, Spain).  

PubMed

The biological colonization of rocks in the Cave of Bats (Cueva de Los Murciélagos, Zuheros, Spain) was studied in order to reveal the diversity of microorganisms involved in the biofilm formation. The culturable, metabolically active fraction of biodeteriogens present on surfaces was investigated focusing on morphological, ultrastructural, and genetic features, and their presence related to the peculiar environmental conditions of the underground site. PCR-ITS analysis and 16S rDNA sequences were used to clusterize and characterize the isolated strains. The presence of bacterial taxa associated to the photosynthetic microflora and fungi within the biofilm contributed to clarify the relationships inside the microbial community and to explain the alteration observed at the different sites. These results will contribute to the application of more successful strategies for the preventive conservation of subterranean archaeological sites. PMID:20607532

Urzì, Clara; De Leo, Filomena; Bruno, Laura; Albertano, Patrizia

2010-07-01

173

Identification of dominant microbial community in aerophilic biofilm reactors by fluorescence in situ hybridization and PCR-denaturing gradient gel electrophoresis  

Microsoft Academic Search

This study was conducted by combining fluorescence in situ hybridization (FISH) performed on 16S rRNA and polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE)\\u000a with 16S CTOs primers to characterize the nitrifying microbial communities in biofilm processes, which were tested to retrofit\\u000a the S municipal wastewater treatment plant in Busan, Korea. Four aerophilic biofilm reactors were operated with hydraulic\\u000a retention

Youngo Kim; Taeho Lee; Sanghyup Lee

2009-01-01

174

Phototrophic biofilm assembly in microbial-mat-derived unicyanobacterial consortia: model systems for the study of autotroph-heterotroph interactions.  

PubMed

Microbial autotroph-heterotroph interactions influence biogeochemical cycles on a global scale, but the diversity and complexity of natural systems and their intractability to in situ manipulation make it challenging to elucidate the principles governing these interactions. The study of assembling phototrophic biofilm communities provides a robust means to identify such interactions and evaluate their contributions to the recruitment and maintenance of phylogenetic and functional diversity over time. To examine primary succession in phototrophic communities, we isolated two unicyanobacterial consortia from the microbial mat in Hot Lake, Washington, characterizing the membership and metabolic function of each consortium. We then analyzed the spatial structures and quantified the community compositions of their assembling biofilms. The consortia retained the same suite of heterotrophic species, identified as abundant members of the mat and assigned to Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes. Autotroph growth rates dominated early in assembly, yielding to increasing heterotroph growth rates late in succession. The two consortia exhibited similar assembly patterns, with increasing relative abundances of members from Bacteroidetes and Alphaproteobacteria concurrent with decreasing relative abundances of those from Gammaproteobacteria. Despite these similarities at higher taxonomic levels, the relative abundances of individual heterotrophic species were substantially different in the developing consortial biofilms. This suggests that, although similar niches are created by the cyanobacterial metabolisms, the resulting webs of autotroph-heterotroph and heterotroph-heterotroph interactions are specific to each primary producer. The relative simplicity and tractability of the Hot Lake unicyanobacterial consortia make them useful model systems for deciphering interspecies interactions and assembly principles relevant to natural microbial communities. PMID:24778628

Cole, Jessica K; Hutchison, Janine R; Renslow, Ryan S; Kim, Young-Mo; Chrisler, William B; Engelmann, Heather E; Dohnalkova, Alice C; Hu, Dehong; Metz, Thomas O; Fredrickson, Jim K; Lindemann, Stephen R

2014-01-01

175

Phototrophic biofilm assembly in microbial-mat-derived unicyanobacterial consortia: model systems for the study of autotroph-heterotroph interactions  

PubMed Central

Microbial autotroph-heterotroph interactions influence biogeochemical cycles on a global scale, but the diversity and complexity of natural systems and their intractability to in situ manipulation make it challenging to elucidate the principles governing these interactions. The study of assembling phototrophic biofilm communities provides a robust means to identify such interactions and evaluate their contributions to the recruitment and maintenance of phylogenetic and functional diversity over time. To examine primary succession in phototrophic communities, we isolated two unicyanobacterial consortia from the microbial mat in Hot Lake, Washington, characterizing the membership and metabolic function of each consortium. We then analyzed the spatial structures and quantified the community compositions of their assembling biofilms. The consortia retained the same suite of heterotrophic species, identified as abundant members of the mat and assigned to Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes. Autotroph growth rates dominated early in assembly, yielding to increasing heterotroph growth rates late in succession. The two consortia exhibited similar assembly patterns, with increasing relative abundances of members from Bacteroidetes and Alphaproteobacteria concurrent with decreasing relative abundances of those from Gammaproteobacteria. Despite these similarities at higher taxonomic levels, the relative abundances of individual heterotrophic species were substantially different in the developing consortial biofilms. This suggests that, although similar niches are created by the cyanobacterial metabolisms, the resulting webs of autotroph-heterotroph and heterotroph-heterotroph interactions are specific to each primary producer. The relative simplicity and tractability of the Hot Lake unicyanobacterial consortia make them useful model systems for deciphering interspecies interactions and assembly principles relevant to natural microbial communities.

Cole, Jessica K.; Hutchison, Janine R.; Renslow, Ryan S.; Kim, Young-Mo; Chrisler, William B.; Engelmann, Heather E.; Dohnalkova, Alice C.; Hu, Dehong; Metz, Thomas O.; Fredrickson, Jim K.; Lindemann, Stephen R.

2014-01-01

176

Life cycle assessment of high-rate anaerobic treatment, microbial fuel cells, and microbial electrolysis cells.  

PubMed

Existing wastewater treatment options are generally perceived as energy intensive and environmentally unfriendly. Much attention has been focused on two new approaches in the past years, (i) microbial fuel cells and (ii) microbial electrolysis cells, which directly generate electrical current or chemical products, respectively, during wastewater treatment. These systems are commonly denominated as bioelectrochemical systems, and a multitude of claims have been made in the past regarding the environmental impact of these treatment options. However, an in-depth study backing these claims has not been performed. Here, we have conducted a life cycle assessment (LCA) to compare the environmental impact of three industrial wastewater treatment options, (i) anaerobic treatment with biogas generation, (ii) a microbial fuel cell treatment, with direct electricity generation, and (iii) a microbial electrolysis cell, with hydrogen peroxide production. Our analysis showed that a microbial fuel cell does not provide a significant environmental benefit relative to the "conventional" anaerobic treatment option. However, a microbial electrolysis cell provides significant environmental benefits through the displacement of chemical production by conventional means. Provided that the target conversion level of 1000 A.m(-3) can be met, the decrease in greenhouse gas emissions and other environmentally harmful emissions (e.g., aromatic hydrocarbons) of the microbial electrolysis cell will be a key driver for the development of an industrial standard for this technology. Evidently, this assessment is highly dependent on the underlying assumptions, such as the used reactor materials and target performance. This provides a challenge and an opportunity for researchers in the field to select and develop appropriate and environmentally benign materials of construction, as well as demonstrate the required 1000 A.m(-3) performance at pilot and full scale. PMID:20356090

Foley, Jeffrey M; Rozendal, René A; Hertle, Christopher K; Lant, Paul A; Rabaey, Korneel

2010-05-01

177

A Fatty Acid Messenger Is Responsible for Inducing Dispersion in Microbial Biofilms  

Microsoft Academic Search

It is well established that in nature, bacteria are found primarily as residents of surface-associated com- munities called biofilms. These structures form in a sequential process initiated by attachment of cells to a surface, followed by the formation of matrix-enmeshed microcolonies, and culminating in dispersion of the bacteria from the mature biofilm. In the present study, we have demonstrated that,

David G. Davies; Claudia N. H. Marques

2009-01-01

178

Presence and effects of marine microbial biofilms on biocide-based antifouling paints  

Microsoft Academic Search

Marine microorganisms are capable of successfully colonizing toxic surfaces through the formation of biofilm structures. In this article, most of the literature reporting the presence of marine biofilms on chemically-active antifouling paints is briefly reviewed. Of special concern is the influence of the dense extracellular polymeric substances (EPS) matrix on the release rate of the compounds involved in antifouling paint

Diego Meseguer Yebra; Søren Kiil; Claus E. Weinell; Kim Dam-Johansen

2006-01-01

179

Experimental and modeling studies of sorption of ceria nanoparticle on microbial biofilms.  

PubMed

This study focuses on the interaction of ceria nanoparticles (CeO2-NPs) with Pseudomonas fluorescens and Mycobacterium smegmatis biofilms. Confocal laser microscopy and transmission electron microscopy determined the distribution of NPs in the complex structures of biofilm at molecular levels. Visual data showed that most of the adsorption takes place on the bacterial cell walls and spores. The interaction of nanoparticles (NPs) with biofilms reached equilibrium after the initial high adsorption rate regardless of biofilm heterogeneity and different nanoparticle concentrations in the bulk liquid. Physical processes may dominate this sorption phenomenon. Pseudo first order sorption kinetics was used to estimate adsorption and desorption rate of CeO2-NPs onto biofilms. When biofilms got exposed to CeO2-NPs, a self-protecting mechanism was observed. Cells moved away from the bulk solution in the biofilm matrix, and portions of biofilm outer layer were detached, hence releasing some CeO2-NPs back to the bulk phase. PMID:24690581

Jing, Hengye; Mezgebe, Bineyam; Aly Hassan, Ashraf; Sahle-Demessie, Endalkachew; Sorial, George A; Bennett-Stamper, Christina

2014-06-01

180

Role of bacterial adhesion in the microbial ecology of biofilms in cooling tower systems  

Microsoft Academic Search

The fate of the three heterotrophic biofilm forming bacteria, Pseudomonas aeruginosa, Klebsiella pneumoniae and Flavobacterium sp. in pilot scale cooling towers was evaluated both by observing the persistence of each species in the recirculating water and the formation of biofilms on steel coupons placed in each cooling tower water reservoir. Two different cooling tower experiments were performed: a short-term study

Yang Liu; Wei Zhang; Tadas Sileika; Richard Warta; Nicholas P. Cianciotto; Aaron Packman

2009-01-01

181

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route  

NASA Astrophysics Data System (ADS)

The incessant use of antibiotics against infectious diseases has translated into a vicious circle of developing new antibiotic drug and its resistant strains in short period of time due to inherent nature of micro-organisms to alter their genes. Many researchers have been trying to formulate inorganic nanoparticles-based antiseptics that may be linked to broad-spectrum activity and far lower propensity to induce microbial resistance than antibiotics. The way-out approaches in this direction are nanomaterials based (1) bactericidal and (2) bacteriostatic activities. We, herein, present hitherto unreported observations on microbial abatement using non-cytotoxic molybdenum disulfide nanostructures (MSNs) which are synthesized using microwave assisted solvothermal route. Inhibition of biofilm formation using MSNs is a unique feature of our study. Furthermore, this study evinces antimicrobial mechanism of MSNs by reactive oxygen species (ROS) dependent generation of superoxide anion radical via disruption of cellular functions.

Qureshi, Nilam; Patil, Rajendra; Shinde, Manish; Umarji, Govind; Causin, Valerio; Gade, Wasudev; Mulik, Uttam; Bhalerao, Anand; Amalnerkar, Dinesh P.

2014-06-01

182

The net of life: reconstructing the microbial phylogenetic network.  

PubMed

It has previously been suggested that the phylogeny of microbial species might be better described as a network containing vertical and horizontal gene transfer (HGT) events. Yet, all phylogenetic reconstructions so far have presented microbial trees rather than networks. Here, we present a first attempt to reconstruct such an evolutionary network, which we term the "net of life". We use available tree reconstruction methods to infer vertical inheritance, and use an ancestral state inference algorithm to map HGT events on the tree. We also describe a weighting scheme used to estimate the number of genes exchanged between pairs of organisms. We demonstrate that vertical inheritance constitutes the bulk of gene transfer on the tree of life. We term the bulk of horizontal gene flow between tree nodes as "vines", and demonstrate that multiple but mostly tiny vines interconnect the tree. Our results strongly suggest that the HGT network is a scale-free graph, a finding with important implications for genome evolution. We propose that genes might propagate extremely rapidly across microbial species through the HGT network, using certain organisms as hubs. PMID:15965028

Kunin, Victor; Goldovsky, Leon; Darzentas, Nikos; Ouzounis, Christos A

2005-07-01

183

On microbial contaminants, micropseudofossils, and the oldest records of life  

USGS Publications Warehouse

Microbial contaminants may be introduced on outcrop as well as en route to or in the laboratory. Micropseudofossils may be natural or man-made. It is possible to recognize such misleading objects and important that they are not allowed to dilute the growing record of authentic pre-Phanerozoic life. Filamentous microbial contaminants from minute cracks in samples of ancient carbonate rocks from Brazil (perhaps 1 Ga old) and South Africa (???2.3 Ga old) are similar to occurrences previously described as fossils. Published records of supposedly Archean microbial life also include microcontaminants and laboratory artifacts. Although microstructures from sedimentary rocks of the Swaziland system could be fossils, they are not demonstrably so. The oldest structurally preserved fossils yet known seem to be the filaments described by Lois Nagy from stromatolitic limestone in the ???2.3 Ga old Malmani Dolomite of South Africa. It will be difficult to establish unequivocal older records in the absence of definitive ultrastructural or micro-chemical evidence. ?? 1979.

Cloud, P.; Morrison, K.

1979-01-01

184

Speciation and quantitative mapping of metal species in microbial biofilms using scanning transmission X-ray microscopy.  

PubMed

A scanning transmission X-ray microscope illuminated with synchrotron light was used to investigate the speciation and spatial distributions of metals in a microbial biofilm cultivated from river water. Metal 2p absorption edge signals were used to provide metal speciation (through shapes of the absorption spectra) and quantitative spatial distributions of the metal species. This paper presents sample data and describes methods for extracting quantitative maps of metal species from image sequences recorded in the region of the metal 2p edges. Comparisons were made with biochemical characterization of the same region using images recorded at the C 1s and O 1s edges. The method is applied to detailed quantitative analysis of ferrous and ferric iron in a river biofilm, in concert with mapping Ni(II) and Mn(II) species in the same region. The distributions of the metal species are discussed in the context of the biofilm structure. These results demonstrate that soft X-ray STXM measurements at the metal 2p absorption edges can be used to speciate metals and to provide quantitative spatial distribution maps for metal species in environmental samples with 50 nm spatial resolution. PMID:16568770

Dynes, James J; Tyliszczak, Tolek; Araki, Tohru; Lawrence, John R; Swerhone, George D W; Leppard, Gary G; Hitchcock, Adam P

2006-03-01

185

Microbial community structure in a biofilm anode fed with a fermentable substrate: the significance of hydrogen scavengers.  

PubMed

We compared the microbial community structures that developed in the biofilm anode of two microbial electrolysis cells fed with ethanol, a fermentable substrate-one where methanogenesis was allowed and another in which it was completely inhibited with 2-bromoethane sulfonate. We observed a three-way syntrophy among ethanol fermenters, acetate-oxidizing anode-respiring bacteria (ARB), and a H2 scavenger. When methanogenesis was allowed, H2-oxidizing methanogens were the H2 scavengers, but when methanogenesis was inhibited, homo-acetogens became a channel for electron flow from H2 to current through acetate. We established the presence of homo-acetogens by two independent molecular techniques: 16S rRNA gene based pyrosequencing and a clone library from a highly conserved region in the functional gene encoding formyltetrahydrofolate synthetase in homo-acetogens. Both methods documented the presence of the homo-acetogenic genus, Acetobacterium, only with methanogenic inhibition. Pyrosequencing also showed a predominance of ethanol-fermenting bacteria, primarily represented by the genus Pelobacter. The next most abundant group was a diverse community of ARB, and they were followed by H(2)-scavenging syntrophic partners that were either H2-oxidizing methanogens or homo-acetogens when methanogenesis was suppressed. Thus, the community structure in the biofilm anode and suspension reflected the electron-flow distribution and H2-scavenging mechanism. PMID:19688868

Parameswaran, Prathap; Zhang, Husen; Torres, César I; Rittmann, Bruce E; Krajmalnik-Brown, Rosa

2010-01-01

186

Hydrophobicity of diverse bacterial populations in activated sludge and biofilm revealed by microbial adhesion to hydrocarbons assay and high-throughput sequencing.  

PubMed

Cell hydrophobicity is one of the key physicochemical properties of bacteria in activated sludge (AS) and biofilms can influence the efficient operation of wastewater treatment plants (WWTPs). In the present study the cell hydrophobicity of diverse bacterial populations in AS and biofilms from the Shatin and Stanley WWTPs of Hong Kong was characterized by combining the microbial adhesion to hydrocarbons (MATH) assay with the Illumina high-throughput sequencing. The results indicated that, at the phylum level, a majority of bacteria in AS and biofilms showed medium hydrophobicity. Most of the top 20 bacterial genera in the AS samples were hydrophilic. However, the top 20 genera in biofilms showed higher hydrophobicity than in the top 20 genera in AS samples, suggesting more hydrophobic bacteria existed in biofilms than in AS. Meanwhile, the hydrophobicity of two specific bacterial groups, including foaming and biosurfactant-producing bacteria, were also evaluated. The results demonstrated that, by combining the MATH assay with the Illumina sequencing approach, bacterial hydrophobicity could be evaluated with high efficiency and coverage in complex systems with high microbial diversity, e.g. AS and biofilms in WWTPs. PMID:24246196

Chao, Yuanqing; Guo, Feng; Fang, Herbert H P; Zhang, Tong

2014-02-01

187

Disruption of Microbial Biofilms by an Extracellular Protein Isolated from Epibiotic Tropical Marine Strain of Bacillus licheniformis  

PubMed Central

Background Marine epibiotic bacteria produce bioactive compounds effective against microbial biofilms. The study examines antibiofilm ability of a protein obtained from a tropical marine strain of Bacillus licheniformis D1. Methodology/Principal Findings B. licheniformis strain D1 isolated from the surface of green mussel, Perna viridis showed antimicrobial activity against pathogenic Candida albicans BH, Pseudomonas aeruginosa PAO1 and biofouling Bacillus pumilus TiO1 cultures. The antimicrobial activity was lost after treatment with trypsin and proteinase K. The protein was purified by ultrafiltration and size-exclusion chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis revealed the antimicrobial agent to be a 14 kDa protein designated as BL-DZ1. The protein was stable at 75°C for 30 min and over a pH range of 3.0 to 11.0. The sequence alignment of the MALDI-fingerprint showed homology with the NCBI entry for a hypothetical protein (BL00275) derived from B. licheniformis ATCC 14580 with the accession number gi52082584. The protein showed minimum inhibitory concentration (MIC) value of 1.6 µg/ml against C. albicans. Against both P. aeruginosa and B. pumilus the MIC was 3.12 µg/ml. The protein inhibited microbial growth, decreased biofilm formation and dispersed pre-formed biofilms of the representative cultures in polystyrene microtiter plates and on glass surfaces. Conclusion/Significance We isolated a protein from a tropical marine strain of B. licheniformis, assigned a function to the hypothetical protein entry in the NCBI database and described its application as a potential antibiofilm agent.

Dusane, Devendra H.; Damare, Samir R.; Nancharaiah, Yarlagadda V.; Ramaiah, N.; Venugopalan, Vayalam P.; Kumar, Ameeta Ravi; Zinjarde, Smita S.

2013-01-01

188

The involvement of rhamnolipids in microbial cell adhesion and biofilm development - an approach for control?  

PubMed

Biofilms are omnipresent in clinical and industrial settings and most of the times cause detrimental side effects. Finding efficient strategies to control surface-growing communities of micro-organisms remains a significant challenge. Rhamnolipids are extracellular secondary metabolites with surface-active properties mainly produced by Pseudomonas aeruginosa. There is growing evidence for the implication of this biosurfactant in different stages of biofilm development of this bacterium. Furthermore, rhamnolipids display a significant potential as anti-adhesive and disrupting agents against established biofilms formed by several bacterial and fungal species. Their low toxicity, biodegradability, efficiency and specificity, compared to synthetic surfactants typically used in biofilm control, might compensate for the economic hurdle still linked to their superior production costs and make them promising antifouling agents. PMID:24372465

Nickzad, A; Déziel, E

2014-05-01

189

Seasonal variation in nutrient limitation of microbial biofilms colonizing organic and inorganic substrata in streams  

Microsoft Academic Search

Humans have increased the availability of nutrients including nitrogen and phosphorus worldwide; therefore, understanding\\u000a how microbes process nutrients is critical for environmental conservation. We examined nutrient limitation of biofilms colonizing\\u000a inorganic (fritted glass) and organic (cellulose sponge) substrata in spring, summer, and autumn in three streams in Michigan,\\u000a USA. Biofilms were enriched with nitrate (NO3\\u000a ?), phosphate (PO4\\u000a 3?), ammonium

Timothy J. Hoellein; Jennifer L. Tank; John J. Kelly; Emma J. Rosi-Marshall

2010-01-01

190

Time to “go large” on biofilm research: advantages of an omics approach  

Microsoft Academic Search

In nature, the biofilm mode of life is of great importance in the cell cycle for many microorganisms. Perhaps because of biofilm\\u000a complexity and variability, the characterization of a given microbial system, in terms of biofilm formation potential, structure\\u000a and associated physiological activity, in a large-scale, standardized and systematic manner has been hindered by the absence\\u000a of high-throughput methods. This

Nuno F. Azevedo; Susana P. Lopes; Charles W. Keevil; Maria O. Pereira; Maria J. Vieira

2009-01-01

191

An aufwuchs chamber slide for high-resolution confocal laser scanning microscopy and stereo imaging of microbial communities in natural biofilms.  

PubMed

Aufwuchs chamber slides were constructed by attaching a silicone rubber gasket to a glass slide with epoxy cement. For biofilm growth, the slides were suspended in Cayuga Lake near Ithaca, NY, for 27 days. Biofilms in the chamber were stained with 0.05% acridine orange. After rinsing, the chamber was filled with molten 1% agarose to stabilize filaments and delicate polymer structures at the biofilm surface. Areas of biofilm approximately 0.5 mm thick on the inner face of the wall of the chamber were selected for side-on optical sectioning in a confocal laser scanning microscope (CLSM). Stacks of high-resolution optical images captured by the CLSM z-sectioning software, were used to create left-right stereo image pairs. At low magnification the stereo pairs showed 3-D details of the microbial landscape in the mature biofilms. Channels, pores, and other structural features of the biofilm matrix were observed in peripheral regions. Higher magnification images revealed the 3-D distribution of specific biofilm components such as filaments of sheathed bacteria projecting outward into the liquid milieu, and organic coatings, including bacterial cells on the surfaces of mineral particles. PMID:14574526

Eaglesham, B S; Lion, L W; Ghiorse, W C

2004-04-01

192

Effect of formation of biofilms and chemical scale on the cathode electrode on the performance of a continuous two-chamber microbial fuel cell.  

PubMed

A two-chamber MFC system was operated continuously for more than 500 days to evaluate effects of biofilm and chemical scale formation on the cathode electrode on power generation. A stable power density of 0.57 W/m(2) was attained after 200 days operation. However, the power density decreased drastically to 0.2 W/m(2) after the cathodic biofilm and chemical scale were removed. As the cathodic biofilm and chemical scale partially accumulated on the cathode, the power density gradually recovered with time. Microbial community structure of the cathodic biofilm was analyzed based on 16S rRNA clone libraries. The clones closely related to Xanthomonadaceae bacterium and Xanthomonas sp. in the Gammaproteobacteria subdivision were most frequently retrieved from the cathodic biofilm. Results of the SEM-EDX analysis revealed that the cation species (Na(+) and Ca(2+)) were main constituents of chemical scale, indicating that these cations diffused from the anode chamber through the Nafion membrane. However, an excess accumulation of the biofilm and chemical scale on the cathode exhibited adverse effects on the power generation due to a decrease in the active cathode surface area and an increase in diffusion resistance for oxygen. Thus, it is important to properly control the formation of chemical scale and biofilm on the cathode during long-term operation. PMID:20923722

Chung, Kyungmi; Fujiki, Itto; Okabe, Satoshi

2011-01-01

193

A life detection problem in a High Arctic microbial community  

NASA Astrophysics Data System (ADS)

Fluorescent labeling of bacterial cell walls, DNA, and metabolic processes demonstrates high (potentially single molecule) sensitivity, is non-invasive, and in some cases can differentiate strains and species. Robust microscopes such as the custom instruments presented here can provide good image quality in the field and are potentially suitable for flight. However, ambiguous or false-positive results with bacterial stains can occur and can create difficulties in interpretation even on Earth. We present a "real" life detection problem in a sample of biofilms taken from the Canadian High Arctic. The samples consisted of numerous small sulfur-oxidizing bacteria and larger structures resembling fungi or diatoms. The identity of these latter structures remained ambiguous until electron microscopy and X-ray spectroscopy were performed, indicating that they were unusual sulfur minerals probably precipitated by the bacterial communities. While such mineral structures may possibly serve as biosignatures after the cells have disappeared, it is important that they not be mistaken for cells themselves. It is also possible that unusual mineral structures will be performed under extraterrestrial conditions, so great care is needed to differentiate cell structures from minerals.

Rogers, J. D.; Perreault, N. N.; Niederberger, T. D.; Lichten, C.; Whyte, L. G.; Nadeau, J. L.

2010-03-01

194

Electrochemical response of a biofilm community to changes in electron-acceptor redox potential elucidated using microbial fuel cells  

NASA Astrophysics Data System (ADS)

Currently, we have limited insight into how mineral properties affect dissimilatory metal-reducing bacteria (DMRB) or the microbial communities that contain them. Advances in our understanding of DMRB metabolism have been achieved using microbial fuel cells (MFCs), which exploit the ability of these organisms to transfer electrons extracellularly. By replacing the mineral electron acceptor with a conductive electrode under potentiostat control, the activity of microorganisms capable of interfacial electron transfer can be quantified by the current flowing through the electrode and related to the thermodynamics of respiration. We seek to understand how communities and their individual members respond to changes in mineralogy, and expect mineral redox potential to be a primary control. The ability to precisely control the redox potential of the electron-accepting anodic electrode is our primary motivation for using MFCs. We inoculated duplicate MFCs containing 10 mM acetate in phosphate buffered media with a slurry of subsurface sediment and groundwater obtained from the Integrated Field-Scale Research Challenge Site at Rifle, CO. Electroactive biofilms were established on graphite anodes poised at a favorable potential (0.0 V vs. SHE) before poising at -0.2 V—a potential representative of natural iron reduction. The current was stable across both anodes over more than 100 days of operation, and the percentage of the electrons in acetate recovered as current ("Coulombic efficiency") was typically 70 to >90%. Current density reached 0.4 A/m2 at -0.2 V, to a max of over 1.0 A/m2 at or above ~0.0 V (based on geometric electrode surface area). Media exchanges and biofilm cyclic voltammetry (CV) experiments indicate that electrode-attached microbial communities were responsible for primary electron transfer. Cryo-electron and confocal fluorescence microscopies of the biofilm reveal numerous morphologies of viable microorganisms that are currently being characterized using 16S rRNA gene clone library analysis. We studied how the microbial activity changed when the anode potential was varied. Altering the anode potential caused reversible changes in the mid-point potential(s), Em, measured using CV. Qualitatively, the average Em always shifted toward the set anode potential. A maximum shift in the peak of the derivative CV spectra of ~100 mV defines the approximate upper and lower Em values for the proteins contributing to this feature. The change in the electrochemical response was complete ~30 minutes after a 400 mV anode-potential step. We attribute these observations to either a switch in the principle electron-transport pathway (different enzymes) that individual species use to deliver electrons to the anode or changes in the relative contributions of different community members, or both. However, some impact of changes in pH within the biofilm could contribute to the change in Em. Ongoing investigations attempt to resolve these possibilities.

Arbour, T.; Wrighton, K. C.; Mullin, S. W.; Luef, B.; Gilbert, B.; Banfield, J. F.

2012-12-01

195

Spatially Oscillating Activity and Microbial Succession of Mercury-Reducing Biofilms in a Technical-Scale Bioremediation System  

PubMed Central

Mercury-contaminated chemical wastewater of a mercury cell chloralkali plant was cleaned on site by a technical-scale bioremediation system. Microbial mercury reduction of soluble Hg(II) to precipitating Hg(0) decreased the mercury load of the wastewater during its flow through the bioremediation system by up to 99%. The system consisted of a packed-bed bioreactor, where most of the wastewater's mercury load was retained, and an activated carbon filter, where residual mercury was removed from the bioreactor effluent by both physical adsorption and biological reduction. In response to the oscillation of the mercury concentration in the bioreactor inflow, the zone of maximum mercury reduction oscillated regularly between the lower and the upper bioreactor horizons or the carbon filter. At low mercury concentrations, maximum mercury reduction occurred near the inflow at the bottom of the bioreactor. At high concentrations, the zone of maximum activity moved to the upper horizons. The composition of the bioreactor and carbon filter biofilms was investigated by 16S-23S ribosomal DNA intergenic spacer polymorphism analysis. Analysis of spatial biofilm variation showed an increasing microbial diversity along a gradient of decreasing mercury concentrations. Temporal analysis of the bioreactor community revealed a stable abundance of two prevalent strains and a succession of several invading mercury-resistant strains which was driven by the selection pressure of high mercury concentrations. In the activated carbon filter, a lower selection pressure permitted a steady increase in diversity during 240 days of operation and the establishment of one mercury-sensitive invader.

von Canstein, Harald; Li, Ying; Leonhauser, Johannes; Haase, Elke; Felske, Andreas; Deckwer, Wolf-Dieter; Wagner-Dobler, Irene

2002-01-01

196

ADAPTATION OF SUBSURFACE MICROBIAL BIOFILM COMMUNITIES IN RESPONSE TO CHEMICAL STRESSORS  

EPA Science Inventory

The impact of this work will help improve our understanding of how subsurface biofilm communities respond to chemical stressors that are likely to be present at hazardous waste sites. Ultimately, these results can be used to determine more effective ways to insure proper envir...

197

Reproducible analyses of microbial food for advanced life support systems  

NASA Technical Reports Server (NTRS)

The use of yeasts in controlled ecological life support systems (CELSS) for microbial food regeneration in space required the accurate and reproducible analysis of intracellular carbohydrate and protein levels. The reproducible analysis of glycogen was a key element in estimating overall content of edibles in candidate yeast strains. Typical analytical methods for estimating glycogen in Saccharomyces were not found to be entirely aplicable to other candidate strains. Rigorous cell lysis coupled with acid/base fractionation followed by specific enzymatic glycogen analyses were required to obtain accurate results in two strains of Candida. A profile of edible fractions of these strains was then determined. The suitability of yeasts as food sources in CELSS food production processes is discussed.

Petersen, Gene R.

1988-01-01

198

Exploration of deep intraterrestrial microbial life: current perspectives.  

PubMed

Intraterrestrial life has been found at depths of several thousand metres in deep sub-sea floor sediments and in the basement crust beneath the sediments. It has also been found at up to 2800-m depth in continental sedimentary rocks, 5300-m depth in igneous rock aquifers and in fluid inclusions in ancient salt deposits from salt mines. The biomass of these intraterrestrial organisms may be equal to the total weight of all marine and terrestrial plants. The intraterrestrial microbes generally seem to be active at very low but significant rates and several investigations indicate chemolithoautotrophs to form a chemosynthetic base. Hydrogen, methane and carbon dioxide gases are continuously generated in the interior of our planet and probably constitute sustainable sources of carbon and energy for deep intraterrestrial biosphere ecosystems. Several prospective research areas are foreseen to focus on the importance of microbial communities for metabolic processes such as anaerobic utilisation of hydrocarbons and anaerobic methane oxidation. PMID:10731600

Pedersen, K

2000-04-01

199

Microbial mats and the early evolution of life  

NASA Technical Reports Server (NTRS)

Microbial mats have descended from perhaps the oldest and most widespread biological communities known. Mats harbor microbes that are crucial for studies of bacterial phylogeny and physiology. They illustrate how several oxygen-sensitive biochemical processes have adapted to oxygen, and they show how life adapted to dry land long before the rise of plants. The search for the earliest grazing protists and metazoa in stromatolites is aided by observations of mats: in them, organic compounds characteristic of ancient photosynthetic protists can be identified. Recent mat studies suggest that the 13C/12C increase observed over geological time in stromatolitic organic matter was driven at least in part by a long-term decline in atmospheric carbon dioxide levels.

Des Marais, D. J.

1990-01-01

201

Retention and Release of Cryptosporidium parvum Oocysts by Experimental Biofilms Composed of a Natural Stream Microbial Community?  

PubMed Central

Cryptosporidium parvum oocysts accumulate on biofilm surfaces. The percentage of oocysts attached to biofilms remained nearly constant while oocysts were supplied to the system but decreased to a new steady-state level once oocysts were removed from the feed. More oocysts attached to summer biofilm cultures than winter biofilm cultures.

Wolyniak, E. A.; Hargreaves, B. R.; Jellison, K. L.

2009-01-01

202

Effects of packing rates of cubic-shaped polyurethane foam carriers on the microbial community and the removal of organics and nitrogen in moving bed biofilm reactors.  

PubMed

The effects of packing rates (20%, 30%, and 40%) of polyurethane foam (PUF) to the removal of organics and nitrogen were investigated by continuously feeding artificial sewage in three aerobic moving bed biofilm reactors. The results indicated that the packing rate of the PUF carriers had little influence on the COD removal efficiency (81% on average). However, ammonium removal was affected by the packing rates, which was presumably due to the different relative abundances of nitrifying bacteria. A high ammonium removal efficiency of 96.3% at a hydraulic retention time of 5h was achieved in 40% packing rate reactor, compared with 37.4% in 20% packing rate. Microprofiles of dissolved oxygen and nitrate revealed that dense biofilm limits the DO transfer distance and nitrate diffusion. Pyrosequencing analysis of the biofilm showed that Proteobacteria, Bacteroidetes and Verrucomicrobia were the three most abundant phyla, but the proportions of the microbial community varied with the packing rate of the PUF carriers. PMID:22621807

Feng, Quan; Wang, Yuxiao; Wang, Tianmin; Zheng, Hao; Chu, Libing; Zhang, Chong; Chen, Hongzhang; Kong, Xiuqin; Xing, Xin-Hui

2012-08-01

203

Comparison of microbial changes in early re-developing biofilms on natural teeth and dentures  

PubMed Central

Background and objective Surfaces and fluids can affect oral bacterial colonization. The aim of this study was to compare re-developing biofilms on natural teeth and dentures. Methods Supragingival plaque samples were taken from 55 dentate subjects and the denture teeth of 62 edentulous subjects before and after professional cleaning. Also, samples from 7 “teeth” in randomly selected quadrants were collected after 1, 2, 4 and 7 days of no oral hygiene. Samples were analyzed using checkerboard DNA-DNA hybridization. Counts and proportions of 41 bacterial taxa were determined at each time point and significant differences were sought using the Mann-Whitney test. Ecological succession was determined using a modified moving window analysis. Results Mean total DNA probe counts were similar pre-cleaning but were higher in dentate subjects at all post-cleaning visits (p<0.01). Pre-cleaning edentate biofilms had higher counts and proportions of Streptococcus mitis, Streptococcus oralis and Streptococcus mutans, whereas dentate subjects had higher proportions of Tannerella forsythia, Selenomonas noxia and Neisseria mucosa. By 2 days, mean counts of all taxa were higher in natural teeth and most remained higher at 7 days (p<0.01). Succession was more rapid and complex in dentate subjects. Both groups demonstrated increased proportions of S. mitis and S. oralis by 1 day. N. mucosa, Veillonella parvula and Eikenella corrodens increased in both groups but later in edentate samples. Conclusions “Mature” natural and denture teeth biofilms have similar total numbers of bacteria but different species proportions. Post-cleaning biofilm re-development is more rapid and more complex on natural than denture teeth.

Teles, F.R.; Teles, R.P.; Sachdeo, A.; Uzel, N.G.; Song, X.Q.; Torresyap, G.; Singh, M.; Papas, A.; Haffajee, A.D.; Socransky, S.S.

2013-01-01

204

Early microbial succession in re-developing dental biofilms in periodontal health and disease  

PubMed Central

Objective To determine the order of bacterial species succession in re-developing supra and subgingival biofilms. Methods Supra and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects immediately after professional cleaning. Samples were taken again from 7 teeth in randomly selected quadrants after 1, 2, 4 and 7 days of no oral hygiene and analyzed using checkerboard DNA-DNA hybridization. % DNA probe counts were averaged within subjects at each time point. Ecological succession was determined using a modified moving window analysis. Results Succession in supragingival biofilms from periodontitis and health was similar. At 1 day, Streptococcus mitis and Neisseria mucosa showed increased proportions, followed by Capnocytophaga gingivalis, Eikenella corrodens, Veillonella parvula and Streptococcus oralis at 1–4 days. At 4–7 days, Campylobacter rectus, Campylobacter showae, Prevotella melaninogenica and Prevotella nigrescens became elevated. Subgingival plaque redevelopment was slower and very different from supragingival. Increased proportions were first observed for S. mitis, followed by V. parvula and C. gingivalis and, at 7 days by Capnocytophaga sputigena and P. nigrescens. No significant increase in proportions of periodontal pathogens was observed in any of the clinical groups or locations. Conclusions There is a defined order in bacterial species succession in early supra and subgingival biofilm re-development after professional cleaning.

TELES, F.R.; TELES, R.P.; UZEL, N.G.; SONG, X.Q.; TORRESYAP, G.; SOCRANSKY, S.S.; HAFFAJEE, A.D.

2011-01-01

205

Characterization of a filamentous biofilm community established in a cellulose-fed microbial fuel cell  

Microsoft Academic Search

BACKGROUND: Microbial fuel cells (MFCs) are devices that exploit microorganisms to generate electric power from organic matter. Despite the development of efficient MFC reactors, the microbiology of electricity generation remains to be sufficiently understood. RESULTS: A laboratory-scale two-chamber microbial fuel cell (MFC) was inoculated with rice paddy field soil and fed cellulose as the carbon and energy source. Electricity-generating microorganisms

Shun'ichi Ishii; Takefumi Shimoyama; Yasuaki Hotta; Kazuya Watanabe

2008-01-01

206

Microbial subpopulations in the biofilm attached to the substratum and in the free flocs of a fixed-bed anaerobic bioreactor  

Microsoft Academic Search

The microbial flora of a fixed-bed anaerobic methanogenic bioreactor fed with acetate\\/propionate\\/butyrate was studied by direct, qualitative and quantitative methods avoiding culture isolation. The aims were to identify species, determine the distribution of microbes between the biofilm attached to the substratum and the free flocs, and define the acidogenic, acetogenic and methanogenic contingents. Optical and scanning electron microscopies showed heterogeneous

G. Zellner; A. J. L. Macario; E. Conway Macario

1996-01-01

207

Continuous power generation and microbial community structure of the anode biofilms in a three-stage microbial fuel cell system  

Microsoft Academic Search

A mediator-less three-stage two-chamber microbial fuel cell (MFC) system was developed and operated continuously for more\\u000a than 1.5 years to evaluate continuous power generation while treating artificial wastewater containing glucose (10 mM) concurrently.\\u000a A stable power density of 28 W\\/m3 was attained with an anode hydraulic retention time of 4.5 h and phosphate buffer as the cathode electrolyte. An overall\\u000a dissolved organic carbon removal

Kyungmi Chung; Satoshi Okabe

2009-01-01

208

Zn biomineralization processes and microbial biofilm in a metal-rich stream (Naracauli, Sardinia).  

PubMed

Several decades after the closure of the Ingurtosu mine (SW Sardinia), a variety of seasonal Zn biomineralizations occurs. In this work, waters, microbial consortia, and seasonal precipitates from the Naracauli stream were sampled to investigate chemical composition of stream waters and biominerals, and microbial strain identity. Molecular and morphological analysis revealed that activity of dominant cyanobacterium Leptolyngbya frigida results in precipitation of Zn silicate. The activity of the cyanobacterium was associated to other bacteria and many kind of diatoms, such as Halamphora subsalina and Encyonopsis microcephala, which are trapped in the process of biomineral growth. In this work, the precipitation process is shown to be the result of many different parameters such as hydrologic regime, microbial community adaptation, and biological mediation. It results in a decrease of dissolved Zn in the stream water, and is a potential tool for Zn pollution abatement. PMID:23872900

Podda, F; Medas, D; De Giudici, G; Ryszka, P; Wolowski, K; Turnau, K

2014-06-01

209

Influence of Disinfectant Residual on Biofilm Development, Microbial Ecology, and Pathogen Fate and Transport in Drinking Water Infrastructure  

EPA Science Inventory

This project focuses on providing basic data to bound risk estimates resulting from pathogens associated with pipe biofilms. Researchers will compare biofilm pathogen effects under two different disinfection scenarios (free chlorine or chloramines) for a conventionally treated s...

210

Effects of nitrate treatment on a mixed species, oil field microbial biofilm.  

PubMed

Biofilms of bacteria, indigenous to oil field produced water, were grown in square section, glass capillary flow cells at 45 degrees C. Initially, in situ image analysis microscopy revealed predominantly coccoid bacteria (length-to-width ratio measurements (l (c):w (c)) of bacterial cells gave a mean value of 1.1), while chemical measurements confirmed sulphate reduction and sulphide production. After nitrate ion addition at 100 and 80 mg/l, in the two repeat experiments respectively, the dominance of rod-shaped bacteria (mean l (c):w (c) = 2.8) was observed. This coincided with the occurrence of nitrate reduction in the treated flow cells. Beneficially, no significant increase in biofilm cover was observed after the addition of nitrate. The dominant culturable nitrate-reducing bacterium was Marinobacter aquaeolei. The l (c):w (c) ratio measured here concurs with previously reported cell dimensions for this organism. Several Marinobacter strains were also isolated from different oil fields in the North Sea where nitrate treatment has been applied to successfully treat reservoir souring, implying that this genus may play an important role in nitrate treatment. PMID:16491355

Dunsmore, Braden; Youldon, James; Thrasher, David R; Vance, Ian

2006-06-01

211

Antifungal therapy with an emphasis on biofilms.  

PubMed

Fungal infections are on the rise as advances in modern medicine prolong the lives of severely ill patients. Fungi are eukaryotic organisms and there are a limited number of targets for antifungal drug development; as a result the antifungal arsenal is exceedingly limited. Azoles, polyenes and echinocandins constitute the mainstay of antifungal therapy for patients with life-threatening mycoses. One of the main factors complicating antifungal therapy is the formation of fungal biofilms, microbial communities displaying resistance to most antifungal agents. A better understanding of fungal biofilms provides for new opportunities for the development of urgently needed novel antifungal agents and strategies. PMID:24011516

Pierce, Christopher G; Srinivasan, Anand; Uppuluri, Priya; Ramasubramanian, Anand K; López-Ribot, José L

2013-10-01

212

Microbial diversities (16S and 18S rRNA gene pyrosequencing) and environmental pathogens within drinking water biofilms grown on the common premise plumbing materials unplasticized polyvinylchloride and copper.  

PubMed

Drinking water (DW) biofilm communities influence the survival of opportunistic pathogens, yet knowledge about the microbial composition of DW biofilms developed on common in-premise plumbing material is limited. Utilizing 16S and 18S rRNA gene pyrosequencing, this study characterized the microbial community structure within DW biofilms established on unplasticized polyvinyl chloride (uPVC) and copper (Cu) surfaces and the impact of introducing Legionella pneumophila (Lp) and Acanthamoeba polyphaga. Mature (> 1 year old) biofilms were developed before inoculation with sterilized DW (control, Con), Lp, or Lp and A. polyphaga (LpAp). Comparison of uPVC and Cu biofilms indicated significant differences between bacterial (P = 0.001) and eukaryotic (P < 0.01) members attributable to the unique presence of several family taxa: Burkholderiaceae, Characeae, Epistylidae, Goniomonadaceae, Paramoebidae, Plasmodiophoridae, Plectidae, Sphenomonadidae, and Toxariaceae within uPVC biofilms; and Enterobacteriaceae, Erythrobacteraceae, Methylophilaceae, Acanthamoebidae, and Chlamydomonadaceae within Cu biofilms. Introduction of Lp alone or with A. polyphaga had no effect on bacterial community profiles (P > 0.05) but did affect eukaryotic members (uPVC, P < 0.01; Cu, P = 0.001). Thus, established DW biofilms host complex communities that may vary based on substratum matrix and maintain consistent bacterial communities despite introduction of Lp, an environmental pathogen. PMID:24490699

Buse, Helen Y; Lu, Jingrang; Lu, Xinxin; Mou, Xiaozhen; Ashbolt, Nicholas J

2014-05-01

213

Microbial shifts during dental biofilm re-development in the absence of oral hygiene in periodontal health and disease  

PubMed Central

Aim to monitor microbial shifts during dental biofilm re-development Methods Supra and subgingival plaque samples were taken separately from 28 teeth in 38 healthy and 17 periodontitis subjects at baseline and immediately after tooth cleaning. Samples were taken again from 7 teeth in randomly selected quadrants during 1, 2, 4 and 7 days of no oral hygiene. Samples were analyzed using checkerboard DNA-DNA hybridization. Species counts were averaged within subjects at each time point. Significant differences in counts between healthy and periodontitis subjects were sought using the Mann-Whitney test. Results Total supra and subgingival counts were significantly higher in periodontitis on entry and reached or exceeded baseline values after day 2. Supragingival counts of Veillonella parvula, Fusobacterium nucleatum ss vincentii and Neisseria mucosa increased from 2 to 7 days. Subgingival counts were greater for Actinomyces, green and orange complex species. Significant differences between groups in supragingival counts occurred for 17 of 41 species at entry, 0 at day 7; for subgingival plaque these values were 39/41 taxa at entry, 17/41 at day 7. Conclusions Supragingival plaque re-development was similar in periodontitis and health, but subgingival species recolonization was more marked in periodontitis.

Uzel, N.G.; Teles, F.R.; Teles, R.P.; Song, X.Q.; Torresyap, G.; Socransky, S.S.; Haffajee, A.D.

2011-01-01

214

Community living long before man: fossil and living microbial mats and early life  

NASA Technical Reports Server (NTRS)

Microbial mats are layered communities of bacteria that form cohesive structures, some of which are preserved in sedimentary rocks as stromatolites. Certain rocks, approximately three and a half thousand million years old and representing the oldest known fossils, are interpreted to derive from microbial mats and to contain fossils of microorganisms. Modern microbial mats (such as the one described here from Matanzas, Cuba) and their fossil counterparts are of great interest in the interpretation of early life on Earth. Since examination of microbial mats and stromatolites increases our understanding of long-term stability and change, within the global environment, such structures should be protected wherever possible as natural science preserves. Furthermore, since they have existed virtually from the time of life's origin, microbial mats have developed exemplary mechanisms of local community persistence and may even play roles in the larger global environment that we do not understand.

Margulis, L.; Lopez Baluja, L.; Awramik, S. M.; Sagan, D.

1986-01-01

215

Search for microbial life in the deep sub-seafloor: preliminary results from ODP Leg 201  

NASA Astrophysics Data System (ADS)

Studies of microbial life in the deep marine subsurface can be used as a model system for the detection of possible microbial life on Mars. Focussed on the methodology, we tested four different approaches to evaluate the number, the identity and the function of the existing microorganisms in deep-sea sediments from the Peru Margin. Specifically, we applied the combined microscopic/molecular method FISH, organic biomarker studies, stable isotopes, DNA isolation and 16S rRNA analysis, and direct cultivation of microorganisms. With this set of methods, the microbial diversity was estimated in that extreme environment.

Warthmann, Rolf; Meister, Patrick; Mauclaire, Laurie; Chatzinotas, Antonis; Neretin, Lev; Bernasconi, Stefano; Vasconcelos, Crisogono; McKenzie, Judith A.

2004-03-01

216

Anti-Microbial, Anti-Biofilm Activities and Cell Selectivity of the NRC-16 Peptide Derived from Witch Flounder, Glyptocephalus cynoglossus  

PubMed Central

Previous studies had identified novel antimicrobial peptides derived from witch flounder. In this work, we extended the search for the activity of peptide that showed antibacterial activity on clinically isolated bacterial cells and bacterial biofilm. Pseudomonas aeruginosa was obtained from otitis media and cholelithiasis patients, while Staphylococcus aureus was isolated from otitis media patients. We found that synthetic peptide NRC-16 displays antimicrobial activity and is not sensitive to salt during its bactericidal activity. Interestingly, this peptide also led to significant inhibition of biofilm formation at a concentration of 4–16 ?M. NRC-16 peptide is able to block biofilm formation at concentrations just above its minimum inhibitory concentration while conventional antibiotics did not inhibit the biofilm formation except ciprofloxacin and piperacillin. It did not cause significant lysis of human RBC, and is not cytotoxic to HaCaT cells and RAW264.7 cells, thereby indicating its selective antimicrobial activity. In addition, the peptide’s binding and permeation activities were assessed by tryptophan fluorescence, calcein leakage and circular dichroism using model mammalian membranes composed of phosphatidylcholine (PC), PC/cholesterol (CH) and PC/sphingomyelin (SM). These experiments confirmed that NRC-16 does not interact with any of the liposomes but the control peptide melittin did. Taken together, we found that NRC-16 has potent antimicrobial and antibiofilm activities with less cytotoxicity, and thus can be considered for treatment of microbial infection in the future.

Gopal, Ramamourthy; Lee, Jun Ho; Kim, Young Gwon; Kim, Myeong-Sun; Seo, Chang Ho; Park, Yoonkyung

2013-01-01

217

Anti-microbial, anti-biofilm activities and cell selectivity of the NRC-16 peptide derived from witch flounder, Glyptocephalus cynoglossus.  

PubMed

Previous studies had identified novel antimicrobial peptides derived from witch flounder. In this work, we extended the search for the activity of peptide that showed antibacterial activity on clinically isolated bacterial cells and bacterial biofilm. Pseudomonas aeruginosa was obtained from otitis media and cholelithiasis patients, while Staphylococcus aureus was isolated from otitis media patients. We found that synthetic peptide NRC-16 displays antimicrobial activity and is not sensitive to salt during its bactericidal activity. Interestingly, this peptide also led to significant inhibition of biofilm formation at a concentration of 4-16 ?M. NRC-16 peptide is able to block biofilm formation at concentrations just above its minimum inhibitory concentration while conventional antibiotics did not inhibit the biofilm formation except ciprofloxacin and piperacillin. It did not cause significant lysis of human RBC, and is not cytotoxic to HaCaT cells and RAW264.7 cells, thereby indicating its selective antimicrobial activity. In addition, the peptide's binding and permeation activities were assessed by tryptophan fluorescence, calcein leakage and circular dichroism using model mammalian membranes composed of phosphatidylcholine (PC), PC/cholesterol (CH) and PC/sphingomyelin (SM). These experiments confirmed that NRC-16 does not interact with any of the liposomes but the control peptide melittin did. Taken together, we found that NRC-16 has potent antimicrobial and antibiofilm activities with less cytotoxicity, and thus can be considered for treatment of microbial infection in the future. PMID:23760014

Gopal, Ramamourthy; Lee, Jun Ho; Kim, Young Gwon; Kim, Myeong-Sun; Seo, Chang Ho; Park, Yoonkyung

2013-06-01

218

Treatment of microbial biofilms in the post-antibiotic era: prophylactic and therapeutic use of antimicrobial peptides and their design by bioinformatics tools.  

PubMed

The treatment for biofilm infections is particularly challenging because bacteria in these conditions become refractory to antibiotic drugs. The reduced effectiveness of current therapies spurs research for the identification of novel molecules endowed with antimicrobial activities and new mechanisms of antibiofilm action. Antimicrobial peptides (AMPs) have been receiving increasing attention as potential therapeutic agents, because they represent a novel class of antibiotics with a wide spectrum of activity and a low rate in inducing bacterial resistance. Over the past decades, a large number of naturally occurring AMPs have been identified or predicted from various organisms as effector molecules of the innate immune system playing a crucial role in the first line of defense. Recent studies have shown the ability of some AMPs to act against microbial biofilms, in particular during early phases of biofilm development. Here, we provide a review of the antimicrobial peptides tested on biofilms, highlighting their advantages and disadvantages for prophylactic and therapeutic applications. In addition, we describe the strategies and methods for de novo design of potentially active AMPs and discuss how informatics and computational tools may be exploited to improve antibiofilm effectiveness. PMID:24515391

Di Luca, Mariagrazia; Maccari, Giuseppe; Nifosì, Riccardo

2014-04-01

219

Pressure as an environmental parameter for microbial life--a review.  

PubMed

Microbial life has been prevailing in the biosphere for the last 3.8 Ga at least. Throughout most of the Earth's history it has experienced a range of pressures; both dynamic pressure when the young Earth was heavily bombarded, and static pressure in subsurface environments that could have served as a refuge and where microbial life nowadays flourishes. In this review, we discuss the extent of high-pressure habitats in early and modern times and provide a short overview of microbial survival under dynamic pressures. We summarize the current knowledge about the impact of microbial activity on biogeochemical cycles under pressures characteristic of the deep subsurface. We evaluate the possibility that pressure can be a limiting parameter for life at depth. Finally, we discuss the open questions and knowledge gaps that exist in the field of high-pressure geomicrobiology. PMID:23891571

Picard, Aude; Daniel, Isabelle

2013-12-15

220

Sulfate and organic carbon removal by microbial fuel cell with sulfate-reducing bacteria and sulfide-oxidising bacteria anodic biofilm.  

PubMed

Biological sulfur removal can be achieved by reducing sulfate to sulfide with sulfate-reducing bacteria (SRB) and then oxidising sulfide to elemental sulfur (S(0)) with sulfide oxidising bacteria (SOB) for recovery. In sulfate-carbon wastewaters lacking electron acceptor for sulfide, excess sulfide will be produced and accumulated in the reactor. This study applied the microbial fuel cell (MFC) cultivated with the SRB+SOB anodic biofilm for treating the sulfate+organic carbon wastewaters. Excess sulfate ions were efficiently converted to sulfide by SRB cells in the biofilm, while the formed sulfide was diffused to the neighboring SOB cells to be irreversibly converted to S(0) with produced electrons being transferred to the anode. The cell-cell sulfide transport principally determined the electron flux of the MFC. Short diffusional distance of sulfide ions between cells significantly reduced the polarization resistances, hence enhancing performance of the MFC. PMID:24480414

Lee, Duu-Jong; Liu, Xiang; Weng, Hsiang-Ling

2014-03-01

221

Energy, ecology and the distribution of microbial life.  

PubMed

Mechanisms that govern the coexistence of multiple biological species have been studied intensively by ecologists since the turn of the nineteenth century. Microbial ecologists in the meantime have faced many fundamental challenges, such as the lack of an ecologically coherent species definition, lack of adequate methods for evaluating population sizes and community composition in nature, and enormous taxonomic and functional diversity. The accessibility of powerful, culture-independent molecular microbiology methods offers an opportunity to close the gap between microbial science and the main stream of ecological theory, with the promise of new insights and tools needed to meet the grand challenges humans face as planetary engineers and galactic explorers. We focus specifically on resources related to energy metabolism because of their direct links to elemental cycling in the Earth's history, engineering applications and astrobiology. To what extent does the availability of energy resources structure microbial communities in nature? Our recent work on sulfur- and iron-oxidizing autotrophs suggests that apparently subtle variations in the concentration ratios of external electron donors and acceptors select for different microbial populations. We show that quantitative knowledge of microbial energy niches (population-specific patterns of energy resource use) can be used to predict variations in the abundance of specific taxa in microbial communities. Furthermore, we propose that resource ratio theory applied to micro-organisms will provide a useful framework for identifying how environmental communities are organized in space and time. PMID:23754819

Macalady, Jennifer L; Hamilton, Trinity L; Grettenberger, Christen L; Jones, Daniel S; Tsao, Leah E; Burgos, William D

2013-07-19

222

Natural and synthetic cathelicidin peptides with anti-microbial and anti-biofilm activity against Staphylococcus aureus  

Microsoft Academic Search

Background  Chronic, infected wounds typically contain multiple genera of bacteria, including Staphylococcus aureus, many of which are strong biofilm formers. Bacterial biofilms are thought to be a direct impediment to wound healing. New\\u000a therapies that focus on a biofilm approach may improve the recovery and healing rate for infected wounds. In this study, cathelicidins\\u000a and related short, synthetic peptides were tested

Scott N Dean; Barney M Bishop; Monique L van Hoek

2011-01-01

223

Bacterial cellulose may provide the microbial-life biosignature in the rock records  

NASA Astrophysics Data System (ADS)

Bacterial cellulose (BC) is a matrix for a biofilm formation, which is critical for survival and persistence of microbes in harsh environments. BC could play a significant role in the formation of microbial mats in pristine ecosystems on Earth. The prime objective of this study was to measure to what extent spectral and other characteristics of BC were changed under the performance of BC interaction with the earthly rock - anorthosite - via microorganisms. The spectral analyses (Fourier Transform Infrared FT-IR, spectroscopy, and atomic absorption spectroscopy) showed unprecedented accumulation of chemical elements in the BC-based biofilm. The absorption capacity of IR by BC was shielded a little by mineral crust formed by microorganisms on the BC-based biofilm surface, especially clearly seen in the range of 1200-900 cm-1 in FT-IR spectra. Confocal scanning laser microscopy analysis revealed that elements bioleached from anorthosite created surface coats on the BC nanofibril web. At the same time, the vibrational spectra bands showed the presence of the characteristic region of anomeric carbons (960-730 cm-1), wherein a band at 897 cm-1 confirmed the presence of ?-1, 4-linkages, which may serve as the cellulose fingerprint region. Results show that BC may be a biosignature for search signs of living organisms in rock records.

Zaets, I.; Podolich, O.; Kukharenko, O.; Reshetnyak, G.; Shpylova, S.; Sosnin, M.; Khirunenko, L.; Kozyrovska, N.; de Vera, J.-P.

2014-03-01

224

Kinetic analysis of microbial sulfate reduction by desulfovibrio desulfuricans in an anaerobic upflow porous media biofilm reactor.  

PubMed

An anaerobic upflow porous media biofilm reactor was designed to study the kinetics and stoichiometry of hydrogen sulfide production by the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans (ATCC 5575) as the first step for the modeling and control of formation souring (H(2)S) in oil field porous media. The reactor was a packed bed (50 x 5.5 cm) tubular reactor. Sea sand (140 to 375 mum) was used as the porous media. The initial indication of souring was the appearance of well-separated black spots (precipitates of iron sulfide) in the sand bed. The blackened zones expanded radially and upward through the column. New spots also appeared and expanded into the cone shapes. Lactate (substrate) was depleted and hydrogen sulfide appeared in the effluent.Analysis of the pseudo-steady state column shows that there were concentration gradients for lactate and hydrogen sulfide along the column. The results indicate that most of the lactate was consumed at the front part of the column. Measurements of SRB biomass on the solid phase (sand) and in the liquid phase indicate that the maximum concentration of SRB biomass resided at the front part of the column while the maximum in the liquid phase occurred further downstream. The stoichiometry regarding lactate consumption and hydrogen sulfide production observed in the porous media reactor was different from that in a chemostat. After analyzing the radial dispersion coefficient for the SRB in porous media and kinetics of microbial growth, it was deduced that transport phenomena dominate the souring process in our porous media reactor system. (c) 1994 John Wiley & Sons, Inc. PMID:18615689

Chen, C I; Mueller, R F; Griebe, T

1994-02-20

225

Discriminative detection and enumeration of microbial life in marine subsurface sediments  

Microsoft Academic Search

Detection and enumeration of microbial life in natural environments provide fundamental information about the extent of the biosphere on Earth. However, it has long been difficult to evaluate the abundance of microbial cells in sedimentary habitats because non-specific binding of fluorescent dye and\\/or auto-fluorescence from sediment particles strongly hampers the recognition of cell-derived signals. Here, we show a highly efficient

Yuki Morono; Takeshi Terada; Noriaki Masui; Fumio Inagaki

2009-01-01

226

Planetary protection and Life detection: a single (but complex) question for microbial ecologists  

NASA Astrophysics Data System (ADS)

Life on Earth is (almost) everywhere, often non visible, with millions of microbes for every cubic centimeter of water, soil or air. For these reasons, to build and launch a sterile spacecraft is totally impossible. As a consequence, some microbial contamination of a spacecraft landing site cannot be rulled out. On the targeted planet, where no big size living forms have been observed, the only possibility for extinct or extant life is microbial-like entities. Finally, on the landing/sampling site, scientists will have to face the following problem: how to detect non viable extraterrestrial life forms (or signatures) among non visible terrestrial forms (or remains) that might have accompanied the spacecraft. This is a typical series of questions for microbial ecologists: Who is there? How many are there? What are they doing? An additionnal difficulty is that both components are almost certainly in a very low density, and in unknown proportions. Such a situation requires to considerably decrease the presently available levels of detections for microbial entities, and stong methodology efforts should be untertaken, with this respect. However, one term of this biological equation can be fixed: the microbial charge of the spacecraft before, and after the flight. A coordinated (through space agencies) efforts should be carried out to study microbial communities associated with spacecrafts in various places and conditions (phylogenetic diversity, physiology, distribution, abundance, etc. Such studies should be carried out at different steps of sterilization procedures, and followed by experiments dedicated to determine the responses of selected organisms to flight conditions. All these studies would feed a data base of spacecraft associated organisms and their post- flight signatures, to serve as a control for in situ life detection experiments, and a guideline for planetary protection policies. Planetary protection studies, Life detection methods are usually run in separate meetings and workshops, although they are dependent on similar concepts and technologies of Microbial Ecology.

Prieur, Daniel

227

Microbial Life in the Deep Subsurface: Deep, Hot and Radioactive  

NASA Technical Reports Server (NTRS)

Recent studies, motivated in part by the search for extraterrestrial life, continue to expand the recognized limits of Earth's biosphere. This work explored evidence for life a high-temperature, radioactive environment in the deep subsurface.

DeStefano, Andrea L.; Ford, Jill C.; Winsor, Seana K.; Allen, Carlton C.; Miller, Judith; McNamara, Karen M.; Gibson, Everett K., Jr.

2000-01-01

228

IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION  

SciTech Connect

This project addressed four major areas of investigation: i) characterization of formation of Cellulomonas uda biofilms on cellulose; ii) characterization of Clostridium phytofermentans biofilm development; colonization of cellulose and its regulation; iii) characterization of Thermobifida fusca biofilm development; colonization of cellulose and its regulation; and iii) description of the architecture of mature C. uda, C. phytofermentans, and T. fusca biofilms. This research is aimed at advancing understanding of biofilm formation and other complex processes involved in the degradation of the abundant cellulosic biomass, and the biology of the microbes involved. Information obtained from these studies is invaluable in the development of practical applications, such as the single-step bioconversion of cellulose-containing residues to fuels and other bioproducts. Our results have clearly shown that cellulose-decomposing microbes rapidly colonize cellulose and form complex structures typical of biofilms. Furthermore, our observations suggest that, as cells multiply on nutritive surfaces during biofilms formation, dramatic cell morphological changes occur. We speculated that morphological changes, which involve a transition from rod-shaped cells to more rounded forms, might be more apparent in a filamentous microbe. In order to test this hypothesis, we included in our research a study of biofilm formation by T. fusca, a thermophilic cellulolytic actinomycete commonly found in compost. The cellulase system of T. fusca has been extensively detailed through the work of David Wilson and colleagues at Cornell, and also, genome sequence of a T. fusca strain has been determine by the DOE Joint Genome Institute. Thus, T. fusca is an excellent subject for studies of biofilm development and its potential impacts on cellulose degradation. We also completed a study of the chitinase system of C. uda. This work provided essential background information for understanding how C. uda 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.

Leschine, Susan

2009-10-31

229

Antimicrobial peptides as potential tool to fight bacterial biofilm.  

PubMed

Recently, the topic of biofilm has met a huge interest of researchers owing to a significant role played by this microbial life form in severe infections. These well organised three-dimensional microbial communities are characterized by a strong resistance to antimicrobials. Biofilms significantly contribute to morbidity and mortality as related infections are very difficult to treat due to their tendency to relapse after the withdrawal of antibiotics. According to the literature, antimicrobial peptides (AMPs) have a high potential as future antibiofilm agents. AMPs can influence various stages of biofilm formation and exhibit antimicrobial activity against a broad spectrum of microorganisms including multi-drug resistant strains. The purpose of the present study was to determine the activity of antimicrobial peptides against biofilms formed by a variety of bacterial strains. To do this, the following antimicrobial peptides were synthesized: Citropin 1.1, Lipopeptides Palm-KK-NH2 and Palm-RR-NH2, Omiganan, Pexiganan and Temporin A. Antimicrobial activity of the compounds and conventional antibiotics was determined for planktonic cells and biofilms formed by reference strains of Gram-positive (Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis) bacteria. AMPs exhibited a strong antibacterial activity against Gram-positive strains, while Gram-negative bacteria were less susceptible. Antimicrobial activity of the tested peptides against biofilms formed by Gram-positive organisms was significantly stronger as compared to that of conventional antimicrobials. PMID:24779193

Dawgul, Ma?gorzata; Maciejewska, Magdalena; Jaskiewicz, Maciej; Karafova, Anna; Kamysz, Wojciech

2014-01-01

230

Functional Tomographic Fluorescence Imaging of pH Microenvironments in Microbial Biofilms by Use of Silica Nanoparticle Sensors? †  

PubMed Central

Attached bacterial communities can generate three-dimensional (3D) physicochemical gradients that create microenvironments where local conditions are substantially different from those in the surrounding solution. Given their ubiquity in nature and their impacts on issues ranging from water quality to human health, better tools for understanding biofilms and the gradients they create are needed. Here we demonstrate the use of functional tomographic imaging via confocal fluorescence microscopy of ratiometric core-shell silica nanoparticle sensors (C dot sensors) to study the morphology and temporal evolution of pH microenvironments in axenic Escherichia coli PHL628 and mixed-culture wastewater biofilms. Testing of 70-, 30-, and 10-nm-diameter sensor particles reveals a critical size for homogeneous biofilm staining, with only the 10-nm-diameter particles capable of successfully generating high-resolution maps of biofilm pH and distinct local heterogeneities. Our measurements revealed pH values that ranged from 5 to >7, confirming the heterogeneity of the pH profiles within these biofilms. pH was also analyzed following glucose addition to both suspended and attached cultures. In both cases, the pH became more acidic, likely due to glucose metabolism causing the release of tricarboxylic acid cycle acids and CO2. These studies demonstrate that the combination of 3D functional fluorescence imaging with well-designed nanoparticle sensors provides a powerful tool for in situ characterization of chemical microenvironments in complex biofilms.

Hidalgo, Gabriela; Burns, Andrew; Herz, Erik; Hay, Anthony G.; Houston, Paul L.; Wiesner, Ulrich; Lion, Leonard W.

2009-01-01

231

Functional tomographic fluorescence imaging of pH microenvironments in microbial biofilms by use of silica nanoparticle sensors.  

PubMed

Attached bacterial communities can generate three-dimensional (3D) physicochemical gradients that create microenvironments where local conditions are substantially different from those in the surrounding solution. Given their ubiquity in nature and their impacts on issues ranging from water quality to human health, better tools for understanding biofilms and the gradients they create are needed. Here we demonstrate the use of functional tomographic imaging via confocal fluorescence microscopy of ratiometric core-shell silica nanoparticle sensors (C dot sensors) to study the morphology and temporal evolution of pH microenvironments in axenic Escherichia coli PHL628 and mixed-culture wastewater biofilms. Testing of 70-, 30-, and 10-nm-diameter sensor particles reveals a critical size for homogeneous biofilm staining, with only the 10-nm-diameter particles capable of successfully generating high-resolution maps of biofilm pH and distinct local heterogeneities. Our measurements revealed pH values that ranged from 5 to >7, confirming the heterogeneity of the pH profiles within these biofilms. pH was also analyzed following glucose addition to both suspended and attached cultures. In both cases, the pH became more acidic, likely due to glucose metabolism causing the release of tricarboxylic acid cycle acids and CO(2). These studies demonstrate that the combination of 3D functional fluorescence imaging with well-designed nanoparticle sensors provides a powerful tool for in situ characterization of chemical microenvironments in complex biofilms. PMID:19801466

Hidalgo, Gabriela; Burns, Andrew; Herz, Erik; Hay, Anthony G; Houston, Paul L; Wiesner, Ulrich; Lion, Leonard W

2009-12-01

232

Influence of a triazine derivative-based biocide on microbial biofilms of cutting fluids in contact with different substrates.  

PubMed

Although biofilms are often associated with hospital infection problems owing to their high resistance to antimicrobial agents, in recent years biofilms have also been studied in the industrial sector, mainly because they are a major cause of contamination outbreaks in facilities and products. The aim of this study was to investigate whether different materials commonly found in the metalworking industries have different biofilm formation characteristics when in contact with contaminated cutting fluid as well as to establish an optimal concentration of a triazine-based antimicrobial agent to protect the oil/water emulsion and also to delay or interrupt the development of biofilms. Biofilms grown on the surface of carbon steel, stainless steel, aluminum, polyvinyl chloride, and glass were analyzed in terms of cell growth and susceptibility to the tested biocide. The results showed that the type of material used had little influence on cell adhesion or on the microbicide concentration required to control and eradicate microorganisms suspended in the emulsion and in the biofilms. PMID:22270891

Lucchesi, Eliane G; Eguchi, Sílvia Y; Moraes, Angela M

2012-05-01

233

Marine Microbial Mats and the Search for Evidence of Life in Deep Time and Space  

NASA Technical Reports Server (NTRS)

Cyanobacterial mats in extensive seawater evaporation ponds at Guerrero Negro, Baja California, Mexico, have been excellent subjects for microbial ecology research. The studies reviewed here have documented the steep and rapidly changing environmental gradients experienced by mat microorganisms and the very high rates of biogeochemical processes that they maintained. Recent genetic studies have revealed an enormous diversity of bacteria as well as the spatial distribution of Bacteria, Archaea and Eukarya. These findings, together with emerging insights into the intimate interactions between these diverse populations, have contributed substantially to our understanding of the origins, environmental impacts, and biosignatures of photosynthetic microbial mats. The biosignatures (preservable cells, sedimentary fabrics, organic compounds, minerals, stable isotope patterns, etc.) potentially can serve as indicators of past life on early Earth. They also can inform our search for evidence of any life on Mars. Mars exploration has revealed evidence of evaporite deposits and thermal spring deposits; similar deposits on Earth once hosted ancient microbial mat ecosystems.

Des Marais, David J.

2011-01-01

234

Membrane Vesicle Release in Bacteria, Eukaryotes, and Archaea: a Conserved yet Underappreciated Aspect of Microbial Life  

PubMed Central

Interaction of microbes with their environment depends on features of the dynamic microbial surface throughout cell growth and division. Surface modifications, whether used to acquire nutrients, defend against other microbes, or resist the pressures of a host immune system, facilitate adaptation to unique surroundings. The release of bioactive membrane vesicles (MVs) from the cell surface is conserved across microbial life, in bacteria, archaea, fungi, and parasites. MV production occurs not only in vitro but also in vivo during infection, underscoring the influence of these surface organelles in microbial physiology and pathogenesis through delivery of enzymes, toxins, communication signals, and antigens recognized by the innate and adaptive immune systems. Derived from a variety of organisms that span kingdoms of life and called by several names (membrane vesicles, outer membrane vesicles [OMVs], exosomes, shedding microvesicles, etc.), the conserved functions and mechanistic strategies of MV release are similar, including the use of ESCRT proteins and ESCRT protein homologues to facilitate these processes in archaea and eukaryotic microbes. Although forms of MV release by different organisms share similar visual, mechanistic, and functional features, there has been little comparison across microbial life. This underappreciated conservation of vesicle release, and the resulting functional impact throughout the tree of life, explored in this review, stresses the importance of vesicle-mediated processes throughout biology.

Deatherage, Brooke L.

2012-01-01

235

Microbial Fuel Cells Applied to the Metabolically Based Detection of Extraterrestrial Life  

NASA Astrophysics Data System (ADS)

Since the 1970s, when the Viking spacecrafts carried out experiments to detect microbial metabolism on the surface of Mars, the search for nonspecific methods to detect life in situ has been one of the goals of astrobiology. It is usually required that a methodology detect life independently from its composition or form and that the chosen biological signature point to a feature common to all living systems, such as the presence of metabolism. In this paper, we evaluate the use of microbial fuel cells (MFCs) for the detection of microbial life in situ. MFCs are electrochemical devices originally developed as power electrical sources and can be described as fuel cells in which the anode is submerged in a medium that contains microorganisms. These microorganisms, as part of their metabolic process, oxidize organic material, releasing electrons that contribute to the electric current, which is therefore proportional to metabolic and other redox processes. We show that power and current density values measured in MFCs that use microorganism cultures or soil samples in the anode are much larger than those obtained with a medium free of microorganisms or sterilized soil samples, respectively. In particular, we found that this is true for extremophiles, which have been proposed as potential inhabitants of extraterrestrial environments. Therefore, our results show that MFCs have the potential to be used for in situ detection of microbial life.

Abrevaya, Ximena C.; Mauas, Pablo J. D.; Cortón, Eduardo

2010-12-01

236

Microbial fuel cells applied to the metabolically based detection of extraterrestrial life.  

PubMed

Since the 1970s, when the Viking spacecrafts carried out experiments to detect microbial metabolism on the surface of Mars, the search for nonspecific methods to detect life in situ has been one of the goals of astrobiology. It is usually required that a methodology detect life independently from its composition or form and that the chosen biological signature point to a feature common to all living systems, such as the presence of metabolism. In this paper, we evaluate the use of microbial fuel cells (MFCs) for the detection of microbial life in situ. MFCs are electrochemical devices originally developed as power electrical sources and can be described as fuel cells in which the anode is submerged in a medium that contains microorganisms. These microorganisms, as part of their metabolic process, oxidize organic material, releasing electrons that contribute to the electric current, which is therefore proportional to metabolic and other redox processes. We show that power and current density values measured in MFCs that use microorganism cultures or soil samples in the anode are much larger than those obtained with a medium free of microorganisms or sterilized soil samples, respectively. In particular, we found that this is true for extremophiles, which have been proposed as potential inhabitants of extraterrestrial environments. Therefore, our results show that MFCs have the potential to be used for in situ detection of microbial life. PMID:21162676

Abrevaya, Ximena C; Mauas, Pablo J D; Cortón, Eduardo

2010-12-01

237

Effects of ocean acidification on microbial community composition of, and oxygen fluxes through, biofilms from the Great Barrier Reef.  

PubMed

Rising anthropogenic CO(2) emissions acidify the oceans, and cause changes to seawater carbon chemistry. Bacterial biofilm communities reflect environmental disturbances and may rapidly respond to ocean acidification. This study investigates community composition and activity responses to experimental ocean acidification in biofilms from the Australian Great Barrier Reef. Natural biofilms grown on glass slides were exposed for 11 d to four controlled pCO(2) concentrations representing the following scenarios: A) pre-industrial (?300 ppm), B) present-day (?400 ppm), C) mid century (?560 ppm) and D) late century (?1140 ppm). Terminal restriction fragment length polymorphism and clone library analyses of 16S rRNA genes revealed CO(2) -correlated bacterial community shifts between treatments A, B and D. Observed bacterial community shifts were driven by decreases in the relative abundance of Alphaproteobacteria and increases of Flavobacteriales (Bacteroidetes) at increased CO(2) concentrations, indicating pH sensitivity of specific bacterial groups. Elevated pCO(2) (C + D) shifted biofilm algal communities and significantly increased C and N contents, yet O(2) fluxes, measured using in light and dark incubations, remained unchanged. Our findings suggest that bacterial biofilm communities rapidly adapt and reorganize in response to high pCO(2) to maintain activity such as oxygen production. PMID:21906222

Witt, Verena; Wild, Christian; Anthony, Kenneth R N; Diaz-Pulido, Guillermo; Uthicke, Sven

2011-11-01

238

Microbial life in cold, hydrologically active oceanic crustal fluids  

NASA Astrophysics Data System (ADS)

It is estimated that at least half of Earth's microbial biomass is found in the deep subsurface, yet very little is known about the diversity and functional roles of these microbial communities due to the limited accessibility of subseafloor samples. Ocean crustal fluids, which may have a profound impact on global nutrient cycles given the large volumes of water moving through the crustal aquifer, are particularly difficult to sample. Access to uncontaminated ocean crustal fluids is possible with CORK (Circulation Obviation Retrofit Kit) observatories, installed through the Integrated Ocean Drilling Program (IODP). Here we present the first microbiological characterization of the formation fluids from cold, oxygenated igneous crust at North Pond on the western flank of the Mid Atlantic Ridge. Fluids were collected from two CORKs installed at IODP boreholes 1382A and 1383C and include fluids from three different depth horizons within oceanic crust. Collection of borehole fluids was monitored in situ using an oxygen optode and solid-state voltammetric electrodes. In addition, discrete samples were analyzed on deck using a comparable lab-based system as well as a membrane-inlet mass spectrometer to quantify all dissolved volatiles up to 200 daltons. The instruments were operated in parallel and both in situ and shipboard geochemical measurements point to a highly oxidized fluid, revealing an apparent slight depletion of oxygen in subsurface fluids (~215?M) relative to bottom seawater (~245?M). We were unable to detect reduced hydrocarbons, e.g. methane. Cell counts indicated the presence of roughly 2 x 10^4 cells per ml in all fluid samples, and DNA was extracted and amplified for the identification of both bacterial and archaeal community members. The utilization of ammonia, nitrate, dissolved inorganic carbon, and acetate was measured using stable isotopes, and oxygen consumption was monitored to provide an estimate of the rate of respiration per cell per day. These results provide the first dataset describing the diversity of microbes present in cold, oxygenated ocean crustal fluids and the biogeochemical processes they mediate in the subseafloor.

Meyer, J. L.; Jaekel, U.; Girguis, P. R.; Glazer, B. T.; Huber, J. A.

2012-12-01

239

Microbial life at high salt concentrations: phylogenetic and metabolic diversity  

Microsoft Academic Search

Halophiles are found in all three domains of life. Within the Bacteria we know halophiles within the phyla Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria, Spirochaetes, and Bacteroidetes. Within the Archaea the most salt-requiring microorganisms are found in the class Halobacteria. Halobacterium and most of its relatives require over 100–150 g\\/l salt for growth and structural stability. Also within the order Methanococci we

Aharon Oren

2008-01-01

240

Spatiometabolic Stratification of Shewanella oneidensis Biofilms  

Microsoft Academic Search

Biofilms, or surface-attached microbial communities, are both ubiquitous and resilient in the environment. Although much is known about how biofilms form, develop, and detach, very little is understood about how these events are related to metabolism and its dynamics. It is commonly thought that large subpopulations of cells within biofilms are not actively producing proteins or generating energy and are

Tracy K. Teal; Douglas P. Lies; Barbara J. Wold; Dianne K. Newman

2006-01-01

241

Exopolysaccharides in biofilms, flocs and related structures  

Microsoft Academic Search

In biofilms, flocs and similar multispecies microbial communities, exopolysaccharides (EPSs) are always present, frequently as the major component other than water. The EPSs vary widely in their composition, structure and properties and thus it is impossible to generalise about their contribution to biofilm or floc structure. Relatively few of the polymers obtained from biofilms and flocs have been adequately purified

I. W. Sutherland

2001-01-01

242

Chemically Specific Cellular Imaging of Biofilm Formation  

Microsoft Academic Search

This document and the accompanying manuscripts summarize the technical accomplishments for our one-year LDRD-ER effort. Biofilm forming microbes have existed on this planet for billions of years and make up 60% of the biological mass on earth. Such microbes exhibit unique biochemical pathways during biofilm formation and play important roles in human health and the environment. Microbial biofilms have been

J L Herberg; C Schaldach; J Horn; E Gjersing; R Maxwell

2006-01-01

243

Characterising the flux of carbon between calcium carbonate substrata, aqueous fluids, bacteria and a biofilm matrix  

NASA Astrophysics Data System (ADS)

Quantification of the flux of elements between minerals, biofilms and aqueous solutions is essential in order to fully elucidate the role of microorganisms in mass transfer processes. Bacteria play a fundamental role in nearly all life and environmental processes and are by far the most abundant organisms on the planet. Their main mode of growth is in the form of biofilms growing on surfaces and although extensive study has been carried out into the problems biofilms cause to humans, the effects of biofilms in the environment are still poorly understood. Much of the published research describing biofilm growth on geological substrata emphasises the species present rather than their effect on the substratum. Although previous studies have shown that the production of organic or mineral acids by microbial biofilms can cause dissolution of mineral substrata, there is little quantitative data on the specific flux of elements between minerals, microbial cells, biofilm matrix and aqueous solutions. With growing evidence that microbial life occurs in abundance in the subsurface, biofilm activity within buried rocks and sediments may have important implications for global geochemical cycling of specific elements. Results will be presented as part of an ongoing laboratory analog experiment which has been designed to quantify the flux of carbon between all matrices in a laboratory substratum-biofilm-aqueous system. Water collected from a limestone cave system (pH 7.5-8; viable count 4.7×10^3 - 2.0×10^4 cfu.ml-1{) is used as innoculum and nutrient source for growing mixed consortium biofilms on a natural calcite (CaCO_3) substratum in a flow-through reaction cell (24 days; 25^oC; 1ml.min^{-1). Portions of the biofilm are periodically removed for microbiological analysis and the mineral surface microscopically examined for extent of alteration. A parallel experiment utilises an isotopically labelled synthetic 13C-CaCO_3 substratum. This enables carbon to be traced from the substratum, through the biofilm and into the aqueous and gas phase by analysing 13C/12C isotopic ratios in all system components. Through this mass-balance approach it is possible to quantify, for the first time, the carbon fluxes into the biofilm and the aqueous solution from the carbonate mineral substrate.

Rankin, S. C.; Cooke, D. A.; Handley, P. S.; Merrifield, C. M.; Wogelius, R. A.

2003-04-01

244

In situ biofilm coupon device  

DOEpatents

An apparatus for characterization of in-situ microbial biofilm populations in subsurface groundwater. The device permits biofilm-forming microorganisms to adhere to packing material while emplaced in a groundwater strata, so that the packing material can be later analyzed for quantity and type of microorganisms, growth rate, and nutrient requirements.

Peyton, Brent M. (Kennewick, WA); Truex, Michael J. (Richland, WA)

1997-01-01

245

In situ biofilm coupon device  

DOEpatents

An apparatus is disclosed for characterization of in-situ microbial biofilm populations in subsurface groundwater. The device permits biofilm-forming microorganisms to adhere to packing material while emplaced in a groundwater strata, so that the packing material can be later analyzed for quantity and type of microorganisms, growth rate, and nutrient requirements. 3 figs.

Peyton, B.M.; Truex, M.J.

1997-06-24

246

Microbial biodiversity, quality and shelf life of microfiltered and pasteurized extended shelf life (ESL) milk from Germany, Austria and Switzerland.  

PubMed

Information on factors limiting the shelf life of extended shelf life (ESL) milk produced by microfiltration and subsequent pasteurization is very limited. In this study, three different batches of ESL milk were analyzed at different stages of the production process and during storage at 4 °C, 8 °C and 10 °C in order to evaluate the changes in bacterial cell counts, microbial diversity and enzymatic quality. Additionally, detailed biodiversity analyses of 250 retail ESL milk packages produced by five manufacturers in Germany, Austria and Switzerland were performed at the end of shelf life. It was observed that microfiltration decreased the microbial loads by 5-6 log?? units to lower than 1 CFU/mL. However, bacterial counts at the end of shelf life were extremely variable and ranged between <1 and 8 log?? CFU/mL. 8% of all samples showed spoilage indicated by cell counts higher than 6 log?? CFU/mL. The main spoilage groups of bacteria were Gram-negative post-process recontaminants (Acinetobacter, Chryseobacterium, Psychrobacter, Sphingomonas) and the spore formers Paenibacillus and Bacillus cereus, while other spore formers and Microbacterium spp. did not reach spoilage levels. Paenibacillus spp. and B. cereus apparently influenced enzymatic spoilage, as indicated by increased free fatty acid production, pH 4.6 soluble peptide fractions and off-flavors. In some cases, enzymatic spoilage was observed although microbial counts were well below 6 log?? CFU/mL. Thirteen B. cereus isolates were characterized for their toxin profiles and psychrotolerance. Hbl, nhe, and cytK toxin genes were detected in ten, thirteen, and four isolates, respectively, whereas the ces gene was always absent. Interestingly, only three of the thirteen isolates could be allocated to psychrotolerant genotypes, as indicated by the major cold shock cspA gene signature. Generally, large discrepancies in microbial loads and biodiversity were observed at the end of shelf life, even among packages of the same production batch. We suggest that such unexpected differences may be due to very low cell counts after ESL treatment, causing stochastic variations of initial species distributions in individual packages. This would result in the development of significantly different bacterial populations during cold storage, including the occasional development of high numbers of pathogenic species such as B. cereus or Acinetobacter. PMID:22240060

Schmidt, Verena S J; Kaufmann, Veronika; Kulozik, Ulrich; Scherer, Siegfried; Wenning, Mareike

2012-03-01

247

Effects of UltraHigh Pressure Homogenization on Microbial and Physicochemical Shelf Life of Milk  

Microsoft Academic Search

The effect of ultra-high pressure homogenization (UHPH) on microbial and physicochemical shelf life of milk during storage at 4°C was studied and compared with a conventional heat preservation technology used in industry. Milk was standardized at 3.5% fat and was processed using a Stansted high-pressure homog- enizer. High-pressure treatments applied were 100, 200, and 300 MPa (single stage) with a

J. Pereda; V. Ferragut; J. M. Quevedo; B. Guamis; A. J. Trujillo

2007-01-01

248

Extremes of Survival Achieved by the Radiophile Deinococcus Radiodurans: A Model for Microbial Life on Mars  

NASA Technical Reports Server (NTRS)

Deinococcus radiodurans is an extremophile in more than one defined way. First it is extreme in its resistance to freeze drying. Second it is probably uniquely extreme on Earth in its resistance to ionizing radiation. The polyextremophilic capacity of D. radiodurans will be considered. The selection pressures on Mars will then be considered in relation to D. radiodurans in order to support a hypothesis that if microbial life exists on Mars, then it likely includes polyextremophiles.

Daly, M.; Sridhar, R.; Richmond, R.

1999-01-01

249

Development and Test of a Probe to Remotely Sense Microbial Life  

Microsoft Academic Search

Fluorescence spectroscopy is a powerful and highly sensitive tool useful for remotely searching for sub-surface microbial life. Ubiquitous biomolecules in microorganisms (e.g. tryptophan and NADH) have unique autofluorescence spectra that allow them to be optically detected at low levels even in the presence of a fluorescence background from minerals. Based on this technique, we have developed and tested a first-generation

N. Bramall; R. Bay; B. Price

2003-01-01

250

Development and Deployment of a Probe for Remotely Sensing Microbial Life at Lake Vida, Antarctica  

Microsoft Academic Search

Fluorescence spectroscopy is a powerful and highly sensitive tool useful for remotely searching for sub-surface microbial life. Ubiquitous biomolecules in microorganisms (e.g. tryptophan and NADH) have unique autofluorescence spectra that allow them to be optically detected at low levels even in the presence of a mineral-based fluorescence background. Other autofluorescing compounds can allow for broad typing of cells, such as

N. Bramall; R. Bay; B. Price

2005-01-01

251

Optical Probes for Remotely Sensing Microbial Life in Antarctica and Beyond  

Microsoft Academic Search

Fluorescence spectroscopy is a powerful and highly sensitive tool useful for remotely searching for sub-surface microbial life. Some ubiquitous biomolecules in microorganisms (e.g. tryptophan) have very strong and distinctive autofluorescence spectra that allow them to be optically detected at low levels even in the presence of a mineral-based fluorescence background. Other autofluorescing compounds, such as F420 and chlorophyll can allow

N. E. Bramall; R. A. Rohde; R. C. Bay; P. Price

2006-01-01

252

PERCHLORATE REDUCTION USING A HOLLOW-FIBER MEMBRANE BIOFILM REACTOR: KINETICS, MICROBIAL ECOLOGY, AND PILOT-SCALE STUDIES  

Microsoft Academic Search

Perchlorate contamination of groundwaters and surface waters is a national concern, and biological treatment may be the most cost-effective option. A hydrogen-based, hollow-fiber membrane biofilm reactor (HFMBfR) is ideal for perchlorate reduction, as hydrogen gas is inexpensive, non-toxic, and leaves little or no residual in the treated water. We studied the HFMBfR at the bench and pilot scale for removal

Robert Nerenberg; Bruce E. Rittmann; Thomas E. Gillogly; Geno E. Lehman; Samer S. Adham

253

Slime Worlds: Possibilities for Detection of Microbial Life on Extrasolar Planets  

NASA Astrophysics Data System (ADS)

We suggest that on extrasolar planets on which life has not made the transition to mult-cellular organisms, land surfaces may be covered by bacterial mats, algae, or slimes. If photosynthetic, such land-based, large-scale microbial colonies would show the well-known "red edge" of chlorophylls in their spectra. They would give much stronger spectral signatures for detection of life on extrasolar planets than microbes/algae in oceans or lakes, and their spectra would resemble the chlorophyll signatures of land vegetation. Therefore, life may be detectable on extrasolar planets early in their history, before the relatively late (if similar to Earth) advent of land plants, or if the transition to multicellular life does not occur at all. We show synthetic spectra of land microorganisms on Earth-like extrasolar planets.

Knacke, R. F.

2004-12-01

254

Deep microbial life in the Altmark natural gas reservoir: baseline characterization prior CO2 injection  

NASA Astrophysics Data System (ADS)

Within the framework of the CLEAN project (CO2 Largescale Enhanced gas recovery in the Altmark Natural gas field) technical basics with special emphasis on process monitoring are explored by injecting CO2 into a gas reservoir. Our study focuses on the investigation of the in-situ microbial community of the Rotliegend natural gas reservoir in the Altmark, located south of the city Salzwedel, Germany. In order to characterize the microbial life in the extreme habitat we aim to localize and identify microbes including their metabolism influencing the creation and dissolution of minerals. The ability of microorganisms to speed up dissolution and formation of minerals might result in changes of the local permeability and the long-term safety of CO2 storage. However, geology, structure and chemistry of the reservoir rock and the cap rock as well as interaction with saline formation water and natural gases and the injected CO2 affect the microbial community composition and activity. The reservoir located at the depth of about 3500m, is characterised by high salinity fluid and temperatures up to 127° C. It represents an extreme environment for microbial life and therefore the main focus is on hyperthermophilic, halophilic anaerobic microorganisms. In consequence of the injection of large amounts of CO2 in the course of a commercial EGR (Enhanced Gas Recovery) the environmental conditions (e.g. pH, temperature, pressure and solubility of minerals) for the autochthonous microorganisms will change. Genetic profiling of amplified 16S rRNA genes are applied for detecting structural changes in the community by using PCR- SSCP (PCR-Single-Strand-Conformation Polymorphism) and DGGE (Denaturing Gradient Gel Electrophoresis). First results of the baseline survey indicate the presence of microorganisms similar to representatives from other saline, hot, anoxic, deep environments. However, due to the hypersaline and hyperthermophilic reservoir conditions, cell numbers are low, so that the quantification of those microorganisms as well as the determination of microbial activity was not yet possible. Microbial monitoring methods have to be further developed to study microbial activities under these extreme conditions to access their influence on the EGR technique and on enhancing the long term safety of the process by fixation of carbon dioxide by precipitation of carbonates. We would like to thank GDF SUEZ for providing the data for the Rotliegend reservoir, sample material and enabling sampling campaigns. The CLEAN project is funded by the German Federal Ministry of Education and Research (BMBF) in the frame of the Geotechnologien Program.

Morozova, Daria; Shaheed, Mina; Vieth, Andrea; Krüger, Martin; Kock, Dagmar; Würdemann, Hilke

2010-05-01

255

Unraveling assembly of stream biofilm communities  

PubMed Central

Microbial biofilms assemble from cells that attach to a surface, where they develop into matrix-enclosed communities. Mechanistic insights into community assembly are crucial to better understand the functioning of natural biofilms, which drive key ecosystem processes in numerous aquatic habitats. We studied the role of the suspended microbial community as the source of the biofilm community in three streams using terminal-restriction fragment length polymorphism and 454 pyrosequencing of the 16S ribosomal RNA (rRNA) and the 16S rRNA gene (as a measure for the active and the bulk community, respectively). Diversity was consistently lower in the biofilm communities than in the suspended stream water communities. We propose that the higher diversity in the suspended communities is supported by continuous inflow from various sources within the catchment. Community composition clearly differed between biofilms and suspended communities, whereas biofilm communities were similar in all three streams. This suggests that biofilm assembly did not simply reflect differences in the source communities, but that certain microbial groups from the source community proliferate in the biofilm. We compared the biofilm communities with random samples of the respective community suspended in the stream water. This analysis confirmed that stochastic dispersal from the source community was unlikely to shape the observed community composition of the biofilms, in support of species sorting as a major biofilm assembly mechanism. Bulk and active populations generated comparable patterns of community composition in the biofilms and the suspended communities, which suggests similar assembly controls on these populations.

Besemer, Katharina; Peter, Hannes; Logue, Jurg B; Langenheder, Silke; Lindstrom, Eva S; Tranvik, Lars J; Battin, Tom J

2012-01-01

256

Biofilm formation in Escherichia coli is affected by 3-(N-morpholino)propane sulfonate (MOPS).  

PubMed

In most natural environments, association with a surface in a structure known as a biofilm is the prevailing microbial life-style. Escherichia coli has been a useful model for the study of biofilm formation. Here we analyzed the amounts of biofilm formed when E. coli was cultured in the presence of MOPS [3-(N-morpholino)propane sulfonatel. We used the "O'Toole and Kolter" method, which consisted of growing cells in PVC microtiter dishes and staining the formed biofilm with crystal violet. Our results showed that: 1) the addition of 100 mM MOPS to the rich Luria-Bertani (LB) medium increased the capacity of biofilm formation of several E. coli strains; and 2) the biofilm formed by cells growing in the presence of MOPS was more evident and well defined than that of cells cultured in LB-only medium. The improved ability of forming biofilms was maintained even for 60 h after removing MOPS from the medium, indicating that this improvement was due to a change in the metabolism of E. coli growing in the presence of MOPS or that, under these conditions, biofilm formation was favored. PMID:12002568

Corona-Izquierdo, F Paola; Membrillo-Hernández, Jorge

2002-04-01

257

Metagenomic Analysis of Showerhead Biofilms from a Hospital in Ohio  

EPA Science Inventory

Background: The National Institute of Health estimated that 80% of human microbial infections are associated with biofilms. Although water supplies and hospital equipments are constantly treated with disinfectants, the presence of biofilms in these areas has been frequently obser...

258

Biogeophysical interactions control the formation of iron oxide microbial biofilms in acidic geothermal outflow channels of Yellowstone National Park  

NASA Astrophysics Data System (ADS)

Amorphous iron oxyhydroxide microbial mats in acidic (pH ~ 3) geothermal outflow channels of Yellowstone National Park (YNP) are habitats for diverse populations of autotrophic and heterotrophic microorganisms from the domains Archaea and Bacteria. These systems have been extensively characterized with regards to geochemical, physical, and microbiological (e.g., metagenomics) analyses; however, there is minimal data describing the formation of these iron oxide microbial mats. A conceptual model of Fe(III)-oxide microbial mat development was created, which includes four distinct stages. Autotrophic archaea (Metallosphaera yellowstonensis) and bacteria (Hydrogenobaculum spp.) are the first colonizers (Stage I) that provide pools of organic carbon for heterotrophic thermophiles (Stage II). M. yellowstonensis is an autotrophic Sulfolobales that is responsible for the oxidation of Fe(II) and can thus be defined as the mat 'architect' creating suitable habitats for microbial niches (e.g., anaerobic microorganisms) (Stage III). The last phase of mat formation (Stage IV) represents a pseudo-steady state mature microbial mat, which has been the subject of all previous microbial surveys of these systems. The conceptual model for Fe(III)-oxide microbial mat development was tested by inserting glass (SiO2) microscope slides into the main flow channels of two acidic geothermal springs in YNP. Slides were removed at various time intervals and analyzed for total iron accretion, microbial community structure (i.e., 16S rRNA gene abundance), and mRNA expression of community members. Routine geochemical and physical (e.g., flow) parameters were also measured to decipher their relative contribution to mat development. Initial and previous results show that autotrophic microorganisms (e.g, M. yellowstonensis) are often the first to colonize the glass slides and their activity was confirmed by mRNA expression of genes related to iron oxidation and carbon fixation. Heterotrophs are rare during the initial stages of Fe (III)-oxide mat formation (< 28 days) and become more abundant after ~28 days, which likely coincides with a higher abundance of organic carbon from autotrophs. Aerobic microorganisms have been detected in greater abundance at the mat/water interface where oxygen microelectrode measurements reveal steep gradients in oxygen consumption (i.e., niche partitioning). A mature microbial mat is typically formed after ~2-4 months and reaches a pseudo-steady state depth of ~7-10 mm. Flow rates had a significant affect on Fe(III)-oxide deposition and community structure. These results suggest that dynamic biological, geochemical, and physical processes control the formation and cycling of Fe(III)-oxide microbial mats in acidic geothermal springs.

Beam, J.; Berstein, H. C.; Jay, Z.; Kozubal, M. A.; Jennings, R. D.; Inskeep, W. P.

2012-12-01

259

Intestinal Microbial Diversity during Early-Life Colonization Shapes Long-Term IgE Levels  

PubMed Central

Summary Microbial exposure following birth profoundly impacts mammalian immune system development. Microbiota alterations are associated with increased incidence of allergic and autoimmune disorders with elevated serum IgE as a hallmark. The previously reported abnormally high serum IgE levels in germ-free mice suggests that immunoregulatory signals from microbiota are required to control basal IgE levels. We report that germ-free mice and those with low-diversity microbiota develop elevated serum IgE levels in early life. B cells in neonatal germ-free mice undergo isotype switching to IgE at mucosal sites in a CD4 T-cell- and IL-4-dependent manner. A critical level of microbial diversity following birth is required in order to inhibit IgE induction. Elevated IgE levels in germ-free mice lead to increased mast-cell-surface-bound IgE and exaggerated oral-induced systemic anaphylaxis. Thus, appropriate intestinal microbial stimuli during early life are critical for inducing an immunoregulatory network that protects from induction of IgE at mucosal sites.

Cahenzli, Julia; Koller, Yasmin; Wyss, Madeleine; Geuking, Markus B.; McCoy, Kathy D.

2013-01-01

260

Microbial trace fossils in Antarctica and the search for evidence of early life on Mars  

NASA Technical Reports Server (NTRS)

It is possible to hypothesize that, if microbial life evolved on early Mars, fossil remnants of these organisms may be preserved on the surface. However, the cooling and drying of Mars probably resembled a cold desert and such an environment is not suitable for the process of fossilization. The frigid Ross Desert of Antarctica is probably the closest terrestrial analog to conditions that may have prevailed on the surface of the cooling and drying Mars. In this desert, cryptoendolithic microbial communities live in the airspaces of porous rocks, the last habitable niche in a hostile outside environment. The organisms produce characteristic chemical and physical changes in the rock substrate. Environmental changes (deterioration of conditions) may result in the death of the community. Although no cellular structures are fossilized, the conspicuous changes in the rock substrate are preserved as trace fossils. Likewise, microbial trace fossils (without cellular structures) may also be preserved on Mars: Discontinuities in structure or chemistry of the rock that are independent of physical or chemical gradients may be of biological origin. Ross Desert trace fossils can be used as a model for planning search strategies and for instrument design to find evidence of past Martian life.

Friedmann, E. Imre; Friedmann, Roseli O.

1989-01-01

261

Development and Test of a Probe to Remotely Sense Microbial Life  

NASA Astrophysics Data System (ADS)

Fluorescence spectroscopy is a powerful and highly sensitive tool useful for remotely searching for sub-surface microbial life. Ubiquitous biomolecules in microorganisms (e.g. tryptophan and NADH) have unique autofluorescence spectra that allow them to be optically detected at low levels even in the presence of a fluorescence background from minerals. Based on this technique, we have developed and tested a first-generation Biospectral Logger (BSL); an instrument suitable for logging boreholes and aquatic environments which uses a 370 nm excitation source and a bank of seven notch-filtered phototubes to record the spectrum of microbial NADH fluorescence. The first generation BSL was constructed and tested in Lake Tahoe, where it recorded chlorophyll fluorescence that peaked at a depth of about 57 m and then decreased with depth. NADH fluorescence was found to peak and fall off with chlorophyll for shallow depths, but then began increasing again at deeper depths, which agrees with the results of independently performed cell counts. In order to optimize the discrimination between microbial life and its environment, we used a laboratory fluorimeter to map out the emission spectra of a diverse collection of microbes and minerals as a function of excitation wavelength, which we varied between 224 nm and 460 nm. Based on these data, we have planned future developments of the BSL technology that make it more selective and able to be used in more extreme environments such as deep mine boreholes, permafrost, deep-ocean settings, and ultimately Martian permafrost, where its greatly-increased sensitivity will be sufficient to detect microbial concentrations down to ~1 cell/cm3 in media with relatively low background

Bramall, N.; Bay, R.; Price, B.

2003-12-01

262

A novel automated waterline cleaning system that facilitates effective and consistent control of microbial biofilm contamination of dental chair unit waterlines: a one-year study.  

PubMed

Microbial contamination of dental chair unit (DCU) output water caused by biofilm growth in dental unit waterlines (DUWs) is a universal problem and a potentially significant source of cross-infection. The microbial quality of output water from a Planmeca Compact i DCU equipped with the novel Water Management System (WMS), an integrated and automated DUW cleaning system, was investigated over a 12-month period with the hydrogen peroxide- and silver ion-containing disinfectants Planosil and Planosil Forte. Four weeks after connection to the potable-water quality mains supply the density of aerobic heterotrophic bacteria, rose from the low levels consistently found in the supply water throughout this study (mean average 77 cfu/mL) to 15,400 cfu/mL. Disinfection of DUWs once weekly with Planosil for 10 weeks resulted in a dramatic reduction in bacterial density immediately following disinfection (mean average 26 cfu/mL). Bacterial density rose steadily between disinfections and by 7 days post-disinfection, water quality failed (mean average 384 cfu/mL) the American Dental Association DCU water quality standard of biofilm, but deterioration of water quality following disinfection was associated with its regrowth. The most common bacterial species cultured from the mains water and the DCU output water were Microcococcus luteus and Sphingomonas spp., respectively, the latter of which are known opportunistic pathogens. The findings of this study show that the Planmeca Compact i DCU equipped with the easy to use and automated WMS, that requires minimal effort on the part of the operator, consistently provides output water that passes the ADA quality standard of

O'Donnell, M J; Shore, A C; Coleman, D C

2006-10-01

263

Microbial biofilm growth versus tissue integration on biomaterials with different wettabilities and a polymer-brush coating.  

PubMed

Biomaterials-associated infections (BAI) constitute a major clinical problem and often necessitate implant replacement. In this study, the race for the surface between Staphylococcus epidermidis ATCC 35983 and U2OS osteosarcoma cells is studied on biomaterials with different wettabilities and on a polymer-brush coating. S. epidermidis was deposited on the different surfaces in a parallel plate flow chamber and then U2OS cells were seeded. Subsequently, staphylococci and U2OS cells were allowed to grow simultaneously on the surfaces for 48 h under low flow conditions. The presence of staphylococci reduced cell growth on all surfaces, but adhering cells spread equally well in the absence and presence of staphylococci. A hydrophilic polymer-brush coating discouraged bacterial and cellular adhesion and growth. Thus, whereas the biomaterials evaluated support both biofilm formation and tissue integration, polymer-brush coatings support neither. Therewith, the outcome of the race for the surface on these surfaces remains uncertain, emphasizing the need for biofunctionalized surfaces that discourage biofilm formation and support tissue growth at the same time. PMID:20186772

Subbiahdoss, Guruprakash; Grijpma, Dirk W; van der Mei, Henny C; Busscher, Henk J; Kuijer, Roel

2010-08-01

264

Biofilm and dental unit waterlines.  

PubMed

Aquatic biofilms, which are well-organized communities of microorganisms, are widespread in nature. They constitute a major problem in many environmental, industrial and medical settings. The use of advanced techniques has revealed biofilm structure, formation and ecology. Special attention was given to the build-up of biofilm in dental unit waterlines (DUWLs), which are small-bore flexible plastic tubing to bring water to different handpieces. They are coated with well-established biofilms. Active biofilm is a source of microbial contamination of DUWLs water. The safety of dental treatment requires a good quality of the water used. The knowledge of nature, formation and the ways to eliminate the biofilm is the first step towards reducing health risk, both for patients and dental personnel. The article reviews these issues. PMID:14677905

Szymanska, Jolanta

2003-01-01

265

Engineering biofilm formation and dispersal  

PubMed Central

Anywhere water is in the liquid state, bacteria will exist as biofilms, which are complex communities of cells cemented together. Although frequently associated with disease and biofouling, biofilms are also important for engineering applications, such as bioremediation, biocatalysis and microbial fuel cells. Here we review approaches to alter genetic circuits and cell signaling toward controlling biofilm formation, and emphasize utilizing these tools for engineering applications. Based on a better understanding of the genetic basis of biofilm formation, we find that biofilms may be controlled by manipulating extracellular signals and that they may be dispersed using conserved intracellular signals and regulators. Biofilms could also be formed at specific locations where they might be engineered to make chemicals or treat human disease.

Wood, Thomas K.; Hong, Seok Hoon; Ma, Qun

2011-01-01

266

Resveratrol treatment controls microbial flora, prolongs shelf life, and preserves nutritional quality of fruit.  

PubMed

Resveratrol is known as a grapevine secondary metabolite with fungicide activity. Its exogenous application on harvested grapes resulted in the reduction of microbial flora growth, and consequently, prolonged shelf life, without affecting the nutritional quality of the fruit. Resveratrol treatment also resulted in being effective on fruit that normally does not accumulate such metabolites as, for example, tomatoes, apples, avocado pears, and peppers. As a result, all treated fruits maintained their post-harvest quality and health longer than the untreated ones. This study demonstrates the potential use of resveratrol as a natural pesticide to reduce post-harvest fungi development on a broad spectrum of fruit types. PMID:15740035

Jiménez, Jorge Bernardo; Orea, José María; Montero, Carlos; Ureña, Angel González; Navas, Elena; Slowing, Karla; Gómez-Serranillos, María Pilar; Carretero, Emilia; De Martinis, Domenico

2005-03-01

267

Trace gases in the atmosphere of Mars - An indicator of microbial life  

NASA Technical Reports Server (NTRS)

The detection of certain trace gases in the atmosphere of Mars would indicate the presence of microbial life on the surface. Candidate biogenic gases include CH4, NH3, N2O, and several reduced sulfur species. Chemical thermodynamic equilibrium and photochemical calculations preclude the presence of these gases in any measurable concentrations in the atmosphere of Mars in the absence of biogenic production. A search for these gases utilizing either high-resolution (spectral and spatial) spectroscopy from a Mars orbiter, such as the Mars Observer orbiter, and/or in situ measurements from a Mars lander or rover is proposed.

Levine, Joel S.; Rinsland, Curtis P.; Boston, Penelope J.; Cofer, Wesley R., III; Chameides, William L.

1989-01-01

268

Biofilm Roughness Determines Cryptosporidium parvum Retention in Environmental Biofilms  

PubMed Central

The genus Cryptosporidium is a group of waterborne protozoan parasites that have been implicated in significant outbreaks of gastrointestinal infections throughout the world. Biofilms trap these pathogens and can contaminate water supplies through subsequent release. Biofilm microbial assemblages were collected seasonally from three streams in eastern Pennsylvania and used to grow biofilms in laboratory microcosms. Daily oocyst counts in the influx and efflux flow allowed the calculation of daily oocyst retention in the biofilm. Following the removal of oocysts from the influx water, oocyst attachment to the biofilm declined to an equilibrium state within 5 days that was sustained for at least 25 days. Varying the oocyst loading rate for the system showed that biofilm retention could be saturated, suggesting that discrete binding sites determined the maximum number of oocysts retained. Oocyst retention varied seasonally but was consistent across all three sites; however, seasonal oocyst retention was not consistent across years at the same site. No correlation between oocyst attachment and any measured water quality parameter was found. However, oocyst retention was strongly correlated with biofilm surface roughness and roughness varied among seasons and across years. We hypothesize that biofilm roughness and oocyst retention are dependent on environmentally driven changes in the biofilm community rather than directly on water quality conditions. It is important to understand oocyst transport dynamics to reduce risks of human infection. Better understanding of factors controlling biofilm retention of oocysts should improve our understanding of oocyst transport at different scales.

Hargreaves, B. R.; Jellison, K. L.

2012-01-01

269

Inhibitory effect of cyclic trihydroxamate siderophore, desferrioxamine E, on the biofilm formation of Mycobacterium species.  

PubMed

Formation of biofilm in pathogenic bacteria defends them from antibiotics and the immune system of a host's life. Hence, investigation of the molecular mechanisms of biofilm formation and search for new substances counteracting this formation are becoming an attractive research area. In the course of our search for new inhibitors of biofilm formation in Mycobacterium species, we rediscovered a cyclic trihydroxamate siderophore, desferrioxamine E, from the culture of the marine-derived Actinomycete MS67. Desferrioxamine E inhibited biofilm formation of Mycobacterium smegmatis and M. bovis BACILLE de CALMETTE et GUÉRIN (BCG) with minimum inhibitory concentration (MIC) value of 10 µM, while no anti-microbial activity was observed up to 160 µM. Desferrioxamine E was also able to restore the anti-microbial activity of isoniazid against M. smegmatis by inhibiting biofilm formation. Mechanistic analysis of desferrioxamine E suggested that such inhibition might come from the depletion of iron in the medium, which is essential for biofilm formation in Mycobacterium species. PMID:21628895

Ishida, Shunsuke; Arai, Masayoshi; Niikawa, Hiroki; Kobayashi, Motomasa

2011-01-01

270

12 Microbial Life in Brines, Evaporites and Saline Sediments: The Search for Life on Mars  

Microsoft Academic Search

When water on a planet begins to evaporate the dissolved minerals become more concentrated, form a brine, eventually precipitating out of solution and forming evaporite deposits. The brines and evaporites form a highly saline environment that is hostile to most life forms, but provides an ideal habitat for organisms that are osmophilic, or halophilic. Halophiles are salt “loving” organisms that

Rocco L. Mancinelli

271

Microbial life in the Lake Medee, the largest deep-sea salt-saturated formation  

PubMed Central

Deep-sea hypersaline anoxic lakes (DHALs) of the Eastern Mediterranean represent some of the most hostile environments on our planet. We investigated microbial life in the recently discovered Lake Medee, the largest DHAL found to-date. Medee has two unique features: a complex geobiochemical stratification and an absence of chemolithoautotrophic Epsilonproteobacteria, which usually play the primary role in dark bicarbonate assimilation in DHALs interfaces. Presumably because of these features, Medee is less productive and exhibits reduced diversity of autochthonous prokaryotes in its interior. Indeed, the brine community almost exclusively consists of the members of euryarchaeal MSBL1 and bacterial KB1 candidate divisions. Our experiments utilizing cultivation and [14C]-assimilation, showed that these organisms at least partially rely on reductive cleavage of osmoprotectant glycine betaine and are engaged in trophic cooperation. These findings provide novel insights into how prokaryotic communities can adapt to salt-saturated conditions and sustain active metabolism at the thermodynamic edge of life.

Yakimov, Michail M.; La Cono, Violetta; Slepak, Vladlen Z.; La Spada, Gina; Arcadi, Erika; Messina, Enzo; Borghini, Mireno; Monticelli, Luis S.; Rojo, David; Barbas, Coral; Golyshina, Olga V.; Ferrer, Manuel; Golyshin, Peter N.; Giuliano, Laura

2013-01-01

272

Microbial ecology and host-microbiota interactions during early life stages  

PubMed Central

The role of human microbiota has been redefined during recent years and its physiological role is now much more important than earlier understood. Intestinal microbial colonization is essential for the maturation of immune system and for the developmental regulation of the intestinal physiology. Alterations in this process of colonization have been shown to predispose and increase the risk to disease later in life. The first contact of neonates with microbes is provided by the maternal microbiota. Moreover, mode of delivery, type of infant feeding and other perinatal factors can influence the establishment of the infant microbiota. Taken into consideration all the available information it could be concluded that the exposure to the adequate microbes early in gestation and neonatal period seems to have a relevant role in health. Maternal microbial environment affects maternal and fetal immune physiology and, of relevance, this interaction with microbes at the fetal-maternal interface could be modulated by specific microbes administered to the pregnant mother. Indeed, probiotic interventions aiming to reduce the risk of immune-mediated diseases may appear effective during early life.

Collado, Maria Carmen; Cernada, Maria; Bauerl, Christine; Vento, Maximo; Perez-Martinez, Gaspar

2012-01-01

273

Complete Nucleotide Sequence and Analysis of Two Conjugative Broad Host Range Plasmids from a Marine Microbial Biofilm  

PubMed Central

The complete nucleotide sequence of plasmids pMCBF1 and pMCBF6 was determined and analyzed. pMCBF1 and pMCBF6 form a novel clade within the IncP-1 plasmid family designated IncP-1 ?. The plasmids were exogenously isolated earlier from a marine biofilm. pMCBF1 (62 689 base pairs; bp) and pMCBF6 (66 729 bp) have identical backbones, but differ in their mercury resistance transposons. pMCBF1 carries Tn5053 and pMCBF6 carries Tn5058. Both are flanked by 5 bp direct repeats, typical of replicative transposition. Both insertions are in the vicinity of a resolvase gene in the backbone, supporting the idea that both transposons are “res-site hunters” that preferably insert close to and use external resolvase functions. The similarity of the backbones indicates recent insertion of the two transposons and the ongoing dynamics of plasmid evolution in marine biofilms. Both plasmids also carry the insertion sequence ISPst1, albeit without flanking repeats. ISPs1is located in an unusual site within the control region of the plasmid. In contrast to most known IncP-1 plasmids the pMCBF1/pMCBF6 backbone has no insert between the replication initiation gene (trfA) and the vegetative replication origin (oriV). One pMCBF1/pMCBF6 block of about 2.5 kilo bases (kb) has no similarity with known sequences in the databases. Furthermore, insertion of three genes with similarity to the multidrug efflux pump operon mexEF and a gene from the NodT family of the tripartite multi-drug resistance-nodulation-division (RND) system in Pseudomonas aeruginosa was found. They do not seem to confer antibiotic resistance to the hosts of pMCBF1/pMCBF6, but the presence of RND on promiscuous plasmids may have serious implications for the spread of antibiotic multi-resistance.

Norberg, Peter; Bergstrom, Maria; Hermansson, Malte

2014-01-01

274

An update on the management of endodontic biofilms using root canal irrigants and medicaments.  

PubMed

Microbial biofilm is defined as a sessile multicellular microbial community characterized by cells that are firmly attached to a surface and enmeshed in a self-produced matrix of extracellular polymeric substances. Biofilms play a very important role in pulp and periradicular pathosis. The aim of this article was to review the role of endodontic biofilms and the effects of root canal irrigants, medicaments as well as lasers on biofilms A Medline search was performed on the English articles published from 1982 to 2013 and was limited to papers published in English. The searched keywords were "Biofilms AND endodontics", "Biofilms AND sodium hypochlorite", "Biofilms AND chlorhexidine", "Biofilms AND MTAD", "Biofilms AND calcium hydroxide", "Biofilms AND ozone", "Biofilms AND lasers" and "Biofilms AND nanoparticles". The reference list of each article was manually searched to find other suitable sources of information. PMID:24688576

Mohammadi, Zahed; Soltani, Mohammad Karim; Shalavi, Sousan

2014-01-01

275

An Update on the Management of Endodontic Biofilms Using Root Canal Irrigants and Medicaments  

PubMed Central

Microbial biofilm is defined as a sessile multicellular microbial community characterized by cells that are firmly attached to a surface and enmeshed in a self-produced matrix of extracellular polymeric substances. Biofilms play a very important role in pulp and periradicular pathosis. The aim of this article was to review the role of endodontic biofilms and the effects of root canal irrigants, medicaments as well as lasers on biofilms A Medline search was performed on the English articles published from 1982 to 2013 and was limited to papers published in English. The searched keywords were “Biofilms AND endodontics”, “Biofilms AND sodium hypochlorite”, "Biofilms AND chlorhexidine", "Biofilms AND MTAD", "Biofilms AND calcium hydroxide", “Biofilms AND ozone”, “Biofilms AND lasers” and "Biofilms AND nanoparticles". The reference list of each article was manually searched to find other suitable sources of information.

Mohammadi, Zahed; Soltani, Mohammad Karim; Shalavi, Sousan

2014-01-01

276

Evaluation of the Microbial Population in the Multibiological Life Support System Experiments  

NASA Astrophysics Data System (ADS)

In order to develop and evaluate a ground-based bioregenerative life support system satisfying half of one crew member's requirement towards O2 , Multibiological Life Support System Exper-iments (MLSSE) have been conducted. The MLSSE involved humans participating in the gas exchange with the closed equipment simulating the future extraterrestrial life support systems, which included three phases. The Phase I test involved one person participating in the gas exchange with lettuce in plant chamber as the primary means of air revitalization for 3 months. The Phase II test involved one person participating in the gas exchange with lettuce in plant chamber and micoalgae in bioreactor as the means of air revitalization for 1 month. In the Phase III test, silkworm was introduced into animal chamber for 2 months based on Phase II. The microbial dynamics in the closed chambers were evaluated during the whole experiments. The surfaces, water, and air of closed equipment were sampled for microbial content during the whole experiments. In general, the numbers of microbes in the chambers slowly increased with length of occupation. Compared with Phase I, the numbers of microbes of Phase II ob-viously increased, however, the numbers of microbes of Phase III did not increase relative to Phase II. The types of microbes found on the surfaces and in the air in all the experimental phases were similar. The most common bacteria were Bacillus sp., Pseudomonas sp., as well as Sphingomonas sp., with Pencillium sp. and Cladosporium sp. the most common fungi. A few opportunistic pathogens were also determined, but neither phase had levels of microbes that would be considered an occupational health threat.

Fu, Yuming; Tong, Ling; Li, Ming; Hu, Enzhu; Hu, Dawei; He, Wenting; Liu, Hong

277

Microbial siderophores: a mini review.  

PubMed

Iron is one of the major limiting factors and essential nutrients of microbial life. Since in nature it is not readily available in the preferred form, microorganisms produce small high affinity chelating molecules called siderophores for its acquisition. Microorganisms produce a wide variety of siderophores controlled at the molecular level by different genes to accumulate, mobilize and transport iron for metabolism. Siderophores also play a critical role in the expression of virulence and development of biofilms by different microbes. Apart from maintaining microbial life, siderophores can be harnessed for the sustainability of human, animals and plants. With the advent of modern molecular tools, a major breakthrough is taking place in the understanding of the multifaceted role of siderophores in nature. This mini review is intended to provide a general overview on siderophore along with its role and applications. PMID:22733623

Saha, Ratul; Saha, Nabaneeta; Donofrio, Robert S; Bestervelt, Lorelle L

2013-04-01

278

Life on the outside: role of biofilms in environmental persistence of Shiga-toxin producing Escherichia coli  

PubMed Central

Escherichia coli is a heterogeneous species that can be part of the normal flora of humans but also include strains of medical importance. Among pathogenic members, Shiga-toxin producing E. coli (STEC) are some of the more prominent pathogenic E. coli within the public sphere. STEC disease outbreaks are typically associated with contaminated beef, contaminated drinking water, and contaminated fresh produce. These water- and food-borne pathogens usually colonize cattle asymptomatically; cows will shed STEC in their feces and the subsequent fecal contamination of the environment and processing plants is a major concern for food and public safety. This is especially important because STEC can survive for prolonged periods of time outside its host in environments such as water, produce, and farm soil. Biofilms are hypothesized to be important for survival in the environment especially on produce, in rivers, and in processing plants. Several factors involved in biofilm formation such as curli, cellulose, poly-N-acetyl glucosamine, and colanic acid are involved in plant colonization and adherence to different surfaces often found in meat processing plants. In food processing plants, contamination of beef carcasses occurs at different stages of processing and this is often caused by the formation of STEC biofilms on the surface of several pieces of equipment associated with slaughtering and processing. Biofilms protect bacteria against several challenges, including biocides used in industrial processes. STEC biofilms are less sensitive than planktonic cells to several chemical sanitizers such as quaternary ammonium compounds, peroxyacetic acid, and chlorine compounds. Increased resistance to sanitizers by STEC growing in a biofilm is likely to be a source of contamination in the processing plant. This review focuses on the role of biofilm formation by STEC as a means of persistence outside their animal host and factors associated with biofilm formation.

Vogeleer, Philippe; Tremblay, Yannick D. N.; Mafu, Akier A.; Jacques, Mario; Harel, Josee

2014-01-01

279

Microfluidics expanding the frontiers of microbial ecology.  

PubMed

Microfluidics has significantly contributed to the expansion of the frontiers of microbial ecology over the past decade by allowing researchers to observe the behaviors of microbes in highly controlled microenvironments, across scales from a single cell to mixed communities. Spatially and temporally varying distributions of organisms and chemical cues that mimic natural microbial habitats can now be established by exploiting physics at the micrometer scale and by incorporating structures with specific geometries and materials. In this article, we review applications of microfluidics that have resulted in insightful discoveries on fundamental aspects of microbial life, ranging from growth and sensing to cell-cell interactions and population dynamics. We anticipate that this flexible multidisciplinary technology will continue to facilitate discoveries regarding the ecology of microorganisms and help uncover strategies to control microbial processes such as biofilm formation and antibiotic resistance. PMID:24773019

Rusconi, Roberto; Garren, Melissa; Stocker, Roman

2014-05-01

280

Biofilms' role in planktonic cell proliferation.  

PubMed

The detachment of single cells from biofilms is an intrinsic part of this surface-associated mode of bacterial existence. Pseudomonas sp. strain CT07gfp biofilms, cultivated in microfluidic channels under continuous flow conditions, were subjected to a range of liquid shear stresses (9.42 mPa to 320 mPa). The number of detached planktonic cells was quantified from the effluent at 24-h intervals, while average biofilm thickness and biofilm surface area were determined by confocal laser scanning microscopy and image analysis. Biofilm accumulation proceeded at the highest applied shear stress, while similar rates of planktonic cell detachment was maintained for biofilms of the same age subjected to the range of average shear rates. The conventional view of liquid-mediated shear leading to the passive erosion of single cells from the biofilm surface, disregards the active contribution of attached cell metabolism and growth to the observed detachment rates. As a complement to the conventional conceptual biofilm models, the existence of a biofilm surface-associated zone of planktonic cell proliferation is proposed to highlight the need to expand the traditional perception of biofilms as promoting microbial survival, to include the potential of biofilms to contribute to microbial proliferation. PMID:24201127

Bester, Elanna; Wolfaardt, Gideon M; Aznaveh, Nahid B; Greener, Jesse

2013-01-01

281

Innovative Strategies to Overcome Biofilm Resistance  

PubMed Central

We review the recent literature concerning the efficiency of antimicrobial photodynamic inactivation toward various microbial species in planktonic and biofilm cultures. The review is mainly focused on biofilm-growing microrganisms because this form of growth poses a threat to chronically infected or immunocompromised patients and is difficult to eradicate from medical devices. We discuss the biofilm formation process and mechanisms of its increased resistance to various antimicrobials. We present, based on data in the literature, strategies for overcoming the problem of biofilm resistance. Factors that have potential for use in increasing the efficiency of the killing of biofilm-forming bacteria include plant extracts, enzymes that disturb the biofilm structure, and other nonenzymatic molecules. We propose combining antimicrobial photodynamic therapy with various antimicrobial and antibiofilm approaches to obtain a synergistic effect to permit efficient microbial growth control at low photosensitizer doses.

Taraszkiewicz, Aleksandra; Fila, Grzegorz; Grinholc, Mariusz; Nakonieczna, Joanna

2013-01-01

282

Optical Probes for Remotely Sensing Microbial Life in Antarctica and Beyond  

NASA Astrophysics Data System (ADS)

Fluorescence spectroscopy is a powerful and highly sensitive tool useful for remotely searching for sub-surface microbial life. Some ubiquitous biomolecules in microorganisms (e.g. tryptophan) have very strong and distinctive autofluorescence spectra that allow them to be optically detected at low levels even in the presence of a mineral-based fluorescence background. Other autofluorescing compounds, such as F420 and chlorophyll can allow for broad typing of cells. Based on this technique, we have developed and deployed different types of Biospectral Loggers (BSLs)-- instruments suitable for logging boreholes and aquatic environments-- that use a bank of seven notch-filtered phototubes and either a 224 nm, 375 nm or 405 nm laser excitation source to record the spectrum of microbial tryptophan, NADH or F420/chlorophyll fluorescence (respectively). A miniaturized logger, dubbed the mini-BSL, is only 51 mm in diameter and has demonstrated capabilities appropriate for off-world deployment in extreme environments such as Martian permafrost. Results from logging a South Pole borehole (ice) and Lake Vida ice will be presented and discussed.

Bramall, N. E.; Rohde, R. A.; Bay, R. C.; Price, P.

2006-12-01

283

Development and Deployment of a Probe for Remotely Sensing Microbial Life at Lake Vida, Antarctica  

NASA Astrophysics Data System (ADS)

Fluorescence spectroscopy is a powerful and highly sensitive tool useful for remotely searching for sub-surface microbial life. Ubiquitous biomolecules in microorganisms (e.g. tryptophan and NADH) have unique autofluorescence spectra that allow them to be optically detected at low levels even in the presence of a mineral-based fluorescence background. Other autofluorescing compounds can allow for broad typing of cells, such as F420 and chlorophyll. Based on this technique, we have developed and tested two miniaturized Biospectral Loggers (mini-BSLs)-- instruments suitable for logging small boreholes and aquatic environments that use a bank of seven notch-filtered phototubes and either a 224 nm or 405 nm laser excitation source to record the spectrum of microbial tryptophan or F420/chlorophyll fluorescence (respectively). The mini-BSL was tested in the perennial ice covering Lake Vida, Antarctica, demonstrating its suitability for off-world deployment in extreme environments such as Martian permafrost. Data and a discussion will be presented.

Bramall, N.; Bay, R.; Price, B.

2005-12-01

284

Electrical Conductivity in a Mixed-Species Biofilm  

PubMed Central

Geobacter sulfurreducens can form electrically conductive biofilms, but the potential for conductivity through mixed-species biofilms has not been examined. A current-producing biofilm grown from a wastewater sludge inoculum was highly conductive with low charge transfer resistance even though microorganisms other than Geobacteraceae accounted for nearly half the microbial community.

Lau, Joanne; Nevin, Kelly P.; Franks, Ashley E.; Tuominen, Mark T.; Lovley, Derek R.

2012-01-01

285

Biofilms Reduce Solar Disinfection of Cryptosporidium parvum Oocysts  

PubMed Central

Solar radiation reduces Cryptosporidium infectivity. Biofilms grown from stream microbial assemblages inoculated with oocysts were exposed to solar radiation. The infectivity of oocysts attached at the biofilm surface and oocysts suspended in water was about half that of oocysts attached at the base of a 32-?m biofilm.

Hargreaves, B. R.; Jellison, K. L.

2012-01-01

286

Rhizome of life, catastrophes, sequence exchanges, gene creations, and giant viruses: how microbial genomics challenges Darwin.  

PubMed

Darwin's theory about the evolution of species has been the object of considerable dispute. In this review, we have described seven key principles in Darwin's book The Origin of Species and tried to present how genomics challenge each of these concepts and improve our knowledge about evolution. Darwin believed that species evolution consists on a positive directional selection ensuring the "survival of the fittest." The most developed state of the species is characterized by increasing complexity. Darwin proposed the theory of "descent with modification" according to which all species evolve from a single common ancestor through a gradual process of small modification of their vertical inheritance. Finally, the process of evolution can be depicted in the form of a tree. However, microbial genomics showed that evolution is better described as the "biological changes over time." The mode of change is not unidirectional and does not necessarily favors advantageous mutations to increase fitness it is rather subject to random selection as a result of catastrophic stochastic processes. Complexity is not necessarily the completion of development: several complex organisms have gone extinct and many microbes including bacteria with intracellular lifestyle have streamlined highly effective genomes. Genomes evolve through large events of gene deletions, duplications, insertions, and genomes rearrangements rather than a gradual adaptative process. Genomes are dynamic and chimeric entities with gene repertoires that result from vertical and horizontal acquisitions as well as de novo gene creation. The chimeric character of microbial genomes excludes the possibility of finding a single common ancestor for all the genes recorded currently. Genomes are collections of genes with different evolutionary histories that cannot be represented by a single tree of life (TOL). A forest, a network or a rhizome of life may be more accurate to represent evolutionary relationships among species. PMID:22973559

Merhej, Vicky; Raoult, Didier

2012-01-01

287

Rhizome of life, catastrophes, sequence exchanges, gene creations, and giant viruses: how microbial genomics challenges Darwin  

PubMed Central

Darwin's theory about the evolution of species has been the object of considerable dispute. In this review, we have described seven key principles in Darwin's book The Origin of Species and tried to present how genomics challenge each of these concepts and improve our knowledge about evolution. Darwin believed that species evolution consists on a positive directional selection ensuring the “survival of the fittest.” The most developed state of the species is characterized by increasing complexity. Darwin proposed the theory of “descent with modification” according to which all species evolve from a single common ancestor through a gradual process of small modification of their vertical inheritance. Finally, the process of evolution can be depicted in the form of a tree. However, microbial genomics showed that evolution is better described as the “biological changes over time.” The mode of change is not unidirectional and does not necessarily favors advantageous mutations to increase fitness it is rather subject to random selection as a result of catastrophic stochastic processes. Complexity is not necessarily the completion of development: several complex organisms have gone extinct and many microbes including bacteria with intracellular lifestyle have streamlined highly effective genomes. Genomes evolve through large events of gene deletions, duplications, insertions, and genomes rearrangements rather than a gradual adaptative process. Genomes are dynamic and chimeric entities with gene repertoires that result from vertical and horizontal acquisitions as well as de novo gene creation. The chimeric character of microbial genomes excludes the possibility of finding a single common ancestor for all the genes recorded currently. Genomes are collections of genes with different evolutionary histories that cannot be represented by a single tree of life (TOL). A forest, a network or a rhizome of life may be more accurate to represent evolutionary relationships among species.

Merhej, Vicky; Raoult, Didier

2012-01-01

288

Microbial fossil record of rocks from the Ross Desert, Antarctica: implications in the search for past life on Mars  

Microsoft Academic Search

Cryptoendolithic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. The extinction of these micro-organisms formerly colonizing sandstone in the Mount Fleming area (Ross Desert), was probably provoked by the hostile environment. This is considered to be a good terrestrial analogue of the first stage of the disappearance of possible life

Jacek Wierzchos; Carmen Ascaso

2002-01-01

289

An Aufwuchs Chamber Slide for High-Resolution Confocal Laser Scanning Microscopy and Stereo Imaging of Microbial Communities in Natural Biofilms  

Microsoft Academic Search

Aufwuchs chamber slides were constructed by attaching a silicone rubber gasket to a glass slide with epoxy cement. For biofilm growth, the slides were suspended in Cayuga Lake near Ithaca, NY, for 27 days. Biofilms in the chamber were stained with 0.05% acridine orange. After rinsing, the chamber was filled with molten 1% agarose to stabilize filaments and delicate polymer

B. S. Eaglesham; L. W. Lion; W. C. Ghiorse

2004-01-01

290

BIOFILMS IN DRINKING WATER DISTRIBUTION SYSTEMS  

EPA Science Inventory

Virtually anywhere a surface comes into contact with the water in a distribution system, one can find biofilms. Biofilms are formed in distribution system pipelines when microbial cells attach to pipe surfaces and multiply to form a film or slime layer on the pipe. Probably withi...

291

Biofilms and Inflammation in Chronic Wounds  

PubMed Central

Significance The incidence, cost, morbidity, and mortality associated with non-healing of chronic skin wounds are dramatic. With the increasing numbers of people with obesity, chronic medical conditions, and an increasing life expectancy, the healthcare cost of non-healing ulcers has recently been estimated at $25 billion annually in the United States. The role played by bacterial biofilm in chronic wounds has been emphasized in recent years, particularly in the context of the prolongation of the inflammatory phase of repair. Recent Advances Rapid high-throughput genomic approaches have revolutionized the ability to identify and quantify microbial organisms from wounds. Defining bacterial genomes and using genetic approaches to knock out specific bacterial functions, then studying bacterial survival on cutaneous wounds is a promising strategy for understanding which genes are essential for pathogenicity. Critical Issues When an animal sustains a cutaneous wound, understanding mechanisms involved in adaptations by bacteria and adaptations by the host in the struggle for survival is central to development of interventions that favor the host. Future Directions Characterization of microbiomes of clinically well characterized chronic human wounds is now under way. The use of in vivo models of biofilm-infected cutaneous wounds will permit the study of the mechanisms needed for biofilm formation, persistence, and potential synergistic interactions among bacteria. A more complete understanding of bacterial survival mechanisms and how microbes influence host repair mechanisms are likely to provide targets for chronic wound therapy.

Zhao, Ge; Usui, Marcia L.; Lippman, Soyeon I.; James, Garth A.; Stewart, Philip S.; Fleckman, Philip; Olerud, John E.

2013-01-01

292

Biofilms On Orbit and On Earth: Current Methods, Future Needs  

NASA Technical Reports Server (NTRS)

Biofilms have played a significant role on the effectiveness of life support hardware on the Space Shuttle and International Space Station (ISS). This presentation will discuss how biofilms impact flight hardware, how on orbit biofilms are analyzed from an engineering and research perspective, and future needs to analyze and utilize biofilms for long duration, deep space missions.

Vega, Leticia

2013-01-01

293

Spatial Arrangement of Legionella Colonies in Intact Biofilms from a Model Cooling Water System  

PubMed Central

There is disagreement among microbiologists about whether Legionella requires a protozoan host in order to replicate. This research sought to determine where in biofilm Legionellae are found and whether all biofilm associated Legionella would be located within protozoan hosts. While it is accepted that Legionella colonizes biofilm, its life cycle and nutritional fastidiousness suggest that Legionella employs multiple survival strategies to persist within microbial systems. Fluorescent in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) demonstrated an undulating biofilm surface architecture and a roughly homogenous distribution of heterotrophic bacteria with clusters of protozoa. Legionella displayed 3 distinct spatial arrangements either contained within or directly associated with protozoa, or dispersed in loosely associated clusters or in tightly packed aggregations of cells forming dense colonial clusters. The formation of discreet clusters of tightly packed Legionella suggests that colony formation is influenced by specific environmental conditions allowing for limited extracellular replication. This work represents the first time that an environmentally representative, multispecies biofilm containing Legionella has been fluorescently tagged and Legionella colony morphology noted within a complex microbial system.

Taylor, Michael; Ross, Kirstin; Bentham, Richard

2013-01-01

294

Spatial arrangement of legionella colonies in intact biofilms from a model cooling water system.  

PubMed

There is disagreement among microbiologists about whether Legionella requires a protozoan host in order to replicate. This research sought to determine where in biofilm Legionellae are found and whether all biofilm associated Legionella would be located within protozoan hosts. While it is accepted that Legionella colonizes biofilm, its life cycle and nutritional fastidiousness suggest that Legionella employs multiple survival strategies to persist within microbial systems. Fluorescent in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) demonstrated an undulating biofilm surface architecture and a roughly homogenous distribution of heterotrophic bacteria with clusters of protozoa. Legionella displayed 3 distinct spatial arrangements either contained within or directly associated with protozoa, or dispersed in loosely associated clusters or in tightly packed aggregations of cells forming dense colonial clusters. The formation of discreet clusters of tightly packed Legionella suggests that colony formation is influenced by specific environmental conditions allowing for limited extracellular replication. This work represents the first time that an environmentally representative, multispecies biofilm containing Legionella has been fluorescently tagged and Legionella colony morphology noted within a complex microbial system. PMID:24826074

Taylor, Michael; Ross, Kirstin; Bentham, Richard

2013-01-01

295

[Urinary catheter biofilm infections].  

PubMed

Urinary tract infections, most of which are biofilm infections in catheterized patients, account for more than 40% of hospital infections. Bacterial colonization of the urinary tract and catheters causes not only infection but also other complications such as catheter blockage by bacterial encrustation, urolithiasis and pyelonephritis. About 50% of long-term catheterized patients face urinary flow obstruction due to catheter encrustation, but no measure is currently available to prevent it. Encrustation has been known either to result from metabolic dysfunction or to be of microbial origin, with urease positive bacterial species implicated most often. Infectious calculi account for about 15-20% of all cases of urolithiasis and are often associated with biofilm colonization of a long-term indwelling urinary catheter or urethral stent. The use of closed catheter systems is helpful in reducing such problems; nevertheless, such a system only delays the inevitable, with infections emerging a little later. Various coatings intended to prevent the bacterial adhesion to the surface of catheters and implants and thus also the emergence of biofilm infections, unfortunately, do not inhibit the microbial adhesion completely and permanently and the only reliable method for biofilm eradication remains the removal of the foreign body from the patient. PMID:18578409

Holá, V; R?zicka, F

2008-04-01

296

Permeabilizing biofilms  

DOEpatents

Methods for permeabilizing biofilms using stress waves are described. The methods involve applying one or more stress waves to a biofilm, e.g., on a surface of a device or food item, or on a tissue surface in a patient, and then inducing stress waves to create transient increases in the permeability of the biofilm. The increased permeability facilitates delivery of compounds, such as antimicrobial or therapeutic agents into and through the biofilm.

Soukos, Nikolaos S. (Revere, MA) [Revere, MA; Lee, Shun (Arlington, VA) [Arlington, VA; Doukas, Apostolos G. (Belmont, MA) [Belmont, MA

2008-02-19

297

Highlights in pathogenic fungal biofilms.  

PubMed

A wide variety of fungi have demonstrated the ability to colonize surfaces and form biofilms. Most studies on fungal biofilms have focused on Candida albicans and more recently, several authors have reported the involvement of other genera of yeasts and Candida species, as well as of filamentous fungi in the formation of biofilms, including: Cryptococcus neoformans, Cryptococcus gattii, Rhodotorula species, Aspergillus fumigatus, Malassezia pachydermatis, Histoplasma capsulatum, Paracoccidioides brasiliensis, Pneumocystis species, Coccidioides immitis, Fusarium species, Saccharomyces cerevisiae, Trichosporon asahii, Mucorales and Blastoschizomyces. There is a current interest in describing the particular characteristics of the biofilm formation by of these fungi. A major concern is the control of biofilms, requiring knowledge of the biofilm mechanisms. However, our knowledge of these microbial communities is limited, due to the complexity of these systems and metabolic interactions that remain unknown. This mini-review aims to highlight recently discovered fungal biofilms and to compare them with the current knowledge on biofilms. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012). PMID:24252828

Sardi, Janaina De Cássia Orlandi; Pitangui, Nayla De Souza; Rodríguez-Arellanes, Gabriela; Taylor, Maria Lucia; Fusco-Almeida, Ana Maria; Mendes-Giannini, Maria José Soares

2014-01-01

298

Biofilms: Survival Mechanisms of Clinically Relevant Microorganisms  

PubMed Central

Though biofilms were first described by Antonie van Leeuwenhoek, the theory describing the biofilm process was not developed until 1978. We now understand that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health. Using tools such as the scanning electron microscope and, more recently, the confocal laser scanning microscope, biofilm researchers now understand that biofilms are not unstructured, homogeneous deposits of cells and accumulated slime, but complex communities of surface-associated cells enclosed in a polymer matrix containing open water channels. Further studies have shown that the biofilm phenotype can be described in terms of the genes expressed by biofilm-associated cells. Microorganisms growing in a biofilm are highly resistant to antimicrobial agents by one or more mechanisms. Biofilm-associated microorganisms have been shown to be associated with several human diseases, such as native valve endocarditis and cystic fibrosis, and to colonize a wide variety of medical devices. Though epidemiologic evidence points to biofilms as a source of several infectious diseases, the exact mechanisms by which biofilm-associated microorganisms elicit disease are poorly understood. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could initiate the disease process. Effective strategies to prevent or control biofilms on medical devices must take into consideration the unique and tenacious nature of biofilms. Current intervention strategies are designed to prevent initial device colonization, minimize microbial cell attachment to the device, penetrate the biofilm matrix and kill the associated cells, or remove the device from the patient. In the future, treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.

Donlan, Rodney M.; Costerton, J. William

2002-01-01

299

Raman microspectroscopy for species identification and mapping within bacterial biofilms  

PubMed Central

A new method of mapping multiple species of oral bacteria in intact biofilms has been developed, using the optical technique of confocal Raman microscopy. A species classification algorithm, developed on dried biofilms, was used to analyze spectra of hydrated biofilms containing two microbial species central to dental health: Streptococcus sanguinis and Streptococcus mutans. The algorithm transferred successfully to the hydrated environment, correctly identifying the species of origin of single-species biofilms. We then used the algorithm successfully both to detect the presence of two species in mixed biofilms and to create spatial maps within these biofilms.

2012-01-01

300

Lava Cave Microbial Communities Within Mats and Secondary Mineral Deposits: Implications for Life Detection on Other Planets  

PubMed Central

Abstract Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai‘i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai‘i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai‘i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies. Key Words: Biosignatures—Astrobiology—Bacteria—Caves—Life detection—Microbial mats. Astrobiology 11, 601–618.

Melim, L.A.; Spilde, M.N.; Hathaway, J.J.M.; Garcia, M.G.; Moya, M.; Stone, F.D.; Boston, P.J.; Dapkevicius, M.L.N.E.; Riquelme, C.

2011-01-01

301

Towards a rapid and comprehensive microbial detection and identification system for life support and planetary protection applications  

NASA Astrophysics Data System (ADS)

Long term manned missions of our Russian colleagues have demonstrated the risks associated with microbial contamination. These risks concern both crew health via the metabolic consumables contamination (water, air,.) but and also the hardware degradation. In parallel to these life support issues, planetary protection experts have agreed to place clear specifications of the microbial quality of future hardware landing on extraterrestrial planets as well as elaborate the requirements of contamination for manned missions on surface. For these activities, it is necessary to have a better understanding of microbial activity, to create culture collections and to develop on-line detection tools. . In this respect, over the last 6 years , ESA has supported active scientific research on the choice of critical genes and functions, including those linked to horizontal gene pool of bacteria and its dissemination. In parallel, ESA and European industries have been developing an automated instrument for rapid microbial detection on air and surface samples. Within this paper, we first present the life support and planetary protection requirements, and the state of the art of the instrument development. Preliminary results at breadboard level, including a mock-up view of the final instrument are also presented. Finally, the remaining steps required to reach a functional instrument for planetary hardware integration and life support flight hardware are also presented.

Lasseur, Christophe

302

Microbial Fuel Cell as Life Detector: Arsenic Cycling in Hypersaline Environments  

NASA Astrophysics Data System (ADS)

Detection of extant life on Mars or Europa is a future goal of exobiology. For the present, biosignatures arising from life in extreme environments on Earth suggest how to search for life elsewhere. One such biosignature is the electrical current derived from the metabolic activity of microorganisms, which may be measured using microbial fuel cells (MFCs). MFCs generate electricity by coupling bacterially mediated redox transformations to electrochemical reactions through a circuit. Our laboratory fuel cell employs solid graphite electrodes and uses a proton exchange membrane to separate anode (anaerobic) and cathode (aerobic) chambers. Mineral salts media are circulated by peristaltic pump through the chambers and through temperature-controlled reservoirs that are sparged with nitrogen (anode) or oxygen (cathode). In experiments with pure cultures, bacteria reduced arsenate to arsenite in the anode chamber, and produced electrical power in the process. Power production was sustained in the MFC only while bacteria were active. An arsenate respiring bacterium, Bacillus selenitireducens, isolated from moderately-hypersaline Mono Lake, CA grew on lactate using arsenate as the electron acceptor and also grew without arsenate, using the anode as the electron acceptor. Power densities (per unit area of anode surface) of 60 ?W m-2 were achieved during growth without arsenate. Less power (3 ?W m-2) was produced when arsenate was available because arsenate acted as an alternate electron acceptor to the anode. Another arsenate respiring bacterium, strain SLAS-1, isolated from extremely-hypersaline Searles Lake, CA respired lactate and reduced arsenate in the MFC, albeit more slowly. An arsenite oxidizing bacterium, Alkalilimnicola ehrlichii, isolated from Mono Lake will also be tested for its ability to generate electricity before proceeding to an examination of biocurrent production using natural sediments and waters from Mono Lake and Searles Lake.

Miller, L. G.; Blum, J. S.; Oremland, R. S.

2006-12-01

303

MstX and a Putative Potassium Channel Facilitate Biofilm Formation in Bacillus subtilis  

PubMed Central

Biofilms constitute the predominant form of microbial life and a potent reservoir for innate antibiotic resistance in systemic infections. In the spore-forming bacterium Bacillus subtilis, the transition from a planktonic to sessile state is mediated by mutually exclusive regulatory pathways controlling the expression of genes required for flagellum or biofilm formation. Here, we identify mstX and yugO as novel regulators of biofilm formation in B. subtilis. We show that expression of mstX and the downstream putative K+ efflux channel, yugO, is necessary for biofilm development in B. subtilis, and that overexpression of mstX induces biofilm assembly. Transcription of the mstX-yugO operon is under the negative regulation of SinR, a transcription factor that governs the switch between planktonic and sessile states. Furthermore, mstX regulates the activity of Spo0A through a positive autoregulatory loop involving KinC, a histidine kinase that is activated by potassium leakage. The addition of potassium abrogated mstX-mediated biofilm formation. Our findings expand the role of Spo0A and potassium homeostasis in the regulation of bacterial development.

Lundberg, Matthew E.; Becker, Eric C.; Choe, Senyon

2013-01-01

304

Bioluminescent Genetically Engineered Micro-Organisms for the Study of Biofilms.  

National Technical Information Service (NTIS)

These studies illustrate the versatility and potential usefulness of this bioluminescent reporter plasmid for studying the roles of EPS in biofilm process and the effects of other environmental insults on these microbial biofilms. Future experiments shoul...

D. C. White G. S. Sayler

1997-01-01

305

Thermal zonation of microbial biogeography in the hydrothermal fields of Guaymas Basin: insights into the limits of life  

NASA Astrophysics Data System (ADS)

Hydrothermally active sediments at Guaymas Basin are rich in organic substrates and host a wide range of shallow subsurface temperatures: from 3°C to 200°C in the upper 45 centimeters. High temperatures and hydrothermal flow cause upward compression of metabolic zones in Guaymas Basin seafloor sediments. Using push core samples collected by the Alvin submersible (Cruises AT15-40 and 56 in 2008 and 2009) we are investigating thermal structure and carbon and sulfur substrate utilization and their influence on microbial biogeography. As a proxy for viable microbial life total RNA is being extracted from seven high temperature cores that approach, and in three of the cores surpass the upper temperature limit for life at 122°C (Takai et al., 2008). We are using reverse transcription PCR and subsequent pyrosequencing of the V5-V8 region of 16S rRNA to determine key hyperthermophilic archaeal and bacterial groups as well as the upper thermal limit for microbial life in situ. Porewater concentrations of sulfur species and concentrations and isotopic values of carbon species have been investigated in parallel to our high temperature cores. A combination of pyrosequencing data and porewater geochemistry profiles of carbon and sulfur species will help to elucidate the boundaries of life and provide insight into physiological mechanisms under extreme environmental conditions.

Mckay, L. J.; Klokman, V.; Teske, A.

2013-12-01

306

Transcriptional profiling of Legionella pneumophila biofilm cells and the influence of iron on biofilm formation  

Microsoft Academic Search

In aquatic environments, biofilms constitute an ecological niche where Legionella pneumophila persists as sessile cells. However, very little information on the sessile mode of life of L. pneumophila is currently available. We report here the development of a model biofilm of L. pneumophila strain Lens and the first transcriptome analysis of L. pneumophila biofilm cells. Global gene expression analysis of

Thomas Hindre; Holger Bruggemann; Carmen Buchrieser; Yann Hechard

2008-01-01

307

DIFFUSION IN BIOFILMS RESPIRING ON ELECTRODES  

PubMed Central

The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that 1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; 2) Drs at a given location decreases with G. sulfurreducens biofilm age; 3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and 4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms.

Renslow, RS; Babauta, JT; Majors, PD; Beyenal, H

2013-01-01

308

Diffusion in biofilms respiring on electrodes  

SciTech Connect

The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed for noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that (1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; (2) Drs at a given location decreases with G. sulfurreducens biofilm age; (3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and (4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms.

Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.; Beyenal, Haluk

2013-02-15

309

Effects of gamma irradiation on chemical, microbial quality and shelf life of shrimp  

NASA Astrophysics Data System (ADS)

In the present study the combined effect of gamma irradiation (1, 3 and 5 kGy) and storage at two temperatures: refrigeration (+4 °C) and frozen (-18 °C), on the shelf-life extension of fresh shrimp meat was investigated. The study was based on microbiological and physicochemical changes occuring in the shrimp samples. Total volatile base nitrogen values and trimethylamine values for irradiated shrimp samples were significantly lower than non-irradiated samples at both storage temperatures, and the rate of decrease was more pronounced in samples irradiated at the higher dose (p<0.05). Thiobarbituric acid values for irradiated shrimp samples were significantly higher than non-irradiated samples at both storage temperatures (p<0.05). pH values of shrimp samples were affected significantly by both irradiating dose and storage temperatures (p<0.05). Microbial counts for non-irradiated shrimp samples were higher than the respective irradiated samples at both storage temperatures (p<0.05). The results revealed that irradiation at high dose (5 kGy) might enhance lipid oxidation, although the growth of microorganisms and protein oxidation was inhibited.

Hocao?lu, Asl?; Sükrü Demirci, Ahmet; Gümüs, Tuncay; Demirci, Mehmet

2012-12-01

310

Temporal pattern of microbial indicators of ready-to-eat rocket salads during shelf life.  

PubMed

Introduction. From 2001-2009 there have been numerous community alerts and notifications about the rocket salad produced in Italy and distributed in Europe. Our study describes the evolution of the microbial quality of ready to eat rocket salad during shelf life among three different Italian producers. Material and methods. Total Mesophilic Count (TMC) and Escherichia coli (EC) count were measured in 248 samples. We used Wilcoxon test to compare the median values of TMC and EC counts and Kruskal Wallis test to compare the producers. Results. The TMC and EC values differed among producers at the stages of raw material and in the finished product (Kruskall Wallis test, p < 0.05). The evolution of bacterial charges had significant differences among producers at expiration date (Wilcoxon test, p < 0.05). More than half of the samples (54.8%) exceed reference standard for TMC after 48 h from packaging. Conclusion. Differences among producers may linked to the different minimal processing technologies adopted after harvesting. PMID:24695258

De Giusti, Maria; Solimini, Angelo G; Cottarelli, Alessia; De Vito, Corrado; Aurigemma, Caterina; Tufi, Daniela; Piccinato, Ludovico; Boccia, Antonio; Marinelli, Lucia

2014-01-01

311

A 'crytic' microbial mat: A new model ecosystem for extant life on Mars  

NASA Technical Reports Server (NTRS)

If life were present on Mars today, it would face potentially lethal environmental conditions such as a lack of water, frigid temperatures, ultraviolet radiation, and soil oxidants. In addition, the Viking missions did not detect near-surface organic carbon available for assimilation. Autotrophic organisms that lived under a protective layer of sand or gravel would be able to circumvent the ultraviolet radiation and lack of fixed carbon. Two terrestrial photosynthetic near-surface microbial communities have been identified, one in the inter- and supertidal of Laguna Ojo de Liebere (Baja California Sur, Mexico) and one in the acidic gravel near several small geysers in Yellowstone National Park (Wyoming, U.S.A.). Both communities have been studied with respect to their ability to fix carbon under different conditions, including elevated levels of inorganic carbon. Although these sand communities have not been exposed to the entire suite of Martian environmental conditions simultaneously, such communities can provide a useful model ecosystem for a potential extant Martian biota.

Rothschild, L. J.

1995-01-01

312

Microfluidics Expanding the Frontiers of Microbial Ecology  

PubMed Central

The ability afforded by microfluidics to observe the behaviors of microbes in highly controlled and confined microenvironments, across scales from a single cell to mixed communities, has significantly contributed to expand the frontiers of microbial ecology over the last decade. Spatially and temporally varying distributions of organisms and chemical cues that mimic natural microbial habitats can now be established by exploiting physics at the micrometer scale and by incorporating structures with specific geometries and materials. Here we review applications of microfluidics that have resulted in highly insightful discoveries on fundamental aspects of microbial life, ranging from growth and sensing to cell-cell interactions and population dynamics. We anticipate that this flexible, multidisciplinary technology will continue to facilitate discoveries regarding the ecology of microorganisms and help uncover strategies to control phenomena such as biofilm formation and antibiotic resistance.

Rusconi, Roberto; Garren, Melissa; Stocker, Roman

2014-01-01

313

A great leap forward in microbial ecology.  

PubMed

Ribosomal RNA (rRNA) sequence-based molecular techniques emerged in the late 1980s, which completely changed our general view of microbial life. Coincidentally, the Japanese Society of Microbial Ecology (JSME) was founded, and its official journal "Microbes and Environments (M&E)" was launched, in 1985. Thus, the past 25 years have been an exciting and fruitful period for M&E readers and microbiologists as demonstrated by the numerous excellent papers published in M&E. In this minireview, recent progress made in microbial ecology and related fields is summarized, with a special emphasis on 8 landmark areas; the cultivation of uncultured microbes, in situ methods for the assessment of microorganisms and their activities, biofilms, plant microbiology, chemolithotrophic bacteria in early volcanic environments, symbionts of animals and their ecology, wastewater treatment microbiology, and the biodegradation of hazardous organic compounds. PMID:21576878

Okabe, Satoshi; Oshiki, Mamoru; Kamagata, Yoichi; Yamaguchi, Nobuyasu; Toyofuku, Masanori; Yawata, Yutaka; Tashiro, Yosuke; Nomura, Nobuhiko; Ohta, Hiroyuki; Ohkuma, Moriya; Hiraishi, Akira; Minamisawa, Kiwamu

2010-01-01

314

Microbial community structures and in situ sulfate-reducing and sulfur-oxidizing activities in biofilms developed on mortar specimens in a corroded sewer system  

Microsoft Academic Search

Microbially induced concrete corrosion (MICC) caused by sulfuric acid attack in sewer systems has been a serious problem for a long time. A better understanding of microbial community structures of sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) and their in situ activities is essential for the efficient control of MICC. In this study, the microbial community structures and the in

Hisashi Satoh; Mitsunori Odagiri; Tsukasa Ito; Satoshi Okabe

2009-01-01

315

Headwaters are critical reservoirs of microbial diversity for fluvial networks  

PubMed Central

Streams and rivers form conspicuous networks on the Earth and are among nature's most effective integrators. Their dendritic structure reaches into the terrestrial landscape and accumulates water and sediment en route from abundant headwater streams to a single river mouth. The prevailing view over the last decades has been that biological diversity also accumulates downstream. Here, we show that this pattern does not hold for fluvial biofilms, which are the dominant mode of microbial life in streams and rivers and which fulfil critical ecosystem functions therein. Using 454 pyrosequencing on benthic biofilms from 114 streams, we found that microbial diversity decreased from headwaters downstream and especially at confluences. We suggest that the local environment and biotic interactions may modify the influence of metacommunity connectivity on local biofilm biodiversity throughout the network. In addition, there was a high degree of variability in species composition among headwater streams that could not be explained by geographical distance between catchments. This suggests that the dendritic nature of fluvial networks constrains the distributional patterns of microbial diversity similar to that of animals. Our observations highlight the contributions that headwaters make in the maintenance of microbial biodiversity in fluvial networks.

Besemer, Katharina; Singer, Gabriel; Quince, Christopher; Bertuzzo, Enrico; Sloan, William; Battin, Tom J.

2013-01-01

316

Imperfect asymmetry of life: earth microbial communities prefer D-lactate but can use L-lactate also.  

PubMed

Asymmetrical utilization of chiral compounds has been sought on Mars as evidence for biological activity. This method was recently validated in glucose. Earth organisms utilize D-glucose, not L-glucose, a perfect asymmetry. In this study, we tested the method in lactate and found utilization of both enantiomers. Soil-, sediment-, and lake-borne microbial communities prefer D-lactate but can consume L-lactate if given extra time to acclimate. This situation is termed imperfect asymmetry. Future life-detection mission investigators need to be aware of imperfect asymmetry so as not to miss relatively subtle signs of life. PMID:20528194

Moazeni, Faegheh; Zhang, Gaosen; Sun, Henry J

2010-05-01

317

Biofilms: Recent Developments on an Old Battle  

Microsoft Academic Search

Microbial cells are able to adhere to surfaces and through an exo-polymeric matrix they establish microbial communities known as biofilms. This form of immobilised biomass can be responsible for heat and mass transfer limitations in industrial processes and be a source of contamination and proliferation of infections in water supply systems and medical devices. Several processes to prevent and destroy

2007-01-01

318

[Biofilms in otolaryngology].  

PubMed

According to the National Institute of Health of the USA, «more than 60% of all microbial infections are caused by biofilms».'This can surprise us, but it is enough to consider that common infections like those of the genito-urinary tract, infections produced by catheters, middle ear infections in children, the formation of dental plaque and gingivitis are caused by biofilms, for this statement to seem more realistic. At present this is one of the subjects of great interest within medicine, particularly in otolaryngology. Bacteria have traditionally been considered to be in a free state without evident organization, partly perhaps by the ease of studying them in this form. Nevertheless, the reality is that, in nature, the great majority of these germs form complex colonies adhered to surfaces, colonies that have received the name of biofilms. These biofilms are more common than previously thought and almost all of the people have been in contact with them in the form of infections in the teeth or humid, slippery areas. New treatments that can eradicate them are currently being investigated. PMID:23245692

Mena Viveros, Nicolás

2014-01-01

319

Towards a hybrid anaerobic digester-microbial fuel cell integrated energy recovery system: an overview of the development of an electrogenic biofilm.  

PubMed

An electrogenic biofilm was developed on a macroporous chitosan-carbon nanotube (CHIT-CNT) electrode under constant poised potential (-0.25V versus Ag/AgCl reference electrode) and flow through conditions utilizing the effluent of an anaerobic digester as both the inoculant and substrate for the electrogenic biofilm. After 125 days of inoculation the bioelectrode demonstrated an open circuit potential of -0.62V and a current density of 9.43?Acm(-3) (at -0.25V). Scanning electron microscopy images indicate thorough surface coverage of the biofilm with a high density of bacterial nanowires physically connecting bacteria to bacteria and bacteria to carbon nanotube (electrode surface) suggesting the nanowires are electrically conductive. DGGE was used to identify the major bacterial and archaeal populations. PMID:23608503

Higgins, Scott R; Lopez, Ryan J; Pagaling, Eulyn; Yan, Tao; Cooney, Michael J

2013-05-10

320

Microbial Diversity in the Columbia River Basalt Group and the Context for Life in Subsurface Basalts  

NASA Astrophysics Data System (ADS)

Large igneous provinces constitute a sizable volume of porous and fractured materials in the Earth's crust and many of these environments exist within the boundaries of survival for subsurface life. The results of microbiological studies of basalts and other igneous materials in subsurface settings hint at the types of microbes that dwell in these environments. We investigated the microbes in aquifers in the Columbia River Basalt Group (CRBG) and also considered the microbial communities in subsurface basalts more broadly to determine if there are recurrent themes in the types of microbes and the nature of diversity present in these geological systems. Bacteria and Archaea collected from five intervals in the CRBG were examined using high-throughput DNA sequencing directed at the 16S rRNA genes. The highest bacterial biomass and the highest bacterial diversity were observed in the deepest samples (>1018 meters below land surface) whereas the highest archaeal diversity was detected in the shallowest samples (<449 mbls). Microbes classified as Proteobacteria, Firmicutes, and Actinobacteria dominated the aquifers. These findings are generally consistent with earlier cultivation- and clone library-based studies performed on microbes from the CRBG and the Snake River Plain aquifer. Microbes associated with marine basalts are similar to those found in terrestrial settings and include Proteobacteria, Firmicutes, candidate division bacterium OP1, Euryarchaeota, and Crenarchaeota. Based on 16S rRNA sequence similarities to known microbes, both basaltic regions have taxa with representative physiologies likely to include hydrogen oxidation, iron and sulfur metabolism, acetogenesis, and hydrocarbon metabolism. Research on the microbiology of basalt rich provinces on the planet has informed our understanding of biogeochemical cycling where igneous rocks dominate. The knowledge gained in these investigations also promotes our ability to verify the remediation of contaminants and the sequestration of carbon in basalts.

Lavalleur, H. J.; Smith, A.; Fisk, M. R.; Colwell, F. S.

2012-12-01

321

Late-life and intergenerational effects of larval exposure to microbial competitors in the burying beetle Nicrophorus vespilloides.  

PubMed

Intergenerational effects can have either adaptive or nonadaptive impacts on offspring performance. Such effects are likely to be of ecological and evolutionary importance in animals with extended parental care, such as birds, mammals and some insects. Here, we studied the effects of exposure to microbial competition during early development on subsequent reproductive success in the burying beetle Nicrophorus vespilloides, an insect with elaborate parental care. We found that exposure to high levels of microbial competition both during a female's larval development and during her subsequent reproduction resulted in females rearing smaller broods than those exposed to lower levels of microbial competition. To determine whether these differences arose before or after offspring hatching, a cross-fostering experiment was conducted. Our results demonstrate that the impact of larval competition with microbes for resources extends into adult life and can negatively affect subsequent generations via impacts on the quality of parental care provided after hatching. However, we also find evidence for some positive effects of previous microbial exposure on prehatch investment, suggesting that the long-term results of competition with microbes may include altering the balance of parental investment between prehatch and post-hatch care. PMID:24797307

McLean, A H C; Arce, A N; Smiseth, P T; Rozen, D E

2014-06-01

322

Effect of nanoporous TiO2 coating and anodized Ca2+ modification of titanium surfaces on early microbial biofilm formation  

PubMed Central

Background The soft tissue around dental implants forms a barrier between the oral environment and the peri-implant bone and a crucial factor for long-term success of therapy is development of a good abutment/soft-tissue seal. Sol-gel derived nanoporous TiO2 coatings have been shown to enhance soft-tissue attachment but their effect on adhesion and biofilm formation by oral bacteria is unknown. Methods We have investigated how the properties of surfaces that may be used on abutments: turned titanium, sol-gel nanoporous TiO2 coated surfaces and anodized Ca2+ modified surfaces, affect biofilm formation by two early colonizers of the oral cavity: Streptococcus sanguinis and Actinomyces naeslundii. The bacteria were detected using 16S rRNA fluorescence in situ hybridization together with confocal laser scanning microscopy. Results Interferometry and atomic force microscopy revealed all the surfaces to be smooth (Sa ? 0.22 ?m). Incubation with a consortium of S. sanguinis and A. naeslundii showed no differences in adhesion between the surfaces over 2 hours. After 14 hours, the level of biofilm growth was low and again, no differences between the surfaces were seen. The presence of saliva increased the biofilm biovolume of S. sanguinis and A. naeslundii ten-fold compared to when saliva was absent and this was due to increased adhesion rather than biofilm growth. Conclusions Nano-topographical modification of smooth titanium surfaces had no effect on adhesion or early biofilm formation by S. sanguinis and A. naeslundii as compared to turned surfaces or those treated with anodic oxidation in the presence of Ca2+. The presence of saliva led to a significantly greater biofilm biovolume but no significant differences were seen between the test surfaces. These data thus suggest that modification with sol-gel derived nanoporous TiO2, which has been shown to improve osseointegration and soft-tissue healing in vivo, does not cause greater biofilm formation by the two oral commensal species tested than the other surfaces.

2011-01-01

323

R&D of long-term life support system by using electrochemically activated biofilm reactor of aquatic animals for space examinations.  

PubMed

We have developed the long-term life support system that enables the experiment of aquatic animals breeding for 90 days or more for the future experiments in orbit. In order to enable long-term breeding of wide aquatic animals, it is necessary to remove nitrate produced by biological nitrification. Then, we examined a denitrification method to use an electrochemical reaction of biofilm-electrode reactor. In this research, we have not kept the aquatic animals actually but imitated breeding of five goldfish. The ammonia of about 250 ppm was added in breeding water through 90 days. As a result, neither ammonia nor nitrite accumulated 0.1 ppm and nitrate could be suppressed to about 10 ppm. PMID:11542801

Ichikawa, K; Nakamura, H K; Ogawa, N; Sakimura, T; Kuroda, M

1999-12-01

324

Molecular Analysis of Shower Curtain Biofilm Microbes  

PubMed Central

Households provide environments that encourage the formation of microbial communities, often as biofilms. Such biofilms constitute potential reservoirs for pathogens, particularly for immune-compromised individuals. One household environment that potentially accumulates microbial biofilms is that provided by vinyl shower curtains. Over time, vinyl shower curtains accumulate films, commonly referred to as “soap scum,” which microscopy reveals are constituted of lush microbial biofilms. To determine the kinds of microbes that constitute shower curtain biofilms and thereby to identify potential opportunistic pathogens, we conducted an analysis of rRNA genes obtained by PCR from four vinyl shower curtains from different households. Each of the shower curtain communities was highly complex. No sequence was identical to one in the databases, and no identical sequences were encountered in the different communities. However, the sequences generally represented similar phylogenetic kinds of organisms. Particularly abundant sequences represented members of the ?-group of proteobacteria, mainly Sphingomonas spp. and Methylobacterium spp. Both of these genera are known to include opportunistic pathogens, and several of the sequences obtained from the environmental DNA samples were closely related to known pathogens. Such organisms have also been linked to biofilm formation associated with water reservoirs and conduits. In addition, the study detected many other kinds of organisms at lower abundances. These results show that shower curtains are a potential source of opportunistic pathogens associated with biofilms. Frequent cleaning or disposal of shower curtains is indicated, particularly in households with immune-compromised individuals.

Kelley, Scott T.; Theisen, Ulrike; Angenent, Largus T.; Amand, Allison St.; Pace, Norman R.

2004-01-01

325

Activity of disinfectants against multispecies biofilms formed by Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa.  

PubMed

Microbial biofilms are a serious threat to human health. Recent studies have indicated that many clinically relevant biofilms are polymicrobial. In the present study, multispecies biofilms were grown in a reproducible manner in a 96-well microtiter plate. The efficacy of nine commercially available disinfectants against Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa in multispecies biofilms was determined and compared. The results showed that the direction and the magnitude of the effect in a multispecies biofilm depend on the strain and the disinfectant used and challenge the common belief that organisms in multispecies biofilms are always less susceptible than in monospecies biofilms. PMID:24579656

Kart, Didem; Tavernier, Sarah; Van Acker, Heleen; Nelis, Hans J; Coenye, Tom

2014-01-01

326

Biofilms: The Stronghold of Legionella pneumophila  

PubMed Central

Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila is ubiquitous in natural and anthropogenic water systems. L. pneumophila is transmitted by inhalation of contaminated aerosols produced by a variety of devices. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. However, we lack information about the chemical and biophysical conditions, as well as the molecular mechanisms that allow the production of biofilms by L. pneumophila. Here, we discuss the molecular basis of biofilm formation by L. pneumophila and the roles of other microbial species in L. pneumophila biofilm colonization. In addition, we discuss the protective roles of biofilms against current L. pneumophila sanitation strategies along with the initial data available on the regulation of L. pneumophila biofilm formation.

Abdel-Nour, Mena; Duncan, Carla; Low, Donald E.; Guyard, Cyril

2013-01-01

327

How Cyanobacterial Distributions Reveal Flow and Irradiance Conditions of Photosynthetic Biofilm Formation  

NASA Technical Reports Server (NTRS)

Microbial life on Earth is enormously abundant at sediment-water interfaces. The fossil record in fact contains abundant evidence of the preservation of life on such surfaces. It is therefore critical to our interpretation of early Earth history, and potentially to history of life on other planets, to be able to recognize life forms at these interfaces. On Earth this life often occurs as organized structures of microbes and their extracellular exudates known as biofilms. When such biofilms occur in areas receiving sunlight photosynthetic biofilms are the dominant form in natural ecosystems due to selective advantage inherent in their ability to utilize solar energy. Cyanobacteria are the dominant phototrophic microbes in most modern and ancient photosynthetic biofilms, microbial mats and stromatolites. Due to their long (3.5 billion year) evolutionary history, this group has extensively diversified resulting in an enormous array of morphologies and physiological abilities. This enormous diversity and specialization results in very specific selection for a particular cyanobacterium in each available photosynthetic niche. Furthermore these organisms can alter their spatial orientation, cell morphology, pigmentation and associations with heterotrophic organisms in order to fine tune their optimization to a given micro-niche. These adaptations can be detected, and if adequate knowledge of the interaction between environmental conditions and organism response is available, the detectable organism response can be used to infer the environmental conditions causing that response. This presentation will detail two specific examples which illustrate this point, Light and water are essential to photosynthesis in cyanobacteria and these organisms have specific detectable behavioural responses to these parameters. We will present cyanobacterial responses to quantified flow and irradiance to demonstrate the interpretative power of distribution and orientation information. This study presents new results, but many such examples are already found in the literature.

Prufert-Bebout, Lee; DeVincenzi, Donald L. (Technical Monitor)

2001-01-01

328

Bacterial Biofilms as Complex Communities  

NASA Astrophysics Data System (ADS)

Many microbial populations form surface-associated multicellular communities known as biofilms. These multicellular communities are encased in a self-produced extracellular matrix composed of polysaccharides and proteins. Division of labor is a key feature of these communities and different cells serve distinct functions. We have found that in biofilms of the bacterium Bacillus subtilis, different cell types including matrix-producing and sporulating cells coexist and localize to distinct regions within the structured community. We were interested in understanding how these different cell types arise. Using fluorescence reporters under the control of promoters that are specific for distinct cell types we were able to follow the dynamics of differentiation throughout biofilm development. We found that a series of extracellular signals leads to differentiation of distinct cell types during biofilm formation. In addition, we found that extracellular matrix functions as a differentiation signal for timely sporulation within a biofilm and mutants unable to produce matrix were delayed in sporulation. Our results indicate that within a biofilm, cell-cell signaling is directional in that one cell type produces a signal that is sensed by another distinct cell type. Furthermore, once differentiated, cells become resistant to the action of other signaling molecules making it possible to maintain distinct cell populations over prolonged periods.

Vlamakis, Hera

2010-03-01

329

Biofilm formation of Malassezia pachydermatis from dogs.  

PubMed

Yeasts of the genus Malassezia are commensals of the normal skin microbial flora of humans and animals. These yeasts may become pathogenic under certain circumstances and their pathogenic role may be related to host immune system as well to yeast virulence factors (e.g., phospholipase production and biofilm formation). This study aims to evaluate the in vitro ability of M. pachydermatis strains to produce biofilm, and its relationship with phospholipase activity and the genetic make-up of isolates from lesioned (n=32) and healthy (n=30) dog skin. The production of biofilm was determined by crystal violet staining and scanning electronic microscopy (SEM). Biofilm was produced by almost all M. pachydermatis isolates (95.2%) from dogs with and without skin lesions at variable level and different structure. At the SEM, biofilm matrix presented adhering blastoconidia clustered in multi- or monolayer structures with variable quantity of extracellular production. Of the three genotypes detected, genotype B showed the lowest ability to produce biofilm. Of the 59 isolates producing biofilm, 33 (55.9%) produced phospholipase, with a higher biofilm formation (p<0.05) in strains collected from animals with skin lesions. It is here suggested that phospholipase production might act in synergism with the biofilm formation by inducing or exacerbating skin lesions in dogs. The results provide evidences for a better understanding of the interactions between yeasts and host immune system, toward revealing the pathogenicity of M. pachydermatis in animals. PMID:22682201

Figueredo, Luciana A; Cafarchia, Claudia; Desantis, Salvatore; Otranto, Domenico

2012-11-01

330

Subseafloor Microbial Life in Venting Fluids from the Mid Cayman Rise Hydrothermal System  

NASA Astrophysics Data System (ADS)

In hard rock seafloor environments, fluids emanating from hydrothermal vents are one of the best windows into the subseafloor and its resident microbial community. The functional consequences of an extensive population of microbes living in the subseafloor remains unknown, as does our understanding of how these organisms interact with one another and influence the biogeochemistry of the oceans. Here we report the abundance, activity, and diversity of microbes in venting fluids collected from two newly discovered deep-sea hydrothermal vents along the ultra-slow spreading Mid-Cayman Rise (MCR). Fluids for geochemical and microbial analysis were collected from the Von Damm and Piccard vent fields, which are located within 20 km of one another, yet have extremely different thermal, geological, and depth regimes. Geochemical data indicates that both fields are highly enriched in volatiles, in particular hydrogen and methane, important energy sources for and by-products of microbial metabolism. At both sites, total microbial cell counts in the fluids ranged in concentration from 5 x 10 4 to 3 x 10 5 cells ml-1 , with background seawater concentrations of 1-2 x 10 4 cells ml-1 . In addition, distinct cell morphologies and clusters of cells not visible in background seawater were seen, including large filaments and mineral particles colonized by microbial cells. These results indicate local enrichments of microbial communities in the venting fluids, distinct from background populations, and are consistent with previous enumerations of microbial cells in venting fluids. Stable isotope tracing experiments were used to detect utilization of acetate, formate, and dissolve inorganic carbon and generation of methane at 70 °C under anaerobic conditions. At Von Damm, a putatively ultra-mafic hosted site located at ~2200 m with a maximum temperature of 226 °C, stable isotope tracing experiments indicate methanogenesis is occurring in most fluid samples. No activity was detected in Piccard vent fluids, a basalt-hosted black smoker site located at ~4950 m with a maximum temperature of 403 °C. However, hyperthermophilic and thermophilic heterotrophs of the genus Thermococcus were isolated from Piccard vent fluids, but not Von Damm. These obligate anaerobes, growing optimally at 55-90 °C, are ubiquitous at hydrothermal systems and serve as a readily cultivable indicator organism of subseafloor populations. Finally, molecular analysis of vent fluids is on-going and will define the microbial population structure in this novel ecosystem and allow for direct comparisons with other deep-sea and subsurface habitats as part of our continuing efforts to explore the deep microbial biosphere on Earth.

Huber, J. A.; Reveillaud, J.; Reddington, E.; McDermott, J. M.; Sylva, S. P.; Breier, J. A.; German, C. R.; Seewald, J.

2012-12-01

331

Microbial life in the unsaturated subsurface under conditions of extremely low recharge: an extreme environment  

NASA Astrophysics Data System (ADS)

Deep unsaturated sediments with very low levels of sediment- associated nutrients and extremely low levels of vertical movement of moisture (i.e., recharge) were studied as a model extreme environment to better understand microbial survival over geologic time periods and the resulting spatial distribution of viable microorganisms. Chloride mass balance measurements indicate that the study site has received an average annual recharge of 15 micrometers since the last Pleistocene flood approximately 13,000 years ago. Viable biomass as determined by measurement of phospholipid fatty acid in 75 g samples was approximately 10(superscript 4) cells/g sediment. However, highly sensitive microbial activity assays failed to detect microbial activity in > 60% of 10 g samples. Microbial activity was not detected in 29% of replicate 10 g samples in the presence of nutrients for 244 days, indicating that viable microorganisms are spatially discontinuous. In separate experiments, microbial activity was not detected in 0.1 g or 1 g samples but was encountered in 37% of the 10 g samples and in 75% of the 100 g samples. These results indicate that viable microorganisms exist in `hotspots' separated by extensive regions of excluding conditions. In addition, the results suggest that if extremely low nutrient flux conditions exist at target extraterrestrial locations, successful recovery of viable microorganisms may require acquisition of many, or large, samples.

Brockman, Fred J.; Murray, Christopher J.; Murphy, Ellyn M.; Bjornstad, Bruce; Balkwill, David; Ringelberg, David B.; Pfiffner, Susan; Griffiths, Robert

1997-07-01

332

Microbial life in frozen boreal soils-environmental constraints on catabolic and anabolic activity  

NASA Astrophysics Data System (ADS)

Microbial activity in frozen soils has recently gained increasing attention and the fact that soil microorganisms can perform significant metabolic activity at temperatures below freezing is apparent. However, to what extent microbial activity is constrained by the environmental conditions prevailing in a frozen soil matrix is still very uncertain. This presentation will address how the fundamental environmental factors of temperature, liquid water availability and substrate availability combine to regulate rates of catabolic and anabolic microbial processes in frozen soils. The presented results are gained from investigations of the surface layers of boreal forest soils with seasonal freezing. We show that the amount and availability of liquid water is an integral factor regulating rates of microbial activity in the frozen soil matrix and can also explain frequently observed deviations in the temperature responses of biogenic CO2 production in frozen soils, as compared to unfrozen soils. In turn, the capacity for a specific soil to retain liquid water at sub-zero temperatures is controlled by the structural composition of the soil, and especially the soil organic matter is of integral importance. We also show that the partitioning of substrate carbon, in the form of monomeric sugar (glucose), for catabolic and anabolic metabolism remain constant in the temperature range of -4C to 9C. This confirms that microbial growth may proceed even when soils are frozen. In addition we present corresponding data for organisms metabolizing polymeric substrates (cellulose) requiring exoenzymatic activity. We conclude that the metabolic response of soil microorganism to controlling factors may change substantially across the freezing point of soil water, and also the patterns of interaction among controlling factors are affected. Thus, it is evident that metabolic response functions derived from investigations of unfrozen soils cannot be superimposed on frozen soils. Nonetheless, the soil microbial population appear very adapted to seasonal freezing with respect to their metabolic performance.

Oquist, M. G.; Sparrman, T.; Haei, M.; Segura, J.; Schleucher, J.; Nilsson, M. B.

2013-12-01

333

A new coupon design for simultaneous analysis of in situ microbial biofilm formation and community structure in drinking water distribution systems  

Microsoft Academic Search

This study presents a new coupon sampling device that can be inserted directly into the pipes within water distribution systems\\u000a (WDS), maintaining representative near wall pipe flow conditions and enabling simultaneous microscopy and DNA-based analysis\\u000a of biofilms formed in situ. To evaluate this sampling device, fluorescent in situ hybridization (FISH) and denaturing gradient\\u000a gel electrophoresis (DGGE) analyses were used to

Peter Deines; Raju Sekar; P. Stewart Husband; Joby B. Boxall; A. Mark Osborn; Catherine A. Biggs

2010-01-01

334

Long-Term Stability of Mercury-Reducing Microbial BiofilmCommunities Analyzed by 16S-23S rDNA Interspacer RegionPolymorphism  

Microsoft Academic Search

  The composition of mercury-reducing communities in two bioreactors retaining Hg(II) from chloralkali electrolysis wastewater\\u000a for 485 days was analyzed based on effluent community DNA. Packed bed bioreactors with lava chips as carrier of the biofilm\\u000a were inoculated with nine Hg(II)-resistant isolates that belonged to the alpha and gamma subdivisions of the proteobacteria.\\u000a A rapid DNA-fingerprinting method was applied, using the

H. F. von Canstein; Y. Li; A. Felske; I. Wagner-Döbler

2001-01-01

335

Coupling Genetic and Chemical Microbiome Profiling Reveals Heterogeneity of Archaeome and Bacteriome in Subsurface Biofilms That Are Dominated by the Same Archaeal Species  

PubMed Central

Earth harbors an enormous portion of subsurface microbial life, whose microbiome flux across geographical locations remains mainly unexplored due to difficult access to samples. Here, we investigated the microbiome relatedness of subsurface biofilms of two sulfidic springs in southeast Germany that have similar physical and chemical parameters and are fed by one deep groundwater current. Due to their unique hydrogeological setting these springs provide accessible windows to subsurface biofilms dominated by the same uncultivated archaeal species, called SM1 Euryarchaeon. Comparative analysis of infrared imaging spectra demonstrated great variations in archaeal membrane composition between biofilms of the two springs, suggesting different SM1 euryarchaeal strains of the same species at both aquifer outlets. This strain variation was supported by ultrastructural and metagenomic analyses of the archaeal biofilms, which included intergenic spacer region sequencing of the rRNA gene operon. At 16S rRNA gene level, PhyloChip G3 DNA microarray detected similar biofilm communities for archaea, but site-specific communities for bacteria. Both biofilms showed an enrichment of different deltaproteobacterial operational taxonomic units, whose families were, however, congruent as were their lipid spectra. Consequently, the function of the major proportion of the bacteriome appeared to be conserved across the geographic locations studied, which was confirmed by dsrB-directed quantitative PCR. Consequently, microbiome differences of these subsurface biofilms exist at subtle nuances for archaea (strain level variation) and at higher taxonomic levels for predominant bacteria without a substantial perturbation in bacteriome function. The results of this communication provide deep insight into the dynamics of subsurface microbial life and warrant its future investigation with regard to metabolic and genomic analyses.

Holman, Hoi-Ying N.; DeSantis, Todd Z.; Wanner, Gerhard; Andersen, Gary L.; Perras, Alexandra K.; Meck, Sandra; Volkel, Jorg; Bechtel, Hans A.; Wirth, Reinhard; Moissl-Eichinger, Christine

2014-01-01

336

Coupling genetic and chemical microbiome profiling reveals heterogeneity of archaeome and bacteriome in subsurface biofilms that are dominated by the same archaeal species.  

PubMed

Earth harbors an enormous portion of subsurface microbial life, whose microbiome flux across geographical locations remains mainly unexplored due to difficult access to samples. Here, we investigated the microbiome relatedness of subsurface biofilms of two sulfidic springs in southeast Germany that have similar physical and chemical parameters and are fed by one deep groundwater current. Due to their unique hydrogeological setting these springs provide accessible windows to subsurface biofilms dominated by the same uncultivated archaeal species, called SM1 Euryarchaeon. Comparative analysis of infrared imaging spectra demonstrated great variations in archaeal membrane composition between biofilms of the two springs, suggesting different SM1 euryarchaeal strains of the same species at both aquifer outlets. This strain variation was supported by ultrastructural and metagenomic analyses of the archaeal biofilms, which included intergenic spacer region sequencing of the rRNA gene operon. At 16S rRNA gene level, PhyloChip G3 DNA microarray detected similar biofilm communities for archaea, but site-specific communities for bacteria. Both biofilms showed an enrichment of different deltaproteobacterial operational taxonomic units, whose families were, however, congruent as were their lipid spectra. Consequently, the function of the major proportion of the bacteriome appeared to be conserved across the geographic locations studied, which was confirmed by dsrB-directed quantitative PCR. Consequently, microbiome differences of these subsurface biofilms exist at subtle nuances for archaea (strain level variation) and at higher taxonomic levels for predominant bacteria without a substantial perturbation in bacteriome function. The results of this communication provide deep insight into the dynamics of subsurface microbial life and warrant its future investigation with regard to metabolic and genomic analyses. PMID:24971452

Probst, Alexander J; Birarda, Giovanni; Holman, Hoi-Ying N; DeSantis, Todd Z; Wanner, Gerhard; Andersen, Gary L; Perras, Alexandra K; Meck, Sandra; Völkel, Jörg; Bechtel, Hans A; Wirth, Reinhard; Moissl-Eichinger, Christine

2014-01-01

337

STRUCTURAL AND BIOCHEMICAL STUDY OF BIOFILMS ON STEELS IN POTABLE WATER WITH ELECTRONIC MICROPROBE TECHNIQUES  

Microsoft Academic Search

It is known that microorganisms can have a damaging effect and induce microbially influenced corrosion. The majority of bacteria grow in enclosed biofilms attached to surfaces. We studied different biofilms grown on four steels grades in the same bio-environmental conditions in order to evaluate their action on the different materials. The study of biofilm composition formed on common steels immerged

F. Feugeas; G. Ehret; A. Cornet

2001-01-01

338

Biofilm and Nanowire Production Leads to Increased Current in Geobacter sulfurreducens Fuel Cells  

Microsoft Academic Search

Geobacter sulfurreducens developed highly structured, multilayer biofilms on the anode surface of a microbial fuel cell converting acetate to electricity. Cells at a distance from the anode remained viable, and there was no decrease in the efficiency of current production as the thickness of the biofilm increased. Genetic studies demonstrated that efficient electron transfer through the biofilm required the presence

Gemma Reguera; Kelly P. Nevin; Julie S. Nicoll; Sean F. Covalla; Trevor L. Woodard; Derek R. Lovley

2006-01-01

339

The role of intermolecular interactions: studies on model systems for bacterial biofilms  

Microsoft Academic Search

The mechanical stability of biofilms and other microbial aggregates is of great importance for both the maintenance of biofilm processes and the removal of undesired biofilms. The binding forces are weak interactions such as London dispersion forces, electrostatic interactions and hydrogen bonds. In a first attempt to rank their contribution, the viscosity of solutions of extracellular polymeric substances (EPS) from

Christian Mayer; Ralf Moritz; Carolin Kirschner; Werner Borchard; Ralf Maibaum; Jost Wingender; Hans-Curt Flemming

1999-01-01

340

Construction of River Model Biofilm for Assessing Pesticide Effects  

Microsoft Academic Search

Due to the high importance of biofilms on river ecosystems, assessment of pesticides’ adverse effects is necessary but is\\u000a impaired by high variability and poor reproducibility of both natural biofilms and those developed in the laboratory. We constructed\\u000a a model biofilm to evaluate the effects of pesticides, consisting in cultured microbial strains, Pedobacter sp. 7-11, Aquaspirillum sp. T-5, Stenotrophomonas sp.

Shohei Hayashi; Ji Eun Jang; Kazuhito Itoh; Kousuke Suyama; Hiroki Yamamoto

2011-01-01

341

Deep microbial life in the Altmark natural gas reservoir: baseline characterization prior CO2 injection  

Microsoft Academic Search

Within the framework of the CLEAN project (CO2 Largescale Enhanced gas recovery in the Altmark Natural gas field) technical basics with special emphasis on process monitoring are explored by injecting CO2 into a gas reservoir. Our study focuses on the investigation of the in-situ microbial community of the Rotliegend natural gas reservoir in the Altmark, located south of the city

Daria Morozova; Mina Shaheed; Andrea Vieth; Martin Krüger; Dagmar Kock; Hilke Würdemann

2010-01-01

342

Characterization of the deep microbial life in the Altmark natural gas reservoir  

Microsoft Academic Search

Within the framework of the CLEAN project (CO2 Largescale Enhanced gas recovery in the Altmark Natural gas field) technical basics with special emphasis on process monitoring are explored by injecting CO2 into a gas reservoir. Our study focuses on the investigation of the in-situ microbial community of the Rotliegend natural gas reservoir in the Altmark, located south of the city

D. Morozova; M. Alawi; A. Vieth-Hillebrand; D. Kock; M. Krüger; H. Wuerdemann

2010-01-01

343

Planetary biology and microbial ecology. Biochemistry of carbon and early life  

NASA Technical Reports Server (NTRS)

Experiments made with cyanobacteria, phototrophic bacteria, and methanogenic bacteria are detailed. Significant carbon isotope fractionation data is included. Taken from well documented extant microbial communities, this data provides a basis of comparison for isotope fractionation values measured in Archean and Proterozoic (preCambrian) rocks. Media, methods, and techniques used to acquire data are also described.

Margulis, L. (editor); Nealson, K. H. (editor); Taylor, I. (editor)

1983-01-01

344

The Impact of Microbially Influenced Corrosion on Spent Nuclear Fuel and Storage Life  

SciTech Connect

A study was performed to evaluate if microbial activity could be considered a threat to spent nuclear fuel integrity. The existing data regarding the impact of microbial influenced corrosion (MIC) on spent nuclear fuel storage does not allow a clear assessment to be made. In order to identify what further data are needed, a literature survey on MIC was accomplished with emphasis on materials used in nuclear fuel fabrication, e.g., A1, 304 SS, and zirconium. In addition, a survey was done at Savannah River, Oak Ridge, Hanford, and the INEL on the condition of their wet storage facilities. The topics discussed were the SNF path forward, the types of fuel, ramifications of damaged fuel, involvement of microbial processes, dry storage scenarios, ability to identify microbial activity, definitions of water quality, and the use of biocides. Information was also obtained at international meetings in the area of biological mediated problems in spent fuel and high level wastes. Topics dis cussed included receiving foreign reactor research fuels into existing pools, synergism between different microbes and other forms of corrosion, and cross contamination.

J. H. Wolfram; R. E. Mizia; R. Jex; L. Nelson; K. M. Garcia

1996-10-01

345

Resistance of bacterial biofilms to disinfectants: a review  

Microsoft Academic Search

A biofilm can be defined as a community of microorganisms adhering to a surface and surrounded by a complex matrix of extrapolymeric substances. It is now generally accepted that the biofilm growth mode induces microbial resistance to disinfection that can lead to substantial economic and health concerns. Although the precise origin of such resistance remains unclear, different studies have shown

A. Bridier; R. Briandet; V. Thomas; F. Dubois-Brissonnet

2011-01-01

346

A Microbial Oasis in the Hypersaline Atacama Subsurface Discovered by a Life Detector Chip: Implications for the Search for Life on Mars  

PubMed Central

Abstract The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5?m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2?m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5?g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260?g kg?1) and perchlorate (41.13??g g?1 maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14??g g?1) or formate (76.06??g g?1) as electron donors, and sulfate (15875??g g?1), nitrate (13490??g g?1), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars. Key Words: Atacama Desert—Life detection—Biosensor—Biopolymers—In situ measurement. Astrobiology 11, 969–996.

de Diego-Castilla, Graciela; Moreno-Paz, Mercedes; Blanco, Yolanda; Cruz-Gil, Patricia; Rodriguez-Manfredi, Jose A.; Fernandez-Remolar, David; Gomez, Felipe; Gomez, Manuel J.; Rivas, Luis A.; Demergasso, Cecilia; Echeverria, Alex; Urtuvia, Viviana N.; Ruiz-Bermejo, Marta; Garcia-Villadangos, Miriam; Postigo, Marina; Sanchez-Roman, Monica; Chong-Diaz, Guillermo; Gomez-Elvira, Javier

2011-01-01

347

Microscale Confinement features in microfluidic devices can affect biofilm  

SciTech Connect

Biofilms are aggregations of microbes that are encased by extra-cellular polymeric substances (EPS) and adhere to surfaces and interfaces. Biofilm development on abiotic surfaces is a dynamic process, which typically proceeds through an initial phase of adhesion of plankntonic microbes to the substrate, followed by events such as growth, maturation and EPS secretion. However, the coupling of hydrodynamics, microbial adhesion and biofilm growth remain poorly understood. Here, we investigate the effect of semiconfined features on biofilm formation. Using a microfluidic device and fluorescent time-lapse microscopy, we establish that confinement features can significantly affect biofilm formation. Biofilm dynamics change not only as a function of confinement features, but also of the total fluid flow rate, and our combination of experimental results and numerical simulations reveal insights into the link between hydrodynamics and biofilm formation.

Kumar, Aloke [ORNL] [ORNL; Karig, David K [ORNL] [ORNL; Neethirajan, Suresh [University of Guelph] [University of Guelph; Acharya, Rajesh K [ORNL] [ORNL; Mukherjee, Partha P [ORNL] [ORNL; Retterer, Scott T [ORNL] [ORNL; Doktycz, Mitchel John [ORNL] [ORNL

2013-01-01

348

Wound biofilms: lessons learned from oral biofilms  

PubMed Central

Biofilms play an important role in the development and pathogenesis of many chronic infections. Oral biofilms, more commonly known as dental plaque,are a primary cause of oral diseases including caries, gingivitis and periodontitis. Oral biofilms are commonly studied as model biofilm systems as they are easily accessible, thus biofilm research in oral diseases is advanced with details of biofilm formation and bacterial interactions being well-elucidated. In contrast, wound research has relatively recently directed attentionto the role biofilms have in chronic wounds. This review discusses the biofilms in periodontal disease and chronic wounds with comparisons focusing on biofilm detection, biofilm formation, the immune response to biofilms, bacterial interaction and quorum sensing. Current treatment modalities used by both fields as well as future therapies are also discussed.

Mancl, Kimberly A.; Kirsner, Robert S.; Ajdic, Dragana

2013-01-01

349

Effects of Bacteriocins on Methicillin-Resistant Staphylococcus aureus Biofilm  

PubMed Central

Control of biofilms formed by microbial pathogens is an important subject for medical researchers, since the development of biofilms on foreign-body surfaces often causes biofilm-associated infections in patients with indwelling medical devices. The present study examined the effects of different kinds of bacteriocins, which are ribosomally synthesized antimicrobial peptides produced by certain bacteria, on biofilms formed by a clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA). The activities and modes of action of three bacteriocins with different structures (nisin A, lacticin Q, and nukacin ISK-1) were evaluated. Vancomycin, a glycopeptide antibiotic used in the treatment of MRSA infections, showed bactericidal activity against planktonic cells but not against biofilm cells. Among the tested bacteriocins, nisin A showed the highest bactericidal activity against both planktonic cells and biofilm cells. Lacticin Q also showed bactericidal activity against both planktonic cells and biofilm cells, but its activity against biofilm cells was significantly lower than that of nisin A. Nukacin ISK-1 showed bacteriostatic activity against planktonic cells and did not show bactericidal activity against biofilm cells. Mode-of-action studies indicated that pore formation leading to ATP efflux is important for the bactericidal activity against biofilm cells. Our results suggest that bacteriocins that form stable pores on biofilm cells are highly potent for the treatment of MRSA biofilm infections.

Zendo, Takeshi; Sugimoto, Shinya; Iwase, Tadayuki; Tajima, Akiko; Yamada, Satomi; Sonomoto, Kenji

2013-01-01

350

Imaging Biofilm Within Porous Media Using Synchrotron Based X-Ray Computed Microtomography  

Microsoft Academic Search

Current understanding of subsurface microbial biofilm formation and their impact on fluid hydrodynamics is limited by our ability to observe the in situ microscale geometry of developed biofilms. Biomass distribution in porous media has been observed primarily in two dimensional systems; currently, no high- resolution 3-dimensional datasets exist that produce sufficient information about microbial distribution such that the impact on

R. T. Armstrong; D. P. Jansik; D. Wildenschild; B. D. Wood

2008-01-01

351

Candida albicans Biofilm-Defective Mutants  

PubMed Central

Biofilm formation plays a key role in the life cycles and subsistence of many microorganisms. For the human fungal pathogen Candida albicans, biofilm development is arguably a virulence trait, because medical implants that serve as biofilm substrates are significant risk factors for infection. The development of C. albicans biofilms in vitro proceeds through an early phase, in which yeast cells populate a substrate, an intermediate phase, in which pseudohyphal and hyphal cell types are produced, and a maturation phase, in which continued cell growth is accompanied by accumulation of an extracellular matrix. Here we report the results of a screen for C. albicans biofilm-defective mutants, in which homozygous insertions in NUP85, MDS3, KEM1, and SUV3 were found to block biofilm development. Confocal microscopic examination suggests that nup85, suv3, and mds3 mutations cause early-phase arrest, whereas the kem1 mutation causes intermediate-phase arrest. All of the mutants are defective in hypha production in several media. Analysis of mixed-biofilm development indicates that all of the mutants are defective in the production of hyphae in the context of a biofilm. Because all of the mutants are defective in the retention of cells in the biofilm, we infer that hyphae provide an adherent scaffold that stabilizes the biofilm structure.

Richard, Mathias L.; Nobile, Clarissa J.; Bruno, Vincent M.; Mitchell, Aaron P.

2005-01-01

352

[Biofilms of pathogenic bacteria and their role in chronization of infectious process. The search for the means to control biofilms].  

PubMed

The role of biofilms in the environment and in the hosts of pathogenic bacteria has recently attracted much attention of researchers. Microorganisms form biofilms at any biotic and abiotic surfaces and thereby cause serious problems in medical practice and other areas of human activity. Biofilms have been shown to be pathogenetic factors responsible for chronization of infectious process. The data are presented illustrating ubiquitous nature of biofilms, their structural and functional characteristics, and modern methods for the study of microbial communities. The discussion is focused on the role of biofilms in chronization of infectious process, enhanced resistance of biofilm organisms to antibiotics and its underlying mechanisms. Approaches to the search for new means for biofilm control during chronic infections are considered. PMID:22168037

Romanova, Iu M; Didenko, L V; Tolordava, É R; Gintsburg, A L

2011-01-01

353

Did mineral surface chemistry and toxicity contribute to evolution of microbial extracellular polymeric substances?  

PubMed

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. PMID:22934560

Xu, Jie; Campbell, Jay M; Zhang, Nianli; Hickey, William J; Sahai, Nita

2012-08-01

354

Seasonal Retention and Release of Cryptosporidium parvum Oocysts by Environmental Biofilms in the Laboratory ?  

PubMed Central

Cryptosporidium is a genus of waterborne protozoan parasites that causes significant gastrointestinal disease in humans. These parasites can accumulate in environmental biofilms and be subsequently released to contaminate water supplies. Natural microbial assemblages were collected each season from an eastern Pennsylvania stream and used to grow biofilms in laboratory microcosms in which influx, efflux, and biofilm retention were determined from daily oocyst counts. For each seasonal biofilm, oocysts attached to the biofilm quickly during oocyst dosing. Upon termination of oocyst dosing, the percentage of oocysts retained within the biofilm decreased to a new steady state within 5 days. Seasonal differences in biofilm retention of oocysts were observed. The spring biofilm retained the greatest percentage of oocysts, followed (in decreasing order) by the winter, summer, and fall biofilms. There was no statistically significant correlation between the percentage of oocysts attached to the biofilm and (i) any measured stream water quality parameter (including temperature, pH, conductivity, and dissolved organic carbon concentration) or (ii) experimental temperature. Seasonal differences in oocyst retention persisted when biofilms were tested with stream water from a different season. These data suggest that seasonal variation in the microbial community and resulting biofilm architecture may be more important to oocyst transport in this stream site than water quality. The biofilm attachment and detachment dynamics of C. parvum oocysts have implications for public health, and the drinking water industry should recognize that the potential exists for pathogen-free water to become contaminated during the distribution process as a result of biofilm dynamics.

Wolyniak, E. A.; Hargreaves, B. R.; Jellison, K. L.

2010-01-01

355

Ice Shelf Microbial Ecosystems in the High Arctic and Implications for Life on Snowball Earth  

Microsoft Academic Search

The Ward Hunt Ice Shelf (83N, 74W) is the largest remaining section of thick (>10?m) landfast sea ice along the northern\\u000a coastline of Ellesmere Island, Canada. Extensive meltwater lakes and streams occur on the surface of the ice and are colonized\\u000a by photosynthetic microbial mat communities. This High Arctic cryo-ecosystem is similar in several of its physical, biological\\u000a and geochemical

W. F. Vincent; J. A. E. Gibson; R. Pienitz; V. Villeneuve; P. A. Broady; P. B. Hamilton; C. Howard-Williams

2000-01-01

356

Spaceflight promotes biofilm formation by Pseudomonas aeruginosa.  

PubMed

Understanding the effects of spaceflight on microbial communities is crucial for the success of long-term, manned space missions. Surface-associated bacterial communities, known as biofilms, were abundant on the Mir space station and continue to be a challenge on the International Space Station. The health and safety hazards linked to the development of biofilms are of particular concern due to the suppression of immune function observed during spaceflight. While planktonic cultures of microbes have indicated that spaceflight can lead to increases in growth and virulence, the effects of spaceflight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Space Shuttle Atlantis missions: STS-132 and STS-135, and the biofilms formed during spaceflight were characterized. Spaceflight was observed to increase the number of viable cells, biofilm biomass, and thickness relative to normal gravity controls. Moreover, the biofilms formed during spaceflight exhibited a column-and-canopy structure that has not been observed on Earth. The increase in the amount of biofilms and the formation of the novel architecture during spaceflight were observed to be independent of carbon source and phosphate concentrations in the media. However, flagella-driven motility was shown to be essential for the formation of this biofilm architecture during spaceflight. These findings represent the first evidence that spaceflight affects community-level behaviors of bacteria and highlight the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight. PMID:23658630

Kim, Wooseong; Tengra, Farah K; Young, Zachary; Shong, Jasmine; Marchand, Nicholas; Chan, Hon Kit; Pangule, Ravindra C; Parra, Macarena; Dordick, Jonathan S; Plawsky, Joel L; Collins, Cynthia H

2013-01-01

357

Molecular mechanisms of antimicrobial tolerance and resistance in bacterial and fungal biofilms.  

PubMed

The formation of microbial biofilms is an important reason for failure of antimicrobial therapy. However, the molecular mechanisms underlying the survival of biofilm cells are still not completely understood. In this review we discuss three mechanisms that play an important role in biofilm survival: (i) biofilm-specific protection against oxidative stress; (ii) biofilm-specific expression of efflux pumps; and (iii) protection provided by matrix polysaccharides. We demonstrate that these mechanisms are found both in bacterial and fungal biofilms and are often surprisingly similar between distantly related organisms. In addition, we give an overview of the data that suggests that these mechanisms may not be independent. PMID:24598086

Van Acker, Heleen; Van Dijck, Patrick; Coenye, Tom

2014-06-01

358

Potential Application of Phage Therapy Against Pseudomonas aeruginosa Biofilm Infection in Cystic Fibrosis Patients  

Microsoft Academic Search

Majority of the microbial activity in humans is in the form of biofilms i.e. an Exopolysaccharide-enclosed bacterial mass. Unlike planktonic cells and the cells on the surface of the biofilm, the biofilm-embedded cells are more resistant to the effects of the antibiotics and the host cellular defense mechanisms. A combination of biofilm growth and inherent resistance prevents effective antibiotics treatment

Aditi Gurkar

2005-01-01

359

Pseudomonas aeruginosa and Saccharomyces cerevisiae biofilm in flow cells.  

PubMed

Many microbial cells have the ability to form sessile microbial communities defined as biofilms that have altered physiological and pathological properties compared to free living microorganisms. Biofilms in nature are often difficult to investigate and reside under poorly defined conditions(1). Using a transparent substratum it is possible to device a system where simple biofilms can be examined in a non-destructive way in real-time: here we demonstrate the assembly and operation of a flow cell model system, for in vitro 3D studies of microbial biofilms generating high reproducibility under well-defined conditions(2,3). The system consists of a flow cell that serves as growth chamber for the biofilm. The flow cell is supplied with nutrients and oxygen from a medium flask via a peristaltic pump and spent medium is collected in a waste container. This construction of the flow system allows a continuous supply of nutrients and administration of e.g. antibiotics with minimal disturbance of the cells grown in the flow chamber. Moreover, the flow conditions within the flow cell allow studies of biofilm exposed to shear stress. A bubble trapping device confines air bubbles from the tubing which otherwise could disrupt the biofilm structure in the flow cell. The flow cell system is compatible with Confocal Laser Scanning Microscopy (CLSM) and can thereby provide highly detailed 3D information about developing microbial biofilms. Cells in the biofilm can be labeled with fluorescent probes or proteins compatible with CLSM analysis. This enables online visualization and allows investigation of niches in the developing biofilm. Microbial interrelationship, investigation of antimicrobial agents or the expression of specific genes, are of the many experimental setups that can be investigated in the flow cell system. PMID:21304454

Weiss Nielsen, Martin; Sternberg, Claus; Molin, Søren; Regenberg, Birgitte

2011-01-01

360

Laser Induced Fluorescence Emission (L.I.F.E.): In Situ Non-Destructive Detection of Microbial Life on Supraglacial Environments  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence emission (L.I.F.E.) is an in situ laser scanning technique to detect photoautotrophic pigments such as phycoerythrin of an ice ecosystem such as supraglacial environments without contamination. The sensitivity of many psychrophiles to even moderate changes in temperature, and the logistical difficulties associated with either in situ analysis or sampling makes it difficult to study microbial metabolism in ice ecosystems in a high resolution. Surface communities of cold ecosystems are highly autotrophic and therefor ideal systems for L.I.F.E examinations. 532nm green lasers excite photopigments in cyanobacteria and produce multiple fluorescence signatures between 550nm and 750nm including carotenoids, phycobiliproteins which would enable a non-invasive in-situ measurement. The sensitivity of many psychrophiles to even moderate changes in temperature, and the logistical difficulties associated with either in situ analysis or sampling makes it difficult to study these cryosphere ecosystems. In general, the ice habitat has to be disrupted using techniques that usually include coring, sawing, and melting. Samples are also often chosen blindly, with little indication of probable biomass. The need for an in situ non-invasive, non-destructive technique to detect, localize, and sample cryosphere biomass in the field is therefore of considerable importance. L.I.F.E has already been tested in remote ecosystems like Antarctica (Lake Untersee, Lake Fryxell), supraglacial environments in the Kongsfjord region in the High Arctic and High Alpine glaciers but until now no calibration was set to convert the L.I.F.E. signal into pigment concentration. Here we describe the standardization for detection of Phycobiliproteins (Phycoerythrine) which are found in red algae, cyanobacteria, and cryptomonads. Similar methods are already used for detection of phytoplankton in liquid systems like oceans and lakes by NASÁs Airborne Oceanographic LIDAR since 1979. The possibility to use L.I.F.E. in ice though is a novelty and provides a promising tool to monitor vanishing ice systems like retreating glaciers.

Sattler, B.; Tilg, M.; Storrie-Lombardi, M.; Remias, D.; Psenner, R.

2012-04-01

361

Marine bacterial isolates inhibit biofilm formation and disrupt mature biofilms of Pseudomonas aeruginosa PAO1  

Microsoft Academic Search

According to the Centers for Disease Control and Prevention, biofilms cause 65% of infections in developed countries. Pseudomonas aeruginosa biofilm cause life threatening infections in cystic fibrosis infection and they are 1,000 times more tolerant to antibiotic\\u000a than the planktonic cells. As quorum sensing, hydrophobicity index and extracellular polysaccharide play a crucial role in\\u000a biofilm formation, extracts from 46 marine

Chari Nithya; Mansur Farzana Begum; Shunmugiah Karutha Pandian

2010-01-01

362

Microbial Life in the Subseafloor at Mid-Ocean Ridges: A Key to Understanding Ancient Ecosystems on Earth and Elsewhere?  

NASA Astrophysics Data System (ADS)

Some planets and moons in our solar system were similar to Earth in their geological properties during the first few hundred million years after accretion. This is the period when life arose and became established on Earth. It follows that understanding the geophysical and geochemical characteristics of early Earth could provide insight into life-supporting environments on other solar bodies that have not evolved "Garden of Eden" conditions. Hydrothermal systems are primordial and their emergence coincided with the accumulation of liquid water on Earth. The interactions of water and rock associated with hydrothermal systems result in predictable suites of dissolved elements and volatiles. While the concentrations of these chemicals vary at different vent locations and were certainly different during the early Archaean, the overall chemical composition of aqueous hydrothermal fluid is likely to be the same because of the basaltic nature of oceanic crust. In present-day hydrothermal systems, those environments not contaminated by electron acceptors produced from pelagic photosynthesis would most closely mimic the earliest conditions on Earth. These conditions include the subseafloor and high temperature, anaerobic environments associated with hydrothermal systems. The microorganisms associated with these environments derive energy from sulfur, iron, hydrogen and organic compounds. New seafloor eruptions and diffuse flow vents provide unprecedented access to deep subseafloor microbial communities. For example, 12 new eruptions have occurred in the past 15 years including five in the Northeast Pacific. Hyperthermophiles were isolated from 5-30oC diffuse vent fluids from new eruption sites at CoAxial within months of the June, 1993 eruption and from the 1998 eruption at Axial Volcano, and from plume fluids within days of the February, 1996 eruption at the N. Gorda Ridge. The presence of such organisms in fluids that are 20 to 50°C below their minimum growth temperature indicates that they originated from a hot subseafloor habitat. Based on the 16S rRNA sequences and the RFLP patterns of the 500 base sequence between the 16S and 23S rRNA genes (intergenic spacer region), these heterotrophic archaea represent new species, and a new genus, within the Thermococcales (Summit and Baross, 1998; 2001). These isolates grow over an unusually wide temperature range and in low levels of organic material. While Thermococcus and Methanococcus species are the most commonly isolated species of hyperthermophiles from subseafloor biotopes, preliminary phylogenetic analyses based on 16S rRNA sequences of microbial communities in the diffuse flow fluids at new eruption sites show a high diversity of archaea that are not related to cultured organisms. Results to date support the hypothesis that subseafloor microbes associated with hydrothermal systems have nutritional, physiological and bioenergetic characteristics that reflect the physical and geochemical properties of their habitat. Moreover, we propose that deep-sea subsurface environments are analogs of ecosystems on other solar bodies. Thus, by examining the chemical and microbial ecology and energetics of the subsurface, and particularly the subsurface associated with hydrothermal systems, a framework for studying the prospects of extraterrestrial life can be developed. It is predicted that if there were life on other hydrothermally active solar bodies, the same energy sources would fuel microbial metabolism even though the molecular characteristics of these life forms may not resemble Earth organisms having identical metabolisms.

Baross, J. A.; Delaney, J. R.

2001-12-01

363

Voronoi Tessellation Captures Very Early Clustering of Single Primary Cells as Induced by Interactions in Nascent Biofilms  

PubMed Central

Biofilms dominate microbial life in numerous aquatic ecosystems, and in engineered and medical systems, as well. The formation of biofilms is initiated by single primary cells colonizing surfaces from the bulk liquid. The next steps from primary cells towards the first cell clusters as the initial step of biofilm formation remain relatively poorly studied. Clonal growth and random migration of primary cells are traditionally considered as the dominant processes leading to organized microcolonies in laboratory grown monocultures. Using Voronoi tessellation, we show that the spatial distribution of primary cells colonizing initially sterile surfaces from natural streamwater community deviates from uniform randomness already during the very early colonisation. The deviation from uniform randomness increased with colonisation — despite the absence of cell reproduction — and was even more pronounced when the flow of water above biofilms was multidirectional and shear stress elevated. We propose a simple mechanistic model that captures interactions, such as cell-to-cell signalling or chemical surface conditioning, to simulate the observed distribution patterns. Model predictions match empirical observations reasonably well, highlighting the role of biotic interactions even already during very early biofilm formation despite few and distant cells. The transition from single primary cells to clustering accelerated by biotic interactions rather than by reproduction may be particularly advantageous in harsh environments — the rule rather than the exception outside the laboratory.

Hodl, Iris; Hodl, Josef; Worman, Anders; Singer, Gabriel; Besemer, Katharina; Battin, Tom J.

2011-01-01

364

Modulation of Metabolism and Switching to Biofilm Prevail over Exopolysaccharide Production in the Response of Rhizobium alamii to Cadmium  

PubMed Central

Heavy metals such as cadmium (Cd2+) affect microbial metabolic processes. Consequently, bacteria adapt by adjusting their cellular machinery. We have investigated the dose-dependent growth effects of Cd2+ on Rhizobium alamii, an exopolysaccharide (EPS)-producing bacterium that forms a biofilm on plant roots. Adsorption isotherms show that the EPS of R. alamii binds cadmium in competition with calcium. A metabonomics approach based on ion cyclotron resonance Fourier transform mass spectrometry has showed that cadmium alters mainly the bacterial metabolism in pathways implying sugars, purine, phosphate, calcium signalling and cell respiration. We determined the influence of EPS on the bacterium response to cadmium, using a mutant of R. alamii impaired in EPS production (MS?GT). Cadmium dose-dependent effects on the bacterial growth were not significantly different between the R. alamii wild type (wt) and MS?GT strains. Although cadmium did not modify the quantity of EPS isolated from R. alamii, it triggered the formation of biofilm vs planktonic cells, both by R. alamii wt and by MS?GT. Thus, it appears that cadmium toxicity could be managed by switching to a biofilm way of life, rather than producing EPS. We conclude that modulations of the bacterial metabolism and switching to biofilms prevails in the adaptation of R. alamii to cadmium. These results are original with regard to the conventional role attributed to EPS in a biofilm matrix, and the bacterial response to cadmium.

Schue, Mathieu; Fekete, Agnes; Ortet, Philippe; Brutesco, Catherine; Heulin, Thierry; Schmitt-Kopplin, Philippe; Achouak, Wafa; Santaella, Catherine

2011-01-01

365

Laser-Induced Fluorescence Emission (L.I.F.E.): In Situ Nondestructive Detection of Microbial Life in the Ice Covers of Antarctic Lakes  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence emission (L.I.F.E.) images were obtained in situ following 532 nm excitation of cryoconite assemblages in the ice covers of annual and perennially frozen Antarctic lakes during the 2008 Tawani International Expedition to Schirmacher Oasis and Lake Untersee in Dronning Maud Land, Antarctica. Laser targeting of a single millimeter-scale cryoconite results in multiple neighboring excitation events secondary to ice/air interface reflection and refraction in the bubbles surrounding the primary target. Laser excitation at 532 nm of cyanobacteria-dominated assemblages produced red and infrared autofluorescence activity attributed to the presence of phycoerythrin photosynthetic pigments. The method avoids destruction of individual target organisms and does not require the disruption of either the structure of the microbial community or the surrounding ice matrix. L.I.F.E. survey strategies described may be of interest for orbital monitoring of photosynthetic primary productivity in polar and alpine glaciers, ice sheets, snow, and lake ice of Earth's cryosphere. The findings open up the possibility of searching from either a rover or from orbit covers of annual and perennially frozen Antarctic lakes during the 2008 Tawani International Expedition to Schirmacher Oasis and Lake Untersee in Dronning Maud Land, Antarctica. Laser targeting of a single millimeter-scale cryoconite results in multiple neighboring excitation events secondary to ice/air interface reflection and refraction in the bubbles surrounding the primary target. Laser excitation at 532 nm of cyanobacteria-dominated assemblages produced red and infrared autofluorescence activity attributed to the presence of phycoerythrin photosynthetic pigments. The method avoids destruction of individual target organisms and does not require the disruption of either the structure of the microbial community or the surrounding ice matrix. L.I.F.E. survey strategies described may be of interest for orbital monitoring of photosynthetic primary productivity in polar and alpine glaciers, ice sheets, snow, and lake ice of Earth's cryosphere. The findings open up the possibility of searching from either a rover or from orbit for signs of life in the polar regions of Mars and the frozen regions of exoplanets in neighboring star systems.

Storrie-Lombardi, Michael C.; Sattler, Birgit

2009-09-01

366

Azolla-Anabaena symbionts and microbial mat as nitrogen-fixing biocatalysts for bioregenerative space life support.  

PubMed

This study was conducted to characterize the responses of selected nitrogen-fixing biocatalysts to various environmental parameters that are likely to be encountered in a scaled-up nitrogen-fixing bioregenerative unit for use in a biologically based life support system (BLSS). The results showed that while both Azolla filiculoides and Azolla nilotica thrived on standard nitrogen-free liquid media, only Azolla filiculoides maintained its growth rate in the presence of 50% by volume of aerobic-bioreactor potato effluent (ABPE) in its liquid medium. The growth rate and Anabaena cavity population of Azolla filiculoides also remained undiminished in the presence of as much as 10 mM of NO3- in its liquid medium. The tolerance of Azolla filiculoides for NO3- however, lay somewhere between 10 and 20 mM of NO3-. Azolla filiculoides failed to grow at 5 mM or greater concentrations of NH4+. The growth rate of the Oscillatoria-dominated microbial mat was significantly elevated by increased silage loading density (16 g/L) as well as by adding 5 mM of NO3- into its liquid medium. Neither the growth rate of Azolla filiculoides nor that of the microbial mat was affected by three levels of photosynthetic photon flux (PPF) (520, 265, and 125 micromoles m-2 s-1) under high-pressure sodium or cool fluorescent lamps. PMID:11871445

Cuello, J L; Rodriguez-Eaton, S; Stryjewski, E C; Sager, J C

1998-01-01

367

Microbial fossil record of rocks from the Ross Desert, Antarctica: implications in the search for past life on Mars  

NASA Astrophysics Data System (ADS)

Cryptoendolithic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. The extinction of these micro-organisms formerly colonizing sandstone in the Mount Fleming area (Ross Desert), was probably provoked by the hostile environment. This is considered to be a good terrestrial analogue of the first stage of the disappearance of possible life on early Mars. To date, only macroscopically observed indirect biomarkers of the past activity of cryptoendoliths in Antarctic rocks have been described. The present paper confirms, for the first time, the existence of cryptoendolith microbial fossils within these sandstone rocks. The novel in situ application of scanning electron microscopy with backscattered electron imaging and simultaneous use of X-ray energy dispersive spectroscopy allowed the clear detection of microfossils left behind by Antarctic endoliths. Careful interpretation of the morphological features of cells, such as preserved cell walls in algae, fungi and bacteria, cytoplasm elements such as chloroplast membranes in algae and organic matter traces, mineral associations, and the spatial context of these structures all point to their identification as cryptoendolith microfossils. This type of investigation will prompt the development of research strategies aimed at locating and identifying the signs that Martian microbiota, probably only bacteria if they existed, may have been left for us to see.

Wierzchos, Jacek; Ascaso, Carmen

2002-01-01

368

Palaeoarchean Barite Deposits in the Barberton Greenstone Belt: Origin and Links to Early Microbial Life  

NASA Astrophysics Data System (ADS)

Barite deposits are considered important for identifying microbial S cycling in Archean rocks since they can provide information about S isotopes in coexisting sulfate and sulfide minerals. However the degree to which barite and pyrite in metasedimentary rocks are related remains unclear. In this study we have investigated the origin of barite and pyrite in four main horizons seen in both outcrop and fresh drill core material from the Lower Mapepe formation (3.26 to 3.23 Ga), Barberton Greenstone Belt, South Africa. Host rocks include shales, cherts, tuffs and conglomerates that are variably silicified and/or affected by carbonate alteration. The high-energy depositional environment of the host rocks, mineralogical textures, barite chemistry and the occurrence of feldspars from the rarely-found celsian-hyalophane-orthoclase series suggest a seafloor exhalative origin for the barite. In contrast pyrite is closely associated with cherts and dolomitic units where rare earth element and Y data support a marine influence. Pyrite chemistry (Co/Ni= 0.1-1, Se/S <5 x 10- 5) also indicates a low temperature sedimentary origin. Multiple S isotope data (32S, 33S, 34S, determined by SIMS) for pyrite indicates a number of arrays with limited ?34S fractionation at constant ?33S associated with individual syn-sedimentary microcrystalline pyrite layers. Isolated euhedral pyrites in massive chert and barite rich units show much more scatter and larger degrees of ?33S variation (-1 to +4 ). Our results are consistent with models invoking microbial mass dependent fractionation of a heterogeneous elemental sulfur source derived from atmospheric photolysis. The sulfate reservoir can also be linked to photolysis but there is no clear relationship between the barite and pyrite S isotope data, suggesting that microbial (or abiotic) sulfate reduction was absent at this time or that the basinal sulfate concentration must have remained significantly lower than the mM level prior to barite precipitation.

Mason, P. R.; Peters, A.; Nijman, W.; Reimer, T. O.; Whitehouse, M. J.

2008-12-01

369

Molecular basis of in-vivo biofilm formation by bacterial pathogens  

PubMed Central

Summary Bacterial biofilms are involved in a multitude of serious chronic infections. In recent years, modeling biofilm infection in vitro led to the identification of microbial determinants governing biofilm development. However, we lack information as to whether biofilm formation mechanisms identified in vitro have relevance for biofilm-associated infection. Here, we discuss the molecular basis of biofilm formation using staphylococci and Pseudomonas aeruginosa to illustrate key points, as their biofilm development process is well-studied. We will focus on in-vivo findings such as obtained in animal infection models, and critically evaluate in-vivo relevance of in-vitro findings. Although results on the role of quorum-sensing in biofilm formation have been conflicting, we now argue that integration of in-vitro and in-vivo studies allows a differentiated view of this mechanism as it relates to biofilm infection.

Joo, Hwang-Soo; Otto, Michael

2012-01-01

370

Characterization of starvation-induced dispersion in Pseudomonas putida biofilms.  

PubMed

The biofilm lifestyle, where microbial cells are aggregated because of expression of cell-to-cell interconnecting compounds, is believed to be of paramount importance to microbes in the environment. Because microbes must be able to alternate between sessile and planktonic states, it is anticipated that they must be able to regulate their ability to form biofilm and to dissolve biofilm. We present an investigation of a biofilm dissolution process occurring in flow-chamber-grown Pseudomonas putida biofilms. Local starvation-induced biofilm dissolution appears to be an integrated part of P. putida biofilm development that causes characteristic structural rearrangements. Rapid global dissolution of entire P. putida biofilms was shown to occur in response to carbon starvation. Genetic analysis suggested that the adjacent P. putida genes PP0164 and PP0165 play a role in P. putida biofilm formation and dissolution. PP0164 encodes a putative periplasmic protein of previously unknown function, and PP0164 mutant bacteria are sticky, and unable to reduce their adhesiveness and dissolve their biofilm in response to carbon starvation. PP0165 encodes a putative transmembrane protein containing GGDEF and EAL domains, and PP0165 mutant bacteria are unable to increase their adhesiveness and form biofilm. We suggest that the PP0164 and PP0165 proteins are involved in the regulation of the adhesiveness of the bacteria; the PP0165 protein through c-di-GMP signalling, and the PP0164 protein as a transducer of the signal. PMID:15892708

Gjermansen, Morten; Ragas, Paula; Sternberg, Claus; Molin, Søren; Tolker-Nielsen, Tim

2005-06-01

371

Biofilm Formation by Pneumocystis spp.? †  

PubMed Central

Pneumocystis spp. can cause a lethal pneumonia in hosts with debilitated immune systems. The manner in which these fungal infections spread throughout the lung, the life cycles of the organisms, and their strategies used for survival within the mammalian host are largely unknown, due in part to the lack of a continuous cultivation method. Biofilm formation is one strategy used by microbes for protection against environmental assaults, for communication and differentiation, and as foci for dissemination. We posited that the attachment and growth of Pneumocystis within the lung alveoli is akin to biofilm formation. An in vitro system comprised of insert wells suspended in multiwell plates containing supplemented RPMI 1640 medium supported biofilm formation by P. carinii (from rat) and P. murina (from mouse).Dramatic morphological changes accompanied the transition to a biofilm. Cyst and trophic forms became highly refractile and produced branching formations that anastomosed into large macroscopic clusters that spread across the insert. Confocal microscopy revealed stacking of viable organisms enmeshed in concanavalin A-staining extracellular matrix. Biofilms matured over a 3-week time period and could be passaged. These passaged organisms were able to cause infection in immunosuppressed rodents. Biofilm formation was inhibited by farnesol, a quorum-sensing molecule in Candida spp., suggesting that a similar communication system may be operational in the Pneumocystis biofilms. Intense staining with a monoclonal antibody to the major surface glycoproteins and an increase in (1,3)-?-d-glucan content suggest that these components contributed to the refractile properties. Identification of this biofilm process provides a tractable in vitro system that should fundamentally advance the study of Pneumocystis.

Cushion, Melanie T.; Collins, Margaret S.; Linke, Michael J.

2009-01-01

372

Nutritional intervention in early life to manipulate rumen microbial colonization and methane output by kid goats postweaning.  

PubMed

The growing interest in reducing methane (CH4) emissions from ruminants by dietary means is constrained by the complexity of the microbial community in the rumen of the adult animal. The aim of this work was to study whether intervention in early life of goat kids has an impact on methane emissions and the microbial ecosystem in the rumen and whether the effects persist postweaning. Sixteen doe goats giving birth to 2 kids each were randomly split into 2 experimental groups: 8 does were treated (D+) with bromochloromethane (BCM) after giving birth and over 2 mo, and the other 8 does were not treated (D-). In both groups of does, 1 kid per doe was treated with BCM (k+) for 3 mo, and the other was untreated (k-), resulting in 4 experimental groups: D+k+, D+k-, D-k+, and D-k-. Methane emissions were recorded, and ruminal samples were collected from kids at 2 mo of age (weaning, W) and 1 (W+1) and 4 (W+4) mo later. At W+1 mo, CH4 emissions by k+ kids were 52% and 59% less than untreated kids (in D+ and D- groups, respectively). However, at W+4 mo, only D+k+ kids remained lower (33%) emitters and exhibited greater daily BW gain (146 g/d) compared with the other 3 groups (121.8 g/d). The analysis of the archaeal community structure by Denaturing Gradient Gel Electrophoresis (DGGE)showed a strong effect of BCM treatment on does and kids that persisted only in D+k+ kids. The study showed that the application of BCM during early life of kids modified the archaeal population that colonized the rumen, which resulted in decreased CH4 emissions around weaning. The effect is influenced by the treatment applied to the doe and persisted 3 mo later in D+k+ kids. PMID:23965388

Abecia, L; Martín-García, A I; Martínez, G; Newbold, C J; Yáñez-Ruiz, D R

2013-10-01

373

A novel planar flow cell for studies of biofilm heterogeneity and flow-biofilm interactions  

PubMed Central

Biofilms are microbial communities growing on surfaces, and are ubiquitous in nature, in bioreactors, and in human infection. Coupling between physical, chemical, and biological processes is known to regulate the development of biofilms; however, current experimental systems do not provide sufficient control of environmental conditions to enable detailed investigations of these complex interactions. We developed a novel planar flow cell that supports biofilm growth under complex two-dimensional fluid flow conditions. This device provides precise control of flow conditions and can be used to create well-defined physical and chemical gradients that significantly affect biofilm heterogeneity. Moreover, the top and bottom of the flow chamber are transparent, so biofilm growth and flow conditions are fully observable using non-invasive confocal microscopy and high-resolution video imaging. To demonstrate the capability of the device, we observed the growth of Pseudomonas aeruginosa biofilms under imposed flow gradients. We found a positive relationship between patterns of fluid velocity and biofilm biomass because of faster microbial growth under conditions of greater local nutrient influx, but this relationship eventually reversed because high hydrodynamic shear leads to the detachment of cells from the surface. These results reveal that flow gradients play a critical role in the development of biofilm communities. By providing new capability for observing biofilm growth, solute and particle transport, and net chemical transformations under user-specified environmental gradients, this new planar flow cell system has broad utility for studies of environmental biotechnology and basic biofilm microbiology, as well as applications in bioreactor design, environmental engineering, biogeochemistry, geomicrobiology, and biomedical research.

Zhang, Wei; Sileika, Tadas S.; Chen, Cheng; Liu, Yang; Lee, Jisun; Packman, Aaron I.

2012-01-01

374

A novel planar flow cell for studies of biofilm heterogeneity and flow-biofilm interactions.  

PubMed

Biofilms are microbial communities growing on surfaces, and are ubiquitous in nature, in bioreactors, and in human infection. Coupling between physical, chemical, and biological processes is known to regulate the development of biofilms; however, current experimental systems do not provide sufficient control of environmental conditions to enable detailed investigations of these complex interactions. We developed a novel planar flow cell that supports biofilm growth under complex two-dimensional fluid flow conditions. This device provides precise control of flow conditions and can be used to create well-defined physical and chemical gradients that significantly affect biofilm heterogeneity. Moreover, the top and bottom of the flow chamber are transparent, so biofilm growth and flow conditions are fully observable using non-invasive confocal microscopy and high-resolution video imaging. To demonstrate the capability of the device, we observed the growth of Pseudomonas aeruginosa biofilms under imposed flow gradients. We found a positive relationship between patterns of fluid velocity and biofilm biomass due to faster microbial growth under conditions of greater local nutrient influx, but this relationship eventually reversed because high hydrodynamic shear leads to the detachment of cells from the surface. These results reveal that flow gradients play a critical role in the development of biofilm communities. By providing new capability for observing biofilm growth, solute and particle transport, and net chemical transformations under user-specified environmental gradients, this new planar flow cell system has broad utility for studies of environmental biotechnology and basic biofilm microbiology, as well as applications in bioreactor design, environmental engineering, biogeochemistry, geomicrobiology, and biomedical research. PMID:21656713

Zhang, Wei; Sileika, Tadas S; Chen, Cheng; Liu, Yang; Lee, Jisun; Packman, Aaron I

2011-11-01

375

Energy-dependent stability of Shewanella oneidensis MR-1 biofilms.  

PubMed

Stability and resistance to dissolution are key features of microbial biofilms. How these macroscopic properties are determined by the physiological state of individual biofilm cells in their local physical-chemical and cellular environment is largely unknown. In order to obtain molecular and energetic insight into biofilm stability, we investigated whether maintenance of biofilm stability is an energy-dependent process and whether transcription and/or translation is required for biofilm dissolution. We found that in 12-hour-old Shewanella oneidensis MR-1 biofilms, a reduction in cellular ATP concentration, induced either by oxygen deprivation or by addition of the inhibitor of oxidative phosphorylation carbonyl cyanide m-chlorophenylhydrazone (CCCP), dinitrophenol (DNP), or CN(-), resulted in massive dissolution. In 60-hour-old biofilms, the extent of uncoupler-induced cell loss was strongly attenuated, indicating that the integrity of older biofilms is maintained by means other than those operating in younger biofilms. In experiments with 12-hour-old biofilms, the transcriptional and translational inhibitors rifampin, tetracycline, and erythromycin were found to be ineffective in preventing energy starvation-induced detachment, suggesting that neither transcription nor translation is required for this process. Biofilms of Vibrio cholerae were also induced to dissolve upon CCCP addition to an extent similar to that in S. oneidensis. However, Pseudomonas aeruginosa and P. putida biofilms remained insensitive to CCCP addition. Collectively, our data show that metabolic energy is directly or indirectly required for maintaining cell attachment, and this may represent a common but not ubiquitous mechanism for stability of microbial biofilms. PMID:21572002

Saville, Renee M; Rakshe, Shauna; Haagensen, Janus A J; Shukla, Soni; Spormann, Alfred M

2011-07-01

376

Evidence of Ancient Microbial Life in an Impact Structure and Its Implications for Astrobiology  

Microsoft Academic Search

The search for present and past life on Mars has drawn major attention from the scientific community, as well as from national\\u000a and international space agencies. A major reason for focusing the search for life on Mars is that, apart from being the closest\\u000a planetary body of major astrobiological interest, Mars may have shared a number of environmental features with

Tomas Hode; Sherry L. Cady; Ilka Dalwigk; Per Kristiansson

377

Searching for microbial life remotely: Satellite-to-rover habitat mapping in the Atacama Desert, Chile  

Microsoft Academic Search

The Atacama Desert, one of the most arid landscapes on Earth, serves as an analog for the dry conditions on Mars and as a test bed in the search for life on other planets. During the Life in the Atacama (LITA) 2004 field experiment, satellite imagery and ground-based rover data were used in concert with a ‘follow-the-water’ exploration strategy to

K. Warren-Rhodes; S. Weinstein; J. Dohm; J. Piatek; E. Minkley; A. Hock; C. Cockell; D. Pane; L. A. Ernst; G. Fisher; S. Emani; A. S. Waggoner; N. A. Cabrol; D. S. Wettergreen; D. Apostolopoulos; P. Coppin; E. Grin; Chong Diaz; J. Moersch; G. G. Oril; T. Smith; K. Stubbs; G. Thomas; M. Wagner; M. Wyatt

2007-01-01

378

Biofilms: United They Stand, Divided They Colonize  

NSDL National Science Digital Library

Curricular materials designed to teach parallel computational modeling to undergraduate or graduate students in science and other STEM disciplines. The module begins with the construction of a cellular automaton model of microbial biofilms using Mathematica. This model is then re-implemented with C and parallelized using MPI.

Shiflet, Angela B.; Shiflet, George W.; Ellison, Shay M.

379

Conflicts of interest in biofilms  

Microsoft Academic Search

High cell density and close proximity of diverse species of microorganisms are typical of life in natural biofilms. These conditions give ample opportunity for both competitive and cooperative interactions between individuals of the same and different species. Cooperative behaviour benefits the group of neighbouring microbes but comes at a fitness cost for the cooperating individuals. This creates a conflict of

J.-U. Kreft

2005-01-01

380

Bovine Mastitis and Biofilms  

Microsoft Academic Search

\\u000a Biofilm formation in bovine mastitis Staphylococcus aureus isolates was studied since the beginnings of biofilm research, even before the name “biofilm” was actually invented. Compared\\u000a to other major bovine mastitis pathogens, such as E. coli and Streptococcus uberis relatively much research information is available on S. aureus biofilm formation, biofilm antimicrobial susceptibility and the role of several biofilm related genes.

Marielle B. Melchior