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Sample records for river microbial biofilm

  1. Biofilm formation and microbial community analysis of the simulated river bioreactor for contaminated source water remediation.

    Science.gov (United States)

    Xu, Xiang-Yang; Feng, Li-Juan; Zhu, Liang; Xu, Jing; Ding, Wei; Qi, Han-Ying

    2012-06-01

    The start-up pattern of biofilm remediation system affects the biofilm characteristics and operating performances. The objective of this study was to evaluate the performances of the contaminated source water remediation systems with different start-up patterns in view of the pollutants removal performances and microbial community succession. The operating performances of four lab-scale simulated river biofilm reactors were examined which employed different start-up methods (natural enrichment and artificial enhancement via discharging sediment with influent velocity gradient increase) and different bio-fillers (Elastic filler and AquaMats® ecobase). At the same time, the microbial communities of the bioreactors in different phases were analyzed by polymerase chain reaction, denaturing gradient gel electrophoresis, and sequencing. The pollutants removal performances became stable in the four reactors after 2 months' operation, with ammonia nitrogen and permanganate index (COD(Mn)) removal efficiencies of 84.41-94.21% and 69.66-76.60%, respectively. The biomass of mature biofilm was higher in the bioreactors by artificial enhancement than that by natural enrichment. Microbial community analysis indicated that elastic filler could enrich mature biofilm faster than AquaMats®. The heterotrophic bacteria diversity of biofilm decreased by artificial enhancement, which favored the ammonia-oxidizing bacteria (AOB) developing on the bio-fillers. Furthermore, Nitrosomonas- and Nitrosospira-like AOB coexisted in the biofilm, and Pseudomonas sp., Sphaerotilus sp., Janthinobacterium sp., Corynebacterium aurimucosum were dominant in the oligotrophic niche. Artificial enhancement via the combination of sediment discharging and influent velocity gradient increasing could enhance the biofilm formation and autotrophic AOB enrichment in oligotrophic niche.

  2. Microbial ecology of phototrophic biofilms

    NARCIS (Netherlands)

    Roeselers, G.

    2007-01-01

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

  3. Manipulatiaon of Biofilm Microbial Ecology

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-08-09

    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.

  4. Manipulation of Biofilm Microbial Ecology

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  5. Antibiotic tolerance and microbial biofilms

    DEFF Research Database (Denmark)

    Folkesson, Anders

    Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We study the dynamics of antibiotic action within hydrodynamic flow chamber biofilms of Escherichia coli and Pseudomonas aeruginosa using isogenic mutants and fluorescent gene...... expression reporters and we address the question of how biofilm organization affects antibiotic susceptibility. The dynamics of microbial killing is monitored by viable count determination, and confocal laser microscopy. Our work shows that the apparent increased antibiotic tolerance is due to the formation...... of antibiotic tolerant subpopulations within the biofilm. The formation of these subpopulations is highly variable and dependent on the antibiotic used, the biofilm structural organization and the induction of specific tolerance mechanisms....

  6. Microbial biofilms: biosurfactants as antibiofilm agents.

    Science.gov (United States)

    Banat, Ibrahim M; De Rienzo, Mayri A Díaz; Quinn, Gerry A

    2014-12-01

    Current microbial inhibition strategies based on planktonic bacterial physiology have been known to have limited efficacy on the growth of biofilm communities. This problem can be exacerbated by the emergence of increasingly resistant clinical strains. All aspects of biofilm measurement, monitoring, dispersal, control, and inhibition are becoming issues of increasing importance. Biosurfactants have merited renewed interest in both clinical and hygienic sectors due to their potential to disperse microbial biofilms in addition to many other advantages. The dispersal properties of biosurfactants have been shown to rival those of conventional inhibitory agents against bacterial and yeast biofilms. This makes them suitable candidates for use in new generations of microbial dispersal agents and for use as adjuvants for existing microbial suppression or eradication strategies. In this review, we explore aspects of biofilm characteristics and examine the contribution of biologically derived surface-active agents (biosurfactants) to the disruption or inhibition of microbial biofilms.

  7. Rotating disk electrodes to assess river biofilm thickness and elasticity.

    Science.gov (United States)

    Boulêtreau, Stéphanie; Charcosset, Jean-Yves; Gamby, Jean; Lyautey, Emilie; Mastrorillo, Sylvain; Azémar, Frédéric; Moulin, Frédéric; Tribollet, Bernard; Garabetian, Frédéric

    2011-01-01

    The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s(-1) in inflow and constricted sections respectively) and containing 24 RDE was immersed in the river for 21 days. Biofilm thickness and elasticity were quantified using an electrochemical assay on 7 and 21 days old RDE-grown biofilms (t(7) and t(21), respectively). Biofilm thickness was affected by colonisation length and flow conditions and ranged from 36 ± 15 μm (mean ± standard deviation, n = 6) in the fast flow section at t(7) to 340 ± 140 μm (n = 3) in the slow flow section at t(21). Comparing the electrochemical signal to stereomicroscopic estimates of biofilms thickness indicated that the method consistently allowed (i) to detect early biofilm colonisation in the river and (ii) to measure biofilm thickness of up to a few hundred μm. Biofilm elasticity, i.e. biofilm squeeze by hydrodynamic constraint, was significantly higher in the slow (1300 ± 480 μm rpm(1/2), n = 8) than in the fast flow sections (790 ± 350 μm rpm(1/2), n = 11). Diatom and bacterial density, and biofilm-covered RDE surface analyses (i) confirmed that microbial accrual resulted in biofilm formation on the RDE surface, and (ii) indicated that thickness and elasticity represent useful integrative parameters of biofilm architecture that could be measured on natural river assemblages using the proposed electrochemical method. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Characterization of Mechanical Properties of Microbial Biofilms

    Science.gov (United States)

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

    2017-11-01

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

  9. Microbial Biofilm as a Smart Material

    DEFF Research Database (Denmark)

    Garde, Christian; Welch, Martin; Ferkinghoff-Borg, Jesper

    2015-01-01

    Microbial biofilm colonies will in many cases form a smart material capable of responding to external threats dependent on their size and internal state. The microbial community accordingly switches between passive, protective, or attack modes of action. In order to decide which strategy to employ......, it is essential for the biofilm community to be able to sense its own size. The sensor designed to perform this task is termed a quorum sensor, since it only permits collective behaviour once a sufficiently large assembly of microbes have been established. The generic quorum sensor construct involves two genes...

  10. Microbial interactions in drinking water biofilms

    OpenAIRE

    Simões, Lúcia C.; Simões, M.; Vieira, M. J.

    2007-01-01

    Drinking water distribution networks may be viewed as a large reactor where a number of chemical and microbiological processes are taking place. Control of microbial growth in drinking water distribution systems (DWDS) often achieved through the addition of disinfectants, is essential to limit the spread of waterborne pathogens. However, microorganisms can resist disinfection through protection within biofilms and resistant host cells. Recent studies into the microbial ecology ...

  11. Microbial pathogenesis and biofilm development

    DEFF Research Database (Denmark)

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

    2004-01-01

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

  12. Microbial Biofilms: Persisters, Tolerance and Dosing

    Science.gov (United States)

    Cogan, N. G.

    2005-03-01

    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.

  13. Biofilm and dental implant: The microbial link

    Directory of Open Access Journals (Sweden)

    Sangeeta Dhir

    2013-01-01

    Full Text Available Mouth provides a congenial environment for the growth of the microorganisms as compared to any other part of the human body by exhibiting an ideal nonshedding surface. Dental plaque happens to be a diverse community of the microorganisms found on the tooth surface. Periodontal disease and the peri-implant disease are specific infections that are originating from these resident microbial species when the balance between the host and the microbial pathogenicity gets disrupted. This review discusses the biofilms in relation to the peri-implant region, factors affecting its presence, and the associated treatment to manage this complex microbial colony. Search Methodology: Electronic search of the medline was done with the search words: Implants and biofilms/dental biofilm formation/microbiology at implant abutment interface/surface free energy/roughness and implant, periimplantitis/local drug delivery and dental implant. Hand search across the journals - clinical oral implant research, implant dentistry, journal of dental research, international journal of oral implantology, journal of prosthetic dentistry, perioodntology 2000, journal of periodontology were performed. The articles included in the review comprised of in vivo studies, in vivo (animal and human studies, abstracts, review articles.

  14. Microbial Activity Influences Electrical Conductivity of Biofilm Anode

    Science.gov (United States)

    This study assessed the conductivity of a Geobacter-enriched biofilm anode along with biofilm activity in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH ...

  15. Marine and estuarine natural microbial biofilms: ecological and biogeochemical dimensions

    Directory of Open Access Journals (Sweden)

    O. Roger Anderson

    2016-08-01

    Full Text Available Marine and estuarine microbial biofilms are ubiquitously distributed worldwide and are increasingly of interest in basic and applied sciences because of their unique structural and functional features that make them remarkably different from the biota in the plankton. This is a review of some current scientific knowledge of naturally occurring microbial marine and estuarine biofilms including prokaryotic and microeukaryotic biota, but excluding research specifically on engineering and applied aspects of biofilms such as biofouling. Because the microbial communities including bacteria and protists are integral to the fundamental ecological and biogeochemical processes that support biofilm communities, particular attention is given to the structural and ecological aspects of microbial biofilm formation, succession, and maturation, as well as the dynamics of the interactions of the microbiota in biofilms. The intent is to highlight current state of scientific knowledge and possible avenues of future productive research, especially focusing on the ecological and biogeochemical dimensions.

  16. MICROBIAL BIOFILMS AS INTEGRATIVE SENSORS OF ENVIRONMENTAL QUALITY

    Science.gov (United States)

    Snyder, Richard A., Michael A. Lewis, Andreas Nocker and Joe E. Lepo. In press. Microbial Biofilms as Integrative Sensors of Environmental Quality. In: Estuarine Indicators Workshop Proceedings. CRC Press, Boca Raton, FL. 34 p. (ERL,GB 1198). Microbial biofilms are comple...

  17. Spatial Patterns in Biofilm Diversity across Hierarchical Levels of River-Floodplain Landscapes.

    Directory of Open Access Journals (Sweden)

    Marc Peipoch

    Full Text Available River-floodplain systems are among the most diverse and productive ecosystems, but the effects of biophysical complexity at multiple scales on microbial biodiversity have not been studied. Here, we investigated how the hierarchical organization of river systems (i.e., region, floodplain, zone, habitats, and microhabitats influences epilithic biofilm community assemblage patterns by characterizing microbial communities using 16S rRNA gene sequence data and analyzing bacterial species distribution across local and regional scales. Results indicate that regional and local environmental filters concurrently sort bacterial species, suggesting that spatial configuration of epilithic biofilms resembles patterns of larger organisms in floodplain ecosystems. Along the hierarchical organization of fluvial systems, floodplains constitute a vector of maximum environmental heterogeneity and consequently act as a major landscape filter for biofilm species. Thus, river basins and associated floodplains may simply reflect very large scale 'patches' within which environmental conditions select for community composition of epilithic biofilms.

  18. Microbial Biofilm as a Smart Material

    Directory of Open Access Journals (Sweden)

    Christian Garde

    2015-02-01

    Full Text Available Microbial biofilm colonies will in many cases form a smart material capable of responding to external threats dependent on their size and internal state. The microbial community accordingly switches between passive, protective, or attack modes of action. In order to decide which strategy to employ, it is essential for the biofilm community to be able to sense its own size. The sensor designed to perform this task is termed a quorum sensor, since it only permits collective behaviour once a sufficiently large assembly of microbes have been established. The generic quorum sensor construct involves two genes, one coding for the production of a diffusible signal molecule and one coding for a regulator protein dedicated to sensing the signal molecules. A positive feedback in the signal molecule production sets a well-defined condition for switching into the collective mode. The activation of the regulator involves a slow dimerization, which allows low-pass filtering of the activation of the collective mode. Here, we review and combine the model components that form the basic quorum sensor in a number of Gram-negative bacteria, e.g., Pseudomonas aeruginosa.

  19. Recent advances in dental biofilm: impacts of microbial interactions on the biofilm ecology and pathogenesis

    Directory of Open Access Journals (Sweden)

    Yung-Hua Li

    2017-05-01

    Full Text Available The human oral cavity is a complex ecosystem harboring hundreds species of microbes that are largely living on the tooth surfaces as dental biofilms. Most microbes in dental biofilms promote oral health by stimulating the immune system or by preventing invasion of pathogens. Species diversity, high cell density and close proximity of cells are typical of life in dental biofilms, where microbes interact with each other and develop complex interactions that can be either competitive or cooperative. Competition between species is a well-recognized ecological force to drive microbial metabolism, species diversity and evolution. However, it was not until recently that microbial cooperative activities are also recognized to play important roles in microbial physiology and ecology. Importantly, these interactions profoundly affect the overall biomass, function, diversity and the pathogenesis in dental biofilms. It is now recognized that every human body contains a personalized oral microbiome that is essential to maintaining the oral health. Remarkably, the indigenous species in dental biofilms often maintain a relatively stable and harmless relationship with the host, despite regular exposure to environmental perturbations and the host defense factors. Such stability or homeostasis results from a dynamic balance of microbial-microbial and microbial-host interactions. Under certain circumstances, however, the homeostasis may breakdown, predisposing a site to diseases. In this review, we describe several examples of microbial interactions and their impacts on the homeostasis and pathogenesis of dental biofilms. We hope to encourage research on microbial interactions in the regulation of the homeostasis in biofilms.

  20. Agriculturally important microbial biofilms: Present status and future prospects.

    Science.gov (United States)

    Velmourougane, Kulandaivelu; Prasanna, Radha; Saxena, Anil Kumar

    2017-07-01

    Microbial biofilms are a fascinating subject, due to their significant roles in the environment, industry, and health. Advances in biochemical and molecular techniques have helped in enhancing our understanding of biofilm structure and development. In the past, research on biofilms primarily focussed on health and industrial sectors; however, lately, biofilms in agriculture are gaining attention due to their immense potential in crop production, protection, and improvement. Biofilms play an important role in colonization of surfaces - soil, roots, or shoots of plants and enable proliferation in the desired niche, besides enhancing soil fertility. Although reports are available on microbial biofilms in general; scanty information is published on biofilm formation by agriculturally important microorganisms (bacteria, fungi, bacterial-fungal) and their interactions in the ecosystem. Better understanding of agriculturally important bacterial-fungal communities and their interactions can have several implications on climate change, soil quality, plant nutrition, plant protection, bioremediation, etc. Understanding the factors and genes involved in biofilm formation will help to develop more effective strategies for sustainable and environment-friendly agriculture. The present review brings together fundamental aspects of biofilms, in relation to their formation, regulatory mechanisms, genes involved, and their application in different fields, with special emphasis on agriculturally important microbial biofilms. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Occurrence and persistence of antibiotic resistance genes in river biofilms after wastewater inputs in small rivers

    International Nuclear Information System (INIS)

    Proia, Lorenzo; Schiller, Daniel von; Sànchez-Melsió, Alexandre; Sabater, Sergi; Borrego, Carles M.; Rodríguez-Mozaz, Sara; Balcázar, José Luis

    2016-01-01

    The extensive use of antibiotics in human and veterinary medicine and their subsequent release into the environment may have direct consequences for autochthonous bacterial communities, especially in freshwater ecosystems. In small streams and rivers, local inputs of wastewater treatment plants (WWTPs) may become important sources of organic matter, nutrients and emerging pollutants, such as antibiotic resistance genes (ARGs). In this study, we evaluated the effect of WWTP effluents as a source of ARGs in river biofilms. The prevalence of genes conferring resistance to main antibiotic families, such as beta-lactams (bla_C_T_X_-_M), fluoroquinolones (qnrS), sulfonamides (sul I), and macrolides (ermB), was determined using quantitative PCR (qPCR) in biofilm samples collected upstream and downstream WWTPs discharge points in four low-order streams. Our results showed that the WWTP effluents strongly modified the hydrology, physico-chemistry and biological characteristics of the receiving streams and favoured the persistence and spread of antibiotic resistance in microbial benthic communities. It was also shown that the magnitude of effects depended on the relative contribution of each WWTP to the receiving system. Specifically, low concentrations of ARGs were detected at sites located upstream of the WWTPs, while a significant increase of their concentrations was observed in biofilms collected downstream of the WWTP discharge points (particularly ermB and sul I genes). These findings suggest that WWTP discharges may favour the increase and spread of antibiotic resistance among streambed biofilms. The present study also showed that the presence of ARGs in biofilms was noticeable far downstream of the WWTP discharge (up to 1 km). It is therefore reasonable to assume that biofilms may represent an ideal setting for the acquisition and spread of antibiotic resistance determinants and thus be considered suitable biological indicators of anthropogenic pollution by active

  2. Spatial & Temporal Geophysical Monitoring of Microbial Growth and Biofilm Formation

    Science.gov (United States)

    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...

  3. Extracellular DNA as matrix component in microbial biofilms

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tolker-Nielsen, Tim

    2010-01-01

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

  4. The biofilm ecology of microbial biofouling, biocide resistance and corrosion

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  5. Microbiële biofilms in tandheelkunde

    NARCIS (Netherlands)

    Krom, B.P.

    2015-01-01

    Aangehechte gemeenschappen van micro-organismen, ook wel biofilms genoemd, zijn altijd en overal aanwezig. Hoewel biofilms een slechte naam hebben, zijn ze meestal natuurlijk, gezond en zelfs gewenst. In de tandartspraktijk komen zowel gezonde (orale biofilms) als ongezonde (bijv. in de waterleiding

  6. Microbiële biofilms in tandheelkunde

    NARCIS (Netherlands)

    Krom, B.P.

    2015-01-01

    Aangehechte gemeenschappen van micro-organismen, ook wel biofilms genoemd, zijn altijd en overal aanwezig. Hoewel biofilms een slechte naam hebben, zijn ze meestal natuurlijk, gezond en zelfs gewenst. In de mondzorgpraktijk komen zowel gezonde (orale biofilms) als ongezonde (bijv. in de waterleiding

  7. Microbial biofilms in water-mixed metalworking fluids; Mikrobielle Biofilme in wassergemischten Kuehlschmierstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Thomas [Wisura GmbH, Bremen (Germany)

    2013-05-15

    The microbial load of water-miscible metalworking fluids (MWF) as well as the hygienic aspects and the cost-related impact on the production process due to the activity of microbes is in the focus of many scientific investigations and documented in the related publications. The majority of this research work is focused on the microbiology of the water body, i.e. with the microbial life in the liquid coolant. The habitat biofilm, i.e. the three-dimensional growth of bacteria and fungi on surfaces of the coolant systems has been scarcely considered. Based on the scientific findings made in the recent years studying biofilms it can be concluded, that the relevant microbial processes for the depletion of the MWF and its recontamination takes predominantly places in biofilms. This paper gives an overview of the structure, the formation and the life in biofilms and represents their relevance in MWF systems. (orig.)

  8. Investigating Microbial Biofilm Formations on Crustal Rock Substrates

    Science.gov (United States)

    Weiser, M.; D'Angelo, T.; Carr, S. A.; Orcutt, B.

    2017-12-01

    Ocean crust hosts microbial life that, in some cases, alter the component rocks as a means of obtaining energy. Variations in crust lithology, included trace metal and mineral content, as well as the chemistry of the fluids circulating through them, provide substrates for some microbes to metabolize, leading to formation of biofilm community structures. Microbes have different parameters for the situations in which they will form biofilms, but they must have some source of energy in excess at the site of biofilm formation for them to become stationary and form the carbohydrate-rich structures connecting the cells to one another and the substrate. Generally, the requirements for microbes to form biofilms on crustal minerals are unclear. We designed two experiments to test (1) mineral preference and biofilm formation rates by natural seawater microbial communities, and (2) biofilm development as a function of phosphate availability for an organism isolated from subseafloor ocean crust. In Experiment 1, we observed that phyric basalt groundmass is preferentially colonized over aphyric basalt or metal sulfides in a shallow water and oxic seawater environment. In experiment 2, tests of the anaerobic heterotroph Thalassospira bacteria isolated from oceanic crustal fluids showed that they preferentially form biofilms, lose motility, and increase exponentially in number over time in higher-PO4 treatments (50 micromolar), including with phosphate-doped basalts, than in treatments with low phosphate concentrations (0.5 micromolar) often found in crustal fluids. These observations suggest phosphate as a main driver of biofilm formation in subsurface crust. Overall, these data suggest that the drivers of microbial biofilm formation on crustal substrates are selective to the substrate conditions, which has important implications for estimating the global biomass of life harbored in oceanic crust.

  9. Coexistence facilitates interspecific biofilm formation in complex microbial communities

    DEFF Research Database (Denmark)

    Madsen, Jonas Stenløkke; Røder, Henriette Lyng; Russel, Jakob

    2016-01-01

    Social interactions in which bacteria respond to one another by modifying their phenotype are central determinants of microbial communities. It is known that interspecific interactions influence the biofilm phenotype of bacteria; a phenotype that is central to the fitness of bacteria. However......, the underlying role of fundamental ecological factors, specifically coexistence and phylogenetic history, in biofilm formation remains unclear. This study examines how social interactions affect biofilm formation in multi-species co-cultures from five diverse environments. We found prevalence of increased...

  10. Microbial diversity and putative opportunistic pathogens in dishwasher biofilm communities

    DEFF Research Database (Denmark)

    Raghupathi, Prem Krishnan; Zupančič, Jerneja; Brejnrod, Asker Daniel

    2018-01-01

    impact the abundance of microbial groups, and investigated on the inter- and intra-kingdom interactions that shape these biofilms. The age, the usage frequency and hardness of incoming tap water of dishwashers had significant impact on bacterial and fungal composition. Representatives ofCandidaspp. were...... and interactions were vital in the process of biofilm formation, where mixed complexes of the two, bacteria and fungi, could provide a preliminary biogenic structure for the establishment of these biofilms.IMPORTANCEWorldwide demand for household appliances, such as dishwashers and washing machines, is increasing...

  11. A short history of microbial biofilms and biofilm infections

    DEFF Research Database (Denmark)

    Høiby, Niels

    2017-01-01

    The observation of aggregated microbes surrounded by a self-produced matrix adhering to surfaces or located in tissues or secretions is old since both Leeuwenhoek and Pasteur have described the phenomenon. In environmental and technical microbiology, biofilms, 80–90 years ago, were already shown ...

  12. Biofilm composition in the Olt River (Romania) reservoirs impacted by a chlor-alkali production plant.

    Science.gov (United States)

    Dranguet, P; Cosio, C; Le Faucheur, S; Hug Peter, D; Loizeau, J-L; Ungureanu, V-Gh; Slaveykova, V I

    2017-05-24

    Freshwater biofilms can be useful indicators of water quality and offer the possibility to assess contaminant effects at the community level. The present field study examines the effects of chlor-alkali plant effluents on the community composition of biofilms grown in the Olt River (Romania) reservoirs. The relationship between ambient water quality variables and community composition alterations was explored. Amplicon sequencing revealed a significant modification of the composition of microalgal, bacterial and fungal communities in the biofilms collected in the impacted reservoirs in comparison with those living in the uncontaminated control reservoir. The abundance corrected Simpson index showed lower richness and diversity in biofilms collected in the impacted reservoirs than in the control reservoir. The biofilm bacterial communities of the impacted reservoirs were characterized by the contaminant-tolerant Cyanobacteria and Bacteroidetes, whereas microalgal communities were predominantly composed of Bacillariophyta and fungal communities of Lecanoromycetes and Paraglomycetes. A principal component analysis revealed that major contaminants present in the waste water of the chlor-alkali production plant, i.e. Na + , Ca 2+ , Cl - and Hg, were correlated with the alteration of biofilm community composition in the impacted reservoirs. However, the biofilm composition was also influenced by water quality variables such as NO 3 - , SO 4 2- , DOC and Zn from unknown sources. The results of the present study imply that, even when below the environmental quality standards, typical contaminants of chlor-alkali plant releases may affect biofilm composition and that their impacts on the microbial biodiversity might be currently overlooked.

  13. Microbial biofilm study by synchrotron X-ray microscopy

    International Nuclear Information System (INIS)

    Pennafirme, S.; Lima, I.; Bitencourt, J.A.; Crapez, M.A.C.; Lopes, R.T.

    2015-01-01

    Microbial biofilm has already being used to remove metals and other pollutants from wastewater. In this sense, our proposal was to isolate and cultivate bacteria consortia from mangrove’s sediment resistant to Zn (II) and Cu (II) at 50 mg L −1 and to observe, through synchrotron X-ray fluorescence microscopy (microXRF), whether the biofilm sequestered the metal. The biofilm area analyzed was 1 mm 2 and a 2D map was generated (pixel size 20×20 μm 2 , counting time 5 s/point). The biofilm formation and retention followed the sequence Zn>Cu. Bacterial consortium zinc resistant formed dense biofilm and retained 63.83% of zinc, while the bacterial consortium copper resistant retained 3.21% of copper, with lower biofilm formation. Dehydrogenase activity of Zn resistant bacterial consortium was not negatively affect by 50 mg ml −1 zinc input, whereas copper resistant bacterial consortium showed a significant decrease on dehydrogenase activity (50 mg mL −1 of Cu input). In conclusion, biofilm may protect bacterial cells, acting as barrier against metal toxicity. The bacterial consortia Zn resistant, composed by Nitratireductor spp. and Pseudomonas spp formed dense biofilm and sequestered metal from water, decreasing the metal bioavailability. These bacterial consortia can be used in bioreactors and in bioremediation programs. - Highlights: • We studied bacterial bioremediation by microXRF. • Dense biofilm may act sequestering metal while protecting bacterial metabolism. • Nitratireductor spp. and Pseudomonas spp decreased seawater metal bioavailability. • Bacterial consortia from polluted areas may be used in bioremediation programs.

  14. Microbial Surface Colonization and Biofilm Development in Marine Environments

    Science.gov (United States)

    2015-01-01

    SUMMARY Biotic and abiotic surfaces in marine waters are rapidly colonized by microorganisms. Surface colonization and subsequent biofilm formation and development provide numerous advantages to these organisms and support critical ecological and biogeochemical functions in the changing marine environment. Microbial surface association also contributes to deleterious effects such as biofouling, biocorrosion, and the persistence and transmission of harmful or pathogenic microorganisms and their genetic determinants. The processes and mechanisms of colonization as well as key players among the surface-associated microbiota have been studied for several decades. Accumulating evidence indicates that specific cell-surface, cell-cell, and interpopulation interactions shape the composition, structure, spatiotemporal dynamics, and functions of surface-associated microbial communities. Several key microbial processes and mechanisms, including (i) surface, population, and community sensing and signaling, (ii) intraspecies and interspecies communication and interaction, and (iii) the regulatory balance between cooperation and competition, have been identified as critical for the microbial surface association lifestyle. In this review, recent progress in the study of marine microbial surface colonization and biofilm development is synthesized and discussed. Major gaps in our knowledge remain. We pose questions for targeted investigation of surface-specific community-level microbial features, answers to which would advance our understanding of surface-associated microbial community ecology and the biogeochemical functions of these communities at levels from molecular mechanistic details through systems biological integration. PMID:26700108

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

    Science.gov (United States)

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

    2015-03-01

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

  16. Microbial biofilm growth on irradiated, spent nuclear fuel cladding

    International Nuclear Information System (INIS)

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

    2009-01-01

    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 x 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

  17. Clinical implications of microbial biofilms in chronic rhinosinusitis and orbital cellulitis

    OpenAIRE

    Nayak, Niranjan; Satpathy, Gita; Prasad, Sujata; Thakar, Alok; Chandra, Mahesh; Nag, TC

    2016-01-01

    Background Discovery of sessile mode of microbial existence (Biofilm state) focussed much interest, during the recent years, on the study of biofilms in many recurring and chronic infections. However, the exact role of microbial biofilms in chronic rhinosinusitis and orbital cellulitis were not elucidated earlier. The purpose of the present study was to look for the adherent property and biofilm producing ability of the clinical isolates in chronic rhinosinusitis and orbital cellulitis, and t...

  18. Spatial & Temporal Geophysical Monitoring of Microbial Growth and Biofilm Formation

    Science.gov (United States)

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

    2009-12-01

    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 (σ”) values. The σ” response corresponds to different stages of biofilm development. That is, we interpret the peak σ” with the maximum biofilm thickness and decreasing σ” 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

  19. Microbial Biofilms and Breast Tissue Expanders

    Directory of Open Access Journals (Sweden)

    Melissa J. Karau

    2013-01-01

    Full Text Available 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.

  20. Microbial biofilm formation and its consequences for the CELSS program

    Science.gov (United States)

    Mitchell, R.

    1994-01-01

    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.

  1. Prostate calcifications: A case series supporting the microbial biofilm theory

    Directory of Open Access Journals (Sweden)

    Tommaso Cai

    2018-05-01

    Full Text Available Purpose: Prostate calcifications are a common finding during transrectal prostate ultrasound in both healthy subjects and patients, but their etiopathogenesis and clinical significance are not fully understood. We aimed to establish a new methodology for evaluating the role of microbial biofilms in the genesis of prostate calcifications. Materials and Methods: Ten consecutive patients who had undergone radical prostatectomy were enrolled in this study. All of the patients presented with prostate calcifications during transrectal ultrasound evaluation before surgery and underwent Meares-Stamey tests and clinical evaluation with the National Institutes of Health Chronic Prostatitis Symptom Index and the International Prostate Symptom Score. At the time of radical prostatectomy, the prostate specimen, after removal, was analyzed with ultrasonography under sterile conditions in the operating room. Core biopsy specimens were taken from the site of prostate calcification and subjected to ultrastructural and microbiological analysis. Results: The results of the Meares-Stamey test showed only 1 of 10 patients (10% with positive cultures for Escherichia coli. Two of five patients (40% had positive cultures from prostate biopsy specimens. Enterococcus faecalis, Enterococcus raffinosus, and Citrobacter freundii were isolated. Ultrastructural analysis of the prostate biopsy specimens showed prostate calcifications in 6 of 10 patients (60%, and a structured microbial biofilm in 1 patient who had positive cultures for E. faecalis and E. raffinosus. Conclusions: Although the findings are supported by a low number of patients, this study highlights the validity of the proposed methodology for investigating the role of bacterial biofilms in the genesis of prostate calcification.

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

    Science.gov (United States)

    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...

  3. COMPOSITION AND METHOD FOR CONTROLLING MICROBIAL ADHESION AND BIOFILM FORMATION OF SURFACES

    DEFF Research Database (Denmark)

    2003-01-01

    The present invention describes how coating of surfaces with an extract, particularly a fish extract, can significantly reduce microbial adhesion, attachment, colonization and biofilm formation on surfaces. Such reduction of microbial adherence, attachment and colonization will be applicable...

  4. Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community

    KAUST Repository

    Xue, Zheng

    2014-07-15

    Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses, storage time at 4°C, and DNA extraction method) on the downstream analysis of nitrifying biofilms grown on ultrafiltration membranes. Both rinse and storage affected biofilm structure, as suggested by their strong correlation with total biovolume, biofilm thickness, roughness and the spatial distribution of EPS. Significant variations in DNA yields and microbial community diversity were also observed among samples treated by different rinses, storage and DNA extraction methods. For the tested biofilms, two rinses, no storage and DNA extraction with both mechanical and chemical cell lysis from attached biofilm were the optimal sample preparation procedures for obtaining accurate information about biofilm structure, EPS distribution and the microbial community. © 2014 © 2014 Taylor & Francis.

  5. Microbial fuel cell based on electroactive sulfate-reducing biofilm

    International Nuclear Information System (INIS)

    Angelov, Anatoliy; Bratkova, Svetlana; Loukanov, Alexandre

    2013-01-01

    Highlights: ► Regulation and management of electricity generation by variation of residence time. ► Design of microbial fuel cell based on electroactive biofilm on zeolite. ► Engineering solution for removing of the obtained elemental sulfur. - abstract: A two chambered laboratory scale microbial fuel cell (MFC) has been developed, based on natural sulfate-reducing bacterium consortium in electroactive biofilm on zeolite. The MFC utilizes potassium ferricyanide in the cathode chamber as an electron acceptor that derives electrons from the obtained in anode chamber H 2 S. The molecular oxygen is finally used as a terminal electron acceptor at cathode compartment. The generated power density was 0.68 W m −2 with current density of 3.2 A m −2 at 150 Ω electrode resistivity. The hydrogen sulfide itself is produced by microbial dissimilative sulfate reduction process by utilizing various organic substrates. Finally, elemental sulfur was identified as the predominant final oxidation product in the anode chamber. It was removed from MFC through medium circulation and gathering in an external tank. This report reveals dependence relationship between the progress of general electrochemical parameters and bacterial sulfate-reduction rate. The presented MFC design can be used for simultaneous sulfate purification of mining drainage wastewater and generation of renewable electricity

  6. Anti-microbial and anti-biofilm compounds from Indonesian medicinal plants

    NARCIS (Netherlands)

    Pratiwi, Sylvia U.T.

    2015-01-01

    Microbial biofilms causing elevated resistance to both most anti-microbial drugs and the host defense systems, which often results in persistent and difficult-to-treat infections. The discovery of anti-infective agents which are active against planktonic and biofilm microorganisms are therefore

  7. Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes

    International Nuclear Information System (INIS)

    Dumas, Claire; Basseguy, Regine; Bergel, Alain

    2008-01-01

    Stainless steel and graphite electrodes were individually addressed and polarized at -0.60 V vs. Ag/AgCl in reactors filled with a growth medium that contained 25 mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75 A m -2 for graphite and 20.5 A m -2 for stainless steel. Cyclic voltammetry performed at the end of the experiment indicated that the reduction started at around -0.30 V vs. Ag/AgCl on stainless steel. Removing the biofilm formed on the electrode surface made the current totally disappear, confirming that the G.sulfurreducens biofilm was fully responsible for the electrocatalysis of fumarate reduction. Similar current densities were recorded when the electrodes were polarized after being kept in open circuit for several days. The reasons for the bacteria presence and survival on non-connected stainless steel coupons were discussed. Chronoamperometry experiments performed at different potential values suggested that the biofilm-driven catalysis was controlled by electrochemical kinetics. The high current density obtained, quite close to the redox potential of the fumarate/succinate couple, presents stainless steel as a remarkable material to support biocathodes

  8. Comparative responses of river biofilms at the community level to common organic solvent and herbicide exposure.

    Science.gov (United States)

    Paule, A; Roubeix, V; Swerhone, G D W; Roy, J; Lauga, B; Duran, R; Delmas, F; Paul, E; Rols, J L; Lawrence, J R

    2016-03-01

    Residual pesticides applied to crops migrate from agricultural lands to surface and ground waters. River biofilms are the first aquatic non-target organisms which interact with pesticides. Therefore, ecotoxicological experiments were performed at laboratory scale under controlled conditions to investigate the community-level responses of river biofilms to a chloroacetanilide herbicide (alachlor) and organic solvent (methanol) exposure through the development referenced to control. Triplicate rotating annular bioreactors, inoculated with river water, were used to cultivate river biofilms under the influence of 1 and 10 μg L(-1) of alachlor and 25 mg L(-1) of methanol. For this purpose, functional (thymidine incorporation and carbon utilization spectra) and structural responses of microbial communities were assessed after 5 weeks of development. Structural aspects included biomass (chlorophyll a, confocal laser scanning microscopy) and composition (fluor-conjugated lectin binding, molecular fingerprinting, and diatom species composition). The addition of alachlor resulted in a significant reduction of bacterial biomass at 1 μg L(-1), whereas at 10 μg L(-1), it induced a significant reduction of exopolymer lectin binding, algal, bacterial, and cyanobacterial biomass. However, there were no changes in biofilm thickness or thymidine incorporation. No significant difference between the bacterial community structures of control and alachlor-treated biofilms was revealed by terminal restriction fragment length polymorphism (T-RFLP) analyses. However, the methanol-treated bacterial communities appeared different from control and alachlor-treated communities. Moreover, methanol treatment resulted in an increase of bacterial biomass and thymidine incorporation as well. Changes in dominant lectin binding suggested changes in the exopolymeric substances and community composition. Chlorophyll a and cyanobacterial biomass were also altered by methanol. This study suggested

  9. Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community

    KAUST Repository

    Xue, Zheng; Lu, Huijie; Liu, Wen-Tso

    2014-01-01

    Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses

  10. Microbial community stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Ruscalleda, Maël; Terada, Akihiko

    of bacterial granules or biofilms. In this sense, completely autotrophic nitrogen removal from high ammonium strength wastewater was achieved in a Membrane-Aereated Biofilm Reactor (MABR) in a single step. Here, a biofilm containing nitrifiers (Aerobic Ammonium and Nitrite Oxidizing Bacteria, AOB and NOB......, respectively) and Anaerobic Ammonium Oxidizing Bacteria (AnAOB) is grown on bubbleless aeration membranes to remove ammonium. Since oxygen permeates through the membrane-biofilm interface while ammonium diffuses into the biofilm from the biofilm-liquid interface, oxygen gradients can be established across...... the biofilm, allowing nitrogen removal in a single reactor by simultaneous activity of the mentioned biocatalysts. This work consists on the analysis of the microbial community existing in two laboratory-scale reactors operated for more than 300 days, which removed up to 5.5 g-N/m2/day. The system contained...

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

    KAUST Repository

    Lee, O.O.; Wang, Y.; Tian, R.; Zhang, W.; Shek, C.S.; Bougouffa, Salim; Al-Suwailem, A.; Batang, Z.B.; Xu, W.; Wang, G.C.; Zhang, Xixiang; Lafi, F.F.; Bajic, Vladimir B.; Qian, P.-Y.

    2014-01-01

    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.

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

    KAUST Repository

    Lee, O.O.

    2014-01-08

    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.

  13. Biodegradation of carbamate pesticides by natural river biofilms in different seasons and their effects on biofilm community structure

    International Nuclear Information System (INIS)

    Tien, Chien-Jung; Lin, Mon-Chu; Chiu, Wan-Hsin; Chen, Colin S.

    2013-01-01

    This study investigated the ability of natural river biofilms from different seasons to degrade the carbamate pesticides methomyl, carbaryl and carbofuran in single and multiple pesticide systems, and the effects of these pesticides on algal and bacterial communities within biofilms. Spring biofilms had the lowest biomass of algae and bacteria but showed the highest methomyl degradation (>99%) and dissipation rates, suggesting that they might contain microorganisms with high methomyl degradation abilities. Degradation of carbofuran (54.1–59.5%) by biofilms in four seasons was similar, but low degradation of carbaryl (0–27.5%) was observed. The coexistence of other pesticides was found to cause certain effects on pesticide degradation and primarily resulted in lower diversity of diatoms and bacteria than when using a single pesticide. The tolerant diatoms and bacteria potentially having the ability to degrade test pesticides were identified. River biofilms could be suitable biomaterials or used to isolate degraders for bioremediating pesticide-contaminated water. -- Highlights: •Natural river biofilms showed high ability to degrade methomyl and carbofuran. •The presence of other pesticides caused certain effects on pesticide degradation. •Carbamate pesticides caused adverse effects on communities of diatoms and bacteria. •The tolerant diatoms and bacteria were found as potential pesticide-degraders. -- Biodegradation of carbamate pesticides by river biofilms

  14. Extracellular DNA as matrix component in microbial biofilms

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tolker-Nielsen, Tim

    2010-01-01

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

  15. Biofilm growth on polyvinylchloride surface incubated in suboptimal microbial warm water and effect of sanitizers on biofilm removal post biofilm formation

    Science.gov (United States)

    An in vitro experiment was conducted to understand the nature of biofilm growth on polyvinyl chloride (PVC) surface when exposed to sub optimal quality microbial water (> 4 log10 cfu/ml) obtained from poultry drinking water source mimicking water in waterlines during the first week of poultry broodi...

  16. Microbial composition of biofilms associated with lithifying rubble of Acropora palmata branches.

    Science.gov (United States)

    Beltrán, Yislem; Cerqueda-García, Daniel; Taş, Neslihan; Thomé, Patricia E; Iglesias-Prieto, Roberto; Falcón, Luisa I

    2016-01-01

    Coral reefs are among the most productive ecosystems on the planet, but are rapidly declining due to global-warming-mediated changes in the oceans. Particularly for the Caribbean region, Acropora sp. stony corals have lost ∼80% of their original coverage, resulting in vast extensions of dead coral rubble. We analyzed the microbial composition of biofilms that colonize and lithify dead Acropora palmata rubble in the Mexican Caribbean and identified the microbial assemblages that can persist under scenarios of global change, including high temperature and low pH. Lithifying biofilms have a mineral composition that includes aragonite and magnesium calcite (16 mole% MgCO(3)) and calcite, while the mineral phase corresponding to coral skeleton is basically aragonite. Microbial composition of the lithifying biofilms are different in comparison to surrounding biotopes, including a microbial mat, water column, sediments and live A. palmata microbiome. Significant shifts in biofilm composition were detected in samples incubated in mesocosms. The combined effect of low pH and increased temperature showed a strong effect after two-week incubations for biofilm composition. Findings suggest that lithifying biofilms could remain as a secondary structure on reef rubble possibly impacting the functional role of coral reefs. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Effects of Miramistin and Phosprenil on Microbial Biofilms.

    Science.gov (United States)

    Danilova, T A; Danilina, G A; Adzhieva, A A; Minko, A G; Nikolaeva, T N; Zhukhovitskii, V G; Pronin, A V

    2017-08-01

    Effects of Miramistin and Phosprenil on biofilms of S. pyogenes, S. aureus, E. coli, L. acidophilus, and L. plantarum were studied. Significant differences in the effects of these substances on mature biofilms of microorganisms and the process of their formation were observed. Miramistin had significant inhibiting effects on the forming of biofilms and on the formed biofilms of all studied microorganisms. Treatment with Miramistin inhibited biofilm formation by 2-3 times compared to the control. This effect was found already after using of Miramistin in the low doses (3.12 μg/ml). Inhibition of the growth of a formed biofilm was observed only after treatment with Miramistin in the high doses (25-50 μg/ml). Phosprenil in the high doses (15-30 mg/ml) inhibited the forming of biofilms, especially the biofilms of S. pyogenes and L. plantarum (by 3-4.5 times). Treatment of formed biofilms with the agent in doses of 6.0 and 0.6 mg/ml was associated with pronounced stimulation of its growth in S. pyogenes, S. aureus, and L. acidophilus.

  18. Formation of industrial mixed culture biofilm in chlorophenol cultivated medium of microbial fuel cell

    Science.gov (United States)

    Hassan, Huzairy; Jin, Bo; Dai, Sheng; Ngau, Cornelius

    2016-11-01

    The formation of microbial biofilm while maintaining the electricity output is a challenging topic in microbial fuel cell (MFC) studies. This MFC critical factor becomes more significant when handling with industrial wastewater which normally contains refractory and toxic compounds. This study explores the formation of industrial mixed culture biofilm in chlorophenol cultivated medium through observing and characterizing microscopically its establishment on MFC anode surface. The mixed culture was found to develop its biofilm on the anode surface in the chlorophenol environment and established its maturity and dispersal stages with concurrent electricity generation and phenolic degradation. The mixed culture biofilm engaged the electron transfer roles in MFC by generating current density of 1.4 mA/m2 and removing 53 % of 2,4-dichlorophenol. The results support further research especially on hazardous wastewater treatment using a benign and sustainable method.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyungmi; Okabe, Satoshi [Hokkaido Univ., Sapporo (Japan). Dept. of Urban and Environmental Engineering

    2009-07-15

    A mediator-less three-stage two-chamber microbial fuel cell (MFC) system was developed and operated continuously for more than 1.5 years to evaluate continuous power generation while treating artificial wastewater containing glucose (10 mM) concurrently. 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 dissolved organic carbon removal ratio was about 85%, and coulombic efficiency was about 46% in this MFC system. We also analyzed the microbial community structure of anode biofilms in each MFC. Since the environment in each MFC was different due to passing on the products to the next MFC in series, the microbial community structure was different accordingly. The anode biofilm in the first MFC consisted mainly of bacteria belonging to the Gammaproteobacteria, identified as Aeromonas sp., while the Firmicutes dominated the anode biofilms in the second and third MFCs that were mainly fed with acetate. Cyclic voltammetric results supported the presence of a redox compound(s) associated with the anode biofilm matrix, rather than mobile (dissolved) forms, which could be responsible for the electron transfer to the anode. Scanning electron microscopy revealed that the anode biofilms were comprised of morphologically different cells that were firmly attached on the anode surface and interconnected each other with anchor-like filamentous appendages, which might support the results of cyclic voltammetry. (orig.)

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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. - Highlights: ► Zn, Cu and Pb concentrations in biofilm and sediments from 23 streams were assessed. ► Bacteria and ciliate protozoa were simultaneously used as biological indicators. ► Zn and Cu were generally enriched in biofilm compared to sediments. ► Metals in biofilm provide a useful assessment of freshwater ecosystem contamination. ► Results highlight the likely ecological importance of biofilm associated metals. - Metal concentrations in stream biofilms provide a good assessment of the effects of trace metal contaminants on freshwater ecosystems.

  1. Clinical implications of microbial biofilms in chronic rhinosinusitis and orbital cellulitis.

    Science.gov (United States)

    Nayak, Niranjan; Satpathy, Gita; Prasad, Sujata; Thakar, Alok; Chandra, Mahesh; Nag, T C

    2016-09-21

    Discovery of sessile mode of microbial existence (Biofilm state) focussed much interest, during the recent years, on the study of biofilms in many recurring and chronic infections. However, the exact role of microbial biofilms in chronic rhinosinusitis and orbital cellulitis were not elucidated earlier. The purpose of the present study was to look for the adherent property and biofilm producing ability of the clinical isolates in chronic rhinosinusitis and orbital cellulitis, and to look for the effects of antimicrobial agents on these biofilms by colorimetric assay and ultrastructural analysis. Organisms were isolated and identified from various clinical samples in patients with chronic sinusitis and orbital cellulitis. Antimicrobial sensitivity testing was carried out by the standard protocol. Biofilms were developed; quantified and antimicrobial drug perfusion through the biofilm model was evaluated by the earlier devised procedure. Electronmicroscopic study of the biofilm was performed by the recommended technique. Of the total of 70 clinical samples processed, 48 i.e. 68.5 % grew bacteria and 13 i.e.(18.6 %) fungi. Staphylococcus aureus (20), S epidermidis (16) and Pseudomonas aeruginosa (6) accounted for the majority of the bacterial isolates. Aspergillus flavus (8), however was the commonest amongst the fungi. A total of 40 bacteria and 8 fungi could be tested for biofilm production. Eighteen (45 %) of the 40 bacterial isolates and 4(50 %) out of the 8 A flavus isolates were found to be biofilm producers. In vitro adherence testing revealed that majority i.e. 16 (88.8 %) of the 18 biofilm positive bacteria were adherent to artificial surfaces. Antimicrobial drug perfusion through the biofilm model was poor. Antimicrobial treatment was totally ineffective against strong biofilm producers, whose electron microscopic picture was quite similar to that observed for biofilm producers without any antimicrobial pre-treatment. Filamentous fungi, like bacteria

  2. The pulsed light inactivation of veterinary relevant microbial biofilms ...

    African Journals Online (AJOL)

    Results show that both Cryptosporidium and Giardia attach to biofilms in large numbers (100-1000 oo/cysts) in as little as 72 hours. Pulsed light successfully inactivated all test species (Listeria, Salmonella, Bacillus, Escherichia) in planktonic and biofilm form with an increase in inactivation for every increase in UV dose.

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

    Science.gov (United States)

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

    2012-01-01

    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.

  4. [Formation of microbial biofilms in causative agents of acute and chronic pyelonephritis].

    Science.gov (United States)

    Lagun, L V; Atanasova, Iu V; Tapal'skiĭ, D V

    2013-01-01

    Study the intensity of formation of microbial biofilms by Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus strains isolated during various forms of pyelonephritis. 150 clinical isolates of microorganisms isolated from urine ofpatientswith acute and chronic pyelonephritiswere included into the study. Determination of intensity of film-formation was carried out by staining of the formed biofilms by crystal violet with consequent extraction of the dye and measurement of its concentration in washout solution. Among causative agents ofpyelonephritis P. aeruginosa isolates had the maximum film-forming ability. The intensity of biofilm formation of these isolates was 2-3 time higher than staphylococcus and enterobacteria strains. Strains isolated from patients with chronic pyelonephritis by ability to form biofilms significantly surpassed strains isolated from acute pyelonephritis patients. A higher ability to form microbial biofilms for microorganisms--causative agents of pyelonephritis progressing against the background ofurolithiasis was noted. The ability to form biofilms is determined by both causative agent species and character of the infectious process in which this microorganism participates. Intensive formation of biofilms by E. coli, P. aeruginosa, K. pneumoniae, S. aureus clinical isolates may be an important factor of chronization of urinary tract infections.

  5. CoBOP: Microbial Biofilms: A Parameter Altering the Apparent Optical Properties of Sediments, Seagrasses and Surfaces

    Science.gov (United States)

    2002-09-30

    CoBOP: Microbial Biofilms: A Parameter Altering the Apparent Optical Properties of Sediments, Seagrasses and Surfaces Alan W. Decho Department...TITLE AND SUBTITLE CoBOP: Microbial Biofilms: A Parameter Altering the Apparent Optical Properties of Sediments, Seagrasses and Surfaces 5a. CONTRACT...structures produced by bacteria. Their growth appears to depend on biofilm processes and light distributions ( photosynthesis ). Therefore, the data acquired

  6. Pyrosequencing assessment of prokaryotic and eukaryotic diversity in biofilm communities from a French river.

    Science.gov (United States)

    Bricheux, Geneviève; Morin, Loïc; Le Moal, Gwenaël; Coffe, Gérard; Balestrino, Damien; Charbonnel, Nicolas; Bohatier, Jacques; Forestier, Christiane

    2013-06-01

    Despite the recent and significant increase in the study of aquatic microbial communities, little is known about the microbial diversity of complex ecosystems such as running waters. This study investigated the biodiversity of biofilm communities formed in a river with 454 Sequencing™. This river has the particularity of integrating both organic and microbiological pollution, as receiver of agricultural pollution in its upstream catchment area and urban pollution through discharges of the wastewater treatment plant of the town of Billom. Different regions of the small subunit (SSU) ribosomal RNA gene were targeted using nine pairs of primers, either universal or specific for bacteria, eukarya, or archaea. Our aim was to characterize the widest range of rDNA sequences using different sets of polymerase chain reaction (PCR) primers. A first look at reads abundance revealed that a large majority (47-48%) were rare sequences (<5 copies). Prokaryotic phyla represented the species richness, and eukaryotic phyla accounted for a small part. Among the prokaryotic phyla, Proteobacteria (beta and alpha) predominated, followed by Bacteroidetes together with a large number of nonaffiliated bacterial sequences. Bacillariophyta plastids were abundant. The remaining bacterial phyla, Verrucomicrobia and Cyanobacteria, made up the rest of the bulk biodiversity. The most abundant eukaryotic phyla were annelid worms, followed by Diatoms, and Chlorophytes. These latter phyla attest to the abundance of plastids and the importance of photosynthetic activity for the biofilm. These findings highlight the existence and plasticity of multiple trophic levels within these complex biological systems. © 2013 The Authors. Microbiology Open published by John Wiley & Sons Ltd.

  7. Effects of pesticides and pharmaceuticals on biofilms in a highly impacted river

    International Nuclear Information System (INIS)

    Proia, L.; Osorio, V.; Soley, S.; Köck-Schulmeyer, M.; Pérez, S.; Barceló, D.; Romaní, A.M.; Sabater, S.

    2013-01-01

    We investigated the effects of pharmaceuticals and pesticides detected in a Mediterranean river, on fluvial biofilms by translocation experiments performed under controlled conditions. Water was sampled from three sites along a pollution gradient. Biofilms grown in mesocosms containing relatively clean water were translocated to heavily polluted water. Several biofilm descriptors were measured before and after translocations. Fifty-seven pharmaceuticals and sixteen pesticides compounds were detected in river waters. The translocation from less to more polluted site was the most effective. Autotrophic biomass and peptidase increased while phosphatase and photosynthetic efficiency decreased. Multivariate analysis revealed that analgesics and anti-inflammatories significantly affected biofilm responses. Ibuprofen and paracetamol were associated with negative effects on photosynthesis, and with the decrease of the green algae/cyanobacteria ratio, while diclofenac was associated with phosphatase activity. The effects of these emerging compounds on biofilms structure and function may cause important alterations in river ecosystem functioning. -- Highlights: •We investigated the pharmaceuticals and pesticides occurrence in the Llobregat River. •We studied the effects on biofilm communities by translocation experiments. •Both authotrophs and heterotrophs responded when translocated to more polluted sites. •Analgesics and anti-inflammatories significantly affected biofilm responses. •Ibuprofen, Paracetamol and Diclofenac are the most effective compounds. -- Analgesics and anti-inflammatories detected in river water significantly affected responses of biofilm communities when translocated along a pollution gradient

  8. Biofilm removal technique using sands as a research tool for accessing microbial attachment on surface

    Directory of Open Access Journals (Sweden)

    Nathanon Trachoo

    2004-01-01

    Full Text Available Biofilms have profound impacts on improved survival of the constituent microorganisms in nature. Biofilms were believed to protect constituent microorganisms from sanitizer treatment, provide a more suitable habitat for microorganisms, and become a site for genetic material exchanges between microorganisms. As we realize more about the significance of biofilm, methods used for biofilm study should be consistently developed and evaluated. To determine microbial attachment on surfaces, usually biofilms are grown on substratum surfaces and removed by vortexing with glass beads or scraping. However, scraping is not as effective as vortexing with glass beads. Another approach is direct-agar overlaying which cannot be used with high density biofilm. In this experiment, we compared effectiveness of glass beads (298±28 μm in diameter and sands (width: 221±55 μm and length: 329±118 μm in removing biofilm of Pseudomonas aeruginosa by vortexing method. The results suggested that acid-washed sands, which are significantly less inexpensive than glass beads, were as effective as (P>0.05 analytical grade glass beads in Pseudomonas aeruginosa biofilm removal without inhibiting growth of the organism.

  9. Maintenance of Geobacter-dominated biofilms in microbial fuel cells treating synthetic wastewater.

    Science.gov (United States)

    Commault, Audrey S; Lear, Gavin; Weld, Richard J

    2015-12-01

    Geobacter-dominated biofilms can be selected under stringent conditions that limit the growth of competing bacteria. However, in many practical applications, such stringent conditions cannot be maintained and the efficacy and stability of these artificial biofilms may be challenged. In this work, biofilms were selected on low-potential anodes (-0.36 V vs Ag/AgCl, i.e. -0.08 V vs SHE) in minimal acetate or ethanol media. Selection conditions were then relaxed by transferring the biofilms to synthetic wastewater supplemented with soil as a source of competing bacteria. We tracked community succession and functional changes in these biofilms. The Geobacter-dominated biofilms showed stability in their community composition and electrochemical properties, with Geobacter sp. being still electrically active after six weeks in synthetic wastewater with power densities of 100±19 mW·m(-2) (against 74±14 mW·m(-2) at week 0) for all treatments. After six weeks, the ethanol-selected biofilms, despite their high taxon richness and their efficiency at removing the chemical oxygen demand (0.8 g·L(-1) removed against the initial 1.3 g·L(-1) injected), were the least stable in terms of community structure. These findings have important implications for environmental microbial fuel cells based on Geobacter-dominated biofilms and suggest that they could be stable in challenging environments. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Characterization of mixed-culture biofilms established in microbial fuel cells

    International Nuclear Information System (INIS)

    Yang, Suling; Du, Fangzhou; Liu, Hong

    2012-01-01

    For the successful operation of a microbial fuel cell, it is important to characterize the biofilm on the anode. The behavior of MFCs during initial biofilm growth and characterization of anodic biofilm were studied using two-chamber MFCs with activated sludge as inoculum. After three times' replacement of the anodic growth medium, the biofilms were well developed, and a maximum closed circuit potential of 0.41 V and 0.37 V (1000 Ω resistor) was achieved using acetate and glucose, respectively. Electron microscopy revealed that there were rod-shaped cells 0.2–0.3 μm wide by 1.5–2.5 μm long in the anode biofilm in the acetate-fed MFC, and these cells were mainly arranged by monolayer. The biofilm in the glucose-fed MFC was made of cocci-shaped cells in chains and a thick matrix. Both using acetate and glucose, the anodic bacterial communities were different than those of the activated sludge. Cyclic voltammograms suggested that extracellular electron transfer in these MFCs was accomplished mainly by the biofilms on the anode and not by bacteria-produced mediators. -- Highlights: ► The mixed-culture biofilms established in MFCs were characterized. ► The possible electron transfer mechanism was presented. ► In these MFCs the anodic area should be much larger.

  11. Unraveling microbial biofilms of importance for food microbiology.

    Science.gov (United States)

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

    2014-07-01

    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.

  12. Sampling natural biofilms: a new route to build efficient microbial anodes.

    Science.gov (United States)

    Erable, Benjamin; Roncato, Marie-Anne; Achouak, Wafa; Bergel, Alain

    2009-05-01

    Electrochemically active biofilms were constructed on graphite anodes under constant polarization at -0.1V vs saturated calomel reference (SCE) with 10 mM acetate as substrate. The reactors were inoculated with three different microbial samples that were drawn from exactly the same place in a French Atlantic coastal port (i) by scraping the biofilm that had formed naturally on the surface of a floating bridge, (ii) by taking marine sediments just under the floating bridge, and (iii) by taking nearby beach sand. Current densities of 2.0 A/m2 were reached using the biofilm sample as inoculum while only 0.4 A/m2 and 0.8 A/m2 were obtained using the underlying sediments and the beach sand, respectively. The structure of bacterial communities forming biofilms was characterized by denaturing gradient gel electrophoresis (DGGE) analysis, and revealed differences between samples with the increase in relative intensities of some bands and the appearance of others. Bacteria close related to Bacteroidetes, Halomonas, and Marinobacterium were retrieved only from the efficient EA-biofilms formed from natural biofilms, whereas, bacteria close related to Mesoflavibacter were predominant on biofilm formed from sediments. The marine biofilm was selected as the inoculum to further optimize the microbial anode. Epifluorescence microscopy and SEM confirmed that maintaining the electrode under constant polarization promoted rapid settlement of the electrode surface by a bacterial monolayer film. The microbial anode was progressively adapted to the consumption of acetate by three serial additions of substrate, thus improving the Coulombic efficiency of acetate consumption from 31 to 89%. The possible oxidation of sulfide played only a very small part in the current production and the biofilm was not able to oxidize hydrogen. Graphite proved to be more efficient than dimensionally stable anode (DSA) or stainless steel butthis result might be due to differences in the surface roughness

  13. Combating biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong

    2012-01-01

    Biofilms are complex microbial communities consisting of microcolonies embedded in a matrix of self-produced polymer substances. Biofilm cells show much greater resistance to environmental challenges including antimicrobial agents than their free-living counterparts. The biofilm mode of life...... is believed to significantly contribute to successful microbial survival in hostile environments. Conventional treatment, disinfection and cleaning strategies do not proficiently deal with biofilm-related problems, such as persistent infections and contamination of food production facilities. In this review......, strategies to control biofilms are discussed, including those of inhibition of microbial attachment, interference of biofilm structure development and differentiation, killing of biofilm cells and induction of biofilm dispersion....

  14. Origin of phagotrophic eukaryotes as social cheaters in microbial biofilms

    Directory of Open Access Journals (Sweden)

    Jékely Gáspár

    2007-01-01

    Full Text Available Abstract 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

  15. Selective feeding of bdelloid rotifers in river biofilms.

    Directory of Open Access Journals (Sweden)

    Benoit Mialet

    Full Text Available In situ pigment contents of biofilm-dwelling bdelloid rotifers of the Garonne River (France were measured by high performance liquid chromatography (HPLC and compared with pigment composition of surrounding biofilm microphytobenthic communities. Among pigments that were detected in rotifers, the presence of carotenoids fucoxanthin and myxoxanthophyll showed that the rotifers fed on diatoms and cyanobacteria. Unexpectedly, while diatoms strongly dominated microphytobenthic communities in terms of biomass, HPLC results hinted that rotifers selectively ingested benthic filamentous cyanobacteria. In doing so, rotifers could daily remove a substantial fraction (up to 28% of this cyanobacterial biomass. The possibility that the rotifers hosted symbiotic myxoxanthophyll-containing cyanobacteria was examined by localisation of chlorophyll fluorescence within rotifers using confocal laser scanning microscopy (CLSM. CLSM results showed an even distribution of quasi-circular fluorescent objects (FO throughout rotifer bodies, whereas myxoxanthophyll is a biomarker pigment of filamentous cyanobacteria, so the hypothesis was rejected. Our results also suggest that rotifers converted β-carotene (provided by ingested algae into echinenone, a photoprotective pigment. This study, which is the first one to detail in situ pigment contents of rotifers, clearly shows that the role of cyanobacteria as a food source for meiobenthic invertebrates has been underestimated so far, and deserves urgent consideration.

  16. The pulsed light inactivation of veterinary relevant microbial biofilms ...

    African Journals Online (AJOL)

    tulyasys

    2016-01-27

    Jan 27, 2016 ... functioning innate and adaptive immune responses, biofilm-based infections ... of parasite species and bacterial endospores has shown this system to be highly ..... chlorine commonly observed with these complex structures ...

  17. Comparison of the microbial communities of hot springs waters and the microbial biofilms in the acidic geothermal area of Copahue (Neuquén, Argentina).

    Science.gov (United States)

    Urbieta, María Sofía; González-Toril, Elena; Bazán, Ángeles Aguilera; Giaveno, María Alejandra; Donati, Edgardo

    2015-03-01

    Copahue is a natural geothermal field (Neuquén province, Argentina) dominated by the Copahue volcano. As a consequence of the sustained volcanic activity, Copahue presents many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. The occurrence of microbial biofilms was observed on the surrounding rocks and the borders of the ponds, where water movements and thermal activity are less intense. Microbial biofilms are particular ecological niches within geothermal environments; they present different geochemical conditions from that found in the water of the ponds and hot springs which is reflected in different microbial community structure. The aim of this study is to compare microbial community diversity in the water of ponds and hot springs and in microbial biofilms in the Copahue geothermal field, with particular emphasis on Cyanobacteria and other photosynthetic species that have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms.

  18. Nanotechnology-based drug delivery systems for control of microbial biofilms: a review.

    Science.gov (United States)

    Dos Santos Ramos, Matheus Aparecido; Da Silva, Patrícia Bento; Spósito, Larissa; De Toledo, Luciani Gaspar; Bonifácio, Bruna Vidal; Rodero, Camila Fernanda; Dos Santos, Karen Cristina; Chorilli, Marlus; Bauab, Taís Maria

    2018-01-01

    Since the dawn of civilization, it has been understood that pathogenic microorganisms cause infectious conditions in humans, which at times, may prove fatal. Among the different virulent properties of microorganisms is their ability to form biofilms, which has been directly related to the development of chronic infections with increased disease severity. A problem in the elimination of such complex structures (biofilms) is resistance to the drugs that are currently used in clinical practice, and therefore, it becomes imperative to search for new compounds that have anti-biofilm activity. In this context, nanotechnology provides secure platforms for targeted delivery of drugs to treat numerous microbial infections that are caused by biofilms. Among the many applications of such nanotechnology-based drug delivery systems is their ability to enhance the bioactive potential of therapeutic agents. The present study reports the use of important nanoparticles, such as liposomes, microemulsions, cyclodextrins, solid lipid nanoparticles, polymeric nanoparticles, and metallic nanoparticles, in controlling microbial biofilms by targeted drug delivery. Such utilization of these nanosystems has led to a better understanding of their applications and their role in combating biofilms.

  19. Inferring energy sources in constructed wetlands through stable isotope analysis of microbial biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Jurkowski, K.; Ciborowski, J. [Windsor Univ., ON (Canada); Daly, C. [Suncor Energy, Fort McMurray, AB (Canada)

    2010-07-01

    This study presented a novel method of sequestering the microbial biofilm in constructed wetland ecosystems. Artificial substrates were fixed within 8 wetlands differing in age and construction materials over a 2 year period at oil sands lease sites in northeastern Alberta. Autotrophic and heterotrophic biofilm samples were collected from both the subsurface and epibenthic zones of the pipe surfaces of each submerged substrate assembly. A mixing model of d13C, d15N and d34S isotopic signatures was used to assess the contribution of 4 potential nutrient sources of the biofilm. Samples included dominant living and senescent emergent as well as submergent macrophytes, particulate organic matter, dissolved organic carbon, and invertebrates. The samples were collected to compare the biofilm signatures of each wetland in relation to the heterotrophic processes caused by the assimilation of oil sands-derived hydrocarbons and autochthonous detrital pools.

  20. Inferring energy sources in constructed wetlands through stable isotope analysis of microbial biofilms

    International Nuclear Information System (INIS)

    Jurkowski, K.; Ciborowski, J.; Daly, C.

    2010-01-01

    This study presented a novel method of sequestering the microbial biofilm in constructed wetland ecosystems. Artificial substrates were fixed within 8 wetlands differing in age and construction materials over a 2 year period at oil sands lease sites in northeastern Alberta. Autotrophic and heterotrophic biofilm samples were collected from both the subsurface and epibenthic zones of the pipe surfaces of each submerged substrate assembly. A mixing model of d13C, d15N and d34S isotopic signatures was used to assess the contribution of 4 potential nutrient sources of the biofilm. Samples included dominant living and senescent emergent as well as submergent macrophytes, particulate organic matter, dissolved organic carbon, and invertebrates. The samples were collected to compare the biofilm signatures of each wetland in relation to the heterotrophic processes caused by the assimilation of oil sands-derived hydrocarbons and autochthonous detrital pools.

  1. INITIAL MICROBIAL ADHESION IS A DETERMINANT FOR THE STRENGTH OF BIOFILM ADHESION

    NARCIS (Netherlands)

    BUSSCHER, HJ; VANDERMEI, HC; Bos, R.R.M.

    1995-01-01

    This paper presents a hypothesis on the importance of initial microbial adhesion in the overall process of biofilm formation. The hypothesis is based on the realization that dynamic shear conditions exist in many environments, such as in the oral cavity, or on rocks and ship hulls. Recognizing that

  2. Microbial Biofilm Community Variation in Flowing Habitats: Potential Utility as Bioindicators of Postmortem Submersion Intervals

    Directory of Open Access Journals (Sweden)

    Jennifer M. Lang

    2016-01-01

    Full Text Available Biofilms are a ubiquitous formation of microbial communities found on surfaces in aqueous environments. These structures have been investigated as biomonitoring indicators for stream heath, and here were used for the potential use in forensic sciences. Biofilm successional development has been proposed as a method to determine the postmortem submersion interval (PMSI of remains because there are no standard methods for estimating the PMSI and biofilms are ubiquitous in aquatic habitats. We sought to compare the development of epinecrotic (biofilms on Sus scrofa domesticus carcasses and epilithic (biofilms on unglazed ceramic tiles communities in two small streams using bacterial automated ribosomal intergenic spacer analysis. Epinecrotic communities were significantly different from epilithic communities even though environmental factors associated with each stream location also had a significant influence on biofilm structure. All communities at both locations exhibited significant succession suggesting that changing communities throughout time is a general characteristic of stream biofilm communities. The implications resulting from this work are that epinecrotic communities have distinctive shifts at the first and second weeks, and therefore the potential to be used in forensic applications by associating successional changes with submersion time to estimate a PMSI. The influence of environmental factors, however, indicates the lack of a successional pattern with the same organisms and a focus on functional diversity may be more applicable in a forensic context.

  3. Selective degradation of ibuprofen and clofibric acid in two model river biofilm systems.

    Science.gov (United States)

    Winkler, M; Lawrence, J R; Neu, T R

    2001-09-01

    A field survey indicated that the Elbe and Saale Rivers were contaminated with both clofibric acid and ibuprofen. In Elbe River water we could detect the metabolite hydroxy-ibuprofen. Analyses of the city of Saskatoon sewage effluent discharged to the South Saskatchewan river detected clofibric acid but neither ibuprofen nor any metabolite. Laboratory studies indicated that the pharmaceutical ibuprofen was readily degraded in a river biofilm reactor. Two metabolites were detected and identified as hydroxy- and carboxy-ibuprofen. Both metabolites were observed to degrade in the biofilm reactors. However, in human metabolism the metabolite carboxy-ibuprofen appears and degrades second whereas the opposite occurs in biofilm systems. In biofilms the pharmacologically inactive stereoisomere of ibuprofen is degraded predominantly. In contrast, clofibric acid was not biologically degraded during the experimental period of 21 days. Similar results were obtained using biofilms developed using waters from either the South Saskatchewan or Elbe River. In a sterile reactor no losses of ibuprofen were observed. These results suggested that abiotic losses and adsorption played only a minimal role in the fate of the pharmaceuticals in the river biofilm reactors.

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

    Science.gov (United States)

    Høiby, Niels

    2014-04-01

    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, 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. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  5. Influence of microbial biofilms on the preservation of primary soft tissue in fossil and extant archosaurs.

    Directory of Open Access Journals (Sweden)

    Joseph E Peterson

    Full Text Available 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.

  6. Quantum dots conjugated zinc oxide nanosheets: Impeder of microbial growth and biofilm

    Science.gov (United States)

    Patil, Rajendra; Gholap, Haribhau; Warule, Sambhaji; Banpurkar, Arun; Kulkarni, Gauri; Gade, Wasudeo

    2015-01-01

    The grieving problem of the 21st century has been the antimicrobial resistance in pathogenic microorganisms to conventional antibiotics. Therefore, developments of novel antibacterial materials which effectively inhibit or kill such resistant microorganisms have become the need of the hour. In the present study, we communicate the synthesis of quantum dots conjugated zinc oxide nanostructures (ZnO/CdTe) as an impeder of microbial growth and biofilm. The as-synthesized nanostructures were characterized by X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The growth impedance property of ZnO and ZnO/CdTe on Gram positive organism, Bacillus subtilis NCIM 2063 and Gram negative, Escherichia coli NCIM 2931 and biofilm impedance activity in Pseudomonas aeruginosa O1 was found to occur due to photocatalytical action on the cell biofilm surfaces. The impedance in microbial growth and biofilm formation was further supported by ruptured appearances of cells and dettrered biofilm under field emission scanning electron and confocal laser scanning microscope. The ZnO/CdTe nanostructures array synthesized by hydrothermal method has an advantage of low growth temperature, and opportunity to fabricate inexpensive material for nano-biotechnological applications.

  7. Photodynamic therapy versus ultrasonic irrigation: interaction with endodontic microbial biofilm, an ex vivo study.

    Science.gov (United States)

    Muhammad, Omid H; Chevalier, Marlene; Rocca, Jean-Paul; Brulat-Bouchard, Nathalie; Medioni, Etienne

    2014-06-01

    Photodynamic therapy was introduced as an adjuvant to conventional chemo-mechanical debridement during endodontic treatment to overcome the persistence of biofilms. The aim of this study was to evaluate the ability of photodynamic therapy (PDT) to disrupt an experimental microbial biofilm inside the root canal in a clinically applicable working time. Thirty extracted teeth were prepared and then divided in three groups. All samples were infected with an artificially formed biofilm made of Enterococcus faecalis, Streptococcus salivarius, Porphyromonas gingivalis and Prevotella intermedia bacteria. First group was treated with Aseptim Plus® photo-activated (LED) disinfection system, second group by a 650 nm Diode Laser and Toluidine blue as photosensitizer, and the third group, as control group, by ultrasonic irrigation (PUI) using EDTA 17% and NaOCl 2.6% solutions. The working time for all three groups was fixed at 3 min. Presence or absence of biofilm was assessed by aerobic and anaerobic cultures. There was no statistically significant difference between results obtained from groups treated by Aseptim Plus® and Diode Laser (Pirrigation and NaOCl and EDTA solutions had the best results (Pendodontic artificial microbial biofilm and could not inhibit bacterial growth in a clinically favorable working time. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Microbial community composition and dynamics of moving bed biofilm reactor systems treating municipal sewage.

    Science.gov (United States)

    Biswas, Kristi; Turner, Susan J

    2012-02-01

    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.

  9. The microbial community of a biofilm contact reactor for the treatment of winery wastewater.

    Science.gov (United States)

    de Beer, D M; Botes, M; Cloete, T E

    2018-02-01

    To utilize a three-tiered approach to provide insight into the microbial community structure, the spatial distribution and the metabolic capabilities of organisms of a biofilm in the two towers of a high-rate biological contact reactor treating winery wastewater. Next-generation sequencing indicated that bacteria primarily responsible for the removal of carbohydrates, sugars and alcohol were more abundant in tower 1 than tower 2 while nitrifying and denitrifying bacteria were more abundant in tower 2. Yeast populations differed in each tower. Fluorescent in situ hybridization coupled with confocal microscopy showed distribution of organisms confirming an oxygen gradient across the biofilm depth. The Biolog system (ECO plates) specified the different carbon-metabolizing profiles of the two biofilms. The three-tiered approach confirmed that the addition of a second subunit to the bioreactor, expanded the treatment capacity by augmenting the microbial and metabolic diversity of the system, improving the treatment scope of the system. A three-tiered biofilm analysis provided data required to optimize the design of a bioreactor to provide favourable conditions for the development of a microbial consortium, which has optimal waste removal properties for the treatment requirements at hand. © 2017 The Society for Applied Microbiology.

  10. Quantum dots conjugated zinc oxide nanosheets: Impeder of microbial growth and biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Rajendra [Department of Biotechnology, Savitribai Phule Pune University, Pune 411007 (India); Gholap, Haribhau, E-mail: haribhau.gholap@fergusson.edu [Department of Physics, Fergusson College, Pune 411004 (India); Warule, Sambhaji [Department of Physics, Nowrosjee Wadia College, Pune 411001 (India); Banpurkar, Arun; Kulkarni, Gauri [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Gade, Wasudeo, E-mail: wngade@unipune.ac.in [Department of Biotechnology, Savitribai Phule Pune University, Pune 411007 (India)

    2015-01-30

    Graphical abstract: The visible light upon incident on ZnO/CdTe initiate the phenomenon of photocatalytical impedance of biofilm. - Highlights: • Synthesis of efficient light photocatalyst ZnO/CdTe nanostructures by hydrothermal method. • ZnO/CdTe nanostructures show a good antibacterial activity by action on cell membrane. • ZnO/CdTe nanostructures show a good antibiofilm activity, and also act on the cells inside the biofilm. - Abstract: The grieving problem of the 21st century has been the antimicrobial resistance in pathogenic microorganisms to conventional antibiotics. Therefore, developments of novel antibacterial materials which effectively inhibit or kill such resistant microorganisms have become the need of the hour. In the present study, we communicate the synthesis of quantum dots conjugated zinc oxide nanostructures (ZnO/CdTe) as an impeder of microbial growth and biofilm. The as-synthesized nanostructures were characterized by X-ray diffraction, ultraviolet–visible spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The growth impedance property of ZnO and ZnO/CdTe on Gram positive organism, Bacillus subtilis NCIM 2063 and Gram negative, Escherichia coli NCIM 2931 and biofilm impedance activity in Pseudomonas aeruginosa O1 was found to occur due to photocatalytical action on the cell biofilm surfaces. The impedance in microbial growth and biofilm formation was further supported by ruptured appearances of cells and dettrered biofilm under field emission scanning electron and confocal laser scanning microscope. The ZnO/CdTe nanostructures array synthesized by hydrothermal method has an advantage of low growth temperature, and opportunity to fabricate inexpensive material for nano-biotechnological applications.

  11. Quantum dots conjugated zinc oxide nanosheets: Impeder of microbial growth and biofilm

    International Nuclear Information System (INIS)

    Patil, Rajendra; Gholap, Haribhau; Warule, Sambhaji; Banpurkar, Arun; Kulkarni, Gauri; Gade, Wasudeo

    2015-01-01

    Graphical abstract: The visible light upon incident on ZnO/CdTe initiate the phenomenon of photocatalytical impedance of biofilm. - Highlights: • Synthesis of efficient light photocatalyst ZnO/CdTe nanostructures by hydrothermal method. • ZnO/CdTe nanostructures show a good antibacterial activity by action on cell membrane. • ZnO/CdTe nanostructures show a good antibiofilm activity, and also act on the cells inside the biofilm. - Abstract: The grieving problem of the 21st century has been the antimicrobial resistance in pathogenic microorganisms to conventional antibiotics. Therefore, developments of novel antibacterial materials which effectively inhibit or kill such resistant microorganisms have become the need of the hour. In the present study, we communicate the synthesis of quantum dots conjugated zinc oxide nanostructures (ZnO/CdTe) as an impeder of microbial growth and biofilm. The as-synthesized nanostructures were characterized by X-ray diffraction, ultraviolet–visible spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The growth impedance property of ZnO and ZnO/CdTe on Gram positive organism, Bacillus subtilis NCIM 2063 and Gram negative, Escherichia coli NCIM 2931 and biofilm impedance activity in Pseudomonas aeruginosa O1 was found to occur due to photocatalytical action on the cell biofilm surfaces. The impedance in microbial growth and biofilm formation was further supported by ruptured appearances of cells and dettrered biofilm under field emission scanning electron and confocal laser scanning microscope. The ZnO/CdTe nanostructures array synthesized by hydrothermal method has an advantage of low growth temperature, and opportunity to fabricate inexpensive material for nano-biotechnological applications

  12. Influence of an oyster reef on development of the microbial heterotrophic community of an estuarine biofilm.

    Science.gov (United States)

    Nocker, Andreas; Lepo, Joe E; Snyder, Richard A

    2004-11-01

    We characterized microbial biofilm communities developed over two very closely located but distinct benthic habitats in the Pensacola Bay estuary using two complementary cultivation-independent molecular techniques. Biofilms were grown for 7 days on glass slides held in racks 10 to 15 cm over an oyster reef and an adjacent muddy sand bottom. Total biomass and optical densities of dried biofilms showed dramatic differences for oyster reef versus non-oyster reef biofilms. This study assessed whether the observed spatial variation was reflected in the heterotrophic prokaryotic species composition. Genomic biofilm DNA from both locations was isolated and served as a template to amplify 16S rRNA genes with universal eubacterial primers. Fluorescently labeled PCR products were analyzed by terminal restriction fragment length polymorphism, creating a genetic fingerprint of the composition of the microbial communities. Unlabeled PCR products were cloned in order to construct a clone library of 16S rRNA genes. Amplified ribosomal DNA restriction analysis was used to screen and define ribotypes. Partial sequences from unique ribotypes were compared with existing database entries to identify species and to construct phylogenetic trees representative of community structures. A pronounced difference in species richness and evenness was observed at the two sites. The biofilm community structure from the oyster reef setting had greater evenness and species richness than the one from the muddy sand bottom. The vast majority of the bacteria in the oyster reef biofilm were related to members of the gamma- and delta-subdivisions of Proteobacteria, the Cytophaga-Flavobacterium -Bacteroides cluster, and the phyla Planctomyces and Holophaga-Acidobacterium. The same groups were also present in the biofilm harvested at the muddy sand bottom, with the difference that nearly half of the community consisted of representatives of the Planctomyces phylum. Total species richness was estimated

  13. A meta-proteomics approach to study the interspecies interactions affecting microbial biofilm development in a model community

    DEFF Research Database (Denmark)

    Herschend, Jakob; Damholt, Zacharias Brimnes Visby; Marquard, Andrea Marion

    2017-01-01

    Microbial biofilms are omnipresent in nature and relevant to a broad spectrum of industries ranging from bioremediation and food production to biomedical applications. To date little is understood about how multi-species biofilm communities develop and function on a molecular level, due...... of fermentation and nitrogen pathways in Paenibacillus amylolyticus and Xanthomonas retroflexus may, however, indicate that competition for limited resources also affects community development. Overall our results demonstrate the multitude of pathways involved in biofilm formation in mixed communities....

  14. Detection of microbial biofilms on food processing surfaces: hyperspectral fluorescence imaging study

    Science.gov (United States)

    Jun, Won; Kim, Moon S.; Chao, Kaunglin; Lefcourt, Alan M.; Roberts, Michael S.; McNaughton, James L.

    2009-05-01

    We used a portable hyperspectral fluorescence imaging system to evaluate biofilm formations on four types of food processing surface materials including stainless steel, polypropylene used for cutting boards, and household counter top materials such as formica and granite. The objective of this investigation was to determine a minimal number of spectral bands suitable to differentiate microbial biofilm formation from the four background materials typically used during food processing. Ultimately, the resultant spectral information will be used in development of handheld portable imaging devices that can be used as visual aid tools for sanitation and safety inspection (microbial contamination) of the food processing surfaces. Pathogenic E. coli O157:H7 and Salmonella cells were grown in low strength M9 minimal medium on various surfaces at 22 +/- 2 °C for 2 days for biofilm formation. Biofilm autofluorescence under UV excitation (320 to 400 nm) obtained by hyperspectral fluorescence imaging system showed broad emissions in the blue-green regions of the spectrum with emission maxima at approximately 480 nm for both E. coli O157:H7 and Salmonella biofilms. Fluorescence images at 480 nm revealed that for background materials with near-uniform fluorescence responses such as stainless steel and formica cutting board, regardless of the background intensity, biofilm formation can be distinguished. This suggested that a broad spectral band in the blue-green regions can be used for handheld imaging devices for sanitation inspection of stainless, cutting board, and formica surfaces. The non-uniform fluorescence responses of granite make distinctions between biofilm and background difficult. To further investigate potential detection of the biofilm formations on granite surfaces with multispectral approaches, principal component analysis (PCA) was performed using the hyperspectral fluorescence image data. The resultant PCA score images revealed distinct contrast between

  15. Characteristics of microbial community involved in early biofilms formation under the influence of wastewater treatment plant effluent.

    Science.gov (United States)

    Peng, Yuke; Li, Jie; Lu, Junling; Xiao, Lin; Yang, Liuyan

    2018-04-01

    Effluents from wastewater treatment plants (WWTPs) containing microorganisms and residual nutrients can influence the biofilm formation. Although the process and mechanism of bacterial biofilm formation have been well characterized, little is known about the characteristics and interaction of bacteria, archaea and eukaryotes in the early colonization, especially under the influence of WWTP effluent. The aim of this study was to characterize the important bacterial, archaeal and eukaryotic species in the early stage of biofilm formation downstream of the WWTP outlet. Water and biofilm samples were collected 24 and 48hr after the deposition of bio-cords in the stream. Illumina Miseq sequencing of the 16S and 18S rDNA showed that, among the three domains, the bacterial biofilm community had the largest alpha and beta diversity. The early bacterial colonizers appeared to be "biofilm-specific", with only a few dominant operational taxonomic units (OTUs) shared between the biofilm and the ambient water environment. Alpha-proteobacteria and Ciliophora tended to dominate the bacterial and eukaryotic communities, respectively, of the early biofilm already at 24hr, whereas archaea played only a minor role during the early stage of colonization. The network analysis showed that the three domains of microbial community connected highly during the early colonization and it might be a characteristic of the microbial communities in the biofilm formation process where co-occurrence relationships could drive coexistence and diversity maintenance within the microbial communities. Copyright © 2017. Published by Elsevier B.V.

  16. Dynamics of development and dispersal in sessile microbial communities: examples from Pseudomonas aeruginosa and Pseudomonas putida model biofilms

    DEFF Research Database (Denmark)

    Klausen, M.; Gjermansen, Morten; Kreft, J.-U.

    2006-01-01

    Surface-associated microbial communities in many cases display dynamic developmental patterns. Model biofilms formed by Pseudomonas aeruginosa and Pseudomonas putida in laboratory flow-chamber setups represent examples of such behaviour. Dependent on the experimental conditions the bacteria...

  17. Molecular Techniques Revealed Highly Diverse Microbial Communities in Natural Marine Biofilms on Polystyrene Dishes for Invertebrate Larval Settlement

    KAUST Repository

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

    2014-01-01

    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

  18. Biofilms.

    Science.gov (United States)

    López, Daniel; Vlamakis, Hera; Kolter, Roberto

    2010-07-01

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

  19. Biofilms

    OpenAIRE

    López, Daniel; Vlamakis, Hera; Kolter, Roberto

    2010-01-01

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

  20. Characterization of microbial degradation of oxytetracycline in river ...

    African Journals Online (AJOL)

    Characterization of microbial degradation of oxytetracycline in river water and sediment using reversed phase high performance liquid chromatography. ... African Journal of Biotechnology ... The present results have shown that microbial degradation plays a major role in the removal of OTC in natural environments.

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

    Science.gov (United States)

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

    2012-03-01

    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. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2014-06-24

    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.

  3. Molecular Techniques Revealed Highly Diverse Microbial Communities in Natural Marine Biofilms on Polystyrene Dishes for Invertebrate Larval Settlement

    KAUST Repository

    Lee, On On

    2014-01-09

    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. © 2014 Springer Science+Business Media New York.

  4. Nanocoatings for Chronic Wound Repair—Modulation of Microbial Colonization and Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Mara Mădălina Mihai

    2018-04-01

    Full Text Available Wound healing involves a complex interaction between immunity and other natural host processes, and to succeed it requires a well-defined cascade of events. Chronic wound infections can be mono- or polymicrobial but their major characteristic is their ability to develop a biofilm. A biofilm reduces the effectiveness of treatment and increases resistance. A biofilm is an ecosystem on its own, enabling the bacteria and the host to establish different social interactions, such as competition or cooperation. With an increasing incidence of chronic wounds and, implicitly, of chronic biofilm infections, there is a need for alternative therapeutic agents. Nanotechnology shows promising openings, either by the intrinsic antimicrobial properties of nanoparticles or their function as drug carriers. Nanoparticles and nanostructured coatings can be active at low concentrations toward a large variety of infectious agents; thus, they are unlikely to elicit emergence of resistance. Nanoparticles might contribute to the modulation of microbial colonization and biofilm formation in wounds. This comprehensive review comprises the pathogenesis of chronic wounds, the role of chronic wound colonization and infection in the healing process, the conventional and alternative topical therapeutic approaches designed to combat infection and stimulate healing, as well as revolutionizing therapies such as nanotechnology-based wound healing approaches.

  5. The nanostructure of microbially-reduced graphene oxide fosters thick and highly-performing electrochemically-active biofilms

    Science.gov (United States)

    Virdis, Bernardino; Dennis, Paul G.

    2017-07-01

    Biofilms of electrochemically-active organisms are used in microbial electrochemical technologies (METs) to catalyze bioreactions otherwise not possible at bare electrodes. At present, however, achievable current outputs are still below levels considered sufficient for economic viability of large-scale METs implementations. Here, we report three-dimensional, self-aggregating biofilm composites comprising of microbial cells embedded with microbially-reduced graphene oxide (rGO) nanoparticles to form a thick macro-porous network with superior electrochemical properties. In the presence of metabolic substrate, these hybrid biofilms are capable of producing up to five times more catalytic current than the control biofilms. Cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy, show that in spite of the increased thickness, the biofilms amended with GO display lower polarization/charge transfer resistance compared to the controls, which we ascribe to the incorporation of rGO into the biofilms, which (1) promotes fast electron transfer, yet conserving a macroporous structure that allows free diffusion of reactants and products, and (2) enhances the interfacial dynamics by allowing a higher load of microbial cells per electrode surface area. These results suggest an easy-to-apply and cost-effective method to produce high-performing electrochemically-active biofilms in situ.

  6. A meta-proteomics approach to study the interspecies interactions affecting microbial biofilm development in a model community

    DEFF Research Database (Denmark)

    Herschend, Jakob; Damholt, Zacharias Brimnes Visby; Marquard, Andrea Marion

    2017-01-01

    Microbial biofilms are omnipresent in nature and relevant to a broad spectrum of industries ranging from bioremediation and food production to biomedical applications. To date little is understood about how multi-species biofilm communities develop and function on a molecular level, due to the co......Microbial biofilms are omnipresent in nature and relevant to a broad spectrum of industries ranging from bioremediation and food production to biomedical applications. To date little is understood about how multi-species biofilm communities develop and function on a molecular level, due...... to the complexity of these biological systems. Here we apply a meta-proteomics approach to investigate the mechanisms influencing biofilm formation in a model consortium of four bacterial soil isolates; Stenotrophomonas rhizophila, Xanthomonas retroflexus, Microbacterium oxydans and Paenibacillus amylolyticus...

  7. Polluted Alamuyo River: Impacts on surrounding wells, microbial ...

    African Journals Online (AJOL)

    The physicochemical analysis and microbial load of polluted Alamuyo River in Ibadan, Nigeria and selected wells along its course were evaluated. Toxic effects of water samples obtained from upstream (A) and down stream (F) of the river were also evaluated using Allium cepa root assay. The result of the analysis revealed ...

  8. The ecology and biogeochemistry of stream biofilms.

    Science.gov (United States)

    Battin, Tom J; Besemer, Katharina; Bengtsson, Mia M; Romani, Anna M; Packmann, Aaron I

    2016-04-01

    Streams and rivers form dense networks, shape the Earth's surface and, in their sediments, provide an immensely large surface area for microbial growth. Biofilms dominate microbial life in streams and rivers, drive crucial ecosystem processes and contribute substantially to global biogeochemical fluxes. In turn, water flow and related deliveries of nutrients and organic matter to biofilms constitute major constraints on microbial life. In this Review, we describe the ecology and biogeochemistry of stream biofilms and highlight the influence of physical and ecological processes on their structure and function. Recent advances in the study of biofilm ecology may pave the way towards a mechanistic understanding of the effects of climate and environmental change on stream biofilms and the biogeochemistry of stream ecosystems.

  9. Adaptation of copper community tolerance levels after biofilm transplantation in an urban river.

    Science.gov (United States)

    Fechner, Lise C; Versace, François; Gourlay-Francé, Catherine; Tusseau-Vuillemin, Marie-Hélène

    2012-01-15

    The Water Framework Directive requires the development of biological tools which can act as early-warning indicators of a sudden increase (accidental pollution) or decrease (recovery due to prevention) of the chemical status of aquatic systems. River biofilms, which respond quickly to modifications of environmental parameters and also play a key part in the functioning of aquatic ecosystems, are therefore good candidates to monitor an increase or a decrease of water pollution. In the present study, we investigated the biological response of biofilms transplanted either upstream (recovery) or downstream (deterioration of exposure levels) the urban area of Paris (France). Both modifications of Cu community tolerance levels and of global bacterial and eukaryotic community structure using automated ribosomal intergenic spacer analysis (ARISA) fingerprints were examined 15 and 30 days after the transplantation. Cu tolerance levels of the heterotrophic component of biofilms were assessed using a short-term toxicity test based on β-glucosidase (heterotrophic) activity. Cu tolerance increased for biofilms transplanted upstream to downstream Paris (5-fold increase on day 30) and conversely decreased for biofilms transplanted downstream to upstream (8-fold decrease on day 30). ARISA fingerprints revealed that bacterial and eukaryotic community structures of transplanted biofilms were closer to the structures of biofilms from the transplantation sites (or sites with similar contamination levels) than to biofilms from their sites of origin. Statistical analysis of the data confirmed that the key factor explaining biofilm Cu tolerance levels is the sampling site and not the site of origin. It also showed that Cu tolerance levels are related to the global urban contamination (both metals and nutrients). The study shows that biofilms adapt fast to modifications of their surroundings. In particular, community tolerance varies quickly and reflects the new exposure levels only 15

  10. Chemical and biological characterisation of biofilms formed on different substrata in Tisza river (Hungary)

    International Nuclear Information System (INIS)

    Kroepfl, Krisztina; Vladar, Peter; Szabo, Katalin; Acs, Eva; Borsodi, Andrea K.; Szikora, Szilvia; Caroli, Sergio; Zaray, Gyula

    2006-01-01

    Natural biofilms were simultaneously grown on granite, polished granite, andesite, polycarbonate and Plexi-glass substrata for six weeks in the Tisza River. Biofilm production and abundance of algae were influenced by the substratum. Magnitude of the substratum effect was andesite < polished granite < Plexi-glass < granite < polycarbonate. The benthic diatom community on polycarbonate had a high population of Achnantes helvetica. Bacterial activity was similar among substrates for 95 different carbon sources. The concentrations of essential elements and heavy metal pollutants (Zn, Ni, Pb and Cu) were highest in biofilms on polished granite or granite. On basis of algological, bacteriological and chemical investigations, as well as literature data, the Plexi-glass substratum is recommended for biomonitoring of river benthic microbiota. - The Plexi-glass substrate is recommended for monitoring river benthic microbiota

  11. Chemical and biological characterisation of biofilms formed on different substrata in Tisza river (Hungary)

    Energy Technology Data Exchange (ETDEWEB)

    Kroepfl, Krisztina [Research Group of Environmental Chemistry, Hungarian Academy of Sciences, H-1518, Budapest, P.O. Box 32 (Hungary); Vladar, Peter [Research Group of Environmental Chemistry, Hungarian Academy of Sciences, H-1518, Budapest, P.O. Box 32 (Hungary); Szabo, Katalin [Department of Microbiology, Eoetvoes University, H-1518, Budapest, P.O. Box 32 (Hungary); Acs, Eva [Danube Research Station of Hungarian Academy of Sciences, H-2131 Goed (Hungary); Borsodi, Andrea K. [Department of Microbiology, Eoetvoes University, H-1518, Budapest, P.O. Box 32 (Hungary); Szikora, Szilvia [Department of Inorganic and Analytical Chemistry, Eoetvoes University, H-1518, Budapest, P.O. Box 32 (Hungary); Caroli, Sergio [Istituto Superiore di Sanita, 00161 Roma, Viale Regina Elena, 299 (Italy); Zaray, Gyula [Research Group of Environmental Chemistry, Hungarian Academy of Sciences, H-1518, Budapest, P.O. Box 32 (Hungary) and Department of Inorganic and Analytical Chemistry, Eoetvoes University, H-1518, Budapest, P.O. Box 32 (Hungary)]. E-mail: zaray@ludens.elte.hu

    2006-11-15

    Natural biofilms were simultaneously grown on granite, polished granite, andesite, polycarbonate and Plexi-glass substrata for six weeks in the Tisza River. Biofilm production and abundance of algae were influenced by the substratum. Magnitude of the substratum effect was andesite < polished granite < Plexi-glass < granite < polycarbonate. The benthic diatom community on polycarbonate had a high population of Achnantes helvetica. Bacterial activity was similar among substrates for 95 different carbon sources. The concentrations of essential elements and heavy metal pollutants (Zn, Ni, Pb and Cu) were highest in biofilms on polished granite or granite. On basis of algological, bacteriological and chemical investigations, as well as literature data, the Plexi-glass substratum is recommended for biomonitoring of river benthic microbiota. - The Plexi-glass substrate is recommended for monitoring river benthic microbiota.

  12. Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

    Science.gov (United States)

    Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

    2011-01-01

    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. 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. 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

  13. Should the biofilm mode of life be taken into consideration for microbial biocontrol agents?

    Science.gov (United States)

    Pandin, Caroline; Le Coq, Dominique; Canette, Alexis; Aymerich, Stéphane; Briandet, Romain

    2017-07-01

    Almost one-third of crop yields are lost every year due to microbial alterations and diseases. The main control strategy to limit these losses is the use of an array of chemicals active against spoilage and unwanted pathogenic microorganisms. Their massive use has led to extensive environmental pollution, human poisoning and a variety of diseases. An emerging alternative to this chemical approach is the use of microbial biocontrol agents. Biopesticides have been used with success in several fields, but a better understanding of their mode of action is necessary to better control their activity and increase their use. Very few studies have considered that biofilms are the preferred mode of life of microorganisms in the target agricultural biotopes. Increasing evidence shows that the spatial organization of microbial communities on crop surfaces may drive important bioprotection mechanisms. The aim of this review is to summarize the evidence of biofilm formation by biocontrol agents on crops and discuss how this surface-associated mode of life may influence their biology and interactions with other microorganisms and the host and, finally, their overall beneficial activity. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  14. Cambrian rivers and floodplains: the significance of microbial cementation, groundwater and aeolian sediment transport

    Science.gov (United States)

    Reesink, A. J. H.; Best, J.; Freiburg, J. T.; Nathan, W.

    2016-12-01

    Rivers that existed before land plants colonized the Earth are commonly considered to be unaffected by microbial activity on their floodplains, because the limited cementation produced by microbial activity is insufficient to stabilize the river banks. Although this assumption is likely correct, such emphasis on channel dynamics ignores the potential role of floodplain dynamics as an integral component of the river system. Detailed analysis of cores from the Cambrian Mount Simon Sandstone, Illinois, suggests that a significant proportion of the terrestrial sequence is composed of flat-bedded `crinkly' structures that provide evidence of cementation by soil crusts and microbial biofilms, and that promoted the adhesion of sediment to sticky surfaces. Wind ripples and local desert pavements were abundant. These findings highlight that sediment deposition on Cambrian floodplains was often dominated by wind in locations where the ground water table reached the surface, and was thus likely independent of sediment transport within the river channel. Erosion by wind would thus have been hindered by surface cementation and the formation of desert pavements. Such ground water control on deposition, and resistance to erosion by floodplain surface hardening, appear to have been the primary controls on Cambrian floodplain topography. Because floodplain topography poses a key control on channel and floodplain flow, these processes may have affected patterns of erosion and deposition, as well as reach-scale dynamics such as channel avulsions. The autonomous operation of wind-and-groundwater controlled floodplains makes pre-vegetated river systems more sensitive to climatic conditions such as precipitation and evaporation, and strikingly different from those that occurred after the development of land plants.

  15. Arsenic Transfer from As-Rich Sediments to River Water in the Presence of Biofilms

    Directory of Open Access Journals (Sweden)

    Diego Martiñá Prieto

    2016-01-01

    Full Text Available The influence of epipsammic biofilms on As release from river sediments was evaluated in a microcosm experiment where biofilms were grown on sediments containing 106 mg kg−1 As, collected in the Anllóns River, and compared with control systems without biofilms. The As transfer to the water column was low (<0.11% of total As in the sediment and was further reduced by 64% in the presence of biofilms. AsV was the predominant species in the overlying water in both systems. AsIII concentration was higher (up to 12% of total dissolved As in the control systems than in the systems with biofilms, where this species was almost absent. This fact is of toxicological relevance due to the usually higher mobility and toxicity of the reduced AsIII species. Control systems exhibited higher As mobility in water, in sulphate solution, and in weak acid medium and higher bioavailability in diffusive gradient in thin films (DGT devices. Arsenic retained by the biofilm was equally distributed between extracellular and intracellular compartments. Inside the cells, significant concentrations of AsIII, monomethylarsonic acid (MMAV, and dimethylarsinic acid (DMAV were detected, suggesting that active methylation (detoxification processes are occurring in the intracellular compartment.

  16. Syntrophic microbial communities on straw as biofilm carrier increase the methane yield of a biowaste-digesting biogas reactor

    Directory of Open Access Journals (Sweden)

    Frank R. Bengelsdorf

    2015-08-01

    Full Text Available Biogas from biowaste can be an important source of renewable energy, but the fermentation process of low-structure waste is often unstable. The present study uses a full-scale biogas reactor to test the hypothesis that straw as an additional biofilm carrier will increase methane yield; and this effect is mirrored in a specific microbial community attached to the straw. Better reactor performance after addition of straw, at simultaneously higher organic loading rate and specific methane yield confirmed the hypothesis. The microbial communities on straw as a biofilm carrier and of the liquid reactor content were investigated using 16S rDNA amplicon sequencing by means of 454 pyrosequencing technology. The results revealed high diversity of the bacterial communities in the liquid reactor content as well as the biofilms on the straw. The most abundant archaea in all samples belonged to the genera Methanoculleus and Methanosarcina. Addition of straw resulted in a significantly different microbial community attached to the biofilm carrier. The bacterium Candidatus Cloacamonas acidaminovorans and methanogenic archaea of the genus Methanoculleus dominated the biofilm on straw. Syntrophic interactions between the hydrogenotrophic Methanoculleus sp. and members of the hydrogen-producing bacterial community within biofilms may explain the improved methane yield. Thus, straw addition can be used to improve and to stabilize the anaerobic process in substrates lacking biofilm-supporting structures.

  17. Effect of UV on De-NOx performance and microbial community of a hybrid catalytic membrane biofilm reactor

    Science.gov (United States)

    Chen, Zhouyang; Huang, Zhensha; He, Yiming; Xiao, Xiaoliang; Wei, Zaishan

    2018-02-01

    The hybrid membrane catalytic biofilm reactor provides a new way of flue gas denitration. However, the effects of UV on denitrification performance, microbial community and microbial nitrogen metabolism are still unknown. In this study, the effects of UV on deNO x performance, nitrification and denitrification, microbial community and microbial nitrogen metabolism of a bench scale N-TiO2/PSF hybrid catalytic membrane biofilm reactor (HCMBR) were evaluated. The change from nature light to UV in the HCMBR leads to the fall of NO removal efficiency of HCMBR from 92.8% to 81.8%. UV affected the microbial community structure, but did not change microbial nitrogen metabolism, as shown by metagenomics sequencing method. Some dominant phyla, such as Gammaproteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, and Alphaproteobacteria, increased in abundance, whereas others, such as Proteobacteria and Betaproteobacteria, decreased. There were nitrification, denitrification, nitrogen fixation, and organic nitrogen metabolism in the HCMBR.

  18. Large-scale environmental controls on microbial biofilms in high-alpine streams

    Directory of Open Access Journals (Sweden)

    T. J. Battin

    2004-01-01

    Full Text Available Glaciers are highly responsive to global warming and important agents of landscape heterogeneity. While it is well established that glacial ablation and snowmelt regulate stream discharge, linkage among streams and streamwater geochemistry, the controls of these factors on stream microbial biofilms remain insufficiently understood. We investigated glacial (metakryal, hypokryal, groundwater-fed (krenal and snow-fed (rhithral streams - all of them representative for alpine stream networks - and present evidence that these hydrologic and hydrogeochemical factors differentially affect sediment microbial biofilms. Average microbial biomass and bacterial carbon production were low in the glacial streams, whereas bacterial cell size, biomass, and carbon production were higher in the tributaries, most notably in the krenal stream. Whole-cell in situ fluorescence hybridization revealed reduced detection rates of the Eubacteria and higher abundance of α-Proteobacteria in the glacial stream, a pattern that most probably reflects the trophic status of this ecosystem. Our data suggest low flow during the onset of snowmelt and autumn as a short period (hot moment of favorable environmental conditions with pulsed inputs of allochthonous nitrate and dissolved organic carbon, and with disproportionately high microbial growth. Tributaries are relatively more constant and favorable environments than kryal streams, and serve as possible sources of microbes and organic matter to the main glacial channel during periods (e.g., snowmelt of elevated hydrologic linkage among streams. Ice and snow dynamics - and their impact on the amount and composition of dissolved organic matter - have a crucial impact on stream biofilms, and we thus need to consider microbes and critical hydrological episodes in future models of alpine stream communities.

  19. Microbial biofilms control economic metal mobility in an acid-sulfate hydrothermal system

    Science.gov (United States)

    Phillips-Lander, C. M.; Roberts, J. A.; Hernandez, W.; Mora, M.; Fowle, D. A.

    2012-12-01

    Trace metal cycling in hydrothermal systems has been the subject of a variety of geochemical and economical geology studies. Typically in these settings these elements are sequestered in sulfide and oxide mineral fractions, however in near-surface low-temperature environments organic matter and microorganisms (typically in mats) have been implicated in their mobility through sorption. Here we specifically examine the role of microbial biofilms on metal partitioning in an acid-sulfate hydrothermal system. We studied the influence of microorganisms and microbial biofilms on trace metal adsorption in Pailas de Aguas I, an acid-sulfate hot spring on the southwest flank of Rincon de la Vieja, a composite stratovolcano in the Guanacaste Province, Costa Rica. Spring waters contain high suspended loads, and are characterized by high T (79.6-89.3oC), low pH (2.6-4), and high ionic strengths (I= 0.5-0.8). Waters contain high concentrations of the biogeochemically active elements Fe (4-6 mmol/l) and SO42- (38 mmol/l), but PO43- are below detection limits (bdl). Silver, Ni, and Mo concentrations are bdl; however other trace metals are present in solution in concentrations of 0.1-0.2 mg/l Cd, 0.2-0.4 mg/l Cr and V, 0.04-1 mg/l Cu,. Preliminary 16S rRNA analyses of microorganisms in sediments reveal several species of algae, including Galderia sp., Cyanidium sp, γ-proteobacteria, Acidithiobacillus caldus, Euryarcheota, and methanogens. To evaluate microbial biofilms' impact on trace metal mobility we analyzed a combination of suspended, bulk and biofilm associated sediment samples via X-ray diffraction (XRD) and trace element sequential extractions (SE). XRD analysis indicated all samples were primarily composed of Fe/Al clay minerals (nontronite, kaolinite), 2- and 6-line ferrihydrite, goethite, and hematite, quartz, and opal-α. SE showed the highest concentrations of Cu, Mo, and V were found in the suspended load. Molybdenum was found primarily in the residual and organic

  20. Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes

    OpenAIRE

    Dumas, Claire; Basséguy, Régine; Bergel, Alain

    2008-01-01

    Stainless steel and graphite electrodes were individually addressed and polarized at−0.60V vs. Ag/AgCl in reactors filled with a growth medium that contained 25mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75Am−2 for graphite and 20.5Am−2 for stainless steel. Cyclic voltamm...

  1. Biofilms as bio-indicator for polluted waters? Total reflection X-ray fluorescence analysis of biofilms of the Tisza river (Hungary)

    Energy Technology Data Exchange (ETDEWEB)

    Mages, Margarete; Ovari, Mihaly; Tuempling, Wolf v. [Department of Inland Water Research Magdeburg, UFZ Centre for Environmental Research Leipzig-Halle, Brueckstrasse 3a, 39114, Magdeburg (Germany); Kroepfl, Krisztina [Department of Chemical Technology and Environmental Chemistry, Eoetvoes University, Pazmany Peter setany 1/A, 1117, Budapest (Hungary)

    2004-02-01

    The aim of this work was to investigate the heavy metal accumulation by natural biofilms living in the catchment area of the Tisza river in Hungary, as well as in biofilms cultivated in vitro. Laboratory tests have demonstrated that metals can be adsorbed on biofilms, depending on their concentration and on the availability of free sorptive places. Biofilms were cultivated in vitro in natural freshwater from the Saale river, Germany. After reaching the plateau phase, Cu was added to reach a concentration of 100 {mu}g/L. An increase of its mass fraction in the biofilm was observed, which caused the decrease of the concentration in the water phase. Unfortunately, the reactor wall was also found to act as adsorbent for Cu. More detailed results of our in vitro experiments will be published in a forthcoming paper. Naturally grown biofilm samples from exposed as well as background places at the Hungarian rivers Szamos and Tisza were collected in 2000 and 2002 after the cyanide spill, and analysed using total reflection X-ray fluorescence analysis (TXRF). Metal mass fraction differences as high as two orders of magnitude were found between polluted and unpolluted (background) sampling points. Extremely high concentration values, e.g. 5600 {mu}g/g Zn in biofilm, were found at highly polluted sampling points. This means an enrichment factor of ca. 10,000 compared to the water phase. (orig.)

  2. Modeling how soluble microbial products (SMP) support heterotrophic bacteria in autotroph-based biofilms

    DEFF Research Database (Denmark)

    Merkey, Brian; Rittmann, Bruce E.; Chopp, David L.

    2009-01-01

    . In this paper, we develop and use a mathematical model to describe a model biofilm system that includes autotrophic and heterotrophic bacteria and the key products produced by the bacteria. The model combines the methods of earlier multi-species models with a multi-component biofilm model in order to explore...... the interaction between species via exchange of soluble microbial products (SMP). We show that multiple parameter sets are able to describe the findings of experimental studies, and that heterotrophs growing on autotrophically produced SMP may pursue either r- or K-strategies to sustain themselves when SMP...... is their only substrate. We also show that heterotrophs can colonize some distance from the autotrophs and still be sustained by autotrophically produced SMP. This work defines the feasible range of parameters for utilization of SMP by heterotrophs and the nature of the interactions between autotrophs...

  3. Development of mixed microbial granular biofilms for denitrification of concentrated wastes

    International Nuclear Information System (INIS)

    Krishna Mohan, T.V.; Nancharaiah, Y.V.; Venugopalan, V.P.; Narasimhan, S.V.; Satyasai, P.M.

    2010-01-01

    Nitrate containing wastes are generated at various stages of the nuclear fuel cycle; fuel fabrication and reprocessing. A treatment process for removing nitrate from such concentrated nitrate bearing effluents is needed. Among other available options, biological denitrification is an economical and technically feasible method for nitrate removal. Granular biofilm based sequencing batch reactors (SBRs) may allow designing a compact and high rate processes suitable for the treatment of concentrated effluents. Hence, experiments were carried out in laboratory scale sequencing batch reactors (SBRs) to develop granular biofilms (composed of mixed microbes) for removing nitrate from the concentrated nitrate containing-media. Microbial granular biofilms, capable of consuming nitrate up to 2710 mg/l nitrate-N, were developed under anaerobic conditions in a 6-litre volume sequencing batch reactor (SBR). The SBR was inoculated with activated sludge flocs and operated with 24-h cycle and 50% volumetric exchange ratio. Synthetic media containing acetate as the energy source and electron donor, at carbon to nitrogen molar ratio of 2:1 and 3:1 was fed into the SBRs. Nitrate-N concentration in the SBR was increased in a step-wise manner starting from 677 to 2710 mg/l (1355 to 5420 mg/l in the feed). Complete removal of influent nitrate occurred within the first few hours of SBR cycle period. Effluent nitrate and nitrite levels (∼3 mg/l nitrate-N or nitrite-N) at the end of SBR cycle period (24 h) were found to be below the discharge limits. Under these conditions biomass predominantly consisted of granular biofilms. Results show the potential of granular biofilm based SBR for converting nitrate to nitrogen gas from concentrated nitrate bearing industrial effluents. (author)

  4. Warming-induced changes in denitrifier community structure modulate the ability of phototrophic river biofilms to denitrify

    Energy Technology Data Exchange (ETDEWEB)

    Boulêtreau, Stéphanie, E-mail: stephanie.bouletreau@univ-tlse3.fr [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Lyautey, Emilie [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Dubois, Sophie [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France); Compin, Arthur [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Delattre, Cécile; Touron-Bodilis, Aurélie [EDF Recherche et Développement, LNHE (Laboratoire National d' Hydraulique et Environnement), 6 quai Watier, F-78401 Chatou (France); Mastrorillo, Sylvain [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Garabetian, Frédéric [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France)

    2014-01-01

    Microbial denitrification is the main nitrogen removing process in freshwater ecosystems. The aim of this study was to show whether and how water warming (+ 2.5 °C) drives bacterial diversity and structuring and how bacterial diversity affects denitrification enzymatic activity in phototrophic river biofilms (PRB). We used water warming associated to the immediate thermal release of a nuclear power plant cooling circuit to produce natural PRB assemblages on glass slides while testing 2 temperatures (mean temperature of 17 °C versus 19.5 °C). PRB were sampled at 2 sampling times during PRB accretion (6 and 21 days) in both temperatures. Bacterial community composition was assessed using ARISA. Denitrifier community abundance and denitrification gene mRNA levels were estimated by q-PCR and qRT-PCR, respectively, of 5 genes encoding catalytic subunits of the denitrification key enzymes. Denitrification enzyme activity (DEA) was measured by the acetylene-block assay at 20 °C. A mean water warming of 2.5 °C was sufficient to produce contrasted total bacterial and denitrifier communities and, therefore, to affect DEA. Indirect temperature effect on DEA may have varied between sampling time, increasing by up to 10 the denitrification rate of 6-day-old PRB and decreasing by up to 5 the denitrification rate of 21-day-old PRB. The present results suggest that indirect effects of warming through changes in bacterial community composition, coupled to the strong direct effect of temperature on DEA already demonstrated in PRB, could modulate dissolved nitrogen removal by denitrification in rivers and streams. - Highlights: •We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5 °C. •We compared their denitrifiers' structuring and functioning in 6d- and 21d-old biofilms. •A difference of 2.5 °C produced contrasted denitrifier communities. •The indirect temperature effect on denitrification activity shifted between biofilm age.

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

    Directory of Open Access Journals (Sweden)

    Hotta Yasuaki

    2008-01-01

    Full Text Available Abstract 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 were enriched by subculturing biofilms that attached onto anode electrodes. An electric current of 0.2 mA was generated from the first enrichment culture, and ratios of the major metabolites (e.g., electric current, methane and acetate became stable after the forth enrichment. In order to investigate the electrogenic microbial community in the anode biofilm, it was morphologically analyzed by electron microscopy, and community members were phylogenetically identified by 16S rRNA gene clone-library analyses. Electron microscopy revealed that filamentous cells and rod-shaped cells with prosthecae-like filamentous appendages were abundantly present in the biofilm. Filamentous cells and appendages were interconnected via thin filaments. The clone library analyses frequently detected phylotypes affiliated with Clostridiales, Chloroflexi, Rhizobiales and Methanobacterium. Fluorescence in-situ hybridization revealed that the Rhizobiales population represented rod-shaped cells with filamentous appendages and constituted over 30% of the total population. Conclusion Bacteria affiliated with the Rhizobiales constituted the major population in the cellulose-fed MFC and exhibited unique morphology with filamentous appendages. They are considered to play important roles in the cellulose-degrading electrogenic community.

  6. Effects of marine microbial biofilms on the biocide release rate from antifouling paints – A model-based analysis

    DEFF Research Database (Denmark)

    Yebra, Diego Meseguer; Kiil, Søren; Erik Weinell, Claus

    2006-01-01

    The antifouling (AF) paint model of Kiil et al. [S. Kiil, C.E. Weinell, M.S. Pedersen, K. Dam-Johansen, Analysis of self-polishing antifouling paints using rotary experiments and mathematical modelling, Ind. Eng. Chem. Res. 40 (2001) 3906-3920] and the simplified biofilm. growth model of Gujer...... and Warmer [W. Gujer, O. Warmer, Modeling mixed population biofilms, in: W.G. Characklis, K.C. Marshall (Eds.), Biofilms, Wiley-Interscience, New York, 1990] are used to provide a reaction engineering-based insight to the effects of marine microbial slimes on biocide leaching and, to a minor extent...

  7. Biofilm Risks

    DEFF Research Database (Denmark)

    Wirtanen, Gun Linnea; Salo, Satu

    2016-01-01

    This chapter on biofilm risks deals with biofilm formation of pathogenic microbes, sampling and detection methods, biofilm removal, and prevention of biofilm formation. Several common pathogens produce sticky and/or slimy structures in which the cells are embedded, that is, biofilms, on various...... surfaces in food processing. Biofilms of common foodborne pathogens are reviewed. The issue of persistent and nonpersistent microbial contamination in food processing is also discussed. It has been shown that biofilms can be difficult to remove and can thus cause severe disinfection and cleaning problems...... in food factories. In the prevention of biofilm formation microbial control in process lines should both limit the number of microbes on surfaces and reduce microbial activity in the process. Thus the hygienic design of process equipment and process lines is important in improving the process hygiene...

  8. Chirality in microbial biofilms is mediated by close interactions between the cell surface and the substratum

    Science.gov (United States)

    Jauffred, Liselotte; Munk Vejborg, Rebecca; Korolev, Kirill S; Brown, Stanley; Oddershede, Lene B

    2017-01-01

    From microbial biofilms to human migrations, spatial competition is central to the evolutionary history of many species. The boundary between expanding populations is the focal point of competition for space and resources and is of particular interest in ecology. For all Escherichia coli strains studied here, these boundaries move in a counterclockwise direction even when the competing strains have the same fitness. We find that chiral growth of bacterial colonies is strongly suppressed by the expression of extracellular features such as adhesive structures and pili. Experiments with other microbial species show that chiral growth is found in other bacteria and exclude cell wall biosynthesis and anisotropic shape as the primary causes of chirality. Instead, intimate contact with the substratum is necessary for chirality. Our results demonstrate that through a handful of surface molecules cells can fundamentally reorganize their migration patterns, which might affect intra- and interspecific competitions through colony morphology or other mechanisms. PMID:28362723

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

    Science.gov (United States)

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

    2009-01-01

    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.

  10. Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

    Directory of Open Access Journals (Sweden)

    Marie Ragon

    Full Text Available 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

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

    Science.gov (United States)

    Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

    2011-01-01

    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

  12. Initial development and structure of biofilms on microbial fuel cell anodes

    Directory of Open Access Journals (Sweden)

    Keller Jürg

    2010-04-01

    Full Text Available Abstract 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 μm and 42 ± 3 μm 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

  13. Biofilms in lab and nature: a molecular geneticist's voyage to microbial ecology.

    Science.gov (United States)

    Kolter, Roberto

    2010-03-01

    This article reviews the latest findings on how extracellular signaling controls cell fate determination during the process of biofilm formation by Bacillus subtilis in the artificial setting of the laboratory. To complement molecular genetic approaches, surface-associated communities in settings as diverse as the pitcher plant Sarracenia purpurea and the human lung were investigated. The study of the pitcher plant revealed that the presence or absence of a mosquito larva in the pitcher plant controlled bacterial diversity in the ecosystem inside the pitcher plant. Through the analysis of the respiratory tract microbiota of humans suffering from cystic fibrosis (CF) a correlation between lung function and bacterial community diversity was found. Those that had lungs in good condition had also more diverse communities, whereas patients harboring Pseudomonas aeruginosa-the predominant CF pathogen-in their lungs had less diverse communities. Further studies focused on interspecies and intraspecies relationships at the molecular level in search for signaling molecules that would promote biofilm formation. Two molecules were found that induced biofilm formation in B. subtilis: nystatin-released by other species-and surfactin-released by B. subtilis itself. This is a role not previously known for two molecules that were known for other activities-nystatin as an antifungal and surfactin as a surfactant. In addition, surfactin was found to also trigger cannibalism under starvation. This could be a strategy to maintain the population because the cells destroyed serve as nutrients for the rest. The path that led the author to the study of microbial biofilms is also described.

  14. Microbial community diversity and composition varies with habitat characteristics and biofilm function in macrophyte-rich streams

    DEFF Research Database (Denmark)

    Levi, Peter S.; Starnawski, Piotr; Poulsen, Britta

    2017-01-01

    Biofilms in streams play an integral role in ecosystem processes and function yet few studies have investigated the broad diversity of these complex prokaryotic and eukaryotic microbial communities. Physical habitat characteristics can affect the composition and abundance of microorganisms...... in these biofilms by creating microhabitats. Here we describe the prokaryotic and eukaryotic microbial diversity of biofilms in sand and macrophyte habitats (i.e. epipsammon and epiphyton, respectively) in five macrophyte-rich streams in Jutland, Denmark. The macrophyte species varied in growth morphology, C......:N stoichiometry, and preferred stream habitat, providing a range in environmental conditions for the epiphyton. Among all habitats and streams, the prokaryotic communities were dominated by common phyla, including Alphaproteobacteria, Bacteriodetes, and Gammaproteobacteria, while the eukaryotic communities were...

  15. Biofouling of reverse osmosis membranes: effects of cleaning on biofilm microbial communities, membrane performance, and adherence of extracellular polymeric substances.

    Science.gov (United States)

    Al Ashhab, Ashraf; Sweity, Amer; Bayramoglu, Bihter; Herzberg, Moshe; Gillor, Osnat

    2017-05-01

    Laboratory-scale reverse osmosis (RO) flat-sheet systems were used with two parallel flow cells, one treated with cleaning agents and a control (ie undisturbed). The cleaning efforts increased the affinity of extracellular polymeric substances (EPS) to the RO membrane and altered the biofilm surface structure. Analysis of the membrane biofilm community composition revealed the dominance of Proteobacteria. However, within the phylum Proteobacteria, γ-Proteobacteria dominated the cleaned membrane biofilm, while β-Proteobacteria dominated the control biofilm. The composition of the fungal phyla was also altered by cleaning, with enhancement of Ascomycota and suppression of Basidiomycota. The results suggest that repeated cleaning cycles select for microbial groups that strongly attach to the RO membrane surface by producing rigid and adhesive EPS that hampers membrane performance.

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

    DEFF Research Database (Denmark)

    Zhang, Yifeng; Angelidaki, Irini

    2011-01-01

    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......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...

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

    Science.gov (United States)

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

    2015-02-01

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

  18. Microbial analysis of in situ biofilm formation in drinking water distribution systems: implications for monitoring and control of drinking water quality.

    Science.gov (United States)

    Douterelo, Isabel; Jackson, M; Solomon, C; Boxall, J

    2016-04-01

    Biofilm formation in drinking water distribution systems (DWDS) is influenced by the source water, the supply infrastructure and the operation of the system. A holistic approach was used to advance knowledge on the development of mixed species biofilms in situ, by using biofilm sampling devices installed in chlorinated networks. Key physico-chemical parameters and conventional microbial indicators for drinking water quality were analysed. Biofilm coverage on pipes was evaluated by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The microbial community structure, bacteria and fungi, of water and biofilms was assessed using pyrosequencing. Conventional wisdom leads to an expectation for less microbial diversity in groundwater supplied systems. However, the analysis of bulk water showed higher microbial diversity in groundwater site samples compared with the surface water site. Conversely, higher diversity and richness were detected in biofilms from the surface water site. The average biofilm coverage was similar among sites. Disinfection residual and other key variables were similar between the two sites, other than nitrates, alkalinity and the hydraulic conditions which were extremely low at the groundwater site. Thus, the unexpected result of an exceptionally low diversity with few dominant genera (Pseudomonas and Basidiobolus) in groundwater biofilm samples, despite the more diverse community in the bulk water, is attributed to the low-flow hydraulic conditions. This finding evidences that the local environmental conditions are shaping biofilm formation, composition and amount, and hence managing these is critical for the best operation of DWDS to safeguard water quality.

  19. Prevention of microbial biofilms - the contribution of micro and nanostructured materials.

    Science.gov (United States)

    Grumezescu, Alexandru Mihai; Chifiriuc, Carmen Mariana

    2014-01-01

    Microbial biofilms are associated with drastically enhanced resistance to most of the antimicrobial agents and with frequent treatment failures, generating the search for novel strategies which can eradicate infections by preventing the persistent colonization of the hospital environment, medical devices or human tissues. Some of the current approaches for fighting biofilms are represented by the development of novel biomaterials with increased resistance to microbial colonization and by the improvement of the current therapeutic solutions with the aid of nano (bio)technology. This special issues includes papers describing the applications of nanotechnology and biomaterials science for the development of improved drug delivery systems and nanostructured surfaces for the prevention and treatment of medical biofilms. Nanomaterials display unique and well-defined physical and chemical properties making them useful for biomedical applications, such as: very high surface area to volume ratio, biocompatibility, biodegradation, safety for human ingestion, capacity to support surface modification and therefore, to be combined with other bioactive molecules or substrata and more importantly being seemingly not attracting antimicrobial resistance. The use of biomaterials is significantly contributing to the reduction of the excessive use of antibiotics, and consequently to the decrease of the emergence rate of resistant microorganisms, as well as of the associated toxic effects. Various biomaterials with intrinsic antimicrobial activity (inorganic nanoparticles, polymers, composites), medical devices for drug delivery, as well as factors influencing their antimicrobial properties are presented. One of the presented papers reviews the recent literature on the use of magnetic nanoparticles (MNP)-based nanomaterials in antimicrobial applications for biomedicine, focusing on the growth inhibition and killing of bacteria and fungi, and, on viral inactivation. The anti

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

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Franck, Stephanie; Gülay, Arda

    2014-01-01

    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...... (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....

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

    KAUST Repository

    Liu, Jia

    2014-09-01

    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. © 2014 Elsevier B.V. All rights reserved.

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

    KAUST Repository

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

    2014-01-01

    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. © 2014 Elsevier B.V. All rights reserved.

  3. OPTIMIZATION OF FLOCCULATION PROCESS BY MICROBIAL COAGULANT IN RIVER WATER

    Directory of Open Access Journals (Sweden)

    Fatin Nabilah Murad

    2017-12-01

    Full Text Available The existing process of coagulation and flocculation are using chemicals that known as cationic coagulant such as alum, ferric sulfate, calcium oxide, and organic polymers.  Thus, this study concentrates on optimizing of flocculation process by microbial coagulant in river water. Turbidity and suspended solids are the main constraints of river water quality in Malaysia. Hence, a study is proposed to produce microbial coagulants isolated locally for river water treatment. The chosen microbe used as the bioflocculant producer is Aspergillus niger. The parameters to optimization in the flocculation process were pH, bioflocculant dosage and effluent concentration. The research was done in the jar test process and the process parameters for maximum turbidity removal was validated. The highest flocculating activity was obtained on day seven of cultivation in the supernatant. The optimum pH and bioflocculant dosage for an optimize sedimentation process were between 4-5 and 2-3 mL for 0.3 g/L of effluent concentration respectively. The model was validated by using a river water sample from Sg. Pusu and the result showed that the model was acceptable to evaluate the bioflocculation process.

  4. Biofilms and Oxidizing Biocides; Evaluation of Disinfection and Removal Effects by Using Established Microbial Systems.

    Science.gov (United States)

    Tachikawa, Mariko

    2017-01-01

    The formation of bacterial biofilms and their disinfection and removal have been important subjects in the maintenance of water quality in areas such as public spas, swimming pools, food processing lines, industrial water systems, and in the hygienic control of medical devices, hospital procedures, etc. Presented here is an outline of biofilm formation, as well as studies on the disinfection and removal of biofilms by oxidizing biocides using established biofilms. These studies using established biofilms may increase the understanding of the variable response of biofilms to planktonic bacteria, and the unique aspects of oxidizing biocides in the disinfection and removal of biofilms.

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

    Science.gov (United States)

    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

    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.

  6. Metagenomic discovery of novel enzymes and biosurfactants in a slaughterhouse biofilm microbial community

    Science.gov (United States)

    Thies, Stephan; Rausch, Sonja Christina; Kovacic, Filip; Schmidt-Thaler, Alexandra; Wilhelm, Susanne; Rosenau, Frank; Daniel, Rolf; Streit, Wolfgang; Pietruszka, Jörg; Jaeger, Karl-Erich

    2016-01-01

    DNA derived from environmental samples is a rich source of novel bioactive molecules. The choice of the habitat to be sampled predefines the properties of the biomolecules to be discovered due to the physiological adaptation of the microbial community to the prevailing environmental conditions. We have constructed a metagenomic library in Escherichia coli DH10b with environmental DNA (eDNA) isolated from the microbial community of a slaughterhouse drain biofilm consisting mainly of species from the family Flavobacteriaceae. By functional screening of this library we have identified several lipases, proteases and two clones (SA343 and SA354) with biosurfactant and hemolytic activities. Sequence analysis of the respective eDNA fragments and subsequent structure homology modelling identified genes encoding putative N-acyl amino acid synthases with a unique two-domain organisation. The produced biosurfactants were identified by NMR spectroscopy as N-acyltyrosines with N-myristoyltyrosine as the predominant species. Critical micelle concentration and reduction of surface tension were similar to those of chemically synthesised N-myristoyltyrosine. Furthermore, we showed that the newly isolated N-acyltyrosines exhibit antibiotic activity against various bacteria. This is the first report describing the successful application of functional high-throughput screening assays for the identification of biosurfactant producing clones within a metagenomic library. PMID:27271534

  7. Determinants of the microbial community structure of eutrophic, hyporheic river sediments polluted with chlorinated aliphatic hydrocarbons

    NARCIS (Netherlands)

    Hamonts, K.; Ryngaert, A.; Smidt, H.; Springael, D.; Dejonghe, W.

    2014-01-01

    Chlorinated aliphatic hydrocarbons (CAHs) often discharge into rivers as contaminated groundwater baseflow. As biotransformation of CAHs in the impacted river sediments might be an effective remediation strategy, we investigated the determinants of the microbial community structure of eutrophic,

  8. Anoxia stimulates microbially catalyzed metal release from Animas River sediments.

    Science.gov (United States)

    Saup, Casey M; Williams, Kenneth H; Rodríguez-Freire, Lucía; Cerrato, José M; Johnston, Michael D; Wilkins, Michael J

    2017-04-19

    The Gold King Mine spill in August 2015 released 11 million liters of metal-rich mine waste to the Animas River watershed, an area that has been previously exposed to historical mining activity spanning more than a century. Although adsorption onto fluvial sediments was responsible for rapid immobilization of a significant fraction of the spill-associated metals, patterns of longer-term mobility are poorly constrained. Metals associated with river sediments collected downstream of the Gold King Mine in August 2015 exhibited distinct presence and abundance patterns linked to location and mineralogy. Simulating riverbed burial and development of anoxic conditions, sediment microcosm experiments amended with Animas River dissolved organic carbon revealed the release of specific metal pools coupled to microbial Fe- and SO 4 2- -reduction. Results suggest that future sedimentation and burial of riverbed materials may drive longer-term changes in patterns of metal remobilization linked to anaerobic microbial metabolism, potentially driving decreases in downstream water quality. Such patterns emphasize the need for long-term water monitoring efforts in metal-impacted watersheds.

  9. Anoxia stimulates microbially catalyzed metal release from Animas River sediments

    International Nuclear Information System (INIS)

    Saup, Casey M.; Williams, Kenneth H.; Rodríguez-Freire, Lucía; Cerrato, José M.; Johnston, Michael D.; Wilkins, Michael J.

    2017-01-01

    The Gold King Mine spill in August 2015 released 11 million liters of metal-rich mine waste to the Animas River watershed, an area that has been previously exposed to historical mining activity spanning more than a century. Although adsorption onto fluvial sediments was responsible for rapid immobilization of a significant fraction of the spill-associated metals, patterns of longer-term mobility are poorly constrained. Metals associated with river sediments collected downstream of the Gold King Mine in August 2015 exhibited distinct presence and abundance patterns linked to location and mineralogy. Simulating riverbed burial and development of anoxic conditions, sediment microcosm experiments amended with Animas River dissolved organic carbon revealed the release of specific metal pools coupled to microbial Fe- and SO 4 2- reduction. Results suggest that future sedimentation and burial of riverbed materials may drive longer-term changes in patterns of metal remobilization linked to anaerobic microbial metabolism, potentially driving decreases in downstream water quality. Such patterns emphasize the need for long-term water monitoring efforts in metal-impacted watersheds.

  10. Next-Generation Pyrosequencing Analysis of Microbial Biofilm Communities on Granular Activated Carbon in Treatment of Oil Sands Process-Affected Water

    Science.gov (United States)

    Islam, M. Shahinoor; Zhang, Yanyan; McPhedran, Kerry N.

    2015-01-01

    The development of biodegradation treatment processes for oil sands process-affected water (OSPW) has been progressing in recent years with the promising potential of biofilm reactors. Previously, the granular activated carbon (GAC) biofilm process was successfully employed for treatment of a large variety of recalcitrant organic compounds in domestic and industrial wastewaters. In this study, GAC biofilm microbial development and degradation efficiency were investigated for OSPW treatment by monitoring the biofilm growth on the GAC surface in raw and ozonated OSPW in batch bioreactors. The GAC biofilm community was characterized using a next-generation 16S rRNA gene pyrosequencing technique that revealed that the phylum Proteobacteria was dominant in both OSPW and biofilms, with further in-depth analysis showing higher abundances of Alpha- and Gammaproteobacteria sequences. Interestingly, many known polyaromatic hydrocarbon degraders, namely, Burkholderiales, Pseudomonadales, Bdellovibrionales, and Sphingomonadales, were observed in the GAC biofilm. Ozonation decreased the microbial diversity in planktonic OSPW but increased the microbial diversity in the GAC biofilms. Quantitative real-time PCR revealed similar bacterial gene copy numbers (>109 gene copies/g of GAC) for both raw and ozonated OSPW GAC biofilms. The observed rates of removal of naphthenic acids (NAs) over the 2-day experiments for the GAC biofilm treatments of raw and ozonated OSPW were 31% and 66%, respectively. Overall, a relatively low ozone dose (30 mg of O3/liter utilized) combined with GAC biofilm treatment significantly increased NA removal rates. The treatment of OSPW in bioreactors using GAC biofilms is a promising technology for the reduction of recalcitrant OSPW organic compounds. PMID:25841014

  11. Next-generation pyrosequencing analysis of microbial biofilm communities on granular activated carbon in treatment of oil sands process-affected water.

    Science.gov (United States)

    Islam, M Shahinoor; Zhang, Yanyan; McPhedran, Kerry N; Liu, Yang; Gamal El-Din, Mohamed

    2015-06-15

    The development of biodegradation treatment processes for oil sands process-affected water (OSPW) has been progressing in recent years with the promising potential of biofilm reactors. Previously, the granular activated carbon (GAC) biofilm process was successfully employed for treatment of a large variety of recalcitrant organic compounds in domestic and industrial wastewaters. In this study, GAC biofilm microbial development and degradation efficiency were investigated for OSPW treatment by monitoring the biofilm growth on the GAC surface in raw and ozonated OSPW in batch bioreactors. The GAC biofilm community was characterized using a next-generation 16S rRNA gene pyrosequencing technique that revealed that the phylum Proteobacteria was dominant in both OSPW and biofilms, with further in-depth analysis showing higher abundances of Alpha- and Gammaproteobacteria sequences. Interestingly, many known polyaromatic hydrocarbon degraders, namely, Burkholderiales, Pseudomonadales, Bdellovibrionales, and Sphingomonadales, were observed in the GAC biofilm. Ozonation decreased the microbial diversity in planktonic OSPW but increased the microbial diversity in the GAC biofilms. Quantitative real-time PCR revealed similar bacterial gene copy numbers (>10(9) gene copies/g of GAC) for both raw and ozonated OSPW GAC biofilms. The observed rates of removal of naphthenic acids (NAs) over the 2-day experiments for the GAC biofilm treatments of raw and ozonated OSPW were 31% and 66%, respectively. Overall, a relatively low ozone dose (30 mg of O3/liter utilized) combined with GAC biofilm treatment significantly increased NA removal rates. The treatment of OSPW in bioreactors using GAC biofilms is a promising technology for the reduction of recalcitrant OSPW organic compounds. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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

    Science.gov (United States)

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

    1985-01-01

    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.

  13. Microbial corrosion of steel in Toarcian argillite: potential influence of bio-films

    International Nuclear Information System (INIS)

    Urios, L.; Desneux, J.; Magot, M.; Perez, A.; Mercier, F.; Dillmann, P.; Wittebroodt, C.; Dauzeres, A.; Marsal, F.

    2012-01-01

    Document available in extended abstract form only. In the context of a geological disposal of radioactive waste in clayey formations, the consequences of microbial activity are of concern regarding the corrosion of metallic components, such as the overpack surrounding vitrified waste. Generalized corrosion is one of the main processes taken into account in the dimensioning of these overpacks. However, the presence of microorganisms such as sulfate- or thiosulfate-reducing bacteria in the host rock in contact with these non-alloy materials may enhance localized corrosion processes, leading to a premature and undesirable loss of watertightness. Moreover, the passive corrosion layer, which is formed progressively during the generalized corrosion process and induces a decrease of corrosion rates, may react with iron-reducing bacteria and thus reactivate corrosion. The formation of bio-films may also lead to significant modifications of environment at the biofilm/metal interface in terms of pH, dissolved oxygen, organic and inorganic species, that may lead to electrochemical reactions that could potentially increase corrosion rates. There is thus a need for further investigations of the potential consequences on the physico-chemical conditions within geological disposal facilities. The French Institute for Radiological Protection and Nuclear Safety (IRSN) has been conducting research programs since 1991 in the Tournemire Underground Research Laboratory (URL), a railway tunnel which crosses a Toarcian argillaceous formation. This geological layer is particularly interesting for its physical and chemical properties close to those of Callovo-Oxfordian argillite. The importance of microbial processes in this formation was first shown by the study of time evolution of the chemical and isotopic compositions of fracture groundwaters collected in several boreholes. These investigations suggested that aqueous sulphates and their isotopic composition were controlled by bacterial

  14. CMEIAS bioimage informatics that define the landscape ecology of immature microbial biofilms developed on plant rhizoplane surfaces

    Directory of Open Access Journals (Sweden)

    Frank B Dazzo

    2015-10-01

    Full Text Available Colonization of the rhizoplane habitat is an important activity that enables certain microorganisms to promote plant growth. Here we describe various types of computer-assisted microscopy that reveal important ecological insights of early microbial colonization behavior within biofilms on plant root surfaces grown in soil. Examples of the primary data are obtained by analysis of processed images of rhizoplane biofilm landscapes analyzed at single-cell resolution using the emerging technology of CMEIAS bioimage informatics software. Included are various quantitative analyses of the in situ biofilm landscape ecology of microbes during their pioneer colonization of white clover roots, and of a rhizobial biofertilizer strain colonized on rice roots where it significantly enhances the productivity of this important crop plant. The results show that spatial patterns of immature biofilms developed on rhizoplanes that interface rhizosphere soil are highly structured (rather than distributed randomly when analyzed at the appropriate spatial scale, indicating that regionalized microbial cell-cell interactions and the local environment can significantly affect their cooperative and competitive colonization behaviors.

  15. Anodic biofilms in microbial fuel cells harbor low numbers of higher-power-producing bacteria than abundant genera

    Energy Technology Data Exchange (ETDEWEB)

    Kiely, Patrick D.; Call, Douglas F.; Yates, Matthew D.; Regan, John M.; Logan, Bruce E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering

    2010-09-15

    Microbial fuel cell (MFC) anode communities often reveal just a few genera, but it is not known to what extent less abundant bacteria could be important for improving performance. We examined the microbial community in an MFC fed with formic acid for more than 1 year and determined using 16S rRNA gene cloning and fluorescent in situ hybridization that members of the Paracoccus genus comprised most ({proportional_to}30%) of the anode community. A Paracoccus isolate obtained from this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m{sup 2}, whereas the original mixed culture produced up to 10 mW/m{sup 2}. Despite the absence of any Shewanella species in the clone library, we isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing a higher-power density (17.4 mW/m{sup 2}) than the mixed culture, although voltage generation was variable. Our results suggest that the numerical abundance of microorganisms in biofilms cannot be assumed a priori to correlate to capacities of these predominant species for high-power production. Detailed screening of bacterial biofilms may therefore be needed to identify important strains capable of high-power generation for specific substrates. (orig.)

  16. Anodic biofilms in microbial fuel cells harbor low numbers of higher-power-producing bacteria than abundant genera

    KAUST Repository

    Kiely, Patrick D.; Call, Douglas F.; Yates, Matthew D.; Regan, John M.; Logan, Bruce E.

    2010-01-01

    Microbial fuel cell (MFC) anode communities often reveal just a few genera, but it is not known to what extent less abundant bacteria could be important for improving performance. We examined the microbial community in an MFC fed with formic acid for more than 1 year and determined using 16S rRNA gene cloning and fluorescent in situ hybridization that members of the Paracoccus genus comprised most (~30%) of the anode community. A Paracoccus isolate obtained from this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m 2, whereas the original mixed culture produced up to 10 mW/m 2. Despite the absence of any Shewanella species in the clone library, we isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing a higher-power density (17.4 mW/m2) than the mixed culture, although voltage generation was variable. Our results suggest that the numerical abundance of microorganisms in biofilms cannot be assumed a priori to correlate to capacities of these predominant species for high-power production. Detailed screening of bacterial biofilms may therefore be needed to identify important strains capable of high-power generation for specific substrates. © 2010 Springer-Verlag.

  17. Anodic biofilms in microbial fuel cells harbor low numbers of higher-power-producing bacteria than abundant genera

    KAUST Repository

    Kiely, Patrick D.

    2010-07-15

    Microbial fuel cell (MFC) anode communities often reveal just a few genera, but it is not known to what extent less abundant bacteria could be important for improving performance. We examined the microbial community in an MFC fed with formic acid for more than 1 year and determined using 16S rRNA gene cloning and fluorescent in situ hybridization that members of the Paracoccus genus comprised most (~30%) of the anode community. A Paracoccus isolate obtained from this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m 2, whereas the original mixed culture produced up to 10 mW/m 2. Despite the absence of any Shewanella species in the clone library, we isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing a higher-power density (17.4 mW/m2) than the mixed culture, although voltage generation was variable. Our results suggest that the numerical abundance of microorganisms in biofilms cannot be assumed a priori to correlate to capacities of these predominant species for high-power production. Detailed screening of bacterial biofilms may therefore be needed to identify important strains capable of high-power generation for specific substrates. © 2010 Springer-Verlag.

  18. Microbial electrochemical energy storage and recovery in a combined electrotrophic and electrogenic biofilm

    Science.gov (United States)

    Electroactive biofilms, used as biocatalysts in bioelectrochemical systems (BESs), are usually operated either as electrogenic (the electrode is the electron acceptor) or electrotrophic (the electrode is the electron donor). Here, we enriched a non-photosynthetic bifunctional electroactive biofilm c...

  19. Biofilms 2015: Multidisciplinary Approaches Shed Light into Microbial Life on Surfaces

    Science.gov (United States)

    Yildiz, Fitnat

    2016-01-01

    The 7th ASM Conference on Biofilms was held in Chicago, Illinois, from 24 to 29 October 2015. The conference provided an international forum for biofilm researchers across academic and industry platforms, and from different scientific disciplines, to present and discuss new findings and ideas. The meeting covered a wide range of topics, spanning environmental sciences, applied biology, evolution, ecology, physiology, and molecular biology of the biofilm lifestyle. This report summarizes the presentations with regard to emerging biofilm-related themes. PMID:26977109

  20. Unravelling the core microbiome of biofilms in cooling tower systems.

    Science.gov (United States)

    Di Gregorio, L; Tandoi, V; Congestri, R; Rossetti, S; Di Pippo, F

    2017-11-01

    In this study, next generation sequencing and catalyzed reporter deposition fluorescence in situ hybridization, combined with confocal microscopy, were used to provide insights into the biodiversity and structure of biofilms collected from four full-scale European cooling systems. Water samples were also analyzed to evaluate the impact of suspended microbes on biofilm formation. A common core microbiome, containing members of the families Sphingomonadaceae, Comamonadaceae and Hyphomicrobiaceae, was found in all four biofilms, despite the water of each coming from different sources (river and groundwater). This suggests that selection of the pioneer community was influenced by abiotic factors (temperature, pH) and tolerances to biocides. Members of the Sphingomonadaceae were assumed to play a key role in initial biofilm formation. Subsequent biofilm development was driven primarily by light availability, since biofilms were dominated by phototrophs in the two studied 'open' systems. Their interactions with other microbial populations then shaped the structure of the mature biofilm communities analyzed.

  1. Herbicide toxicity on river biofilms assessed by pulse amplitude modulated (PAM) fluorometry

    International Nuclear Information System (INIS)

    Kim Tiam, Sandra; Laviale, Martin; Feurtet-Mazel, Agnès; Jan, Gwilherm; Gonzalez, Patrice; Mazzella, Nicolas; Morin, Soizic

    2015-01-01

    Highlights: • Rapid Light Curves were shown to be early markers of toxicant exposure. • Diuron and norflurazon effects were significant at environmentally realistic concentrations. • Toxic effects in intact biofilms seem to be delayed compared to disrupted biofilms. - Abstract: The use of Rapid light curves (RLCs) as a toxicity endpoint for river biofilms was examined in this study and compared to “classical fluorescence parameters” i.e. minimal fluorescence (F 0 ), optimal and effective quantum yields of photosystem II (F v /F m and Φ PSII ). Measurements were performed after exposure to five concentrations of diuron (from 0.3 to 33.4 μg L −1 ), its main degradation product (DCPMU) (from 1.0 to 1014 μg L −1 ) and norflurazon (from 0.6 to 585 μg L −1 ) with the lowest exposure concentrations corresponding to levels regularly encountered in chronically contaminated sites. Biofilm responses were evaluated after 1, 5, 7 and 14 days of exposure to the different toxicants. Overall, the responses of both “classical fluorescence parameters” and RLC endpoints were highly time dependent and related to the mode of action of the different compounds. Interestingly, parameters calculated from RLCs (α, ETR max and I k ) were useful early markers of pesticide exposure since they revealed significant effects of all the tested toxicants from the first day of exposure. In comparison, classical fluorescence endpoints (F 0 and F v /F m ) measured at day 1 were only affected in the DCPMU treatment. Our results demonstrated the interest of RLCs as early markers of toxicant exposure particularly when working with toxicants with less specific mode of action than PSII inhibitors

  2. Herbicide toxicity on river biofilms assessed by pulse amplitude modulated (PAM) fluorometry

    Energy Technology Data Exchange (ETDEWEB)

    Kim Tiam, Sandra, E-mail: sandra.kimtiam@gmail.com [Irstea, UR EABX, 50 Avenue de Verdun, F-33612, Cestas Cedex (France); Université de Bordeaux, EPOC, UMR 5805, F-33120 Arcachon (France); Laviale, Martin [Departamento de Biologia and CESAM – Centro de Estudos do Ambiente e do Mar Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Observatoire Océanologique, F-06230, Villefranche-Sur-Mer (France); CNRS, UMR 7093, LOV, Observatoire Océanologique, F-06230, Villefranche-Sur-Mer France (France); Feurtet-Mazel, Agnès [Université de Bordeaux, EPOC, UMR 5805, F-33120 Arcachon (France); Jan, Gwilherm [Irstea, UR EABX, 50 Avenue de Verdun, F-33612, Cestas Cedex (France); Gonzalez, Patrice [Université de Bordeaux, EPOC, UMR 5805, F-33120 Arcachon (France); Mazzella, Nicolas; Morin, Soizic [Irstea, UR EABX, 50 Avenue de Verdun, F-33612, Cestas Cedex (France)

    2015-08-15

    Highlights: • Rapid Light Curves were shown to be early markers of toxicant exposure. • Diuron and norflurazon effects were significant at environmentally realistic concentrations. • Toxic effects in intact biofilms seem to be delayed compared to disrupted biofilms. - Abstract: The use of Rapid light curves (RLCs) as a toxicity endpoint for river biofilms was examined in this study and compared to “classical fluorescence parameters” i.e. minimal fluorescence (F{sub 0}), optimal and effective quantum yields of photosystem II (F{sub v}/F{sub m} and Φ{sub PSII}). Measurements were performed after exposure to five concentrations of diuron (from 0.3 to 33.4 μg L{sup −1}), its main degradation product (DCPMU) (from 1.0 to 1014 μg L{sup −1}) and norflurazon (from 0.6 to 585 μg L{sup −1}) with the lowest exposure concentrations corresponding to levels regularly encountered in chronically contaminated sites. Biofilm responses were evaluated after 1, 5, 7 and 14 days of exposure to the different toxicants. Overall, the responses of both “classical fluorescence parameters” and RLC endpoints were highly time dependent and related to the mode of action of the different compounds. Interestingly, parameters calculated from RLCs (α, ETR{sub max} and I{sub k}) were useful early markers of pesticide exposure since they revealed significant effects of all the tested toxicants from the first day of exposure. In comparison, classical fluorescence endpoints (F{sub 0} and F{sub v}/F{sub m}) measured at day 1 were only affected in the DCPMU treatment. Our results demonstrated the interest of RLCs as early markers of toxicant exposure particularly when working with toxicants with less specific mode of action than PSII inhibitors.

  3. Microbial structures in an Alpine Thermal Spring - Microscopic techniques for the examination of Biofilms in a Subsurface Environment

    Science.gov (United States)

    Dornmayr-Pfaffenhuemer, Marion; Pierson, Elisabeth; Janssen, Geert-Jan; Stan-Lotter, Helga

    2010-05-01

    The research into extreme environments hast important implications for biology and other sciences. Many of the organisms found there provide insights into the history of Earth. Life exists in all niches where water is present in liquid form. Isolated environments such as caves and other subsurface locations are of interest for geomicrobiological studies. And because of their "extra-terrestrial" conditions such as darkness and mostly extreme physicochemical state they are also of astrobiological interest. The slightly radioactive thermal spring at Bad Gastein (Austria) was therefore examined for the occurrence of subsurface microbial communities. The surfaces of the submerged rocks in this warm spring were overgrown by microbial mats. Scanning electron microscopy (SEM) performed by the late Dr. Wolfgang Heinen revealed an interesting morphological diversity in biofilms found in this environment (1, 2). Molecular analysis of the community structure of the radioactive subsurface thermal spring was performed by Weidler et al. (3). The growth of these mats was simulated using sterile glass slides which were exposed to the water stream of the spring. Those mats were analysed microscopically. Staining, using fluorescent dyes such as 4',6-Diamidino-2-phenylindol (DAPI), gave an overview of the microbial diversity of these biofilms. Additional SEM samples were prepared using different fixation protocols. Scanning confocal laser microscopy (SCLM) allowed a three dimensional view of the analysed biofilms. This work presents some electron micrographs of Dr. Heinen and additionally new microscopic studies of the biofilms formed on the glass slides. The appearances of the new SEM micrographs were compared to those of Dr. Heinen that were done several years ago. The morphology and small-scale distribution in the microbial mat was analyzed by fluorescence microscopy. The examination of natural biomats and biofilms grown on glass slides using several microscopical techniques

  4. Analysis of Microbial Communities in Biofilms from CSTR-Type Hollow Fiber Membrane Biofilm Reactors for Autotrophic Nitrification and Hydrogenotrophic Denitrification.

    Science.gov (United States)

    Shin, Jung-Hun; Kim, Byung-Chun; Choi, Okkyoung; Kim, Hyunook; Sang, Byoung-In

    2015-10-01

    Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH4(+)-N/m(3)/d and 0.10-0.21 kg NO3(-)-N/m(3)/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH4(+) or NO3(-) loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs.

  5. Microbial Adhesion and Biofilm Formation on Microfiltration Membranes: A Detailed Characterization Using Model Organisms with Increasing Complexity

    Directory of Open Access Journals (Sweden)

    L. Vanysacker

    2013-01-01

    Full Text Available Since many years, membrane biofouling has been described as the Achilles heel of membrane fouling. In the present study, an ecological assay was performed using model systems with increasing complexity: a monospecies assay using Pseudomonas aeruginosa or Escherichia coli separately, a duospecies assay using both microorganisms, and a multispecies assay using activated sludge with or without spiked P. aeruginosa. The microbial adhesion and biofilm formation were evaluated in terms of bacterial cell densities, species richness, and bacterial community composition on polyvinyldifluoride, polyethylene, and polysulfone membranes. The data show that biofouling formation was strongly influenced by the kind of microorganism, the interactions between the organisms, and the changes in environmental conditions whereas the membrane effect was less important. The findings obtained in this study suggest that more knowledge in species composition and microbial interactions is needed in order to understand the complex biofouling process. This is the first report describing the microbial interactions with a membrane during the biofouling development.

  6. Microbial Adhesion and Biofilm Formation on Microfiltration Membranes: A Detailed Characterization Using Model Organisms with Increasing Complexity

    Science.gov (United States)

    Vanysacker, L.; Denis, C.; Declerck, P.; Piasecka, A.; Vankelecom, I. F. J.

    2013-01-01

    Since many years, membrane biofouling has been described as the Achilles heel of membrane fouling. In the present study, an ecological assay was performed using model systems with increasing complexity: a monospecies assay using Pseudomonas aeruginosa or Escherichia coli separately, a duospecies assay using both microorganisms, and a multispecies assay using activated sludge with or without spiked P. aeruginosa. The microbial adhesion and biofilm formation were evaluated in terms of bacterial cell densities, species richness, and bacterial community composition on polyvinyldifluoride, polyethylene, and polysulfone membranes. The data show that biofouling formation was strongly influenced by the kind of microorganism, the interactions between the organisms, and the changes in environmental conditions whereas the membrane effect was less important. The findings obtained in this study suggest that more knowledge in species composition and microbial interactions is needed in order to understand the complex biofouling process. This is the first report describing the microbial interactions with a membrane during the biofouling development. PMID:23986906

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

    KAUST Repository

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

    2011-01-01

    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 4. days, 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 6. weeks. 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. © 2010 Elsevier Ltd.

  8. Soluble Microbial Product Characterization of Biofilm Formation in Bench-Scale

    KAUST Repository

    Mines, Paul

    2012-12-01

    The biological process known as activated sludge (AS) in conjunction with membrane separation technology for the treatment of wastewater has been employed for over four decades. While, membrane biological reactors (MBR) are now widely employed, the phenomenon of membrane fouling is still the most significant factor leading to performance decline of MBRs. Although much research has been done on the subject of MBR fouling over the past two decades, many questions remain unanswered, and consensus within the scientific community is rare. However, research has led to one system parameter generally being regarded as a contributor to membrane fouling, extracellular polymeric compounds (EPS). EPS, and more specifically, the soluble fraction of EPS known as soluble microbial products (SMP), must be further investigated in order to better understand membrane fouling. The biological activity and performance of the MBR is affected by myriad operational parameters, which in turn affects the SMP generated. A commonly varied operational parameter is, depending on the specific treatment needs of a MBR, the sludge retention time (SRT). This study aims to characterize the SMP in three bench-scale MBRs as the SRT is gradually lowered. By studying how the SMP change as the operation of the system is altered, greater understanding of how SMP are related to fouling can be achieved. At the onset of the study, a steady state was established in the system with a SRT of 20 days. Upon stabilization of a 20 day SRT, the system was gradually transitioned to a five and a half day SRT, in stepwise adjustments. Initially, both the trans-membrane pressure (TMP) and the SMP concentrations were at relatively low values, indicating the presence of minimal amounts of biofilm on the membrane surfaces. As the system was altered and more activated sludge was wasted from the reactors, the SRT inherently decreased. As the lower SRT was transitioned and established, the data from TMP measurements, as well

  9. Effect of anode polarization on biofilm formation and electron transfer in Shewanella oneidensis/graphite felt microbial fuel cells.

    Science.gov (United States)

    Pinto, David; Coradin, Thibaud; Laberty-Robert, Christel

    2018-04-01

    In microbial fuel cells, electricity generation is assumed by bacterial degradation of low-grade organics generating electrons that are transferred to an electrode. The nature and efficiency of the electron transfer from the bacteria to the electrodes are determined by several chemical, physical and biological parameters. Specifically, the application of a specific potential at the bioanode has been shown to stimulate the formation of an electro-active biofilm, but the underlying mechanisms remain poorly understood. In this study, we have investigated the effect of an applied potential on the formation and electroactivity of biofilms established by Shewanella oneidensis bacteria on graphite felt electrodes in single- and double-chamber reactor configurations in oxic conditions. Using amperometry, cyclic voltammetry, and OCP/Power/Polarization curves techniques, we showed that a potential ranging between -0.3V and +0.5V (vs. Ag/AgCl/KCl sat.) and its converse application to a couple of electrodes leads to different electrochemical behaviors, anodic currents and biofilm architectures. For example, when the bacteria were confined in the anodic compartment of a double-chamber cell, a negative applied potential (-0.3V) at the bioanode favors a mediated electron transfer correlated with the progressive formation of a biofilm that fills the felt porosity and bridges the graphite fibers. In contrast, a positive applied potential (+0.3V) at the bioanode stimulates a direct electron transfer resulting in the fast-bacterial colonization of the fibers only. These results provide significant insight for the understanding of the complex bacteria-electrode interactions in microbial fuel cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. In Situ Ecophysiology of Microbial Biofilm Communities Analyzed by CMEIAS Computer-Assisted Microscopy at Single-Cell Resolution

    Directory of Open Access Journals (Sweden)

    Youssef G. Yanni

    2013-06-01

    Full Text Available This paper describes the utility of CMEIAS (Center for Microbial Ecology Image Analysis System computer-assisted microscopy to extract data from accurately segmented images that provide 63 different insights into the ecophysiology of microbial populations and communities within biofilms and other habitats. Topics include quantitative assessments of: (i morphological diversity as an indicator of impacts that substratum physicochemistries have on biofilm community structure and dominance-rarity relationships among populations; (ii morphotype-specific distributions of biovolume body size that relate microbial allometric scaling, metabolic activity and growth physiology; (iii fractal geometry of optimal cellular positioning for efficient utilization of allocated nutrient resources; (iv morphotype-specific stress responses to starvation, environmental disturbance and bacteriovory predation; (v patterns of spatial distribution indicating positive and negative cell–cell interactions affecting their colonization behavior; and (vi significant methodological improvements to increase the accuracy of color-discriminated ecophysiology, e.g., differentiation of cell viability based on cell membrane integrity, cellular respiratory activity, phylogenetically differentiated substrate utilization, and N-acyl homoserine lactone-mediated cell–cell communication by bacteria while colonizing plant roots. The intensity of these ecophysiological attributes commonly varies at the individual cell level, emphasizing the importance of analyzing them at single-cell resolution and the proper spatial scale at which they occur in situ.

  11. Surface-to-surface biofilm transfer: a quick and reliable startup strategy for mixed culture microbial fuel cells.

    Science.gov (United States)

    Vogl, Andreas; Bischof, Franz; Wichern, Marc

    2016-01-01

    The startup of microbial fuel cells (MFCs) is known to be prone to failure or result in erratic performance impeding the research. The aim of this study was to advise a quick launch strategy for laboratory-scale MFCs that ensures steady operation performance in a short period of time. Different startup strategies were investigated and compared with membraneless single chamber MFCs. A direct surface-to-surface biofilm transfer (BFT) in an operating MFC proved to be the most efficient method. It provided steady power densities of 163 ± 13 mWm(-2) 4 days after inoculation compared to 58 ± 15 mWm(-2) after 30 days following a conventional inoculation approach. The in situ BFT eliminates the need for microbial acclimation during startup and reduces performance fluctuations caused by shifts in microbial biodiversity. Anaerobic pretreatment of the substrate and addition of suspended enzymes from an operating MFC into the new MFC proved to have a beneficial effect on startup and subsequent operation. Polarization methods were applied to characterize the startup phase and the steady state operation in terms of power densities, internal resistance and power overshoot during biofilm maturation. Applying this method a well-working MFC can be multiplied into an array of identically performing MFCs.

  12. The efficacy of different anti-microbial metals at preventing the formation of, and eradicating bacterial biofilms of pathogenic indicator strains.

    Science.gov (United States)

    Gugala, Natalie; Lemire, Joe A; Turner, Raymond J

    2017-06-01

    The emergence of multidrug-resistant pathogens and the prevalence of biofilm-related infections have generated a demand for alternative anti-microbial therapies. Metals have not been explored in adequate detail for their capacity to combat infectious disease. Metal compounds can now be found in textiles, medical devices and disinfectants-yet, we know little about their efficacy against specific pathogens. To help fill this knowledge gap, we report on the anti-microbial and antibiofilm activity of seven metals: silver, copper, titanium, gallium, nickel, aluminum and zinc against three bacterial strains, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. To evaluate the capacity of metal ions to prevent the growth of, and eradicate biofilms and planktonic cells, bacterial cultures were inoculated in the Calgary Biofilm Device (minimal biofilm eradication concentration) in the presence of the metal salts. Copper, gallium and titanium were capable of preventing planktonic and biofilm growth, and eradicating established biofilms of all tested strains. Further, we observed that the efficacies of the other tested metal salts displayed variable efficacy against the tested strains. Further, contrary to the enhanced resistance anticipated from bacterial biofilms, particular metal salts were observed to be more effective against biofilm communities versus planktonic cells. In this study, we have demonstrated that the identity of the bacterial strain must be considered before treatment with a particular metal ion. Consequent to the use of metal ions as anti-microbial agents to fight multidrug-resistant and biofilm-related infections increases, we must aim for more selective deployment in a given infectious setting.

  13. Exposure to Crude Oil and Chemical Dispersant May Impact Marine Microbial Biofilm Composition and Steel Corrosion

    Directory of Open Access Journals (Sweden)

    Jennifer L. Salerno

    2018-06-01

    Full Text Available The release of hydrocarbons and chemical dispersant in marine environments may disrupt benthic ecosystems, including artificial reefs, formed by historic steel shipwrecks, and their associated organisms. Experiments were performed to determine the impacts of crude oil, dispersed crude oil, and dispersant on the community structure and function of microorganisms in seawater (SW and biofilms formed on carbon steel, a common ship hull construction material. Steel corrosion was also monitored to illustrate how oil spills may impact preservation of steel shipwrecks. Microcosms were filled with seawater (SW and incubated at 4°C. Carbon steel disks (CSDs were placed in each tank, and tanks were amended with crude oil and/or dispersant or no treatment. SW and CSD biofilms were sampled biweekly for genetic analysis using Illumina sequencing of 16S ribosomal RNA gene amplicons. Predicted and sequenced bacterial metagenomes were analyzed to examine impacts of oil and dispersant on metabolic function. Gammaproteobacteria, Alphaproteobacteria, and Flavobacteriia dominated SW and biofilms. Bacterial community structure differed significantly between treatments for SW and biofilms. OTUs affiliated with known (Pseudomonas and potential (Marinomonas hydrocarbon-degraders were roughly twice as abundant in biofilms treated with oil and dispersed oil, and steel corrosion of CSDs in these treatments was higher compared to control and dispersant treatments. OTUs affiliated with the Rhodobacteraceae family (biofilm formers and potential oil degraders were less abundant in the dispersant treatment compared to other treatments in biofilm and SW samples, but OTUs affiliated with the Pseudoalteromonas genus (biofilm formers and proposed hydrocarbon degraders were more abundant in dispersant-treated biofilms. Overall, functional gene analyses revealed a decrease in genes (predicted using PICRUSt and observed in sequenced metagenomes associated with hydrocarbon degradation

  14. Effect of biofilm and selective mixed culture on microbial fuel cell for the treatment of tempeh industrial wastewater

    Science.gov (United States)

    Arbianti, Rita; Surya Utami, Tania; Leondo, Vifki; Elisabeth; Andyah Putri, Syafira; Hermansyah, Heri

    2018-03-01

    Microbial Fuel Cell (MFC) provides a new alternative in the treatment of organic waste. MFC produces 50-90% less sludge to be disposed than other methods. MFC technology can utilize existing microorganisms in the waste as a catalyst to generate electricity and simultaneously also serves as a wastewater treatment unit itself. Tempeh wastewater is one of the abundant industrial wastewater which can be processed using MFC. Research using the selective mixed culture is very likely to do due to the good result on COD removals by adding mixed culture. Microorganisms in tempeh wastewater consist of bacteria gram positive and gram negative. This study focused on the aspects of waste treatment which is determined by decreased levels of COD and BOD. Variations in this study are the formation time of biofilm and the addition of selective gram. MFC operated for 50 hours. For a variation of biofilm formation, experiments were performed after incubation by replacing incubation substrates used in the formation of biofilms. Biofilm formation time in this study was 3 days, 5 days, 7 days and 14 days. Gram positive and gram negative bacteria were used in selective mixed culture experiments. Selective mixed culture added to the reactor by 1 mL and 5 mL. Selection of gram-positive or gram-negative bacteria carried by growing mixed culture on selective media. COD and BOD levels were measured in the wastewater before and after the experiment conducted in each variation. Biofilm formation optimum time is 7 days which decrease COD and BOD levels by 18.2% and 35.9%. The addition of gram negative bacteria decreases COD and BOD levels by 29.32% and 51.32%. Further research is needed in order to get a better result on decreasing levels of COD and BOD.

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

    KAUST Repository

    Yan, Hengjing

    2012-05-01

    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. © 2012 Elsevier Ltd.

  16. Recent Advances in the Study of Marine Microbial Biofilm: From the Involvement of Quorum Sensing in Its Production up to Biotechnological Application of the Polysaccharide Fractions

    Directory of Open Access Journals (Sweden)

    Paola Di Donato

    2016-05-01

    Full Text Available The present review will explore the most relevant findings on marine microbial biofilm, with particular attention towards its polysaccharide fraction, namely exopolysaccharide (EPS. EPSs of microbial origin are ubiquitous in nature, possess unique properties and can be isolated from the bacteria living in a variety of habitats, including fresh water or marine environments, extreme environments or different soil ecosystems. These biopolymers have many application in the field of biotechnology. Several studies showed that the biofilm formation is closely related to quorum sensing (QS systems, which is a mechanism relying on the production of small molecules defined as “autoinducers” that bacteria release in the surrounding environment where they accumulate. In this review, the involvement of microbial chemical communication, by QS mechanism, in the formation of marine biofilm will also be discussed.

  17. An overview of the structure and function of microbial biofilms, with ...

    African Journals Online (AJOL)

    As a food resource, streambed biofilms are intensively grazed by protozoans and macrobenthos, their quality as a food source for grazing organisms affecting the diversity, abundance and distribution of macrobenthic invertebrates. Biofilms are indicators of environmental quality and are active sites for species evolution.

  18. Stratification of Microbial Processes and Populations in Biofilms Treating Pig Farm Waste Air

    DEFF Research Database (Denmark)

    Juhler, Susanne; Saunders, Aaron Marc; Pedersen, Kristina

    2006-01-01

    Biological air filters have been developed to reduce odor and ammonia emissions resulting from the rapidly expanding pig farm industry in many European countries. In contrast to aqueous biofilm environments, the biofilms of these filters are air-fed, allowing for extreme metabolite accumulation...

  19. Biofilm Infections

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Jensen, Peter Østrup; Moser, Claus Ernst

    A still increasing interest and emphasis on the sessile bacterial lifestyle biofilms has been seen since it was realized that the vast majority of the total microbial biomass exists as biofilms. Aggregation of bacteria was first described by Leeuwenhoek in 1677, but only recently recognized...... as being important in chronic infection. In 1993 the American Society for Microbiology (ASM) recognized that the biofilm mode of growth was relevant to microbiology. This book covers both the evidence for biofilms in many chronic bacterial infections as well as the problems facing these infections...... such as diagnostics, pathogenesis, treatment regimes and in vitro and in vivo models for studying biofilms. This is the first scientific book on biofilm infections, chapters written by the world leading scientist and clinicians. The intended audience of this book is scientists, teachers at university level as well...

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Role of Fusobacterium nucleatum and Coaggregation in Anaerobe Survival in Planktonic and Biofilm Oral Microbial Communities during Aeration

    Science.gov (United States)

    Bradshaw, David J.; Marsh, Philip D.; Watson, G. Keith; Allison, Clive

    1998-01-01

    Coaggregation is a well-characterized phenomenon by which specific pairs of oral bacteria interact physically. The aim of this study was to examine the patterns of coaggregation between obligately anaerobic and oxygen-tolerant species that coexist in a model oral microbial community. Obligate anaerobes other than Fusobacterium nucleatum coaggregated only poorly with oxygen-tolerant species. In contrast, F. nucleatum was able to coaggregate not only with both oxygen-tolerant and other obligately anaerobic species but also with otherwise-noncoaggregating obligate anaerobe–oxygen-tolerant species pairs. The effects of the presence or absence of F. nucleatum on anaerobe survival in both the biofilm and planktonic phases of a complex community of oral bacteria grown in an aerated (gas phase, 200 ml of 5% CO2 in air · min−1) chemostat system were then investigated. In the presence of F. nucleatum, anaerobes persisted in high numbers (>107 · ml−1 in the planktonic phase and >107 · cm−2 in 4-day biofilms). In an equivalent culture in the absence of F. nucleatum, the numbers of black-pigmented anaerobes (Porphyromonas gingivalis and Prevotella nigrescens) were significantly reduced (P ≤ 0.001) in both the planktonic phase and in 4-day biofilms, while the numbers of facultatively anaerobic bacteria increased in these communities. Coaggregation-mediated interactions between F. nucleatum and other species facilitated the survival of obligate anaerobes in aerated environments. PMID:9746571

  3. Shift in the microbial community composition of surface water and sediment along an urban river.

    Science.gov (United States)

    Wang, Lan; Zhang, Jing; Li, Huilin; Yang, Hong; Peng, Chao; Peng, Zhengsong; Lu, Lu

    2018-06-15

    Urban rivers represent a unique ecosystem in which pollution occurs regularly, leading to significantly altered of chemical and biological characteristics of the surface water and sediments. However, the impact of urbanization on the diversity and structure of the river microbial community has not been well documented. As a major tributary of the Yangtze River, the Jialing River flows through many cities. Here, a comprehensive analysis of the spatial microbial distribution in the surface water and sediments in the Nanchong section of Jialing River and its two urban branches was conducted using 16S rRNA gene-based Illumina MiSeq sequencing. The results revealed distinct differences in surface water bacterial composition along the river with a differential distribution of Proteobacteria, Cyanobacteria, Actinobacteria, Bacteroidetes and Acidobacteria (P urban water. PICRUSt metabolic inference analysis revealed a growing number of genes associated with xenobiotic metabolism and nitrogen metabolism in the urban water, indicating that urban discharges might act as the dominant selective force to alter the microbial communities. Redundancy analysis suggested that the microbial community structure was influenced by several environmental factors. TP (P urban river. These results highlight that river microbial communities exhibit spatial variation in urban areas due to the joint influence of chemical variables associated with sewage discharging and construction of hydropower stations. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Effect of engineered environment on microbial community structure in biofilter and biofilm on reverse osmosis membrane

    KAUST Repository

    Jeong, Sanghyun; Cho, Kyungjin; Jeong, Dawoon; Lee, Seockheon; Leiknes, TorOve; Vigneswaran, Saravanamuthu; Bae, Hyokwan

    2017-01-01

    Four dual media filters (DMFs) were operated in a biofiltration mode with different engineered environments (DMF I and II: coagulation with/without acidification and DMF III and IV: without/with chlorination). Designed biofilm enrichment reactors

  5. Microbial biofilm detection on food contact surfaces by macro-scale fluorescence imaging

    Science.gov (United States)

    Hyperspectral fluorescence imaging methods were utilized to evaluate the potential of multispectral fluorescence methods for detection of pathogenic biofilm formations on four types of food contact surface materials: stainless steel, high density polyethylene (HDPE) commonly used for cutting boards,...

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

    Directory of Open Access Journals (Sweden)

    Vladimír Vietoris

    2012-02-01

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

  7. Shared effects of organic microcontaminants and environmental stressors on biofilms and invertebrates in impaired rivers.

    Science.gov (United States)

    Sabater, S; Barceló, D; De Castro-Català, N; Ginebreda, A; Kuzmanovic, M; Petrovic, M; Picó, Y; Ponsatí, L; Tornés, E; Muñoz, I

    2016-03-01

    Land use type, physical and chemical stressors, and organic microcontaminants were investigated for their effects on the biological communities (biofilms and invertebrates) in several Mediterranean rivers. The diversity of invertebrates, and the scores of the first principal component of a PCA performed with the diatom communities were the best descriptors of the distribution patterns of the biological communities against the river stressors. These two metrics decreased according to the progressive site impairment (associated to higher area of agricultural and urban-industrial, high water conductivity, higher dissolved organic carbon and dissolved inorganic nitrogen concentrations, and higher concentration of organic microcontaminants, particularly pharmaceutical and industrial compounds). The variance partition analyses (RDAs) attributed the major share (10%) of the biological communities' response to the environmental stressors (nutrients, altered discharge, dissolved organic matter), followed by the land use occupation (6%) and of the organic microcontaminants (2%). However, the variance shared by the three groups of descriptors was very high (41%), indicating that their simultaneous occurrence determined most of the variation in the biological communities. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Disruption of microbial biofilms by an extracellular protein isolated from epibiotic tropical marine strain of Bacillus licheniformis.

    Directory of Open Access Journals (Sweden)

    Devendra H Dusane

    Full Text Available 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.

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

    Science.gov (United States)

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

    2013-01-01

    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. PMID:23691235

  10. Effect of engineered environment on microbial community structure in biofilter and biofilm on reverse osmosis membrane.

    Science.gov (United States)

    Jeong, Sanghyun; Cho, Kyungjin; Jeong, Dawoon; Lee, Seockheon; Leiknes, TorOve; Vigneswaran, Saravanamuthu; Bae, Hyokwan

    2017-11-01

    Four dual media filters (DMFs) were operated in a biofiltration mode with different engineered environments (DMF I and II: coagulation with/without acidification and DMF III and IV: without/with chlorination). Designed biofilm enrichment reactors (BERs) containing the removable reverse osmosis (RO) coupons, were connected at the end of the DMFs in parallel to analyze the biofilm on the RO membrane by DMF effluents. Filtration performances were evaluated in terms of dissolved organic carbon (DOC) and assimilable organic carbon (AOC). Organic foulants on the RO membrane were also quantified and fractionized. The bacterial community structures in liquid (seawater and effluent) and biofilm (DMF and RO) samples were analyzed using 454-pyrosequencing. The DMF IV fed with the chlorinated seawater demonstrated the highest reductions of DOC including LMW-N as well as AOC among the other DMFs. The DMF IV was also effective in reducing organic foulants on the RO membrane surface. The bacterial community structure was grouped according to the sample phase (i.e., liquid and biofilm samples), sampling location (i.e., DMF and RO samples), and chlorination (chlorinated and non-chlorinated samples). In particular, the biofilm community in the DMF IV differed from the other DMF treatments, suggesting that chlorination exerted as stronger selective pressure than pH adjustment or coagulation on the biofilm community. In the DMF IV, several chemoorganotrophic chlorine-resistant biofilm-forming bacteria such as Hyphomonas, Erythrobacter, and Sphingomonas were predominant, and they may enhance organic carbon degradation efficiency. Diverse halophilic or halotolerant organic degraders were also found in other DMFs (i.e., DMF I, II, and III). Various kinds of dominant biofilm-forming bacteria were also investigated in RO membrane samples; the results provided possible candidates that cause biofouling when DMF process is applied as the pretreatment option for the RO process. Copyright

  11. Effect of engineered environment on microbial community structure in biofilter and biofilm on reverse osmosis membrane

    KAUST Repository

    Jeong, Sanghyun

    2017-07-25

    Four dual media filters (DMFs) were operated in a biofiltration mode with different engineered environments (DMF I and II: coagulation with/without acidification and DMF III and IV: without/with chlorination). Designed biofilm enrichment reactors (BERs) containing the removable reverse osmosis (RO) coupons, were connected at the end of the DMFs in parallel to analyze the biofilm on the RO membrane by DMF effluents. Filtration performances were evaluated in terms of dissolved organic carbon (DOC) and assimilable organic carbon (AOC). Organic foulants on the RO membrane were also quantified and fractionized. The bacterial community structures in liquid (seawater and effluent) and biofilm (DMF and RO) samples were analyzed using 454-pyrosequencing. The DMF IV fed with the chlorinated seawater demonstrated the highest reductions of DOC including LMW-N as well as AOC among the other DMFs. The DMF IV was also effective in reducing organic foulants on the RO membrane surface. The bacterial community structure was grouped according to the sample phase (i.e., liquid and biofilm samples), sampling location (i.e., DMF and RO samples), and chlorination (chlorinated and non-chlorinated samples). In particular, the biofilm community in the DMF IV differed from the other DMF treatments, suggesting that chlorination exerted as stronger selective pressure than pH adjustment or coagulation on the biofilm community. In the DMF IV, several chemoorganotrophic chlorine-resistant biofilm-forming bacteria such as Hyphomonas, Erythrobacter, and Sphingomonas were predominant, and they may enhance organic carbon degradation efficiency. Diverse halophilic or halotolerant organic degraders were also found in other DMFs (i.e., DMF I, II, and III). Various kinds of dominant biofilm-forming bacteria were also investigated in RO membrane samples; the results provided possible candidates that cause biofouling when DMF process is applied as the pretreatment option for the RO process.

  12. Evaluating Microbial Indicators of Environmental Condition in Oregon Rivers

    Science.gov (United States)

    Pennington, Alan T.; Harding, Anna K.; Hendricks, Charles W.; Campbell, Heidi M. K.

    2001-12-01

    Traditional bacterial indicators used in public health to assess water quality and the Biolog® system were evaluated to compare their response to biological, chemical, and physical habitat indicators of stream condition both within the state of Oregon and among ecoregion aggregates (Coast Range, Willamette Valley, Cascades, and eastern Oregon). Forty-three randomly selected Oregon river sites were sampled during the summer in 1997 and 1998. The public health indicators included heterotrophic plate counts (HPC), total coliforms (TC), fecal coliforms (FC) and Escherichia coli (EC). Statewide, HPC correlated strongly with physical habitat (elevation, riparian complexity, % canopy presence, and indices of agriculture, pavement, road, pasture, and total disturbance) and chemistry (pH, dissolved O2, specific conductance, acid-neutralizing capacity, dissolved organic carbon, total N, total P, SiO2, and SO4). FC and EC were significantly correlated generally with the river chemistry indicators. TC bacteria significantly correlated with riparian complexity, road disturbance, dissolved O2, and SiO2 and FC. Analyzing the sites by ecoregion, eastern Oregon was characterized by high HPC, FC, EC, nutrient loads, and indices of human disturbance, whereas the Cascades ecoregion had correspondingly low counts of these indicators. The Coast Range and Willamette Valley presented inconsistent indicator patterns that are more difficult to characterize. Attempts to distinguish between ecoregions with the Biolog system were not successful, nor did a statistical pattern emerge between the first five principle components and the other environmental indicators. Our research suggests that some traditional public health microbial indicators may be useful in measuring the environmental condition of lotic systems.

  13. Development of photosynthetic biofilms affected by dissolved and sorbed copper in a eutrophic river

    NARCIS (Netherlands)

    Barranguet, C.; Plans, M.; Van der Grinten, E.; Sinke, J.J.; Admiraal, W.

    2002-01-01

    Photosynthetic biofilms are capable of immobilizing important concentrations of metals, therefore reducing bioavailability to organisms. But also metal pollution is believed to produce changes in the microalgal species composition of biofilms. We investigated the changes undergone by natural

  14. Shared effects of organic microcontaminants and environmental stressors on biofilms and invertebrates in impaired rivers

    International Nuclear Information System (INIS)

    Sabater, S.; Barceló, D.; De Castro-Català, N.; Ginebreda, A.; Kuzmanovic, M.; Petrovic, M.; Picó, Y.; Ponsatí, L.; Tornés, E.; Muñoz, I.

    2016-01-01

    Land use type, physical and chemical stressors, and organic microcontaminants were investigated for their effects on the biological communities (biofilms and invertebrates) in several Mediterranean rivers. The diversity of invertebrates, and the scores of the first principal component of a PCA performed with the diatom communities were the best descriptors of the distribution patterns of the biological communities against the river stressors. These two metrics decreased according to the progressive site impairment (associated to higher area of agricultural and urban-industrial, high water conductivity, higher dissolved organic carbon and dissolved inorganic nitrogen concentrations, and higher concentration of organic microcontaminants, particularly pharmaceutical and industrial compounds). The variance partition analyses (RDAs) attributed the major share (10%) of the biological communities' response to the environmental stressors (nutrients, altered discharge, dissolved organic matter), followed by the land use occupation (6%) and of the organic microcontaminants (2%). However, the variance shared by the three groups of descriptors was very high (41%), indicating that their simultaneous occurrence determined most of the variation in the biological communities. - Highlights: • River impairment was associated to increasing agricultural and urban-industrial areas, and sites were having waters with high water conductivity and nutrient concentrations, and higher concentrations of organic microcontaminants, particularly pharmaceutical and alkylphenol compounds. • Physico-chemical stressors (high nutrients and dissolved organic matter, altered water flow) were the ones mostly affecting biodiversity. • The simultaneous occurrence of microcontaminants with physico-chemical stressors in urban-industrial areas produced a much higher effect than the simple addition of stressors. - Organic microcontaminants reinforce the effects of environmental and land use stressors on

  15. Resilience and recovery: The effect of triclosan exposure timing during development, on the structure and function of river biofilm communities

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.R., E-mail: john.lawrence@ec.gc.ca [Environment Canada, 11 Innovation Blvd., Saskatoon, SK S7N 3H5 (Canada); Topp, E. [Agriculture and Agri-Food Canada, London, ON (Canada); Waiser, M.J.; Tumber, V.; Roy, J.; Swerhone, G.D.W. [Environment Canada, 11 Innovation Blvd., Saskatoon, SK S7N 3H5 (Canada); Leavitt, P. [University of Regina, Regina, SK (Canada); Paule, A. [Global Institute for Water Security, University of Saskatchewan, Saskatoon, SK (Canada); Korber, D.R. [Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK (Canada)

    2015-04-15

    Highlights: • Triclosan negatively affected structure and metabolism of biofilms under all exposure conditions. • Biofilm age, timing and exposure regime alter the effects of triclosan. • Regardless of exposure regime algae and cyanobacteria were the most affected. • Although recovery was evident no community regained the reference condition. • Initial recruitment may be significant in determining community recovery. - Abstract: Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 μg l{sup −1} TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: (i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and (ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (p < 0.05) reductions in cyanobacterial biomass. No significant effects were observed on bacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism

  16. Resilience and recovery: The effect of triclosan exposure timing during development, on the structure and function of river biofilm communities

    International Nuclear Information System (INIS)

    Lawrence, J.R.; Topp, E.; Waiser, M.J.; Tumber, V.; Roy, J.; Swerhone, G.D.W.; Leavitt, P.; Paule, A.; Korber, D.R.

    2015-01-01

    Highlights: • Triclosan negatively affected structure and metabolism of biofilms under all exposure conditions. • Biofilm age, timing and exposure regime alter the effects of triclosan. • Regardless of exposure regime algae and cyanobacteria were the most affected. • Although recovery was evident no community regained the reference condition. • Initial recruitment may be significant in determining community recovery. - Abstract: Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 μg l −1 TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: (i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and (ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (p < 0.05) reductions in cyanobacterial biomass. No significant effects were observed on bacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism

  17. Application of Biofilm Covered Activated Carbon Particles as a Microbial Inoculum Delivery System for Enhanced Bioaugmentation of PCBs in Contaminated Sediment

    Science.gov (United States)

    2013-09-01

    after anaerobic digestion at thermophilic conditions (60- 70C). Application of biofilm covered activated carbon particles as a microbial inoculum...Sludge Thickener; Sludge = Sludge after anaerobic digestion at thermophilic conditions (60- 70C). C3. Microscopic evaluation of dechlorinating...associated enzymes are capable of opening the biphenyl ring structure and transform the molecule into a linear structure, this changed structure was not

  18. Hydraulic continuity and biological effects of low strength very low frequency electromagnetic waves: Case of microbial biofilm growth in water treatment.

    Science.gov (United States)

    Gérard, Merlin; Noamen, Omri; Evelyne, Gonze; Eric, Valette; Gilles, Cauffet; Marc, Henry

    2015-10-15

    This study aims to elucidate the interactions between water, subjected to electromagnetic waves of very low frequency (VLF) (kHz) with low strength electromagnetic fields (3.5 mT inside the coils), and the development of microbial biofilms in this exposed water. Experimental results demonstrate that in water exposed to VLF electromagnetic waves, the biomass of biofilm is limited if hydraulic continuity is achieved between the electromagnetic generator and the biofilm media. The measured amount of the biofilm's biomass is approximately a factor two lower for exposed biofilm than the non-exposed biofilm. Measurements of electromagnetic fields in the air and simulations exhibit very low intensities of fields (electromagnetic generator. Exposure to electric and magnetic fields of the quoted intensities cannot explain thermal and ionizing effects on the biofilm. A variable electrical potential with a magnitude close to 20 mV was detected in the tank in hydraulic continuity with the electromagnetic generator. The application of quantum field theory may help to explain the observed effects in this case. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Graphene/biofilm composites for enhancement of hexavalent chromium reduction and electricity production in a biocathode microbial fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tian-shun [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816 (China); College of Life Science and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816 (China); Jiangsu Branch of China Academy of Science & Technology Development, Nanjing (China); Jin, Yuejuan; Bao, Jingjing [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816 (China); College of Life Science and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816 (China); Kang, Dongzhou, E-mail: kangdz@ybu.edu.cn [College of Pharmacy, Yanbian University, Yanji 133002 (China); Xie, Jingjing, E-mail: xiej@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816 (China); College of Life Science and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816 (China); Jiangsu Branch of China Academy of Science & Technology Development, Nanjing (China); College of Pharmacy, Yanbian University, Yanji 133002 (China); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing 211816 (China)

    2016-11-05

    Highlights: • Graphene/biofilm was microbially fabricated to cathode of a Cr(VI)-reducing MFC. • High Cr(VI) reduction rate was generated by self-assembled graphene biocathode MFC. • Graphene biocathode improves the electricity production of Cr(VI)-reducing MFC. • High surface area of the graphene provides more adsorption sites for Cr(VI). • Graphene biocathode improves the electron transfer rate in the MFC. - Abstract: In this study, a simple method of biocathode fabrication in a Cr(VI)-reducing microbial fuel cell (MFC) is demonstrated. A self-assembling graphene was decorated onto the biocathode microbially, constructing a graphene/biofilm, in situ. The maximum power density of the MFC with a graphene biocathode is 5.7 times that of the MFC with a graphite felt biocathode. Cr(VI) reduction was also enhanced, resulting in 100% removal of Cr(VI) within 48 h, at 40 mg/L Cr(VI), compared with only 58.3% removal of Cr(VI) in the MFC with a graphite felt biocathode. Cyclic voltammogram analyses showed that the graphene biocathode had faster electron transfer kinetics than the graphite felt version. Energy dispersive spectrometer (EDS) and X-ray photoelectron spectra (XPS) analysis revealed a possible adsorption-reduction mechanism for Cr(VI) reduction via the graphene biocathode. This study attempts to improve the efficiency of the biocathode in the Cr(VI)-reducing MFC, and provides a useful candidate method for the treatment of Cr(VI) contaminated wastewater, under neutral conditions.

  20. Application of Microbial Technology Used in Bioremediation of Urban Polluted River: A Case Study of Chengnan River, China

    Directory of Open Access Journals (Sweden)

    Hong Gao

    2018-05-01

    Full Text Available Contrary to the constraints in time, investment, and management of the traditional technology for waste water treatment, this paper seeks to propose a more advanced, reliable, and affordable new technology to restore urban polluted rivers to pristine quality levels. The paper also presents new ideas on the selection and use of microbial agents to improve the efficiency of pollution removal. It presents the successful implementation of microbial technology (MT on Chengnan River, which was heavily polluted before MT implementation. Without artificial aeration, sediment dredging, or complete sewage interception, we directly sprayed a previously configured HP-RPe-3 Microbial Agent into the water body and sediment. We considered the feasibility of MT for treating polluted urban rivers from the perspective of several water quality indices evaluation methods. After the treatment, the concentration of dissolved oxygen (DO reached 5.0 mg/L, the removal rates of ammonia nitrogen (NH3-N and chemical oxygen demand (COD reached 20% and 38% respectively, and the average degradation rate of total phosphorus (TP along river was close to 15%. Also, the Nemerow Index of the river was reduced from 2.7 to 1.9. The Fuzzy Comprehensive Index shows a tendency for improvement from Inferior Grade V to a better grade (approximately Grade III. The color of the river water changed, from black or dark green, to its original color. The results indicate that the bioremediation technology of directly adding microbial agents mainly aimed for the degradation of NH3-N can preliminarily eliminate the black-odor phenomenon of urban rivers, and improve their water quality. It is expected that the MT application, and the concept of how to select the corresponding microbial agents according to main pollutants, can be widely accepted and applied to similar cases.

  1. Microbial activity catalyzes oxygen transfer in membrane-aerated nitritating biofilm reactors

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Domingo Felez, Carlos; Lackner, Susanne

    2013-01-01

    The remarkable oxygen transfer efficiencies attainable in membrane-aerated biofilm reactors (MABRs) are expected to favor their prompt industrial implementation. However, tests in clean water, currently used for the estimation of their oxygen transfer potential, lead to wrong estimates once biofilm...... is present, significantly complicating reactor modelling and control. This study shows for the first time the factors affecting oxygen mass transfer across membranes during clean water tests and reactor operation via undisturbed microelectrode inspection and bulk measurements. The mass transfer resistance...... of the liquid boundary layer developed at the membrane-liquid interface during clean water tests accounted for two thirds of the total mass transfer resistance, suggesting a strong underestimation of the oxygen transfer rates when it is absent (e.g. after biofilm growth). Reactor operation to attain partial...

  2. Evaluation on the microbial interactions of anaerobic ammonium oxidizers and heterotrophs in Anammox biofilm

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Ruscalleda, Mael; Smets, Barth F.

    2012-01-01

    and the affecting factors were evaluated with both experimental and modeling approaches. Fluorescent in situ hybridization (FISH) analysis illustrated that Anammox bacteria and heterotrophs accounted for 77% and 23% of the total bacteria, respectively, even without addition of an external carbon source....... Experimental results showed the heterotrophs could grow both on SMP and decay released substrate from the metabolism of the Anammox bacteria. However, heterotrophic growth in Anammox biofilm (23%) was significantly lower than that of nitrifying biofilm (30–50%). The model predictions matched well...... with the experimental observations of the bacterial distribution, as well as the nitrogenous transformations in batch and continuous experiments. The modeling results showed that low nitrogen surface loading resulted in a lower availability of SMP leading to low heterotrophic growth in Anammox biofilm, but high...

  3. Microbial investigation of biofilms recovered from endotracheal tubes using sonication in intensive care unit pediatric patients

    Directory of Open Access Journals (Sweden)

    Thiago de Oliveira Ferreira

    2016-09-01

    Conclusions: Our study demonstrated that sonication technique can be applied to ET biofilms to identify microorganisms attached to their surface with a great variety of species identified. However, we did not find significant differences in comparison with the traditional tracheal aspirate culture approach.

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

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Franck, Stephanie; Gülay, Arda

    2014-01-01

    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...

  5. Benzene degradation in a denitrifying biofilm reactor : activity and microbial community composition

    NARCIS (Netherlands)

    van der Waals, Marcelle J.; Atashgahi, Siavash; da Rocha, Ulisses Nunes; van der Zaan, Bas M.; Smidt, Hauke; Gerritse, Jan

    2017-01-01

    Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more than

  6. Distribution and rate of microbial processes in ammonia-loaded air filter biofilm

    DEFF Research Database (Denmark)

    Juhler, Susanne; Nielsen, Lars Peter; Schramm, Andreas

    2009-01-01

    The in situ activity and distribution of heterotrophic and nitrifying bacteria and their potential interactions were investigated in a full-scale, two-section, trickling filter designed for biological degradation of volatile organics and NH3 in ventilation air from pig farms. The filter biofilm...

  7. Detection of microbial biofilms on food processing surfaces: Hyperspectral fluorescence imaging study

    Science.gov (United States)

    We used a portable hyperspectral fluorescence imaging system to evaluate biofilm formations on four types of food processing surface materials including stainless steel, polypropylene used for cutting boards, and household counter top materials such as formica and granite. The objective of this inve...

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

    Czech Academy of Sciences Publication Activity Database

    Holá, V.; Růžička, F.; Horká, Marie

    2010-01-01

    Roč. 59, č. 3 (2010), s. 525-528 ISSN 0928-8244 R&D Projects: GA MZd(CZ) NS9678 Institutional research plan: CEZ:AV0Z40310501 Keywords : biofilm * sonication * urinary tract infection * catheter Subject RIV: CA - Inorganic Chemistry Impact factor: 2.494, year: 2010

  9. Bovine mastitis disease/pathogenicity: evidence of the potential role of microbial biofilms.

    Science.gov (United States)

    Gomes, Fernanda; Saavedra, Maria José; Henriques, Mariana

    2016-04-01

    Bovine mastitis (BM) is a disease with high incidence worldwide and one of the most relevant bovine pathologies and the most costly to the dairy industry. BM is an inflammation of the udder and represents one of the most difficult veterinary diseases to control. Biofilm formation is considered a selective advantage for pathogens causing mastitis, facilitating bacterial persistence in the udder. In fact, recently some authors drew attention to the biofilm formation ability presented by several mastitis causing pathogens and to its possible relation with recurrent mastitis infections and with the increased resistance to antimicrobial agents and host immune defence system. Actually, up to now, several researchers reported the potential role of cells in this mode of growth in the previous facts mentioned. As a consequence of the presence of biofilms, the infection here focused is more difficult to treat and eradicate, making this problem a more relevant pressing issue. Thus, we believe that a deeper knowledge of these structures in mastitis can help to determine the best control strategy to be used in veterinary practice in order to reduce losses in the dairy industry and to ensure milk safety and quality. The aim of this paper was to review the existing research and consequently to provide an overview of the role of biofilms in BM infections. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. Effect of Different Disinfection Protocols on Microbial and Biofilm Contamination of Dental Unit Waterlines in Community Dental Practices

    Directory of Open Access Journals (Sweden)

    Laura Dallolio

    2014-02-01

    Full Text Available Output water from dental unit waterlines (DUWLs may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two underwent continuous disinfection with hydrogen peroxide/silver ions (0.02% and stabilized chlorine dioxide (0.22%, respectively. After three months of applying the disinfection protocols, continuous disinfection systems were more effective than intermittent systems in reducing the microbial contamination of the water, allowing compliance with the CDC guidelines and the European Council regulatory thresholds for drinking water. P. aeruginosa, Legionella spp, sulphite-reducing Clostridium spores, S. aureus and β-haemolytic streptococci were also absent from units treated with continuous disinfection. The biofilm covering the DUWLs was more extensive, thicker and more friable in the intermittent disinfection dental units than in those with continuous disinfection. Overall, the findings showed that the products used for continuous disinfection of dental unit waterlines showed statistically better results than the intermittent treatment products under the study conditions.

  11. Effect of different disinfection protocols on microbial and biofilm contamination of dental unit waterlines in community dental practices.

    Science.gov (United States)

    Dallolio, Laura; Scuderi, Amalia; Rini, Maria S; Valente, Sabrina; Farruggia, Patrizia; Sabattini, Maria A Bucci; Pasquinelli, Gianandrea; Acacci, Anna; Roncarati, Greta; Leoni, Erica

    2014-02-18

    Output water from dental unit waterlines (DUWLs) may be a potential source of infection for both dental healthcare staff and patients. This study compared the efficacy of different disinfection methods with regard to the water quality and the presence of biofilm in DUWLs. Five dental units operating in a public dental health care setting were selected. The control dental unit had no disinfection system; two were disinfected intermittently with peracetic acid/hydrogen peroxide 0.26% and two underwent continuous disinfection with hydrogen peroxide/silver ions (0.02%) and stabilized chlorine dioxide (0.22%), respectively. After three months of applying the disinfection protocols, continuous disinfection systems were more effective than intermittent systems in reducing the microbial contamination of the water, allowing compliance with the CDC guidelines and the European Council regulatory thresholds for drinking water. P. aeruginosa, Legionella spp, sulphite-reducing Clostridium spores, S. aureus and β-haemolytic streptococci were also absent from units treated with continuous disinfection. The biofilm covering the DUWLs was more extensive, thicker and more friable in the intermittent disinfection dental units than in those with continuous disinfection. Overall, the findings showed that the products used for continuous disinfection of dental unit waterlines showed statistically better results than the intermittent treatment products under the study conditions.

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

    Science.gov (United States)

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

    2013-11-01

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

  13. Novel Approaches to Manipulating Bacterial Pathogen Biofilms: Whole-Systems Design Philosophy and Steering Microbial Evolution.

    Science.gov (United States)

    Penn, Alexandra S

    2016-01-01

    Understanding and manipulating bacterial biofilms is crucial in medicine, ecology and agriculture and has potential applications in bioproduction, bioremediation and bioenergy. Biofilms often resist standard therapies and the need to develop new means of intervention provides an opportunity to fundamentally rethink our strategies. Conventional approaches to working with biological systems are, for the most part, "brute force", attempting to effect control in an input and effort intensive manner and are often insufficient when dealing with the inherent non-linearity and complexity of living systems. Biological systems, by their very nature, are dynamic, adaptive and resilient and require management tools that interact with dynamic processes rather than inert artefacts. I present an overview of a novel engineering philosophy which aims to exploit rather than fight those properties, and hence provide a more efficient and robust alternative. Based on a combination of evolutionary theory and whole-systems design, its essence is what I will call systems aikido; the basic principle of aikido being to interact with the momentum of an attacker and redirect it with minimal energy expenditure, using the opponent's energy rather than one's own. In more conventional terms, this translates to a philosophy of equilibrium engineering, manipulating systems' own self-organisation and evolution so that the evolutionarily or dynamically stable state corresponds to a function which we require. I illustrate these ideas with a description of a proposed manipulation of environmental conditions to alter the stability of co-operation in the context of Pseudomonas aeruginosa biofilm infection of the cystic fibrosis lung.

  14. The formation of green rust induced by tropical river biofilm components

    International Nuclear Information System (INIS)

    Jorand, F.; Zegeye, A.; Ghanbaja, J.; Abdelmoula, M.

    2011-01-01

    In the Sinnamary Estuary (French Guiana), a dense red biofilm grows on flooded surfaces. In order to characterize the iron oxides in this biofilm and to establish the nature of secondary minerals formed after anaerobic incubation, we conducted solid analysis and performed batch incubations. Elemental analysis indicated a major amount of iron as inorganic compartment along with organic matter. Solid analysis showed the presence of two ferric oxides ferrihydrite and lepidocrocite. Bacteria were abundant and represented more than 10 11 cells g -1 of dry weight among which iron reducers were revealed. Optical and electronic microscopy analysis revealed than the bacteria were in close vicinity of the iron oxides. After anaerobic incubations with exogenous electron donors, the biofilm's ferric material was reduced into green rust, a Fe II -Fe III layered double hydroxide. This green rust remained stable for several years. From this study and previous reports, we suggest that ferruginous biofilms should be considered as a favorable location for GR biomineralization when redox conditions and electron donors availability are gathered. - Research highlights: → Characterization of ferruginous biofilm components by solid analysis methods. → Lepidocrocite and ferrihydrite were the main iron oxides. → Anaerobic incubation of biofilm with electron donors produced green rust. → Biofilm components promote the formation of the green rust. → Ferruginous biofilm could contribute to the natural mercury attenuation.

  15. The formation of green rust induced by tropical river biofilm components

    Energy Technology Data Exchange (ETDEWEB)

    Jorand, F., E-mail: jorand@pharma.uhp-nancy.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France); Zegeye, A. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France); Ghanbaja, J. [Service Commun de Microscopies Electroniques et Microanalyses X (SCMEM), Nancy-Universite, Bvd des Aiguillettes, BP 239, 54506, Vandoeuvre-les-Nancy (France); Abdelmoula, M. [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME) UMR 7564, CNRS-Nancy-Universite, Institut Jean Barriol, 405 rue de Vandoeuvre, F-54600 Villers-les Nancy (France)

    2011-06-01

    In the Sinnamary Estuary (French Guiana), a dense red biofilm grows on flooded surfaces. In order to characterize the iron oxides in this biofilm and to establish the nature of secondary minerals formed after anaerobic incubation, we conducted solid analysis and performed batch incubations. Elemental analysis indicated a major amount of iron as inorganic compartment along with organic matter. Solid analysis showed the presence of two ferric oxides ferrihydrite and lepidocrocite. Bacteria were abundant and represented more than 10{sup 11} cells g{sup -1} of dry weight among which iron reducers were revealed. Optical and electronic microscopy analysis revealed than the bacteria were in close vicinity of the iron oxides. After anaerobic incubations with exogenous electron donors, the biofilm's ferric material was reduced into green rust, a Fe{sup II}-Fe{sup III} layered double hydroxide. This green rust remained stable for several years. From this study and previous reports, we suggest that ferruginous biofilms should be considered as a favorable location for GR biomineralization when redox conditions and electron donors availability are gathered. - Research highlights: {yields} Characterization of ferruginous biofilm components by solid analysis methods. {yields} Lepidocrocite and ferrihydrite were the main iron oxides. {yields} Anaerobic incubation of biofilm with electron donors produced green rust. {yields} Biofilm components promote the formation of the green rust. {yields} Ferruginous biofilm could contribute to the natural mercury attenuation.

  16. Biophysics of biofilm infection.

    Science.gov (United States)

    Stewart, Philip S

    2014-04-01

    This article examines a likely basis of the tenacity of biofilm infections that has received relatively little attention: the resistance of biofilms to mechanical clearance. One way that a biofilm infection persists is by withstanding the flow of fluid or other mechanical forces that work to wash or sweep microorganisms out of the body. The fundamental criterion for mechanical persistence is that the biofilm failure strength exceeds the external applied stress. Mechanical failure of the biofilm and release of planktonic microbial cells is also important in vivo because it can result in dissemination of infection. The fundamental criterion for detachment and dissemination is that the applied stress exceeds the biofilm failure strength. The apparent contradiction for a biofilm to both persist and disseminate is resolved by recognizing that biofilm material properties are inherently heterogeneous. There are also mechanical aspects to the ways that infectious biofilms evade leukocyte phagocytosis. The possibility of alternative therapies for treating biofilm infections that work by reducing biofilm cohesion could (1) allow prevailing hydrodynamic shear to remove biofilm, (2) increase the efficacy of designed interventions for removing biofilms, (3) enable phagocytic engulfment of softened biofilm aggregates, and (4) improve phagocyte mobility and access to biofilm. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  17. Discriminating activated sludge flocs from biofilm microbial communities in a novel pilot-scale reciprocation MBR using high-throughput 16S rRNA gene sequencing.

    Science.gov (United States)

    De Sotto, Ryan; Ho, Jaeho; Lee, Woonyoung; Bae, Sungwoo

    2018-03-29

    Membrane bioreactors (MBRs) are a well-established filtration technology that has become a popular solution for treating wastewater. One of the drawbacks of MBRs, however, is the formation of biofilm on the surface of membrane modules. The occurrence of biofilms leads to biofouling, which eventually compromises water quality and damages the membranes. To prevent this, it is vital to understand the mechanism of biofilm formation on membrane surfaces. In this pilot-scale study, a novel reciprocation membrane bioreactor was operated for a period of 8 months and fed with domestic wastewater from an aerobic tank of a local WWTP. Water quality parameters were monitored and the microbial composition of the attached biofilm and suspended aggregates was evaluated in this reciprocating MBR configuration. The abundance of nitrifiers and composition of microbial communities from biofilm and suspended solids samples were investigated using qPCR and high throughput 16S amplicon sequencing. Removal efficiencies of 29%, 16%, and 15% of chemical oxygen demand, total phosphorus and total nitrogen from the influent were observed after the MBR process with average effluent concentrations of 16 mg/L, 4.6 mg/L, and 5.8 mg/L respectively. This suggests that the energy-efficient MBR, apart from reducing the total energy consumption, was able to maintain effluent concentrations that are within regulatory standards for discharge. Molecular analysis showed the presence of amoA Bacteria and 16S Nitrospira genes with the occurrence of nitrification. Candidatus Accumulibacter, a genus with organisms that can accumulate phosphorus, was found to be present in both groups which explains why phosphorus removal was observed in the system. High-throughput 16S rRNA amplicon sequencing revealed the genus Saprospira to be the most abundant species from the total OTUs of both the membrane tank and biofilm samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. 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

    Directory of Open Access Journals (Sweden)

    Parro Víctor

    2010-06-01

    Full Text Available Abstract 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

  19. 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.

    Science.gov (United States)

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

    2010-06-24

    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. 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. Our results indicate that the acidophilic filaments are dynamic structures

  20. Impact of a Novel, Anti-microbial Dressing on In Vivo, Pseudomonas aeruginosa Wound Biofilm: Quantitative Comparative Analysis using a Rabbit Ear Model

    Science.gov (United States)

    2014-12-01

    therapies such as debridement , lavage, and antimicrobials, but with little evidence that they improve chronic wound healing in a quantitative and... TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Impact of a novel, anti-microbial dressing on in vivo, Pseudomonas aeruginosa wound biofilm...study. Bacterial strains and culture Wild- type strains of P. aeruginosa (obtained from the labora- tory of Dr. Barbara H. Iglewski, University of

  1. Microbial succession within an anaerobic sequencing batch biofilm reactor (ASBBR treating cane vinasse at 55ºC

    Directory of Open Access Journals (Sweden)

    Maria Magdalena Ferreira Ribas

    2009-08-01

    Full Text Available The aim of this work was to investigate the anaerobic biomass formation capable of treating vinasse from the production of sugar cane alcohol, which was evolved within an anaerobic sequencing batch biofilm reactor (ASBBR as immobilized biomass on cubes of polyurethane foam at the temperature of 55ºC. The reactor was inoculated with mesophilic granular sludge originally treating poultry slaughterhouse wastewater. The evolution of the biofilm in the polyurethane foam matrices was assessed during seven experimental phases which were thus characterized by the changes in the organic matter concentrations as COD (1.0 to 20.0 g/L. Biomass characterization proceeded with the examination of sludge samples under optical and scanning electron microscopy. The reactor showed high microbial morphological diversity along the trial. The predominance of Methanosaeta-like cells was observed up to the organic load of 2.5 gCOD/L.d. On the other hand, Methanosarcinalike microorganisms were the predominant archaeal population within the foam matrices at high organic loading ratios above 3.3 gCOD/L.d. This was suggested to be associated to a higher specific rate of acetate consumption by the later organisms.Este trabalho investigou a formação de um biofilme anaeróbio capaz de tratar vinhaça da produção de álcool de cana-de-açúcar, que evoluiu dentro de um reator operado em bateladas seqüenciais com biofilme (ASBBR tendo a biomassa imobilizada em cubos de espuma de poliuretano na temperatura de 55ºC. O reator foi inoculado com lodo granular mesofílico tratando água residuária de abatedouro de aves. A evolução do biofilme nas matrizes de espuma de poliuretano foi observada durante sete fases experimentais que foram caracterizadas por mudanças nas concentrações de matéria orgânica como DQO (1,0 a 20,0 g/L. A caracterização da biomassa foi feita por exames de amostras do lodo em microscopia ótica e eletrônica de varredura. O reator apresentou

  2. Microbial Gene Abundance and Expression Patterns across a River to Ocean Salinity Gradient.

    Directory of Open Access Journals (Sweden)

    Caroline S Fortunato

    Full Text Available Microbial communities mediate the biogeochemical cycles that drive ecosystems, and it is important to understand how these communities are affected by changing environmental conditions, especially in complex coastal zones. As fresh and marine waters mix in estuaries and river plumes, the salinity, temperature, and nutrient gradients that are generated strongly influence bacterioplankton community structure, yet, a parallel change in functional diversity has not been described. Metagenomic and metatranscriptomic analyses were conducted on five water samples spanning the salinity gradient of the Columbia River coastal margin, including river, estuary, plume, and ocean, in August 2010. Samples were pre-filtered through 3 μm filters and collected on 0.2 μm filters, thus results were focused on changes among free-living microbial communities. Results from metagenomic 16S rRNA sequences showed taxonomically distinct bacterial communities in river, estuary, and coastal ocean. Despite the strong salinity gradient observed over sampling locations (0 to 33, the functional gene profiles in the metagenomes were very similar from river to ocean with an average similarity of 82%. The metatranscriptomes, however, had an average similarity of 31%. Although differences were few among the metagenomes, we observed a change from river to ocean in the abundance of genes encoding for catabolic pathways, osmoregulators, and metal transporters. Additionally, genes specifying both bacterial oxygenic and anoxygenic photosynthesis were abundant and expressed in the estuary and plume. Denitrification genes were found throughout the Columbia River coastal margin, and most highly expressed in the estuary. Across a river to ocean gradient, the free-living microbial community followed three different patterns of diversity: 1 the taxonomy of the community changed strongly with salinity, 2 metabolic potential was highly similar across samples, with few differences in

  3. Microbial Gene Abundance and Expression Patterns across a River to Ocean Salinity Gradient.

    Science.gov (United States)

    Fortunato, Caroline S; Crump, Byron C

    2015-01-01

    Microbial communities mediate the biogeochemical cycles that drive ecosystems, and it is important to understand how these communities are affected by changing environmental conditions, especially in complex coastal zones. As fresh and marine waters mix in estuaries and river plumes, the salinity, temperature, and nutrient gradients that are generated strongly influence bacterioplankton community structure, yet, a parallel change in functional diversity has not been described. Metagenomic and metatranscriptomic analyses were conducted on five water samples spanning the salinity gradient of the Columbia River coastal margin, including river, estuary, plume, and ocean, in August 2010. Samples were pre-filtered through 3 μm filters and collected on 0.2 μm filters, thus results were focused on changes among free-living microbial communities. Results from metagenomic 16S rRNA sequences showed taxonomically distinct bacterial communities in river, estuary, and coastal ocean. Despite the strong salinity gradient observed over sampling locations (0 to 33), the functional gene profiles in the metagenomes were very similar from river to ocean with an average similarity of 82%. The metatranscriptomes, however, had an average similarity of 31%. Although differences were few among the metagenomes, we observed a change from river to ocean in the abundance of genes encoding for catabolic pathways, osmoregulators, and metal transporters. Additionally, genes specifying both bacterial oxygenic and anoxygenic photosynthesis were abundant and expressed in the estuary and plume. Denitrification genes were found throughout the Columbia River coastal margin, and most highly expressed in the estuary. Across a river to ocean gradient, the free-living microbial community followed three different patterns of diversity: 1) the taxonomy of the community changed strongly with salinity, 2) metabolic potential was highly similar across samples, with few differences in functional gene abundance

  4. Assessment of the microbial quality of river water sources in rural ...

    African Journals Online (AJOL)

    drinie

    2002-07-03

    Jul 3, 2002 ... Assessment of the microbial quality of river water sources ... These untreated water sources are used for drinking and domestic purposes and pose a serious threat to ... These diseases cause crippling, devastating and debilitating effects ..... gastrointestinal illness, due mainly by enteric viruses in sewage.

  5. Resistance and recovery of river biofilms receiving short pulses of Triclosan and Diuron.

    Science.gov (United States)

    Proia, L; Morin, S; Peipoch, M; Romaní, A M; Sabater, S

    2011-08-01

    The effects of the herbicide Diuron (DIU) and the bactericide Triclosan (TCS) were assessed on laboratory-grown stream biofilms. Four week-old biofilms were exposed in mesocosms to 48-hours of short pulses of either DIU or TCS. The direct and indirect effects of each toxicant on the biofilms, and the subsequent recovery of the biofilms, were evaluated according to structural and functional biomarkers. These parameters were analyzed immediately before exposure, immediately after exposure, and 9 and 16days post-exposure. DIU caused an increase in diatom mortality (+79%), which persisted until the end of the experiment. TCS also affected diatom mortality (+41%), although the effect did not appear until 1week post-exposure. TCS caused an increase in bacterial mortality (+45%); however, this parameter returned to normal values 1week post-exposure. TCS compromised the cellular integrity of the green alga Spirogyra sp., whereas DIU did not. TCS also strongly inhibited phosphate uptake (-71%), which did not return to normal values until 2weeks post-exposure. DIU directly affected algae, but barely affected the heterotrophs, whereas TCS seriously impaired bacteria (direct effect) as well as autotrophs (indirect effect). However, the biofilms recovered their normal structure and function within only a few days to a few weeks. These findings demonstrate the capacity of biofilms to cope with periodic inputs of toxicants, but also the risks associated to repeated exposure or multi-contamination in aquatic ecosystems. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Microbial Interactions Associated with Biofilms Attached to Trichodesmium spp. and Detrital Particles in the Ocean

    Science.gov (United States)

    2010-06-01

    Wire devotee) and Maya Bhatia (running buddy, climbing partner, fellow coffee addict) were with me (nearly) to the bitter end. Dave Griffith...Naturwissenschaften 65: 598-599. Hewson, I., Poretsky, R. S., Dyhrman, S. T., Zielinski , B., White, A. E., Tripp, H. J. et al. (2009) Microbial community gene

  7. Metagenome Analyses of Corroded Concrete Wastewater Pipe Biofilms Reveals a Complex Microbial System

    Science.gov (United States)

    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. Taxonomic and functio...

  8. Modification of the surfaces of medical devices to prevent microbial adhesion and biofilm formation.

    Science.gov (United States)

    Desrousseaux, C; Sautou, V; Descamps, S; Traoré, O

    2013-10-01

    The development of devices with surfaces that have an effect against microbial adhesion or viability is a promising approach to the prevention of device-related infections. To review the strategies used to design devices with surfaces able to limit microbial adhesion and/or growth. A PubMed search of the published literature. One strategy is to design medical devices with a biocidal agent. Biocides can be incorporated into the materials or coated or covalently bonded, resulting either in release of the biocide or in contact killing without release of the biocide. The use of biocides in medical devices is debated because of the risk of bacterial resistance and potential toxicity. Another strategy is to modify the chemical or physical surface properties of the materials to prevent microbial adhesion, a complex phenomenon that also depends directly on microbial biological structure and the environment. Anti-adhesive chemical surface modifications mostly target the hydrophobicity features of the materials. Topographical modifications are focused on roughness and nanostructures, whose size and spatial organization are controlled. The most effective physical parameters to reduce bacterial adhesion remain to be determined and could depend on shape and other bacterial characteristics. A prevention strategy based on reducing microbial attachment rather than on releasing a biocide is promising. Evidence of the clinical efficacy of these surface-modified devices is lacking. Additional studies are needed to determine which physical features have the greatest potential for reducing adhesion and to assess the usefulness of antimicrobial coatings other than antibiotics. Copyright © 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  9. Soil Gas Dynamics and Microbial Activity in the Unsaturated Zone of a Regulated River

    Science.gov (United States)

    Christensen, H.; Ferencz, S. B.; Cardenas, M. B.; Neilson, B. T.; Bennett, P. C.

    2017-12-01

    Over 60% of the world's rivers are dammed, and are therefore regulated. In some river systems, river regulation is the dominant factor governing fluid exchange and soil gas dynamics in the hyporheic region and overlying unsaturated zone of the river banks. Where this is the case, it is important to understand the effects that an artificially-induced change in river stage can have on the chemical, plant, and microbial components of the unsaturated zone. Daily releases from an upstream dam cause rapid stage fluctuations in the Lower Colorado River east of Austin, Texas. For this study, we utilized an array of water and gas wells along a transect perpendicular to the river to investigate the biogeochemical process occurring in this mixing zone. The gas wells were installed at several depths up to 1.5 meters, and facilitated the continuous monitoring of soil gases as the pulse percolated through the river bank. Water samples collected from the screened wells penetrated to depths below the water table and were analyzed for nutrients, carbon, and major ions. Additionally, two soil cores were taken at different distances from the river and analyzed for soil moisture and grain size. These cores were also analyzed for microbial activity using the total heterotroph count method and the acetylene inhibition technique, a sensitive method of measuring denitrifying activity. The results provide a detailed picture of soil gas flux and biogeochemical processes in the bank environment in a regulated river. Findings indicate that a river pulse that causes a meter-scale change in river stage causes small, centimeter-scale pulses in the water table. We propose that these conditions create an area of elevated microbial respiration at the base of the unsaturated zone that appears to be decoupled from normal diurnal fluctuations. Along the transect, CO2 concentrations increased with increasing depth down to the water table. CO2 concentrations were highest in the time following a pulse

  10. Microbial functional genes enriched in the Xiangjiang River sediments with heavy metal contamination.

    Science.gov (United States)

    Jie, Shiqi; Li, Mingming; Gan, Min; Zhu, Jianyu; Yin, Huaqun; Liu, Xueduan

    2016-08-08

    Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River. A total of 25595 functional genes involved in different biogeochemical processes have been detected in three sites, and different diversities and structures of microbial functional genes were observed. The analysis of gene overlapping, unique genes, and various diversity indices indicated a significant correlation between the level of heavy metal contamination and the functional diversity. Plentiful resistant genes related to various metal were detected, such as copper, arsenic, chromium and mercury. The results indicated a significantly higher abundance of genes involved in metal resistance including sulfate reduction genes (dsr) in studied site with most serious heavy metal contamination, such as cueo, mer, metc, merb, tehb and terc gene. With regard to the relationship between the environmental variables and microbial functional structure, S, Cu, Cd, Hg and Cr were the dominating factor shaping the microbial distribution pattern in three sites. This study suggests that high level of heavy metal contamination resulted in higher functional diversity and the abundance of metal resistant genes. These variation therefore significantly contribute to the resistance, resilience and stability of the microbial community subjected to the gradient of heavy metals contaminant in Xiangjiang River.

  11. Stimulation of electro-fermentation in single-chamber microbial electrolysis cells driven by genetically engineered anode biofilms

    Science.gov (United States)

    Awate, Bhushan; Steidl, Rebecca J.; Hamlischer, Thilo; Reguera, Gemma

    2017-07-01

    Unwanted metabolites produced during fermentations reduce titers and productivity and increase the cost of downstream purification of the targeted product. As a result, the economic feasibility of otherwise attractive fermentations is low. Using ethanol fermentation by the consolidated bioprocessing cellulolytic bacterium Cellulomonas uda, we demonstrate the effectiveness of anodic electro-fermentations at maximizing titers and productivity in a single-chamber microbial electrolysis cell (SCMEC) without the need for metabolic engineering of the fermentative microbe. The performance of the SCMEC platform relied on the genetic improvements of anode biofilms of the exoelectrogen Geobacter sulfurreducens that prevented the oxidation of cathodic hydrogen and improved lactate oxidation. Furthermore, a hybrid bioanode was designed that maximized the removal of organic acids in the fermentation broth. The targeted approach increased cellobiose consumption rates and ethanol titers, yields, and productivity three-fold or more, prevented pH imbalances and reduced batch-to-batch variability. In addition, the sugar substrate was fully consumed and ethanol was enriched in the broth during the electro-fermentation, simplifying its downstream purification. Such improvements and the possibility of scaling up SCMEC configurations highlight the potential of anodic electro-fermentations to stimulate fermentative bacteria beyond their natural capacity and to levels required for industrial implementation.

  12. The Microbial contamination of the Hornad river drainage

    Directory of Open Access Journals (Sweden)

    Zdenka Maťašová

    2005-11-01

    Full Text Available This article deals with the microbiological aspect of the quality assessment of the Hornád river drainage surface waters. The Microbiological parameters were studied in Hornád, Torysa, and Hnilec rivers. During the study period, water quality increase by one degree was observed in most of the sampled areas. Water quality in the sampled areas ranged between polluted and very strongly polluted. The main cause of the pollution is the increased abundance of coliform and thermo-tolerant coliform bacteria. Main reason for the found increased abundance is: public sewage water, waste water from the nearby settlements and allotments, and waste waters from hospitals and sanatoria.

  13. Polluted Alamuyo River: Impacts on surrounding wells, microbial ...

    African Journals Online (AJOL)

    SERVER

    2008-02-19

    Feb 19, 2008 ... (A) and down stream (F) of the river were also evaluated using ... pathogens isolated from the wastewater can survive in ... and control were fixed in ethanol- glacial acetic acid (3:1, v/v). The ..... aquatic toixity and characterization of chemical and micro- ... wastewater in anaerobic sequencing batch reactors.

  14. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

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

  15. Microbial biofilms for the removal of Cu²⁺ from CMP wastewater.

    Science.gov (United States)

    Mosier, Aaron P; Behnke, Jason; Jin, Eileen T; Cady, Nathaniel C

    2015-09-01

    The modern semiconductor industry relies heavily on a process known as chemical mechanical planarization, which uses physical and chemical processes to remove excess material from the surface of silicon wafers during microchip fabrication. This process results in large volumes of wastewater containing dissolved metals including copper (Cu(2+)), which must then be filtered and treated before release into municipal waste systems. We have investigated the potential use of bacterial and fungal biomass as an alternative to the currently used ion-exchange resins for the adsorption of dissolved Cu(2+) from high-throughput industrial waste streams. A library of candidate microorganisms, including Lactobacillus casei and Pichia pastoris, was screened for ability to bind Cu(2+) from solution and to form static biofilm communities within packed-bed adsorption columns. The binding efficiency of these biomass-based adsorption columns was assessed under various flow conditions and compared to that of industrially used ion-exchange resins. We demonstrated the potential to regenerate the biomass within the adsorption columns through the use of a hydrochloric acid wash, and subsequently reuse the columns for additional copper binding. While the binding efficiency and capacity of the developed L. casei/P. pastoris biomass filters was inferior to ion-exchange resin, the potential for repeated reuse of these filters, coupled with the advantages of a more sustainable "green" adsorption process, make this technique an attractive candidate for use in industrial-scale CMP wastewater treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. The Impact of Human Activities on Microbial Quality of Rivers in the Vhembe District, South Africa

    Directory of Open Access Journals (Sweden)

    Afsatou N. Traoré

    2016-08-01

    Full Text Available Background: Water quality testing is dictated by microbial agents found at the time of sampling in reference to their acceptable risk levels. Human activities might contaminate valuable water resources and add to the microbial load present in water bodies. Therefore, the effects of human activities on the microbial quality of rivers collected from twelve catchments in the Vhembe District in South Africa were investigated, with samples analyzed for total coliform (TC and Eschericha coli (E. coli contents. Methods: Physical parameters and various human activities were recorded for each sampling site. The Quanti-Tray® method was adopted for the assessment of TC and E. coli contents in the rivers over a two-year period. A multiplex polymerase chain (PCR method was used to characterize the strains of E. coli found. Results: The microbial quality of the rivers was poor with both TC and E. coli contents found to be over acceptable limits set by the South African Department of Water and Sanitation (DWS. No significant difference (p > 0.05 was detected between TC and E. coli risks in dry and wet seasons. All six pathogenic E. coli strains were identified and Enteroaggregative E. coli (EAEC, atypical Enteropathogenic E. coli (a-EPEC and Enterotoxigenic E. coli (ETEC were the most prevalent E. coli strains detected (respectively, 87%, 86% and 83%. Conclusions: The study indicated that contamination in the majority of sampling sites, due to human activities such as car wash, animal grazing and farming, poses health risks to communities using the rivers for various domestic chores. It is therefore recommended that more education by the respective departments is done to avert pollution of rivers and prevent health risks to the communities in the Vhembe District.

  17. Microbial water quality in the upper Olifants River catchment: implications for health

    CSIR Research Space (South Africa)

    Le Rouw, Wouter J

    2012-09-01

    Full Text Available poor to fair condition. Mining-related disturbances were seen as *Corresponding author. E-mail: wleroux@csir.co.za. Tel: (+27)12 841 2189. the main cause of impairment of river health in the upper parts of the catchment, with the exception... relationship, N50: median infectious dose, r: parameter characterised by dose-response relationship. Microbial monitoring Microbial water quality was monitored over a two year period. During the first year, faecal indicator counts (E. coli) levels...

  18. Metal Transport, Heavy Metal Speciation and Microbial Fixation Through Fluvial Subenvironments, Lower Coeur D'Alene River Valley, Idaho

    Science.gov (United States)

    Hooper, R. L.; Mahoney, J. B.

    2001-12-01

    and authigenic carbonate and sulfide phases. Marshes subjected to periodic subaerial exposure/flooding are even more complex and dominated by authigenic and biogenic mineralization. Lacustrine environments are dominated by nanocrystalline inorganic and biogenic sulfide minerals in the upper third of the contaminated sediment column with increasing amounts of silt sized detrital sulfides (especially sphalerite) closer to the premining surface. In pH-neutral subenvironments within the wetlands and lateral lakes of the lower Coeur d'Alene River Valley, microbial fixation plays a critical role in sequestering metals. Complex metal oxyhydroxide phases provided via flood recharge to river edge, marsh and lacustrine environments rapidly dissolve upon encountering anoxic conditions. Microbial activity is extremely effective in removing heavy metals from the water column, producing a nanocrystalline biofilm substrate characterized by ZnS (sphalerite) and non-stoichiometric PbS, FeS, and mixed metal sulfides. These solid phases are inherently unstable, and the sequestered metals become readily available through changes in redox or pH conditions, particularly dam-controlled annual fluctuations in base level, or during removal by bottom-feeding aquatic water fowl. The recognition of the inherent complexity and instability of microbially produced sulfidic material in a pH-neutral environment has important implications for remediation efforts utilizing wetland filtration methods.

  19. Organic priority substances and microbial processes in river sediments subject to contrasting hydrological conditions.

    Science.gov (United States)

    Zoppini, Annamaria; Ademollo, Nicoletta; Amalfitano, Stefano; Casella, Patrizia; Patrolecco, Luisa; Polesello, Stefano

    2014-06-15

    Flood and drought events of higher intensity and frequency are expected to increase in arid and semi-arid regions, in which temporary rivers represent both a water resource and an aquatic ecosystem to be preserved. In this study, we explored the variation of two classes of hazardous substances (Polycyclic Aromatic Hydrocarbons and Nonylphenols) and the functioning of the microbial community in river sediments subject to hydrological fluctuations (Candelaro river basin, Italy). Overall, the concentration of pollutants (∑PAHs range 8-275ngg(-1); ∑NPs range 299-4858ngg(-1)) suggests a moderate degree of contamination. The conditions in which the sediments were tested, flow (high/low) and no flow (wet/dry/arid), were associated to significant differences in the chemical and microbial properties. The total organic carbon contribution decreased together with the stream flow reduction, while the contribution of C-PAHs and C-NPs tended to increase. NPs were relatively more concentrated in sediments under high flow, while the more hydrophobic PAHs accumulated under low and no flow conditions. Passing from high to no flow conditions, a gradual reduction of microbial processes was observed, to reach the lowest specific bacterial carbon production rates (0.06fmolCh(-1)cell(-1)), extracellular enzyme activities, and the highest doubling time (40h) in arid sediments. In conclusion, different scenarios for the mobilization of pollutants and microbial processes can be identified under contrasting hydrological conditions: (i) the mobilization of pollutants under high flow and a relatively higher probability for biodegradation; (ii) the accumulation of pollutants during low flow and lower probability for biodegradation; (iii) the drastic reduction of pollutant concentrations under dry and arid conditions, probably independently from the microbial activity (abiotic processes). Our findings let us infer that a multiple approach has to be considered for an appropriate water

  20. Linking community tolerance and structure with low metallic contamination: a field study on 13 biofilms sampled across the Seine river basin.

    Science.gov (United States)

    Fechner, Lise C; Gourlay-Francé, Catherine; Tusseau-Vuillemin, Marie-Hélène

    2014-03-15

    It is difficult to assess the biological consequences of diffuse water contamination by micropollutants which are present in rivers at low, even sublethal levels. River biofilms, which respond quickly to changes of environmental parameters, are good candidates to acquire knowledge on the response of aquatic organisms to diffuse chemical contamination in the field. The study was designed as an attempt to link biofilm metal tolerance and metallic contamination in a field survey covering 13 different sampling sites in the Seine river basin (north of France) with low contamination levels. Cd and Zn tolerance of heterotrophic communities was assessed using a short-term toxicity test based on β-glucosidase activity. Metal tolerance levels varied between sites but there was no obvious correlation between tolerance and corresponding water contamination levels for Cd and Zn. Indeed, metallic contamination at the sampling sites remained subtle when compared to water quality standards (only two sampling sites had either Zn or both Cu and Zn concentrations exceeding the Environmental Quality Standards set by the EU Water Framework Directive). Yet, multivariate analysis of the data using Partial Least Squares Regression revealed that both metallic and environmental parameters were important variables explaining the variability of metal tolerance levels. Automated Ribosomal Intergenic Spacer Analysis (ARISA) was also performed on both bacterial and eukaryotic biofilm communities from the 13 sampling sites. Multivariate analysis of ARISA fingerprints revealed that biofilms with similar tolerance levels have similar ARISA profiles. Those results confirm that river biofilms are potential indicators of low, diffuse contamination levels of aquatic systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Confocal microscopy imaging of the biofilm matrix

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Meyer, Rikke L

    2017-01-01

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

  2. Energy Harvesting From River Sediment Using a Microbial Fuel Cell: Preliminary Results

    Directory of Open Access Journals (Sweden)

    Philippe Namour

    2014-05-01

    Full Text Available We have built a sedimentary fuel cell or Sediment Microbial Fuel Cell (SMFC. The device works on the principle of microbial fuel cells by exploiting directly the energy contained in sedimentary organic matter. It converts in electricity the sediment potential, thanks to microorganisms able to waste electrons from their metabolism directly to a solid anode instead of their natural electron acceptors, such as oxygen or nitrate. The sediment microbial fuel cell was made of a non-corrodible anode (graphite buried in anoxic sediments layer and connected via an electrical circuit to a cathode installed in surface water. We present the first results of laboratory sedimentary fuel cell and a prototype installed in the river.

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

    KAUST Repository

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

    2012-01-01

    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

  4. Effects of porous carrier size on biofilm development, microbial distribution and nitrogen removal in microaerobic bioreactors

    KAUST Repository

    Ahmad, Muhammad; Liu, Sitong; Mahmood, Nasir; Mahmood, Asif; Ali, Muhammad; Zheng, Maosheng; Ni, Jinren

    2017-01-01

    In this study, effects of porous carrier’s size (polyurethane-based) on microbial characteristics were systematically investigated in addition to nitrogen removal performance in six microaerobic bioreactors. Among different sized carriers (50, 30, 20, 15,10, 5 mm), 15 mm carrier showed highest nitrogen removal (98%) due to optimal micro-environments created for aerobic nitrifiers in outer layer (0∼7 mm), nitrifiers and denitrifiers in middle layer (7∼10 mm) and anaerobic denitrifiers in inner layer (10∼15 mm). Candidatus brocadia, a dominant anammox bacteria, was solely concentrated close to centroid (0∼70 μm) and strongly co-aggregated with other bacterial communities in the middle layer of the carrier. Contrarily, carriers with a smaller (<15 mm) or larger size (>15 mm) either destroy the effective zone for anaerobic denitrifiers or damage the microaerobic environments due to poor mass transfer. This study is of particular use for optimal design of carriers in enhancing simultaneous nitrification-denitrification in microaerobic wastewater treatment processes.

  5. Effects of porous carrier size on biofilm development, microbial distribution and nitrogen removal in microaerobic bioreactors

    KAUST Repository

    Ahmad, Muhammad

    2017-03-15

    In this study, effects of porous carrier’s size (polyurethane-based) on microbial characteristics were systematically investigated in addition to nitrogen removal performance in six microaerobic bioreactors. Among different sized carriers (50, 30, 20, 15,10, 5 mm), 15 mm carrier showed highest nitrogen removal (98%) due to optimal micro-environments created for aerobic nitrifiers in outer layer (0∼7 mm), nitrifiers and denitrifiers in middle layer (7∼10 mm) and anaerobic denitrifiers in inner layer (10∼15 mm). Candidatus brocadia, a dominant anammox bacteria, was solely concentrated close to centroid (0∼70 μm) and strongly co-aggregated with other bacterial communities in the middle layer of the carrier. Contrarily, carriers with a smaller (<15 mm) or larger size (>15 mm) either destroy the effective zone for anaerobic denitrifiers or damage the microaerobic environments due to poor mass transfer. This study is of particular use for optimal design of carriers in enhancing simultaneous nitrification-denitrification in microaerobic wastewater treatment processes.

  6. A miniature microbial fuel cell with conducting nanofibers-based 3D porous biofilm

    International Nuclear Information System (INIS)

    Jiang, Huawei; Dong, Liang; Halverson, Larry J

    2015-01-01

    Miniature microbial fuel cell (MFC) technology has received growing interest due to its potential applications in high-throughput screening of bacteria and mutants to elucidate mechanisms of electricity generation. This paper reports a novel miniature MFC with an improved output power density and short startup time, utilizing electrospun conducting poly(3,4-ethylenedioxythiophene) (PEDOT) nanofibers as a 3D porous anode within a 12 μl anolyte chamber. This device results in 423 μW cm −3 power density based on the volume of the anolyte chamber, using Shewanella oneidensis MR-1 as a model biocatalyst without any optimization of bacterial culture. The device also excels in a startup time of only 1hr. The high conductivity of the electrospun nanofibers makes them suitable for efficient electron transfer. The mean pore size of the conducting nanofibers is several micrometers, which is favorable for bacterial penetration and colonization of surfaces of the nanofibers. We demonstrate that S. oneidensis can fully colonize the interior region of this nanofibers-based porous anode. This work represents a new attempt to explore the use of electrospun PEDOT nanofibers as a 3D anode material for MFCs. The presented miniature MFC potentially will provide a high-sensitivity, high-throughput tool to screen suitable bacterial species and mutant strains for use in large-size MFCs. (paper)

  7. A synoptic survey of microbial respiration, organic matter decomposition, and carbon efflux in U.S. streams and rivers

    Science.gov (United States)

    We analyzed microbial respiration and ecoenzyme activities related to organic matter processing in 1879 streams and rivers across the continental US as part of the USEPA’s 2008-2009 National Rivers and Streams Assessment. Ecoenzymatic stoichiometry was used to construct models fo...

  8. Dental biofilm: ecological interactions in health and disease

    NARCIS (Netherlands)

    Marsh, P.D.; Zaura, E.

    Background: The oral microbiome is diverse and exists as multispecies microbial communities on oral surfaces in structurally and functionally organized biofilms. Aim: To describe the network of microbial interactions (both synergistic and antagonistic) occurring within these biofilms and assess

  9. A prospective study on evaluation of pathogenesis, biofilm formation, antibiotic susceptibility of microbial community in urinary catheter

    Science.gov (United States)

    Younis, Khansa Mohammed; Usup, Gires; Ahmad, Asmat

    2015-09-01

    This study is aimed to isolate, detect biofilm formation ability and antibiotic susceptibility of urinary catheter adherent microorganisms from elderly hospitalized patient at the Universiti Kebangsaan Malaysia Medical Center. Microorganisms were isolated from three samples of urinary catheters (UC) surface; one of the acute vascular rejection patient (UCB) and two from benign prostate hyperplasia patients (UCC and UCD). A total of 100 isolates was isolated with 35 from UCB, 38 (UCC) and 28 (UCD). Ninety six were identified as Gram-negative bacilli, one Gram-positive bacilli and three yeasts. Results of biofilm forming on sterile foley catheter showed that all the isolates can form biofilm at different degrees; strong biofilm forming: 32% from the 35 isolates (UCB), 25% out of 38 isolates (UCC), 26% out of 28 isolates (UCD). As for moderate biofilm forming; 3% from UCB, 10% from UCC and 2% from UCD. Weak biofilm forming in UCC (3%). The antibiotic susceptibility for (UCB) isolates showed highly resistant to ampicillin, novobiocin and penicillin 100 (%), kanamycin (97%), tetracycline (94%), chloramphenicol (91%), streptomycin (77%) and showed low level of resistance to gentamycin (17%), while all the isolates from (UCC-D) showed high resistant towards ampicillin and penicillin, novobiocin (94%), tetracycline (61%), streptomycin (53%), gentamycin (50%) and low level of resistance to kanamycin (48%), chloramphenicol (47%). The findings indicate that these isolates can spread within the community on urinary catheters surface and produce strong biofilm, therefore, monitoring antibiotic susceptibility of bacteria isolated in the aggregation is recommended.

  10. Synchrotron Radiation X-Ray Fluorescence nanoanalyses of the metallome of a ~3.3 Ga-old microbial biofilm from the Barberton greenstone belt, South Africa.

    Science.gov (United States)

    Hubert, A.; Lemelle, L.; Salome, M.; Cloetens, P.; Westall, F.; Simionovici, A.

    2012-04-01

    Combining in situ nanometer-scale techniques on the fossilized Josefsdal Chert Microbial Biofilm (JCMB) reveals a distinct vertical structural and compositional organisation: the lower part is calcified as aragonite, while the upper non-calcified kerogenous layer is characterised by up to 1% sulphur [1]. The in situ analysis of all the metals as a group represents a useful microbial fingerprint [2] and we will continue to explore it. Synchrotron Radiation X-Ray Fluorescence maps of high spatial resolution (Conference Proceedings, 1221, 131-138. 4. Bleuet P., et al., 2008. App. Phys. Lett., 92, 213111-1-3. 5. Golosio B., et al., 2003. Appl. Phys., 94, 145-157. 6. M. Haschke, 2003. PhD dissertation, T.U. Berlin. 7. Simionovici A. S., et al., 2010. Proceedings of the Meteoritical Society Conference, N.Y., USA. 8. Solé V.A., et al., 2006, Elsevier, 62, 63-68.

  11. Model-Based Analysis of the Potential of Macroinvertebrates as Indicators for Microbial Pathogens in Rivers

    Directory of Open Access Journals (Sweden)

    Rubén Jerves-Cobo

    2018-03-01

    Full Text Available The quality of water prior to its use for drinking, farming or recreational purposes must comply with several physicochemical and microbiological standards to safeguard society and the environment. In order to satisfy these standards, expensive analyses and highly trained personnel in laboratories are required. Whereas macroinvertebrates have been used as ecological indicators to review the health of aquatic ecosystems. In this research, the relationship between microbial pathogens and macrobenthic invertebrate taxa was examined in the Machangara River located in the southern Andes of Ecuador, in which 33 sites, according to their land use, were chosen to collect physicochemical, microbiological and biological parameters. Decision tree models (DTMs were used to generate rules that link the presence and abundance of some benthic families to microbial pathogen standards. The aforementioned DTMs provide an indirect, approximate, and quick way of checking the fulfillment of Ecuadorian regulations for water use related to microbial pathogens. The models built and optimized with the WEKA package, were evaluated based on both statistical and ecological criteria to make them as clear and simple as possible. As a result, two different and reliable models were obtained, which could be used as proxy indicators in a preliminary assessment of pollution of microbial pathogens in rivers. The DTMs can be easily applied by staff with minimal training in the identification of the sensitive taxa selected by the models. The presence of selected macroinvertebrate taxa in conjunction with the decision trees can be used as a screening tool to evaluate sites that require additional follow up analyses to confirm whether microbial water quality standards are met.

  12. Influences of Coupled Hydrologic and Microbial Processes on River Corridor Biogeochemistry and Ecology

    Science.gov (United States)

    Scheibe, T. D.; Song, H. S.; Stegen, J.; Graham, E.; Bao, J.; Goldman, A.; Zhou, T.; Crump, A.; Hou, Z.; Hammond, G. E.; Chen, X.; Huang, M.; Zhang, X.; Nelson, W. C.; Garayburu-Caruso, V. A.

    2017-12-01

    The exchange of water between rivers and surrounding subsurface environments (hydrologic exchange flows or HEFs) is a vital aspect of river ecology and watershed function. HEFs play a key role in water quality, nutrient cycling, and ecosystem health, and they modulate water temperatures and enhance exchange of terrestrial and aquatic nutrients, which lead to elevated biogeochemical activity. However, these coupled hydrologic and microbiological processes are not well understood, particularly in the context of large managed river systems with highly variable discharge, and are poorly represented in system-scale quantitative models. Using the 75 km Hanford Reach of the Columbia River as the research domain, we apply high-resolution flow simulations supported by field observations to understand how variable river discharge interacts with hydromorphic and hydrogeologic structures to generate HEFs and distributions of subsurface residence times. We combine this understanding of hydrologic processes with microbiological activity measurements and reactive transport models to elucidate the holistic impacts of variable discharge on river corridor (surface and subsurface) ecosystems. In particular, our project seeks to develop and test new conceptual and numerical models that explicitly incorporate i) the character (chemical speciation and thermodynamics) of natural organic matter as it varies along flow paths and through mixing of groundwater and surface water, and ii) the history-dependent response of microbial communities to varying time scales of inundation associated with fluctuations in river discharge. The results of these high-resolution mechanistic models are guiding formulation and parameterization of reduced-order models applicable at reach to watershed scales. New understanding of coupled hydrology and microbiology in the river corridor will play a key role in reduction of uncertainties associated with major Earth system biogeochemical fluxes, improving

  13. [The use of self-adapting system files (SAF) for controlling microbial biofilms of root canals in the treatment of apical periodontitis].

    Science.gov (United States)

    Tsarev, V N; Mamedova, L A; Siukaeva, T N; Podporin, M S

    The aim of this study was to conduct a clinical and laboratory study and evaluate the effectiveness of endodontic root canal treatment using a self-adapting files system (SAF) in the complex treatment of patients with chronic apical periodontitis. 3% sodium hypochlorite solution was used as irrigation agent in all groups which included 20 patients treated with conventional manual tools, 21 patients receiving treatment with ultrasonic activation of irrigant and 26 patients treated with SAF system. Root canal biofilm structure was studied by scanning electron microscopy (SEM) using a Quantum 3D microscope (USA). Clinical efficiency of the root canal treatment was assessed by complications frequency a year after treatment. SEM revealed the presence of high levels of microbial contamination of dentine tubules in the apical portion of the tooth. In standard method group the percentage of re-treatment and surgery was higher than in the studied groups. Use of SAF irrigation system was associated with a decrease in the number of identified pathogens. However, the study revealed high resistance of Enterococcus spp., Porphyromonas gingivalis, Candida albicans to all types of endodontic treatment, so the improvement of methods of root canal microbial biofilms removing need to be continued.

  14. Influence of Wastewater Discharge on the Metabolic Potential of the Microbial Community in River Sediments.

    Science.gov (United States)

    Li, Dong; Sharp, Jonathan O; Drewes, Jörg E

    2016-01-01

    To reveal the variation of microbial community functions during water filtration process in river sediments, which has been utilized widely in natural water treatment systems, this study investigates the influence of municipal wastewater discharge to streams on the phylotype and metabolic potential of the microbiome in upstream and particularly various depths of downstream river sediments. Cluster analyses based on both microbial phylogenetic and functional data collectively revealed that shallow upstream sediments grouped with those from deeper subsurface downstream regions. These sediment samples were distinct from those found in shallow downstream sediments. Functional genes associated with carbohydrate, xenobiotic, and certain amino acid metabolisms were overrepresented in upstream and deep downstream samples. In contrast, the more immediate contact with wastewater discharge in shallow downstream samples resulted in an increase in the relative abundance of genes associated with nitrogen, sulfur, purine and pyrimidine metabolisms, as well as restriction-modification systems. More diverse bacterial phyla were associated with upstream and deep downstream sediments, mainly including Actinobacteria, Planctomycetes, and Firmicutes. In contrast, in shallow downstream sediments, genera affiliated with Betaproteobacteria and Gammaproteobacteria were enriched with putative functions that included ammonia and sulfur oxidation, polyphosphate accumulation, and methylotrophic bacteria. Collectively, these results highlight the enhanced capabilities of microbial communities residing in deeper stream sediments for the transformation of water contaminants and thus provide a foundation for better design of natural water treatment systems to further improve the removal of contaminants.

  15. Influence of Wastewater Discharge on the Metabolic Potential of the Microbial Community in River Sediments

    KAUST Repository

    Li, Dong

    2015-09-24

    To reveal the variation of microbial community functions during water filtration process in river sediments, which has been utilized widely in natural water treatment systems, this study investigates the influence of municipal wastewater discharge to streams on the phylotype and metabolic potential of the microbiome in upstream and particularly various depths of downstream river sediments. Cluster analyses based on both microbial phylogenetic and functional data collectively revealed that shallow upstream sediments grouped with those from deeper subsurface downstream regions. These sediment samples were distinct from those found in shallow downstream sediments. Functional genes associated with carbohydrate, xenobiotic, and certain amino acid metabolisms were overrepresented in upstream and deep downstream samples. In contrast, the more immediate contact with wastewater discharge in shallow downstream samples resulted in an increase in the relative abundance of genes associated with nitrogen, sulfur, purine and pyrimidine metabolisms, as well as restriction–modification systems. More diverse bacterial phyla were associated with upstream and deep downstream sediments, mainly including Actinobacteria, Planctomycetes, and Firmicutes. In contrast, in shallow downstream sediments, genera affiliated with Betaproteobacteria and Gammaproteobacteria were enriched with putative functions that included ammonia and sulfur oxidation, polyphosphate accumulation, and methylotrophic bacteria. Collectively, these results highlight the enhanced capabilities of microbial communities residing in deeper stream sediments for the transformation of water contaminants and thus provide a foundation for better design of natural water treatment systems to further improve the removal of contaminants. © 2015, Springer Science+Business Media New York.

  16. Flow cytometry combined with viSNE for the analysis of microbial biofilms and detection of microplastics

    Science.gov (United States)

    Sgier, Linn; Freimann, Remo; Zupanic, Anze; Kroll, Alexandra

    2016-01-01

    Biofilms serve essential ecosystem functions and are used in different technical applications. Studies from stream ecology and waste-water treatment have shown that biofilm functionality depends to a great extent on community structure. Here we present a fast and easy-to-use method for individual cell-based analysis of stream biofilms, based on stain-free flow cytometry and visualization of the high-dimensional data by viSNE. The method allows the combined assessment of community structure, decay of phototrophic organisms and presence of abiotic particles. In laboratory experiments, it allows quantification of cellular decay and detection of survival of larger cells after temperature stress, while in the field it enables detection of community structure changes that correlate with known environmental drivers (flow conditions, dissolved organic carbon, calcium) and detection of microplastic contamination. The method can potentially be applied to other biofilm types, for example, for inferring community structure for environmental and industrial research and monitoring. PMID:27188265

  17. Growing and analyzing biofilms in flow chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber-grown biofilms are addressed....

  18. Seasonal Changes in Microbial Community Structure in Freshwater Stream Sediment in a North Carolina River Basin

    Directory of Open Access Journals (Sweden)

    John P. Bucci

    2014-01-01

    Full Text Available This study examined seasonal differences in microbial community structure in the sediment of three streams in North Carolina’s Neuse River Basin. Microbes that reside in sediment are at the base of the food chain and have a profound influence on the health of freshwater stream environments. Terminal-Restriction Fragment Length Polymorphism (T-RFLP, molecular fingerprint analysis of 16S rRNA genes was used to examine the diversity of bacterial species in stream sediment. Sediment was sampled in both wet and dry seasons from an agricultural (Bear, mixed urban (Crabtree and forested (Marks Creek, and the microbiota examined. Gamma, Alpha and Beta proteobacteria were prevalent species of microbial taxa represented among all sites. Actinobacteria was the next most prevalent species observed, with greater occurrence in dry compared to the wet season. Discernable clustering was observed of Marks and Bear Creek samples collected during the wetter period (September–April, which corresponded with a period of higher precipitation and cooler surface water temperatures. Although not statistically significant, microbial community structure appeared different between season (ANOSIM, R = 0.60; p < 0.10. Principal components analysis confirmed this pattern and showed that the bacterial groups were separated by wet and dry seasonal periods. These results suggest seasonal differences among the microbial community structure in sediment of freshwater streams and that these communities may respond to changes in precipitation during wetter periods.

  19. Role of microbial biofilms in the maintenance of oral health and in the development of dental caries and periodontal diseases : Consensus report of group 1 of the Joint EFP/ORCA workshop on the boundaries between caries and periodontal disease

    NARCIS (Netherlands)

    Sanz, M.; Beighton, D.; Curtis, M.A.; Cury, J.A.; Dige, I.; Dommisch, H.; Ellwood, R.; Giacaman, R.A.; Herrera, D.; Herzberg, M.C.; Könönen, E.; Marsh, P.D.; Meyle, J.; Mira, A.; Molina, A.; Mombelli, A.; Quirynen, M.; Reynolds, E.C.; Shapira, L.; Zaura, E.

    Background and Aims: The scope of this working group was to review (1) ecological interactions at the dental biofilm in health and disease, (2) the role of microbial communities in the pathogenesis of periodontitis and caries, and (3) the innate host response in caries and periodontal diseases.

  20. Microbially influenced corrosion: studies on enterobacteria isolated from seawater environment and influence of toxic metals on bacterial biofilm and bio-corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Bermond-Tilly, D.; Pineau, S.; Dupont-Morral, I. [Corrodys, 50 - Equeurdreville (France); Janvier, M.; Grimont, P.A.D. [Institut Pasteur, Unite BBPE, 75 - Paris (France)

    2004-07-01

    Full text of publication follows: The most widely involved bacteria in Microbially Induced Corrosion (MIC usually called bio-corrosion) are sulfate/thiosulfate-reducing bacteria. The sulfate-reducing bacteria (SRB) are major contributors to the anaerobic bio-corrosion of steel. However, corrosion process of pipelines (or off shores platforms) was found to be associated with many other bacteria. These bacteria are able to produce sulfides from the reduction of thiosulfate in anaerobic conditions. By this way, a thiosulfate-reducing non sulfate-reducing bacteria, Dethiosulfovibrio peptidovorans, showed a significant corrosive activity similar to or higher than that recorded for SRB involved in bio-corrosion, (Magot et al., 1997). Furthermore, a bacteria, Citrobacter amalonaticus, which belongs to the family of the Enterobacteriaceae, is involved in severe pitting corrosion process (Angeles Chavez et al., 2002). Recently, some bacteria (Citrobacter freundii, Proteus mirabilis and Klebsiella planticola characterized as belonging to the family of Enterobacteriaceae) were isolated from biofilm developed on carbon steel coupons immersed in natural seawater. The latter bacteria were also associated in severe pitting corrosion process on carbon steel coupons (Bermond-Tilly et al., 2003). Biofilm forms a protective layer, reducing the exposure of the metal surface to the external environment. However, bacteria included in the biofilm could also cause localized corrosion by consuming cathodic hydrogen from the steel or by producing corrosive metabolic end products and by the Extracellular Polymeric Substances (EPS) production. Thus, EPS can also play an important role in the corrosion of the metals (e.g. can complex metal ions). However, sulfate/thiosulfate-reducing bacteria and some Enterobacteria are highly efficient to bioremediation by precipitation of toxic metals from wastewater as metal sulfides. Recently it was shown that toxic metal may be involved in the formation

  1. Precipitation effects on microbial pollution in a river: lag structures and seasonal effect modification.

    Directory of Open Access Journals (Sweden)

    Andreas Tornevi

    Full Text Available BACKGROUND: The river Göta Älv is a source of freshwater for 0.7 million swedes. The river is subject to contamination from sewer systems discharge and runoff from agricultural lands. Climate models projects an increase in precipitation and heavy rainfall in this region. This study aimed to determine how daily rainfall causes variation in indicators of pathogen loads, to increase knowledge of variations in river water quality and discuss implications for risk management. METHODS: Data covering 7 years of daily monitoring of river water turbidity and concentrations of E. coli, Clostridium and coliforms were obtained, and their short-term variations in relation with precipitation were analyzed with time series regression and non-linear distributed lag models. We studied how precipitation effects varied with season and compared different weather stations for predictive ability. RESULTS: Generally, the lowest raw water quality occurs 2 days after rainfall, with poor raw water quality continuing for several more days. A rainfall event of >15 mm/24-h (local 95 percentile was associated with a three-fold higher concentration of E. coli and 30% higher turbidity levels (lag 2. Rainfall was associated with exponential increases in concentrations of indicator bacteria while the effect on turbidity attenuated with very heavy rainfall. Clear associations were also observed between consecutive days of wet weather and decreased water quality. The precipitation effect on increased levels of indicator bacteria was significant in all seasons. CONCLUSIONS: Rainfall elevates microbial risks year-round in this river and freshwater source and acts as the main driver of varying water quality. Heavy rainfall appears to be a better predictor of fecal pollution than water turbidity. An increase of wet weather and extreme events with climate change will lower river water quality even more, indicating greater challenges for drinking water producers, and suggesting better

  2. Life cycle as a stable trait in the evaluation of diversity of Nostoc from biofilms in rivers.

    Science.gov (United States)

    Mateo, Pilar; Perona, Elvira; Berrendero, Esther; Leganés, Francisco; Martín, Marta; Golubić, Stjepko

    2011-05-01

    The diversity within the genus Nostoc is still controversial and more studies are needed to clarify its heterogeneity. Macroscopic species have been extensively studied and discussed; however, the microscopic forms of the genus, especially those from running waters, are poorly known and likely represented by many more species than currently described. Nostoc isolates from biofilms of two Spanish calcareous rivers were characterized comparing the morphology and life cycle in two culture media with different levels of nutrients and also comparing the 16S rRNA gene sequences. The results showed that trichome shape and cellular dimensions varied considerably depending on the culture media used, whereas the characteristics expressed in the course of the life cycle remained stable for each strain independent of the culture conditions. Molecular phylogenetic analysis confirmed the distinction between the studied strains established on morphological grounds. A balanced approach to the evaluation of diversity of Nostoc in the service of autecological studies requires both genotypic information and the evaluation of stable traits. The results of this study show that 16S rRNA gene sequence similarity serves as an important criterion for characterizing Nostoc strains and is consistent with stable attributes, such as the life cycle. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  3. [Microbial community in nitrogen cycle of aquaculture water of the Pearl River Delta].

    Science.gov (United States)

    Cai, Xiaolong; Luo, Jianfei; Lin, Weitie; Tian, Guoliang

    2012-05-04

    In order to study the characteristic of nitrogen transport, the community structure and diversity of related microorganisms in aquaculture water of the Pearl River Delta. We established an artificial aquaculture ecosystem to study the microbial community of 15N-stable isotope probing (15N-SIP) labeled nitrogen transport microorganisms. The 15N-labeled DNA was separated by CsCl-ethidium bromide density gradient centrifugation, and was used to construct 16S rRNA gene clone libraries of bacteria and archaea. Phylogenetic analysis shows that 19 Operational Taxonomic Units (OTUs) from bacterial library were clustered in Proteobacteria and Planctomycetes. Proteobacteria (99.2%) was the dominant group, mainly consisted of Comamonas (15.7%), Nitrosomonas (12.4%), Enterobacteriaceae (11.5%) and Nitrobacter (11.5%). From archaeal library 9 OTUs were divided into 3 phyla: Thaumarchaeota, Crenarchaeota and Euryarchaeota. We successfully elucidated the microbial community of nitrogen transport microorganisms in aquaculture water of Pearl River Delta by using 15N-SIP. The data of the community will provide essential information for isolating nitrogen degrading microorganism, and provide scientific basis for creating a healthy aquaculture environment.

  4. Presence and Expression of Microbial Genes Regulating Soil Nitrogen Dynamics Along the Tanana River Successional Sequence

    Science.gov (United States)

    Boone, R. D.; Rogers, S. L.

    2004-12-01

    We report on work to assess the functional gene sequences for soil microbiota that control nitrogen cycle pathways along the successional sequence (willow, alder, poplar, white spruce, black spruce) on the Tanana River floodplain, Interior Alaska. Microbial DNA and mRNA were extracted from soils (0-10 cm depth) for amoA (ammonium monooxygenase), nifH (nitrogenase reductase), napA (nitrate reductase), and nirS and nirK (nitrite reductase) genes. Gene presence was determined by amplification of a conserved sequence of each gene employing sequence specific oligonucleotide primers and Polymerase Chain Reaction (PCR). Expression of the genes was measured via nested reverse transcriptase PCR amplification of the extracted mRNA. Amplified PCR products were visualized on agarose electrophoresis gels. All five successional stages show evidence for the presence and expression of microbial genes that regulate N fixation (free-living), nitrification, and nitrate reduction. We detected (1) nifH, napA, and nirK presence and amoA expression (mRNA production) for all five successional stages and (2) nirS and amoA presence and nifH, nirK, and napA expression for early successional stages (willow, alder, poplar). The results highlight that the existing body of previous process-level work has not sufficiently considered the microbial potential for a nitrate economy and free-living N fixation along the complete floodplain successional sequence.

  5. Evaluation and selection of Bacillus species based on enzyme production, antimicrobial activity and biofilm synthesis as direct-fed microbials candidates for poultry

    Directory of Open Access Journals (Sweden)

    Juan D Latorre

    2016-10-01

    Full Text Available Social concern about misuse of antibiotics as growth promoters (AGP and generation of multidrug-resistant bacteria have restricted the dietary inclusion of antibiotics in livestock feed in several countries. Direct-fed microbials (DFM are one of the multiple alternatives commonly evaluated as substitutes of AGP. Sporeformer bacteria from the genus Bacillus have been extensively investigated because of their extraordinary properties to form highly-resistant endospores, production of antimicrobial compounds and synthesize different exogenous enzymes. The purpose of the present study was to evaluate and select Bacillus spp. from environmental and poultry sources as DFM candidates, considering their enzyme production profile, biofilm synthesis capacity and pathogen-inhibition activity. Thirty one Bacillus isolates were screened for in vitro relative enzyme activity of amylase, protease, lipase and phytase using a selective media for each enzyme, with 3/31 strains selected as superior enzyme producers. These three isolates were identified as B. subtilis (1/3, and B. amyloliquefaciens (2/3 based on biochemical tests and 16S rRNA sequence analysis. For evaluation of biofilm synthesis, the generation of an adherent crystal violet-stained ring was determined in polypropylene tubes, resulting in 11/31 strains showing a strong biofilm formation. Moreover, all Bacillus strains were evaluated for growth inhibition activity against Salmonella enterica serovar Enteritidis (26/31, Escherichia coli (28/31 and Clostridioides difficile (29/31. Additionally, in previous in vitro and in vivo studies, these selected Bacillus strains have shown to be resistant to different biochemical conditions of the gastrointestinal tract of poultry. Results of the present study suggest that the selection and consumption of Bacillus-DFM, producing a variable set of enzymes and antimicrobial compounds may contribute to enhanced performance through improving nutrient digestibility

  6. A Physico-Chemical water quality and Microbial content Analysis in Upstream of Langat River, Selangor

    International Nuclear Information System (INIS)

    Muhammad Barzani Gasim; Nazirah Zakaria; Roslan Umar; Roslan Umar; Ahmad Dasuki Mustafa

    2015-01-01

    Water quality study of the selected physico-chemical and microbial parameters of the Langat River were carried out to determine and classified their values. Sampling was carried out twice; first on 9 June 2011 and the second was on 22 February 2012. The sampling site consist of seven stations; five stations representing for Langat River branches while two stations are located in Langat River. The in-situ measurements are: dissolved oxygen, electrical conductivity, total dissolved solids, pH and temperature were performed using YSI 556 multiparameter, while the laboratory analysis were based on HACH and APHA methods. Result shows; temperature (23.4 - 27.7 degree Celsius), pH (5.07 to 6.15), EC (29.3 . 61.5 μS/ cm), TDS (19.7 - 47.0 mg/L), DO (3.68 - 5.72 mg/L), BOD (1.29 - 3.76 mg/L), COD (13.5 - 77.85 mg/L), TSS (9.5 - 86.5 mg/L), NH_3N (0.15 - 0.79 mg/L), NO_3 (0.8 - 4.9 mg/L), PO_4"3"- (0.15 - 0.7 mg/L), SO_4"2"- (0.5 - 12.5 mg/L) and biological parameters of faecal coliform (2.58 x 10"4 - 4.74 x 10"6 cfu/ 100 ml). Based on water quality index and the National Water Quality Standards classifications, they belong to the class I, II, III and V. One-way ANOVA for repeated measures and Pearson correlation test been used. The overall results showed the selected rivers in upstream of Langat River were classified as moderately polluted. (author)

  7. Microsensor Measurements of Sulfate Reduction and Sulfide Oxidation in Compact Microbial Communities of Aerobic Biofilms Rid A-1977-2009

    DEFF Research Database (Denmark)

    KUHL, M.; JØRGENSEN, BB

    1992-01-01

    The microzonation of O2 respiration, H2S oxidation, and SO4(2-) reduction in aerobic trickling-filter biofilms was studied by measuring concentration profiles at high spatial resolution (25 to 100-mu-m) with microsensors for O2, S2-, and pH. Specific reaction rates were calculated from measured...

  8. The effect of titanium implant surface modification on the dynamic process of initial microbial adhesion and biofilm formation

    NARCIS (Netherlands)

    Han, A.; Li, X.; Huang, B.; Tsoi, J.K.-H.; Matinlinna, J.P.; Chen, Z.; Deng, D.M.

    2016-01-01

    Purpose: The aim of the study was to investigate the dynamic process of biofilm adhesion on titanium implant with two surface treatments, either pickled (PT) or moderately roughened by sandblasting with large grits and acid-etched (SLA). Materials and methods: Two types of titanium disks with

  9. Bacterial biofilm and associated infections

    Directory of Open Access Journals (Sweden)

    Muhsin Jamal

    2018-01-01

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

  10. Microbial responses to polycyclic aromatic hydrocarbon contamination in temporary river sediments: Experimental insights.

    Science.gov (United States)

    Zoppini, Annamaria; Ademollo, Nicoletta; Amalfitano, Stefano; Capri, Silvio; Casella, Patrizia; Fazi, Stefano; Marxsen, Juergen; Patrolecco, Luisa

    2016-01-15

    Temporary rivers are characterized by dry-wet phases and represent an important water resource in semi-arid regions worldwide. The fate and effect of contaminants have not been firmly established in temporary rivers such as in other aquatic environments. In this study, we assessed the effects of sediment amendment with Polycyclic Aromatic Hydrocarbons (PAHs) on benthic microbial communities. Experimental microcosms containing natural (Control) and amended sediments (2 and 20 mg PAHs kg(-1) were incubated for 28 days. The PAH concentrations in sediments were monitored weekly together with microbial community structural (biomass and phylogenetic composition by TGGE and CARD-FISH) and functional parameters (ATP concentration, community respiration rate, bacterial carbon production rate, extracellular enzyme activities). The concentration of the PAH isomers did not change significantly with the exception of phenanthrene. No changes were observed in the TGGE profiles, whereas the occurrence of Alpha- and Beta-Proteobacteria was significantly affected by the treatments. In the amended sediments, the rates of carbon production were stimulated together with aminopeptidase enzyme activity. The community respiration rates showed values significantly lower than the Control after 1 day from the amendment then recovering the Control values during the incubation. A negative trend between the respiration rates and ATP concentration was observed only in the amended sediments. This result indicates a potential toxic effect on the oxidative phosphorylation processes. The impoverishment of the energetic resources that follows the PAH impact may act as a domino on the flux of energy from prokaryotes to the upper level of the trophic chain, with the potential to alter the temporary river functioning.

  11. Role of microbial biofilms in the maintenance of oral health and in the development of dental caries and periodontal diseases. Consensus report of group 1 of the Joint EFP/ORCA workshop on the boundaries between caries and periodontal disease.

    Science.gov (United States)

    Sanz, Mariano; Beighton, David; Curtis, Michael A; Cury, Jaime A; Dige, Irene; Dommisch, Henrik; Ellwood, Roger; Giacaman, Rodrigo A; Herrera, David; Herzberg, Mark C; Könönen, Eija; Marsh, Philip D; Meyle, Joerg; Mira, Alex; Molina, Ana; Mombelli, Andrea; Quirynen, Marc; Reynolds, Eric C; Shapira, Lior; Zaura, Egija

    2017-03-01

    The scope of this working group was to review (1) ecological interactions at the dental biofilm in health and disease, (2) the role of microbial communities in the pathogenesis of periodontitis and caries, and (3) the innate host response in caries and periodontal diseases. A health-associated biofilm includes genera such as Neisseria, Streptococcus, Actinomyces, Veillonella and Granulicatella. Microorganisms associated with both caries and periodontal diseases are metabolically highly specialized and organized as multispecies microbial biofilms. Progression of these diseases involves multiple microbial interactions driven by different stressors. In caries, the exposure of dental biofilms to dietary sugars and their fermentation to organic acids results in increasing proportions of acidogenic and aciduric species. In gingivitis, plaque accumulation at the gingival margin leads to inflammation and increasing proportions of proteolytic and often obligately anaerobic species. The natural mucosal barriers and saliva are the main innate defence mechanisms against soft tissue bacterial invasion. Similarly, enamel and dentin are important hard tissue barriers to the caries process. Given that the present state of knowledge suggests that the aetiologies of caries and periodontal diseases are mutually independent, the elements of innate immunity that appear to contribute to resistance to both are somewhat coincidental. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Improved performance of microbial fuel cells enriched with natural microbial inocula and treated by electrical current

    International Nuclear Information System (INIS)

    Lin, Hongjian; Wu, Xiao; Miller, Curtis; Zhu, Jun

    2013-01-01

    Microbial fuel cells (MFCs) are increasingly attracting attention as a sustainable technology as they convert chemical energy in organic wastes to electricity. In this study, the effects of different inoculum sources (river sediment, activated sludge and anaerobic sludge) and electrical current stimulation were evaluated using single-chamber air-cathode MFCs as model reactors based on performance in enrichment process and electrochemical characteristics of the reactors. The result revealed the rapid anodic biofilm development and substrate utilization of the anaerobic sludge-inoculated MFC. It was also found that the river sediment-inoculated MFC achieved the highest power output of 195 μW, or 98 mW m −2 , due to better developed anodic biofilm confirmed by scanning electron microscopy. The current stimulation enhanced the anodic biofilm attachment over time, and therefore reduced the MFC internal resistance by 27%, increased the electrical capacitance by four folds, and improved the anodic biofilm resilience against substrate deprivation. For mature MFCs, a transient application of a negative voltage (−3 V) improved the cathode activity and maximum power output by 37%. This improvement was due to the bactericidal effect of the electrode potential higher than +1.5 V vs. SHE, demonstrating a substantial benefit of treating MFC cathode after long-term operation using suitable direct electrical current. -- Highlights: •Voltage stimulation (+2 V) during inoculation reduced MFC internal resistance and improved biofilm resilience. •Voltage stimulation increased biofilm electrical capacitance by 5-fold. •Negative voltage stimulation (−3 V) enhanced the maximum power output by 37%. •River sediment MFC obtained higher power due to better anodic biofilm coverage. •Anaerobic sludge quickly developed anodic biofilm for MFC and quickly utilized volatile fatty acids

  13. Inocula selection in microbial fuel cells based on anodic biofilm abundance of Geobacter sulfurreducens

    DEFF Research Database (Denmark)

    Sun, Guotao; Rodrigues, Diogo De Sacadura; Thygesen, Anders

    2016-01-01

    with naturally occurring mixed inocula. In this study, the electrochemical performance of MFCs and microbial community evolution were evaluated for three inocula including domestic wastewater (DW), lake sediment (LS) and biogas sludge (BS) with varying substrate loading (Lsub) and external resistance (Rext....... The data obtained contribute to understanding the microbial community response to Lsub and Rext for optimizing electricity generation in MFCs....

  14. Spatio-temporal variations in biomass and mercury concentrations of epiphytic biofilms and their host in a large river wetland (Lake St. Pierre, Qc, Canada)

    International Nuclear Information System (INIS)

    Hamelin, Stéphanie; Planas, Dolors; Amyot, Marc

    2015-01-01

    Within wetlands, epiphytes and macrophytes play an important role in storage and transfer of metals, through the food web. However, there is a lack of information about spatial and temporal changes in their metal levels, including those of mercury (Hg), a key priority contaminant of aquatic systems. We assessed total mercury (THg) and methylmercury (MeHg) concentrations of epiphyte/macrophyte complexes in Lake St. Pierre, a large fluvial lake of the St. Lawrence River (Québec, Canada). THg and MeHg concentrations were ten fold higher in epiphytes than in macrophytes. THg concentrations in epiphytes linearly decreased as a function of the autotrophic index, suggesting a role of algae in epiphyte Hg accumulation, and % of MeHg in epiphytes reached values as high as 74%. Spatio-temporal variability in THg and MeHg concentrations in epiphytes and macrophytes were influenced by water temperature, available light, host species, water level, dissolved organic carbon and dissolved oxygen. - Highlights: • Epiphytes and macrophytes are sites of Hg accumulation in a large temperate river. • Epiphytic biofilms are ten fold more contaminated than their macrophyte host. • Physico-chemical variables influences Hg levels in epiphytes and macrophytes. • Up to 74% of total Hg is in the methylated form in epiphytes. • Epiphytes, should be included in Hg foodweb modeling. - Epiphytic biofilms are key sites of methylmercury accumulation in large river wetlands

  15. Impact of a wastewater treatment plant on microbial community composition and function in a hyporheic zone of a eutrophic river

    NARCIS (Netherlands)

    Atashgahi, S.; Aydin, R.; Rocha Dimitrov, M.; Sipkema, D.; Hamonts, K.; Lahti, Leo; Maphosa, F.; Kruse, T.; Saccenti, E.; Springael, D.; Dejonghe, W.; Smidt, H.

    2015-01-01

    The impact of the installation of a technologically advanced wastewater treatment plant (WWTP) on the benthic microbial community of a vinyl chloride (VC) impacted eutrophic river was examined two years before, and three and four years after installation of the WWTP. Reduced dissolved organic carbon

  16. Colonization Habitat Controls Biomass, Composition, and Metabolic Activity of Attached Microbial Communities in the Columbia River Hyporheic Corridor

    Energy Technology Data Exchange (ETDEWEB)

    Stern, Noah; Ginder-Vogel, Matthew; Stegen, James C.; Arntzen, Evan; Kennedy, David W.; Larget, Bret R.; Roden, Eric E.; Kostka, Joel E.

    2017-06-09

    Hydrologic exchange plays a critical role in biogeochemical cycling within the hyporheic zone (the interface between river water and groundwater) of riverine ecosystems. Such exchange may set limits on the rates of microbial metabolism and impose deterministic selection on microbial communities that adapt to dynamically changing dissolved organic carbon (DOC) sources. This study examined the response of attached microbial communities (in situcolonized sand packs) from groundwater, hyporheic, and riverbed habitats within the Columbia River hyporheic corridor to “cross-feeding” with either groundwater, river water, or DOC-free artificial fluids. Our working hypothesis was that deterministic selection duringin situcolonization would dictate the response to cross-feeding, with communities displaying maximal biomass and respiration when supplied with their native fluid source. In contrast to expectations, the major observation was that the riverbed colonized sand had much higher biomass and respiratory activity, as well as a distinct community structure, compared with those of the hyporheic and groundwater colonized sands. 16S rRNA gene amplicon sequencing revealed a much higher proportion of certain heterotrophic taxa as well as significant numbers of eukaryotic algal chloroplasts in the riverbed colonized sand. Significant quantities of DOC were released from riverbed sediment and colonized sand, and separate experiments showed that the released DOC stimulated respiration in the groundwater and piezometer colonized sand. These results suggest that the accumulation and degradation of labile particulate organic carbon (POC) within the riverbed are likely to release DOC, which may enter the hyporheic corridor during hydrologic exchange, thereby stimulating microbial activity and imposing deterministic selective pressure on the microbial community composition.

    IMPORTANCEThe influence of river water

  17. Biogenic selenium and tellurium nanoparticles synthesized by environmental microbial isolates efficaciously inhibit bacterial planktonic cultures and biofilms

    Directory of Open Access Journals (Sweden)

    Emanuele eZonaro

    2015-06-01

    Full Text Available The present study deals with Se0- and Te0-based nanoparticles bio-synthesized by two selenite- and tellurite-reducing bacterial strains, namely Stenotrophomonas maltophilia SeITE02 and Ochrobactrum sp. MPV1, isolated from polluted sites. We discovered that, by regulating culture conditions and exposure time to the selenite and tellurite oxyanions, differently sized zero-valent Se and Te nanoparticles were produced. The results revealed that these Se0 and Te0 nanoparticles possess antimicrobial and biofilm eradication activity against E. coli JM109, P. aeruginosa PAO1, and S. aureus ATCC 25923. In particular, Se0 nanoparticles exhibited antimicrobial activity at quite low concentrations, below that of selenite. Toxic effects of both Se0 and Te0 nanoparticles can be related to the production of reactive oxygen species upon exposure of the bacterial cultures. Evidence so far achieved suggests that the antimicrobial activity seems to be strictly linked to the dimensions of the nanoparticles: indeed, the highest activity was shown by nanoparticles of smaller sizes. In particular, it is worth noting how the bacteria tested in biofilm mode responded to the treatment by Se0 and Te0 nanoparticles with a susceptibility similar to that observed in planktonic cultures. This suggests a possible exploitation of both Se0 and Te0 nanoparticles as efficacious antimicrobial agents with a remarkable biofilm eradication capacity.

  18. Current and future trends for biofilm reactors for fermentation processes.

    Science.gov (United States)

    Ercan, Duygu; Demirci, Ali

    2015-03-01

    Biofilms in the environment can both cause detrimental and beneficial effects. However, their use in bioreactors provides many advantages including lesser tendencies to develop membrane fouling and lower required capital costs, their higher biomass density and operation stability, contribution to resistance of microorganisms, etc. Biofilm formation occurs naturally by the attachment of microbial cells to the support without use of any chemicals agent in biofilm reactors. Biofilm reactors have been studied and commercially used for waste water treatment and bench and pilot-scale production of value-added products in the past decades. It is important to understand the fundamentals of biofilm formation, physical and chemical properties of a biofilm matrix to run the biofilm reactor at optimum conditions. This review includes the principles of biofilm formation; properties of a biofilm matrix and their roles in the biofilm formation; factors that improve the biofilm formation, such as support materials; advantages and disadvantages of biofilm reactors; and industrial applications of biofilm reactors.

  19. Diversity of microbial plankton across the Three Gorges Dam of the Yangtze River, China

    Directory of Open Access Journals (Sweden)

    Shang Wang

    2012-05-01

    Full Text Available The Three Gorges Dam (TGD of the Yangtze River, China, is one of the largest irrigation and hydroelectric engineering projects in the world. The effects of huge man-made projects like TGD on fauna and macrophyte are obvious, mainly through changes of water dynamics and flow pattern; however, it is less clear how microorganisms respond to such changes. This research was aimed to examine differences in microbial diversity at different seasons and locations (in front of and behind the TGD. In addition, differences between particle-attached and free-living communities were also examined. The community structures of total and potentially active microorganisms in the water columns behind and in front of the TGD were analyzed with the DNA- and RNA-based 16S rRNA gene phylogenetic approaches over three different seasons. Clone libraries of 16S rRNA genes were prepared after amplification from extracted DNA and, for some samples, after preparing cDNA from extracted rRNA. Differences were observed between sites at different seasons and between free-living and particle-attached communities. Both bacterial and archaeal communities were more diverse in summer than in winter, due to higher nutrient levels and warmer temperature in summer than in winter. Particle-attached microorganisms were more diverse than free-living communities, possibly because of higher nutrient levels and heterogeneous geochemical micro-environments in particles. Spatial variations in bacterial community structure were observed, i.e., the water reservoir behind the TGD (upstream hosted more diverse bacterial populations than in front of the dam (downstream, because of diverse sources of sediments and waters from upstream to the reservoir. These results have important implications for our understanding of responses of microbial communities to environmental changes in river ecosystems affected by dam construction.

  20. Microbial Community Structure and Function Indicate the Severity of Chromium Contamination of the Yellow River

    Directory of Open Access Journals (Sweden)

    Yaxin Pei

    2018-01-01

    Full Text Available The Yellow River is the most important water resource in northern China. In the recent past, heavy metal contamination has become severe due to industrial processes and other anthropogenic activities. In this study, riparian soil samples with varying levels of chromium (Cr pollution severity were collected along the Gansu industrial reach of the Yellow River, including samples from uncontaminated sites (XC, XGU, slightly contaminated sites (LJX, XGD, and heavily contaminated sites (CG, XG. The Cr concentrations of these samples varied from 83.83 mg⋅kg-1 (XGU to 506.58 mg⋅kg-1 (XG. The chromate [Cr (VI] reducing ability in the soils collected in this study followed the sequence of the heavily contaminated > slightly contaminated > the un-contaminated. Common Cr remediation genes chrA and yieF were detected in the XG and CG samples. qRT-PCR results showed that the expression of chrA was up-regulated four and threefold in XG and CG samples, respectively, whereas the expression of yieF was up-regulated 66- and 7-fold in the same samples after 30 min treatment with Cr (VI. The copy numbers of chrA and yieF didn’t change after 35 days incubation with Cr (VI. The microbial communities in the Cr contaminated sampling sites were different from those in the uncontaminated samples. Especially, the relative abundances of Firmicutes and Bacteroidetes were higher while Actinobacteria was lower in the contaminated group than uncontaminated group. Further, potential indicator species, related to Cr such as Cr-remediation genera (Geobacter, PSB-M-3, Flavobacterium, and Methanosarcina; the Cr-sensitive genera (Skermanella, Iamia, Arthrobacter, and Candidatus Nitrososphaera were also identified. These data revealed that Cr shifted microbial composition and function. Further, Cr (VI reducing ability could be related with the expression of Cr remediation genes.

  1. Discovering Biofilms: Inquiry-Based Activities for the Classroom

    Science.gov (United States)

    Redelman, Carly V.; Marrs, Kathleen; Anderson, Gregory G.

    2012-01-01

    In nature, bacteria exist in and adapt to different environments by forming microbial communities called "biofilms." We propose simple, inquiry-based laboratory exercises utilizing a biofilm formation assay, which allows controlled biofilm growth. Students will be able to qualitatively assess biofilm growth via staining. Recently, we developed a…

  2. Biofilm ved kronisk rhinosinuitis og cystisk fibrose

    DEFF Research Database (Denmark)

    Fisker, Jacob; Buchwald, Christian von; Johansen, Helle Krogh

    2011-01-01

    Microbial biofilms are known to cause persistent foreign-body infections and have recently been acknowledged as involved in more than 65% of all human infections. Microbial biofilms have been detected in chronic rhinosinusitis, and chronic rhinosinusitis is mandatory in patients with cystic...

  3. Biomarker Analysis of Samples Visually Identified as Microbial in the Eocene Green River Formation: An Analogue for Mars.

    Science.gov (United States)

    Olcott Marshall, Alison; Cestari, Nicholas A

    2015-09-01

    One of the major exploration targets for current and future Mars missions are lithofacies suggestive of biotic activity. Although such lithofacies are not confirmation of biotic activity, they provide a way to identify samples for further analyses. To test the efficacy of this approach, we identified carbonate samples from the Eocene Green River Formation as "microbial" or "non-microbial" based on the macroscale morphology of their laminations. These samples were then crushed and analyzed by gas chromatography/mass spectroscopy (GC/MS) to determine their lipid biomarker composition. GC/MS analysis revealed that carbonates visually identified as "microbial" contained a higher concentration of more diverse biomarkers than those identified as "non-microbial," suggesting that this could be a viable detection strategy for selecting samples for further analysis or caching on Mars.

  4. Elimination of biofilm and microbial contamination reservoirs in hospital washbasin U-bends by automated cleaning and disinfection with electrochemically activated solutions.

    Science.gov (United States)

    Swan, J S; Deasy, E C; Boyle, M A; Russell, R J; O'Donnell, M J; Coleman, D C

    2016-10-01

    Washbasin U-bends are reservoirs of microbial contamination in healthcare environments. U-Bends are constantly full of water and harbour microbial biofilm. To develop an effective automated cleaning and disinfection system for U-bends using two solutions generated by electrochemical activation of brine including the disinfectant anolyte (predominantly hypochlorous acid) and catholyte (predominantly sodium hydroxide) with detergent properties. Initially three washbasin U-bends were manually filled with catholyte followed by anolyte for 5min each once weekly for five weeks. A programmable system was then developed with one washbasin that automated this process. This U-bend had three cycles of 5min catholyte followed by 5min anolyte treatment per week for three months. Quantitative bacterial counts from treated and control U-bends were determined on blood agar (CBA), R2A, PAS, and PA agars following automated treatment and on CBA and R2A following manual treatment. The average bacterial density from untreated U-bends throughout the study was >1×10(5) cfu/swab on all media with Pseudomonas aeruginosa accounting for ∼50% of counts. Manual U-bend electrochemically activated (ECA) solution treatment reduced counts significantly (<100cfu/swab) (P<0.01 for CBA; P<0.005 for R2A). Similarly, counts from the automated ECA-treatment U-bend were significantly reduced with average counts for 35 cycles on CBA, R2A, PAS, and PA of 2.1±4.5 (P<0.0001), 13.1±30.1 (P<0.05), 0.7±2.8 (P<0.001), and 0 (P<0.05) cfu/swab, respectively. P. aeruginosa was eliminated from all treated U-bends. Automated ECA treatment of washbasin U-bends consistently minimizes microbial contamination. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  5. Microbial exoenzymes as bioindicators of acid rock drainage impacts in the Finniss River

    International Nuclear Information System (INIS)

    Hammerton, K.M.

    2002-01-01

    Sediment samples were collected from several sites along the East Branch of the Finniss River during the dry season (June, 1999), when the East Branch is drying into a series of ponds. The sites included those upstream from the Rum Jungle mine site (EB8A, EB8B, FCA, FCB), a site receiving acid leachate from the waste rock (WO), sites downstream from the mine that are impacted by acid and metal contamination (EB6, TCP, EB5D, EB4U, EB2) and reference sites not subject to acid rock drainage (HS, EB4S, LFRB). Exoenzyme activities were measured with a spectrofluorometric technique that involved measuring the increase in fluorescence when an artificial fluorogenic substrate (that mimics the natural substrate) is hydrolysed to a highly fluorescent product. The present findings indicate that the acid rock drainage impacted sediments contain acidophilic, heterotrophic microorganisms, bacteria and/or fungi, producing extracellular enzymes adapted to the acid conditions. This study has demonstrated that measurements of extracellular enzyme activities in river sediments provide a rapid, sensitive technique for determining microbial activity and productivity. In aquatic ecosystems some exoenzymes, particularly leucine-aminopeptidase, could be used as bioindicators of pollution from acid rock drainage

  6. Differentiation of Microbial Species and Strains in Coculture Biofilms by Multivariate Analysis of Laser Desorption Postionization Mass Spectra

    Energy Technology Data Exchange (ETDEWEB)

    University of Illinois at Chicago; Montana State University; Bhardwaj, Chhavi; Cui, Yang; Hofstetter, Theresa; Liu, Suet Yi; Bernstein, Hans C.; Carlson, Ross P.; Ahmed, Musahid; Hanley, Luke

    2013-04-01

    7.87 to 10.5 eV vacuum ultraviolet (VUV) photon energies were used in laser desorption postionization mass spectrometry (LDPI-MS) to analyze biofilms comprised of binary cultures of interacting microorganisms. The effect of photon energy was examined using both tunable synchrotron and laser sources of VUV radiation. Principal components analysis (PCA) was applied to the MS data to differentiate species in Escherichia coli-Saccharomyces cerevisiae coculture biofilms. PCA of LDPI-MS also differentiated individual E. coli strains in a biofilm comprised of two interacting gene deletion strains, even though these strains differed from the wild type K-12 strain by no more than four gene deletions each out of approximately 2000 genes. PCA treatment of 7.87 eV LDPI-MS data separated the E. coli strains into three distinct groups two ?pure? groups and a mixed region. Furthermore, the ?pure? regions of the E. coli cocultures showed greater variance by PCA when analyzed by 7.87 eV photon energies than by 10.5 eV radiation. Comparison of the 7.87 and 10.5 eV data is consistent with the expectation that the lower photon energy selects a subset of low ionization energy analytes while 10.5 eV is more inclusive, detecting a wider range of analytes. These two VUV photon energies therefore give different spreads via PCA and their respective use in LDPI-MS constitute an additional experimental parameter to differentiate strains and species.

  7. Accelerating anodic biofilms formation and electron transfer in microbial fuel cells: Role of anionic biosurfactants and mechanism.

    Science.gov (United States)

    Zhang, Yunshu; Jiang, Junqiu; Zhao, Qingliang; Gao, YunZhi; Wang, Kun; Ding, Jing; Yu, Hang; Yao, Yue

    2017-10-01

    Anodic electron transfer is the predominant electricity generation process of MFCs. To accelerate anodic biofilms formation and electron transfer, 40mg/L, 80mg/L, and 120mg/L of rhamnolipid biosurfactants were added to the anolyte, resulting in an increased abiotic capacitance from 15.12F/m 2 (control) to 16.54F/m 2 , 18.00F/m 2 , and 19.39F/m 2 , respectively. Anodic biofilm formation was facilitated after dosing 40mg/L of rhamnolipids on the 7th day after inoculation, resulting in an increased anodic biofilm coverage from 0.43% to 42.51%, and an increased maximum power density from 6.92±1.18W/m 3 to 9.93±0.88W/m 3 . Furthermore, the adsorption of rhamnolipids on the anode caused the Frumkin effect, leading to a decrease of equilibrium potential from -0.43V to -0.56V, and an increase of exchange current density from 5.09×10 -3 A/m 2 to 8.72×10 -3 A/m 2 . However, electron transfer was blocked when the rhamnolipid concentration was further increased to 80mg/L, and 120mg/L. Analysis of the anodic bacterial communities revealed that rhamnolipids facilitated the enrichment of exoelectrogen, increasing the total proportion from 65% to 81%. Additionally, biosurfactants were found to have significant impacts on the composition of exoelectrogens. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Nitrogen cycling processes and microbial community composition in bed sediments in the Yukon River at Pilot Station

    Science.gov (United States)

    Repert, Deborah A.; Underwood, Jennifer C.; Smith, Richard L.; Song, Bongkeun

    2014-01-01

    Information on the contribution of nitrogen (N)-cycling processes in bed sediments to river nutrient fluxes in large northern latitude river systems is limited. This study examined the relationship between N-cycling processes in bed sediments and N speciation and loading in the Yukon River near its mouth at the Bering Sea. We conducted laboratory bioassays to measure N-cycling processes in sediment samples collected over distinct water cycle seasons. In conjunction, the microbial community composition in the bed sediments using genes involved in N-cycling (narG, napA, nosZ, and amoA) and 16S rRNA gene pyrosequences was examined. Temporal variation was observed in net N mineralization, nitrate uptake, and denitrification rate potentials and correlated strongly with sediment carbon (C) and extractable N content and microbial community composition rather than with river water nutrient concentrations. The C content of the bed sediment was notably impacted by the spring flood, ranging from 1.1% in the midst of an ice-jam to 0.1% immediately after ice-out, suggesting a buildup of organic material (OM) prior to scouring of the bed sediments during ice break up. The dominant members of the microbial community that explained differences in N-processing rates belonged to the genera Crenothrix,Flavobacterium, and the family of Comamonadaceae. Our results suggest that biogeochemical processing rates in the bed sediments appear to be more coupled to hydrology, nutrient availability in the sediments, and microbial community composition rather than river nutrient concentrations at Pilot Station.

  9. Metagenomic Analysis of Showerhead Biofilms from a Hospital in Ohio

    Science.gov (United States)

    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...

  10. Studying bacterial multispecies biofilms

    DEFF Research Database (Denmark)

    Røder, Henriette Lyng; Sørensen, Søren Johannes; Burmølle, Mette

    2016-01-01

    The high prevalence and significance of multispecies biofilms have now been demonstrated in various bacterial habitats with medical, industrial, and ecological relevance. It is highly evident that several species of bacteria coexist and interact in biofilms, which highlights the need for evaluating...... the approaches used to study these complex communities. This review focuses on the establishment of multispecies biofilms in vitro, interspecies interactions in microhabitats, and how to select communities for evaluation. Studies have used different experimental approaches; here we evaluate the benefits...... and drawbacks of varying the degree of complexity. This review aims to facilitate multispecies biofilm research in order to expand the current limited knowledge on interspecies interactions. Recent technological advances have enabled total diversity analysis of highly complex and diverse microbial communities...

  11. Spatial and seasonal variation in diversity and structure of microbial biofilms on marine plastics in Northern European waters.

    Science.gov (United States)

    Oberbeckmann, Sonja; Loeder, Martin G J; Gerdts, Gunnar; Osborn, A Mark

    2014-11-01

    Plastic pollution is now recognised as a major threat to marine environments and marine biota. Recent research highlights that diverse microbial species are found to colonise plastic surfaces (the plastisphere) within marine waters. Here, we investigate how the structure and diversity of marine plastisphere microbial community vary with respect to season, location and plastic substrate type. We performed a 6-week exposure experiment with polyethylene terephthalate (PET) bottles in the North Sea (UK) as well as sea surface sampling of plastic polymers in Northern European waters. Scanning electron microscopy revealed diverse plastisphere communities comprising prokaryotic and eukaryotic microorganisms. Denaturing gradient gel electrophoresis (DGGE) and sequencing analysis revealed that plastisphere microbial communities on PET fragments varied both with season and location and comprised of bacteria belonging to Bacteroidetes, Proteobacteria, Cyanobacteria and members of the eukaryotes Bacillariophyceae and Phaeophyceae. Polymers sampled from the sea surface mainly comprised polyethylene, polystyrene and polypropylene particles. Variation within plastisphere communities on different polymer types was observed, but communities were primarily dominated by Cyanobacteria. This research reveals that the composition of plastisphere microbial communities in marine waters varies with season, geographical location and plastic substrate type. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  12. Impact of drinking water conditions and copper materials on downstream biofilm microbial communities and legionella pneumophila colonization

    Science.gov (United States)

    Legionella pneumophila, the medically important species within the genus Legionella, is a concern in engineered water systems. Its ability to amplify within free-living amoebae is well documented, but its interactions/ecology within the microbial community of drinking water biofi...

  13. Biofilm roughness determines Cryptosporidium parvum retention in environmental biofilms.

    Science.gov (United States)

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

    2012-06-01

    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.

  14. Biofilm in endodontics: A review

    Science.gov (United States)

    Jhajharia, Kapil; Parolia, Abhishek; Shetty, K Vikram; Mehta, Lata Kiran

    2015-01-01

    Endodontic disease is a biofilm-mediated infection, and primary aim in the management of endodontic disease is the elimination of bacterial biofilm from the root canal system. The most common endodontic infection is caused by the surface-associated growth of microorganisms. It is important to apply the biofilm concept to endodontic microbiology to understand the pathogenic potential of the root canal microbiota as well as to form the basis for new approaches for disinfection. It is foremost to understand how the biofilm formed by root canal bacteria resists endodontic treatment measures. Bacterial etiology has been confirmed for common oral diseases such as caries and periodontal and endodontic infections. Bacteria causing these diseases are organized in biofilm structures, which are complex microbial communities composed of a great variety of bacteria with different ecological requirements and pathogenic potential. The biofilm community not only gives bacteria effective protection against the host's defense system but also makes them more resistant to a variety of disinfecting agents used as oral hygiene products or in the treatment of infections. Successful treatment of these diseases depends on biofilm removal as well as effective killing of biofilm bacteria. So, the fundamental to maintain oral health and prevent dental caries, gingivitis, and periodontitis is to control the oral biofilms. From these aspects, the formation of biofilms carries particular clinical significance because not only host defense mechanisms but also therapeutic efforts including chemical and mechanical antimicrobial treatment measures have the most difficult task of dealing with organisms that are gathered in a biofilm. The aim of this article was to review the mechanisms of biofilms’ formation, their roles in pulpal and periapical pathosis, the different types of biofilms, the factors influencing biofilm formation, the mechanisms of their antimicrobial resistance, techniques to

  15. Subsurface Nitrogen-Cycling Microbial Communities at Uranium Contaminated Sites in the Colorado River Basin

    Science.gov (United States)

    Cardarelli, E.; Bargar, J.; Williams, K. H.; Dam, W. L.; Francis, C.

    2015-12-01

    Throughout the Colorado River Basin (CRB), uranium (U) persists as a relic contaminant of former ore processing activities. Elevated solid-phase U levels exist in fine-grained, naturally-reduced zone (NRZ) sediments intermittently found within the subsurface floodplain alluvium of the following Department of Energy-Legacy Management sites: Rifle, CO; Naturita, CO; and Grand Junction, CO. Coupled with groundwater fluctuations that alter the subsurface redox conditions, previous evidence from Rifle, CO suggests this resupply of U may be controlled by microbially-produced nitrite and nitrate. Nitrification, the two-step process of archaeal and bacterial ammonia-oxidation followed by bacterial nitrite oxidation, generates nitrate under oxic conditions. Our hypothesis is that when elevated groundwater levels recede and the subsurface system becomes anoxic, the nitrate diffuses into the reduced interiors of the NRZ and stimulates denitrification, the stepwise anaerobic reduction of nitrate/nitrite to dinitrogen gas. Denitrification may then be coupled to the oxidation of sediment-bound U(IV) forming mobile U(VI), allowing it to resupply U into local groundwater supplies. A key step in substantiating this hypothesis is to demonstrate the presence of nitrogen-cycling organisms in U-contaminated, NRZ sediments from the upper CRB. Here we investigate how the diversity and abundances of nitrifying and denitrifying microbial populations change throughout the NRZs of the subsurface by using functional gene markers for ammonia-oxidation (amoA, encoding the α-subunit of ammonia monooxygenase) and denitrification (nirK, nirS, encoding nitrite reductase). Microbial diversity has been assessed via clone libraries, while abundances have been determined through quantitative polymerase chain reaction (qPCR), elucidating how relative numbers of nitrifiers (amoA) and denitrifiers (nirK, nirS) vary with depth, vary with location, and relate to uranium release within NRZs in sediment

  16. In Situ Identification and Stratification of Monochloramine Inhibition Effects on Nitrifying Biofilms as Determined by the Use of Microelectrodes

    Science.gov (United States)

    The nitrifying biofilm grown in an annular biofilm reactor and the microbial deactivation achieved after monochloramine treatment were investigated using microelectrodes. The nitrifying biofilm ammonium microprofile was measured and the effect of monochloramine on nitrifying bio...

  17. Role of Fusobacterium nucleatum and Coaggregation in Anaerobe Survival in Planktonic and Biofilm Oral Microbial Communities during Aeration

    OpenAIRE

    Bradshaw, David J.; Marsh, Philip D.; Watson, G. Keith; Allison, Clive

    1998-01-01

    Coaggregation is a well-characterized phenomenon by which specific pairs of oral bacteria interact physically. The aim of this study was to examine the patterns of coaggregation between obligately anaerobic and oxygen-tolerant species that coexist in a model oral microbial community. Obligate anaerobes other than Fusobacterium nucleatum coaggregated only poorly with oxygen-tolerant species. In contrast, F. nucleatum was able to coaggregate not only with both oxygen-tolerant and other obligate...

  18. Modelling the impact of future socio-economic and climate change scenarios on river microbial water quality.

    Science.gov (United States)

    Islam, M M Majedul; Iqbal, Muhammad Shahid; Leemans, Rik; Hofstra, Nynke

    2018-03-01

    Microbial surface water quality is important, as it is related to health risk when the population is exposed through drinking, recreation or consumption of irrigated vegetables. The microbial surface water quality is expected to change with socio-economic development and climate change. This study explores the combined impacts of future socio-economic and climate change scenarios on microbial water quality using a coupled hydrodynamic and water quality model (MIKE21FM-ECOLab). The model was applied to simulate the baseline (2014-2015) and future (2040s and 2090s) faecal indicator bacteria (FIB: E. coli and enterococci) concentrations in the Betna river in Bangladesh. The scenarios comprise changes in socio-economic variables (e.g. population, urbanization, land use, sanitation and sewage treatment) and climate variables (temperature, precipitation and sea-level rise). Scenarios have been developed building on the most recent Shared Socio-economic Pathways: SSP1 and SSP3 and Representative Concentration Pathways: RCP4.5 and RCP8.5 in a matrix. An uncontrolled future results in a deterioration of the microbial water quality (+75% by the 2090s) due to socio-economic changes, such as higher population growth, and changes in rainfall patterns. However, microbial water quality improves under a sustainable scenario with improved sewage treatment (-98% by the 2090s). Contaminant loads were more influenced by changes in socio-economic factors than by climatic change. To our knowledge, this is the first study that combines climate change and socio-economic development scenarios to simulate the future microbial water quality of a river. This approach can also be used to assess future consequences for health risks. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  19. Construction and evaluation of a modular biofilm-forming chamber for microbial recovery of neodymium and semi-continuous biofilm preparation. Tolerance of Serratia sp.N14 on acidic conditions and neutralized aqua regia.

    Science.gov (United States)

    Vavlekas, Dimitrios A

    2017-02-01

    Recovery of neodymium from liquid metallic wastes and scrap leachates is a crucial step for its recycling, which can take place through the immobilized biofilms of Serratia sp. N14. These biofilms are produced in a fermentor vessel with a turnaround time of 10-14 days, which is unacceptable from an economic point of view for an industrial process. This study proposes the construction and evaluation of a modular system, whereby a biofilm-forming chamber is inserted into the continuous biomass outflow of the main chemostat vessel, for an alternative semi-continuous and economic production of biofilm. The activity of the biofilm from the outflow chamber was found to be the same as the one from the main chamber, which was stored in a cold room (4°C), for 9-12 months, depending on a 24 h nucleation step.Moreover, the ability of the biofilm to function in the presence of a leaching agent (aqua regia) or in acidic conditions was also evaluated. The biofilm of the main chamber can remain active even at 50% neutralized aqua regia (pH 3.0), while at acidic conditions, phosphate release of the cells is reduced to 50%. This strain proves to be very tolerant in low pH or high salt concentration solutions. The biofilm produced from the outflow of the main fermentor vessel is of acceptable activity, rather than being disposed.

  20. Complete nucleotide sequence and analysis of two conjugative broad host range plasmids from a marine microbial biofilm.

    Directory of Open Access Journals (Sweden)

    Peter Norberg

    Full Text Available 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 ς. 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.

  1. A Bacillus sp. isolated from sediments of the Sarno River mouth, Gulf of Naples (Italy) produces a biofilm biosorbing Pb(II)

    Energy Technology Data Exchange (ETDEWEB)

    Pepi, Milva; Borra, Marco [Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli (Italy); Tamburrino, Stella [Consiglio Nazionale delle Ricerche, Istituto per l' Ambiente Marino Costiero UOS Capo Granitola, Palermo (Italy); Saggiomo, Maria [Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli (Italy); Viola, Alfio [Università di Catania, Corso Italia 57, I-95129 Catania (Italy); Biffali, Elio; Balestra, Cecilia [Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli (Italy); Sprovieri, Mario [Consiglio Nazionale delle Ricerche, Istituto per l' Ambiente Marino Costiero UOS Capo Granitola, Palermo (Italy); Casotti, Raffaella, E-mail: raffaella.casotti@szn.it [Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli (Italy)

    2016-08-15

    A Pb-resistant bacterial strain (named hereinafter Pb15) has been isolated from highly polluted marine sediments at the Sarno River mouth, Italy, using an enrichment culture to which Pb(II) 0.48 mmol l{sup −1} were added. 16S rRNA gene sequencing (Sanger) allowed assignment of the isolate to the genus Bacillus, with Bacillus pumilus as the closest species. The isolate is resistant to Pb(II) with a minimum inhibitory concentration (MIC) of 4.8 mmol l{sup −1} and is also resistant to Cd(II) and Mn(II) with MIC of 2.22 mmol l{sup −1} and 18.20 mmol l{sup −1}, respectively. Inductively coupled plasma atomic emission spectrometry (ICP-AES) showed that Pb inoculated in the growth medium is absorbed by the bacterial cells at removal efficiencies of 31.02% and 28.21% in the presence of 0.48 mmol l{sup −1} or 1.20 mmol l{sup −1} Pb(II), respectively. Strain Pb15 forms a brown and compact biofilm when grown in presence of Pb(II). Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS) confirm that the biofilm contains Pb, suggesting an active biosorption of this metal by the bacterial cells, sequestering 14% of inoculated Pb as evidenced by microscopic analyses. Altogether, these observations support evidence that strain Pb15 has potentials for being used in bioremediation of its native polluted sediments, with engineering solutions to be found in order to eliminate the adsorbed Pb before replacement of sediments in situ. - Highlights: • The strain is able to sequester Pb by biosorption in a biofilm. • A Pb-resistant Bacillus sp. isolated from marine polluted sediments. • The strain is proposed as a tool for bioremediation of Pb-polluted marine sediments.

  2. A Bacillus sp. isolated from sediments of the Sarno River mouth, Gulf of Naples (Italy) produces a biofilm biosorbing Pb(II)

    International Nuclear Information System (INIS)

    Pepi, Milva; Borra, Marco; Tamburrino, Stella; Saggiomo, Maria; Viola, Alfio; Biffali, Elio; Balestra, Cecilia; Sprovieri, Mario; Casotti, Raffaella

    2016-01-01

    A Pb-resistant bacterial strain (named hereinafter Pb15) has been isolated from highly polluted marine sediments at the Sarno River mouth, Italy, using an enrichment culture to which Pb(II) 0.48 mmol l −1 were added. 16S rRNA gene sequencing (Sanger) allowed assignment of the isolate to the genus Bacillus, with Bacillus pumilus as the closest species. The isolate is resistant to Pb(II) with a minimum inhibitory concentration (MIC) of 4.8 mmol l −1 and is also resistant to Cd(II) and Mn(II) with MIC of 2.22 mmol l −1 and 18.20 mmol l −1 , respectively. Inductively coupled plasma atomic emission spectrometry (ICP-AES) showed that Pb inoculated in the growth medium is absorbed by the bacterial cells at removal efficiencies of 31.02% and 28.21% in the presence of 0.48 mmol l −1 or 1.20 mmol l −1 Pb(II), respectively. Strain Pb15 forms a brown and compact biofilm when grown in presence of Pb(II). Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS) confirm that the biofilm contains Pb, suggesting an active biosorption of this metal by the bacterial cells, sequestering 14% of inoculated Pb as evidenced by microscopic analyses. Altogether, these observations support evidence that strain Pb15 has potentials for being used in bioremediation of its native polluted sediments, with engineering solutions to be found in order to eliminate the adsorbed Pb before replacement of sediments in situ. - Highlights: • The strain is able to sequester Pb by biosorption in a biofilm. • A Pb-resistant Bacillus sp. isolated from marine polluted sediments. • The strain is proposed as a tool for bioremediation of Pb-polluted marine sediments.

  3. Metagenomic analysis of planktonic microbial consortia from a non-tidal urban-impacted segment of James River.

    Science.gov (United States)

    Brown, Bonnie L; LePrell, Rebecca V; Franklin, Rima B; Rivera, Maria C; Cabral, Francine M; Eaves, Hugh L; Gardiakos, Vicki; Keegan, Kevin P; King, Timothy L

    2015-01-01

    Knowledge of the diversity and ecological function of the microbial consortia of James River in Virginia, USA, is essential to developing a more complete understanding of the ecology of this model river system. Metagenomic analysis of James River's planktonic microbial community was performed for the first time using an unamplified genomic library and a 16S rDNA amplicon library prepared and sequenced by Ion PGM and MiSeq, respectively. From the 0.46-Gb WGS library (GenBank:SRR1146621; MG-RAST:4532156.3), 4 × 10(6) reads revealed >3 × 10(6) genes, 240 families of prokaryotes, and 155 families of eukaryotes. From the 0.68-Gb 16S library (GenBank:SRR2124995; MG-RAST:4631271.3; EMB:2184), 4 × 10(6) reads revealed 259 families of eubacteria. Results of the WGS and 16S analyses were highly consistent and indicated that more than half of the bacterial sequences were Proteobacteria, predominantly Comamonadaceae. The most numerous genera in this group were Acidovorax (including iron oxidizers, nitrotolulene degraders, and plant pathogens), which accounted for 10 % of assigned bacterial reads. Polaromonas were another 6 % of all bacterial reads, with many assignments to groups capable of degrading polycyclic aromatic hydrocarbons. Albidiferax (iron reducers) and Variovorax (biodegraders of a variety of natural biogenic compounds as well as anthropogenic contaminants such as polycyclic aromatic hydrocarbons and endocrine disruptors) each accounted for an additional 3 % of bacterial reads. Comparison of these data to other publically-available aquatic metagenomes revealed that this stretch of James River is highly similar to the upper Mississippi River, and that these river systems are more similar to aquaculture and sludge ecosystems than they are to lakes or to a pristine section of the upper Amazon River. Taken together, these analyses exposed previously unknown aspects of microbial biodiversity, documented the ecological responses of microbes to urban

  4. Community shift of biofilms developed in a full-scale drinking water distribution system switching from different water sources.

    Science.gov (United States)

    Li, Weiying; Wang, Feng; Zhang, Junpeng; Qiao, Yu; Xu, Chen; Liu, Yao; Qian, Lin; Li, Wenming; Dong, Bingzhi

    2016-02-15

    The bacterial community of biofilms in drinking water distribution systems (DWDS) with various water sources has been rarely reported. In this research, biofilms were sampled at three points (A, B, and C) during the river water source phase (phase I), the interim period (phase II) and the reservoir water source phase (phase III), and the biofilm community was determined using the 454-pyrosequencing method. Results showed that microbial diversity declined in phase II but increased in phase III. The primary phylum was Proteobacteria during three phases, while the dominant class at points A and B was Betaproteobacteria (>49%) during all phases, but that changed to Holophagae in phase II (62.7%) and Actinobacteria in phase III (35.6%) for point C, which was closely related to its water quality. More remarkable community shift was found at the genus level. In addition, analysis results showed that water quality could significantly affect microbial diversity together, while the nutrient composition (e.g. C/N ration) of the water environment might determine the microbial community. Furthermore, Mycobacterium spp. and Pseudomonas spp. were detected in the biofilm, which should give rise to attention. This study revealed that water source switching produced substantial impact on the biofilm community. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Characterization and fluorescence of yellow biofilms in karst caves, southwest Slovenia

    Directory of Open Access Journals (Sweden)

    Janez Mulec

    2015-05-01

    Full Text Available Biofilms of different colours that colonize surfaces within karst caves represent a source of nutrients. They occur commonly and abundantly at sites with sediments, and close to seepages or underground rivers. Golden-yellow subaerial biofilms are particularly well observed because of their contrast with their surroundings, the characteristics of the pigment and recently, even more, due to the characteristics of light-emitting diode (LED illumination. Yellow microbial biofilms were sampled from three caves in southwestern Slovenia, Dimnice, Križna jama and Sveta jama. The highest concentration of cultivable microbes (2.33×108 CFU/g and the biggest number of identified bacteria (66.0% were retrieved from a sample from Sveta jama. Using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight for bacterial identification showed that different species of Pseudomonas prevailed in all samples. Yellow biofilms showed an absorption peak around 400 nm, and two emission peaks, a major in the blue (~460 nm and a minor in the orange (~600 nm parts of the spectrum when excited at 405 nm. Microbial mats that colonize surfaces are probably frequently overlooked in caves because they are difficult to observe when they have no pigmentation and the contrast with their surroundings is low. Additional studies are needed to aid the understanding of the role of pigmented biofilms and their interactions with underlying substrata in respect of the evolution of substrate micromorphology.

  6. Current understanding of multi-species biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong

    2011-01-01

    every year worldwide to deal with damage to equipment, contaminations of products, energy losses, and infections in human beings resulted from microbial biofilms. Microorganisms compete, cooperate, and communicate with each other in multi-species biofilms. Understanding the mechanisms of multi......Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually......-species biofilm formation will facilitate the development of methods for combating bacterial biofilms in clinical, environmental, industrial, and agricultural areas. The most recent advances in the understanding of multi-species biofilms are summarized and discussed in the review....

  7. Candida Biofilms: Development, Architecture, and Resistance

    Science.gov (United States)

    CHANDRA, JYOTSNA; MUKHERJEE, PRANAB K.

    2015-01-01

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

  8. Does reactor staging influence microbial structure and functions in biofilm systems? The case of pre-denitrifying MBBRs

    DEFF Research Database (Denmark)

    Polesel, Fabio; Torresi, Elena; Jensen, Marlene Mark

    -stage MBBR system (S1+S2+S3), fed with pre-clarified wastewater, was operated at laboratory-scale with (i) controlled biomass exposure to organic substrate (COD); and (ii) enhanced the physical retention of biomass, thus inducing adaptation to different substrate exposure conditions. During long...... (exposed to lowest availability). These findings indicate that the exposure to tiered substrate availability influenced the capacity of utilizing a different range of carbon sources in each MBBR, thus impacting denitrification and pharmaceutical biotransformation. Preliminary analysis on the microbial...

  9. Estimation of the fate of microbial water-quality contaminants in a South-African river

    CSIR Research Space (South Africa)

    Hohls, D

    1995-01-01

    Full Text Available The aim of this study was to evaluate the validity of assumptions, regarding assimilative capacity for microbial contaminants, implicit in microbial water quality management in South Africa. A one dimensional steady state stream water quality model...

  10. Growing and Analyzing Biofilms in Flow Chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber–grown biofilms are addressed. Curr. Protoc. Microbiol. 21:1B.2.1-1B.2.17. © 2011 by John Wiley & Sons, Inc....

  11. Mercury methylation and demethylation by periphyton biofilms and their host in a fluvial wetland of the St. Lawrence River (QC, Canada)

    International Nuclear Information System (INIS)

    Hamelin, Stéphanie; Planas, Dolors; Amyot, Marc

    2015-01-01

    Wetlands in large rivers are important sites of production of the neurotoxin methylmercury (MeHg), and the periphyton growing on wetland macrophytes are increasingly recognized as key players in this production and transfer in food webs. Information is lacking about mercury methylation (K m ) and demethylation (K d ) rates in periphytic biofilms from the Northern Hemisphere, as well as about the drivers of net MeHg production, hampering ecosystem modeling of Hg cycling. Mercury methylation and demethylation rates were measured in periphytic biofilms growing on submerged plants in a shallow fluvial lake located in a temperate cold region (St. Lawrence River, Quebec, Canada). Incubations were performed in situ within macrophyte beds using low-level spikes of 199 HgO and Me 200 Hg stable isotopes as tracers. A direct relationship was observed between K m (0.002 to 0.137 d −1 ) and [MeHg] in periphyton. A similar relationship was found between K d (0.096 to 0.334 d −1 ) and [inorganic Hg]. Periphyton of Lake St. Pierre reached high levels of net MeHg production that were two orders of magnitude higher than those found in local sediment. This production varied through the plant growing season and was mainly driven by environmental variables such as depth of growth, available light, dissolved oxygen, temperature, plant community structure, and productivity of the habitat. - Highlights: • Periphyton Hg methylation and demethylation were studied in a large fluvial lake. • Addition of stable Hg isotopes was used to obtain in situ rates for these processes. • Net methylation was higher in periphyton than in local sediments. • Methylation and demethylation rates fluctuated during the summer. • Key drivers of rates were depth, light, temperature, and community structure

  12. Mercury methylation and demethylation by periphyton biofilms and their host in a fluvial wetland of the St. Lawrence River (QC, Canada)

    Energy Technology Data Exchange (ETDEWEB)

    Hamelin, Stéphanie; Planas, Dolors [GRIL, Département de sciences biologiques, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montreal, Quebec H3C 3P8 (Canada); Amyot, Marc [GRIL, Département de sciences biologiques, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Quebec H3C 3J7 (Canada)

    2015-04-15

    Wetlands in large rivers are important sites of production of the neurotoxin methylmercury (MeHg), and the periphyton growing on wetland macrophytes are increasingly recognized as key players in this production and transfer in food webs. Information is lacking about mercury methylation (K{sub m}) and demethylation (K{sub d}) rates in periphytic biofilms from the Northern Hemisphere, as well as about the drivers of net MeHg production, hampering ecosystem modeling of Hg cycling. Mercury methylation and demethylation rates were measured in periphytic biofilms growing on submerged plants in a shallow fluvial lake located in a temperate cold region (St. Lawrence River, Quebec, Canada). Incubations were performed in situ within macrophyte beds using low-level spikes of {sup 199}HgO and Me{sup 200}Hg stable isotopes as tracers. A direct relationship was observed between K{sub m} (0.002 to 0.137 d{sup −1}) and [MeHg] in periphyton. A similar relationship was found between K{sub d} (0.096 to 0.334 d{sup −1}) and [inorganic Hg]. Periphyton of Lake St. Pierre reached high levels of net MeHg production that were two orders of magnitude higher than those found in local sediment. This production varied through the plant growing season and was mainly driven by environmental variables such as depth of growth, available light, dissolved oxygen, temperature, plant community structure, and productivity of the habitat. - Highlights: • Periphyton Hg methylation and demethylation were studied in a large fluvial lake. • Addition of stable Hg isotopes was used to obtain in situ rates for these processes. • Net methylation was higher in periphyton than in local sediments. • Methylation and demethylation rates fluctuated during the summer. • Key drivers of rates were depth, light, temperature, and community structure.

  13. Biofilm in endodontics: a review

    OpenAIRE

    Zambrano de la Peña, Sonia; Salcedo-Moncada, Doris; Petkova- Gueorguieva, Marieta; Ventocilla Huasupoma, María

    2017-01-01

    It is demonstrated the efforts made endodontic microbiology and science to get to decipher the secrets of this unique structure although every day new questions arise. We need the treatments we use to combat biofilm achieve oxygenate the periapical ecosystem and basically scrape and loosen the tightly adhering bacteria Knowing the process of biofilm formation, microbial metabolism and strategies that they use to resist and remain hidden but active , we know why we observe refractory periapica...

  14. Impacts of Salinity and Oxygen on Particle-Associated Microbial Communities in the Broadkill River, Lewes DE

    Directory of Open Access Journals (Sweden)

    Kristin M. Yoshimura

    2018-03-01

    Full Text Available Particulate matter in estuarine systems hosts microbial communities that can impact biogeochemical cycles. While the bacterial community composition on suspended particles has been previously investigated, especially with regards to how salinity may structure these communities, the archaeal fraction of the microbial community has not received the same attention. Here we investigate both the bacterial and archaeal community composition on two sizes of particles along a riverine discharge gradient in the Broadkill River, DE, USA, to determine whether the archaeal community is selected by similar environmental stressors as the bacteria. We measured salinity, nutrients, and diatom abundances, and use particle size as a proxy for oxygen concentrations. We show that salinity is a strong environmental factor that controls both bacterial and archaeal community composition and oxygen is an additional factor, impacting archaea more than bacteria.

  15. Salmonella biofilms

    NARCIS (Netherlands)

    Castelijn, G.A.A.

    2013-01-01

    Biofilm formation by Salmonellaspp. is a problem in the food industry, since biofilms may act as a persistent source of product contamination. Therefore the aim of this study was to obtain more insight in the processes involved and the factors contributing to Salmonellabiofilm

  16. Strategies for combating bacterial biofilm infections

    DEFF Research Database (Denmark)

    Wu, Hong; Moser, Claus Ernst; Wang, Heng-Zhuang

    2015-01-01

    Formation of biofilm is a survival strategy for bacteria and fungi to adapt to their living environment, especially in the hostile environment. Under the protection of biofilm, microbial cells in biofilm become tolerant and resistant to antibiotics and the immune responses, which increases the di.......International Journal of Oral Science advance online publication, 12 December 2014; doi:10.1038/ijos.2014.65....

  17. Antibiotic tolerance and resistance in biofilms

    DEFF Research Database (Denmark)

    Ciofu, Oana; Tolker-Nielsen, Tim

    2010-01-01

    One of the most important features of microbial biofilms is their tolerance to antimicrobial agents and components of the host immune system. The difficulty of treating biofilm infections with antibiotics is a major clinical problem. Although antibiotics may decrease the number of bacteria...... in biofilms, they will not completely eradicate the bacteria in vivo which may have important clinical consequences in form of relapses of the infection....

  18. A network model shows the importance of coupled processes in the microbial N cycle in the Cape Fear River Estuary

    Science.gov (United States)

    Hines, David E.; Lisa, Jessica A.; Song, Bongkeun; Tobias, Craig R.; Borrett, Stuart R.

    2012-06-01

    Estuaries serve important ecological and economic functions including habitat provision and the removal of nutrients. Eutrophication can overwhelm the nutrient removal capacity of estuaries and poses a widely recognized threat to the health and function of these ecosystems. Denitrification and anaerobic ammonium oxidation (anammox) are microbial processes responsible for the removal of fixed nitrogen and diminish the effects of eutrophication. Both of these microbial removal processes can be influenced by direct inputs of dissolved inorganic nitrogen substrates or supported by microbial interactions with other nitrogen transforming pathways such as nitrification and dissimilatory nitrate reduction to ammonium (DNRA). The coupling of nitrogen removal pathways to other transformation pathways facilitates the removal of some forms of inorganic nitrogen; however, differentiating between direct and coupled nitrogen removal is difficult. Network modeling provides a tool to examine interactions among microbial nitrogen cycling processes and to determine the within-system history of nitrogen involved in denitrification and anammox. To examine the coupling of nitrogen cycling processes, we built a nitrogen budget mass balance network model in two adjacent 1 cm3 sections of bottom water and sediment in the oligohaline portion of the Cape Fear River Estuary, NC, USA. Pathway, flow, and environ ecological network analyses were conducted to characterize the organization of nitrogen flow in the estuary and to estimate the coupling of nitrification to denitrification and of nitrification and DNRA to anammox. Centrality analysis indicated NH4+ is the most important form of nitrogen involved in removal processes. The model analysis further suggested that direct denitrification and coupled nitrification-denitrification had similar contributions to nitrogen removal while direct anammox was dominant to coupled forms of anammox. Finally, results also indicated that partial

  19. Dynamic interactions of neutrophils and biofilms

    Directory of Open Access Journals (Sweden)

    Josefine Hirschfeld

    2014-12-01

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

  20. Visco-elastic properties of biofilms

    NARCIS (Netherlands)

    Peterson, Brandon Wade

    2013-01-01

    Microbiële biofilms aanpakken door ze te laten resoneren Naar schatting tachtig procent van alle bacteriële infecties die door dokters behandeld worden, wordt veroorzaakt door biofilms, dunne laagjes micro-organismen. Brandon Peterson stelt in preklinisch onderzoek de hypothese op dat de hechting

  1. BIOFILMS IN DRINKING WATER DISTRIBUTION SYSTEMS

    Science.gov (United States)

    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...

  2. Biofilm Induced Tolerance Towards Antimicrobial Peptides

    DEFF Research Database (Denmark)

    Folkesson, Anders; Haagensen, Janus Anders Juul; Zampaloni, Claudia

    2008-01-01

    Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We address the question of how biofilm organization affects antibiotic susceptibility. We established Escherichia coli biofilms with differential structural organization due...... to the presence of IncF plasmids expressing altered forms of the transfer pili in two different biofilm model systems. The mature biofilms were subsequently treated with two antibiotics with different molecular targets, the peptide antibiotic colistin and the fluoroquinolone ciprofloxacin. The dynamics...... of microbial killing were monitored by viable count determination, and confocal laser microscopy. Strains forming structurally organized biofilms show an increased bacterial survival when challenged with colistin, compared to strains forming unstructured biofilms. The increased survival is due to genetically...

  3. Microelectrodes as novel research tools for environmental biofilm studies

    International Nuclear Information System (INIS)

    Yu, T.; Lu, R.; Bishop, L.

    2002-01-01

    Biofilm processes are widely utilized in environmental engineering for biodegradation of contaminated waters, gases and soils. It is important to understand the structure and functions of biofilms. Microelectrodes are novel experimental tools for environmental biofilm studies. The authors reviewed the techniques of oxygen, sulfide, redox potential and pH microelectrode. These microelectrodes have tip diameters of 3 to 20 μm, resulting a high spatial resolution. They enable us directly measure the chemical conditions as results of microbial activities in biofilms. The authors also reported the laboratory and field studies of wastewater biofilms using microelectrode techniques. The results of these studies provided experimental evidence on the stratification of microbial processes and the associated redox potential change in wastewater biofilms: (1) The oxygen penetration depth was only a fraction of the biofilm thickness. This observation, first made under laboratory conditions, has been confirmed under field conditions. (2) The biofilms with both aerobic oxidation and sulfate reduction had a clearly stratified structure. This was evidenced by a sharp decrease of redox potential near the interface between the aerobic zone and the sulfate reduction zone within the biofilm. In this type of biofilms, aerobic oxidation took place only in a shallow layer near the biofilm surface and sulfate reduction occurred in the deeper anoxic zone. (3) The redox potential changed with the shift of primary microbial process in biofilms, indicating that it is possible to use redox potential to help illustrate the structure and functions of biofilms. (author)

  4. Mercury and selenium concentrations in biofilm, macroinvertebrates, and fish collected in the Yankee Fork of the Salmon River, Idaho, USA, and their potential effects on fish health

    Science.gov (United States)

    Rhea, Darren T.; Farag, Aïda M.; Harper, David D.; McConnell, Elizabeth; Brumbaugh, William G.

    2013-01-01

    The Yankee Fork is a large tributary of the Salmon River located in central Idaho, USA, with an extensive history of placer and dredge-mining activities. Concentrations of selenium (Se) and mercury (Hg) in various aquatic trophic levels were measured in the Yankee Fork during 2001 and 2002. Various measurements of fish health were also performed. Sites included four on the mainstem of the Yankee Fork and two off-channel sites in partially reclaimed dredge pools used as rearing habitat for cultured salmonid eggs and fry. Hg concentrations in whole mountain whitefish and shorthead sculpin ranged from 0.28 to 0.56 μg/g dry weight (dw), concentrations that are generally less than those reported to have significant impacts on fish. Biofilm and invertebrates ranged from 0.05 to 0.43 μg Hg/g dw. Se concentrations measured in biota samples from the Yankee Fork were greater than many representative samples collected in the Snake and Columbia watersheds and often exceeded literature-based toxic thresholds. Biofilm and invertebrates ranged from 0.58 to 4.66 μg Se/g dw. Whole fish ranged from 3.92 to 7.10 μg Se/g dw, and gonads ranged from 6.91 to 31.84 μg Se/g dw. Whole-body Se concentrations exceeded reported toxicological thresholds at three of four sites and concentrations in liver samples were mostly greater than concentrations shown to have negative impacts on fish health. Histological examinations performed during this study noted liver abnormalities, especially in shorthead sculpin, a bottom-dwelling species.

  5. Experimental evolution in biofilm populations

    Science.gov (United States)

    Steenackers, Hans P.; Parijs, Ilse; Foster, Kevin R.; Vanderleyden, Jozef

    2016-01-01

    Biofilms are a major form of microbial life in which cells form dense surface associated communities that can persist for many generations. The long-life of biofilm communities means that they can be strongly shaped by evolutionary processes. Here, we review the experimental study of evolution in biofilm communities. We first provide an overview of the different experimental models used to study biofilm evolution and their associated advantages and disadvantages. We then illustrate the vast amount of diversification observed during biofilm evolution, and we discuss (i) potential ecological and evolutionary processes behind the observed diversification, (ii) recent insights into the genetics of adaptive diversification, (iii) the striking degree of parallelism between evolution experiments and real-life biofilms and (iv) potential consequences of diversification. In the second part, we discuss the insights provided by evolution experiments in how biofilm growth and structure can promote cooperative phenotypes. Overall, our analysis points to an important role of biofilm diversification and cooperation in bacterial survival and productivity. Deeper understanding of both processes is of key importance to design improved antimicrobial strategies and diagnostic techniques. PMID:26895713

  6. Microbial eukaryotic diversity and distribution in a river plume and cyclonic eddy-influenced ecosystem in the South China Sea.

    Science.gov (United States)

    Wu, Wenxue; Wang, Lei; Liao, Yu; Huang, Bangqin

    2015-10-01

    To evaluate microbial eukaryotic diversity and distribution in mesoscale processes, we investigated 18S rDNA diversity in a river plume and cyclonic eddy-influenced ecosystem in the southwestern South China Sea (SCS). Restriction fragment length polymorphism analysis was carried out using multiple primer sets. Relative to a wide range of previous similar studies, we observed a significantly higher proportion of sequences of pigmented taxa. Among the photosynthetic groups, Haptophyta accounted for 27.7% of the sequenced clones, which belonged primarily to Prymnesiophyceae. Unexpectedly, five operational taxonomic units of Cryptophyta were closely related to freshwater species. The Chlorophyta mostly fell within the Prasinophyceae, which was comprised of six clades, including Clade III, which is detected in the SCS for the first time in this study. Among the photosynthetic stramenopiles, Chrysophyceae was the most diverse taxon, which included seven clades. The majority of 18S rDNA sequences affiliated with the Dictyochophyceae, Eustigmatophyceae, and Pelagophyceae were closely related to those of pure cultures. The results of redundancy analysis and the permutation Mantel test based on unweighted UniFrac distances, conducted for spatial analyses of the Haptophyta subclades suggested that the Mekong River plume and cyclonic eddy play important roles in regulating microbial eukaryotic diversity and distribution in the southwestern SCS. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  7. Use of the MicroRespTM method to assess pollution-induced community tolerance to metals for lotic biofilms

    International Nuclear Information System (INIS)

    Tlili, Ahmed; Marechal, Marjorie; Montuelle, Bernard; Volat, Bernadette; Dorigo, Ursula; Berard, Annette

    2011-01-01

    Understanding the ecological status of aquatic ecosystems and the impact of anthropogenic contamination requires correlating exposure to toxicants with impact on biological communities. Several tools exist for assessing the ecotoxicity of substances, but there is still a need for new tools that are ecologically relevant and easy to use. We have developed a protocol based on the substrate-induced respiration of a river biofilm community, using the MicroResp TM technique, in a pollution-induced community tolerance approach. The results show that MicroResp TM can be used in bioassays to assess the toxicity toward biofilm communities of a wide range of metals (Cu, Zn, Cd, Ag, Ni, Fe, Co, Al and As). Moreover, a community-level physiological profile based on the mineralization of different carbon substrates was established. Finally, the utility of MicroResp TM was confirmed in an in-situ study showing gradient of tolerance to copper correlated to a contamination gradient of this metal in a small river. - A modified MicroResp TM technique as a tool for measuring induced tolerance to heavy metals of a microbial biofilm community. - Research highlights: → MicroResp TM allows to plot dose-response curves with various tested metals. → Induced-tolerance to copper of heterotrophic biofilm community was successfully measured. → No co-tolerance detected between copper, silver and cadmium by using MicroResp TM . → MicroResp TM allows assessment of change in catabolic diversity in microbial community.

  8. The Exopolysaccharide Matrix: A Virulence Determinant of Cariogenic Biofilm

    OpenAIRE

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

    2013-01-01

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

  9. QMRAcatch - faecal microbial quality of water resources in a river-floodplain area affected by urban sources and recreational visitors

    Science.gov (United States)

    Derx, Julia; Schijven, Jack; Sommer, Regina; Kirschner, Alexander; Farnleitner, Andreas H.; Blaschke, Alfred Paul

    2016-04-01

    QMRAcatch, a tool to simulate microbial water quality including infection risk assessment, was previously developed and successfully tested at a Danube river site (Schijven et al. 2015). In the tool concentrations of target faecal microorganisms and viruses (TMVs) are computed at a point of interest (PI) along the main river and the floodplain river at daily intervals for a one year period. Even though faecal microbial pathogen concentrations in water resources are usually below the sample limit of detection, this does not ensure, that the water quality complies with a certain required health based target. The aim of this study was therefore to improve the predictability of relevant human pathogenic viruses, i.e. enterovirus and norovirus, in the studied river/floodplain area. This was done by following an innovative calibration strategy based on human-associated microbial source tracking (MST) marker data which were determined following the HF183 TaqMan assay (Green et al. 2011). The MST marker is strongly associated with human faeces and communal sewage, occurring there in numbers by several magnitudes higher than for human enteric pathogens (Mayer et al 2015). The calibrated tool was then evaluated with measured enterovirus concentrations at the PI and in the floodplain river. In the simulation tool the discharges of 5 wastewater treatment plants (WWTPs) were considered with point discharges along a 200 km reach of the Danube river. The MST marker and target virus concentrations at the PI at a certain day were computed based on the concentrations of the previous day, plus the wastewater concentrations times the WWTP discharge divided by the river discharge. A ratio of the river width was also considered, over which the MST marker and virus particles have fully mixed with river water. In the tool, the excrements from recreational visitors frequenting the floodplain area every day were assumed to be homogeneously distributed in the area. A binomial distributed

  10. Studies on the effect of abattior and microbial quality of Aba river in ...

    African Journals Online (AJOL)

    The predominant bacterial forms include Staphylococcus species, Streptococcus faecalis, Escherichia coli, Salmonella species, Bacillus and Clostridium species implying that the abattoir wastes discharged into the river may have had a significant impact on the river ecosystem. African Journal of Biotechnology Vol. 4 (3), pp ...

  11. In situ and Enriched Microbial Community Composition and Function Associated with Coal Bed Methane from Powder River Basin Coals

    Science.gov (United States)

    Barnhart, Elliott; Davis, Katherine; Varonka, Matthew; Orem, William; Fields, Matthew

    2016-04-01

    Coal bed methane (CBM) is a relatively clean source of energy but current CBM production techniques have not sustained long-term production or produced enough methane to remain economically practical with lower natural gas prices. Enhancement of the in situ microbial community that actively generates CBM with the addition of specific nutrients could potentially sustain development. CBM production more than doubled from native microbial populations from Powder River Basin (PRB) coal beds, when yeast extract and several individual components of yeast extract (proteins and amino acids) were added to laboratory microcosms. Microbial populations capable of hydrogenotrophic (hydrogen production/utilization) methanogenesis were detected in situ and under non-stimulated conditions. Stimulation with yeast extract caused a shift in the community to microorganisms capable of acetoclastic (acetate production/utilization) methanogenesis. Previous isotope analysis from CBM production wells indicated a similar microbial community shift as observed in stimulation experiments: hydrogenotrophic methanogenesis was found throughout the PRB, but acetoclastic methanogenesis dominated major recharge areas. In conjunction, a high proportion of cyanobacterial and algal SSU rRNA gene sequences were detected in a CBM well within a major recharge area, suggesting that these phototrophic organisms naturally stimulate methane production. In laboratory studies, adding phototrophic (algal) biomass stimulated CBM production by PRB microorganisms similarly to yeast extract (~40μg methane increase per gram of coal). Analysis of the British thermal unit (BTU) content of coal from long-term incubations indicated >99.5% of BTU content remained after CBM stimulation with either algae or yeast extract. Biomimicry of in situ algal CBM stimulation could lead to technologies that utilize coupled biological systems (photosynthesis and methane production) that sustainably enhance CBM production and generate

  12. Microbial water quality during the northern migration of Sandhill Cranes (Grus canadensis) at the central Platte River, Nebraska

    Science.gov (United States)

    Moser, Matthew T.

    2014-01-01

    The central Platte River is an important resource in Nebraska. Its water flows among multiple channels and supports numerous beneficial uses such as drinking water, irrigation for agriculture, groundwater recharge, and recreational activities. The central Platte River valley is an important stopover for migratory waterfowl and cranes, such as the Whooping (Grus americana) and Sandhill Cranes (Grus canadensis), in their annual northward traversal of the Central Flyway. Waterfowl, cranes, and other migratory birds moving across international and intercontinental borders may provide long-range transportation for any microbial pathogen they harbor, particularly through the spread of feces. Samples were collected weekly in the study reach from three sites (upstream, middle, and downstream from the roosting locations) during the spring of 2009 and 2010. The samples were analyzed for avian influenza, Escherichia coli, Cryptosporidium, Giardia, Campylobacter, and Legionella. Analysis indicates that several types of fecal indicator bacteria and a range of viral, protozoan, and bacterial pathogens were present in Sandhill Crane excreta. These bacteria and pathogens were present at a significantly higher frequency and densities in water and sediments when the Sandhill Cranes were present, particularly during evening roosts within the Platte River environment.

  13. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    OpenAIRE

    Joe A. Lemire; Marc A. Demeter; Iain George; Howard Ceri; Raymond J. Turner

    2015-01-01

    Moving bed biofilm reactors (MBBRs) are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR) carriers (biofilm support materials), allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that ...

  14. Characterization of starvation-induced dispersion in Pseudomonas putida biofilms

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Sternberg, Claus

    2005-01-01

    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...

  15. Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Ren, Dawei

    The coexistence of hugely diverse microbes in most environments highlights the intricate interactions in microbial communities, which are central to their properties, such as productivity, stability and the resilience to disturbance. Biofilm, in environmental habitats, is such a spatially...... multispecies biofilm models, oral microbial community, also known as “dental plaque” is thoroughly investigated as a focal point to describe the interspecies interactions [1]. However, owing to the lack of a reliable high throughput and quantitative approach for exploring the interplay between multiple...... bacterial species, the study to elucidate the impact of interaction networks on the multispecies biofilms in natural ecosystems, especially in soil, is still at an early stage. The diverse patterns of interactions within the mixed communities as well as the predatorprey relationship between protozoa...

  16. Exploiting social evolution in biofilms

    DEFF Research Database (Denmark)

    Boyle, Kerry E; Heilmann, Silja; van Ditmarsch, Dave

    2013-01-01

    Bacteria are highly social organisms that communicate via signaling molecules, move collectively over surfaces and make biofilm communities. Nonetheless, our main line of defense against pathogenic bacteria consists of antibiotics-drugs that target individual-level traits of bacterial cells...... and thus, regrettably, select for resistance against their own action. A possible solution lies in targeting the mechanisms by which bacteria interact with each other within biofilms. The emerging field of microbial social evolution combines molecular microbiology with evolutionary theory to dissect...... the molecular mechanisms and the evolutionary pressures underpinning bacterial sociality. This exciting new research can ultimately lead to new therapies against biofilm infections that exploit evolutionary cheating or the trade-off between biofilm formation and dispersal....

  17. Conductive properties of methanogenic biofilms.

    Science.gov (United States)

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

    2018-02-01

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

  18. Quantitative microbial risk assessment (QMRA) shows increased public health risk associated with exposure to river water under conditions of riverbed sediment resuspension

    CSIR Research Space (South Africa)

    Abia

    2016-10-01

    Full Text Available of The Total Environment, 556-557, pp 1143-1151 Quantitative microbial risk assessment (QMRA) shows increased public health risk associated with exposure to river water under conditions of riverbed sediment resuspension Akebe Luther King Abia a...

  19. [Biofilms and their significance in medical microbiology].

    Science.gov (United States)

    Cernohorská, L; Votava, M

    2002-11-01

    Microorganisms are able to adhere to various surfaces and to form there a three-dimensional structure known as biofilm. In biofilms, microbial cells show characteristics and behaviours different from those of plankton cells. Intercellular signalizations of the quorum-sensing type regulate interaction between members of the biofilm. Bacteria embedded in the biofilm can escape and form well known planktonic forms, that are obviously only a part of the bacterial life cycle. Bacteria adhere also to medically important surfaces such as catheters, either urinary or intravenous ones, artificial heart valves, orthopedic implants and so on and contribute to device-related infections like cystitis, catheter-related sepsis, endocarditis etc. Once a biofilm has been established on a surface, the bacteria harboured inside are less exposed to the host's immune response and less susceptible to antibiotics. As an important cause of nosocomial infections the biofilm must remain in the centre of the microbiologist's attention.

  20. [Biofilms in otolaryngology].

    Science.gov (United States)

    Mena Viveros, Nicolás

    2014-01-01

    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. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  1. An electrochemical impedance model for integrated bacterial biofilms

    International Nuclear Information System (INIS)

    Ben-Yoav, Hadar; Freeman, Amihay; Sternheim, Marek; Shacham-Diamand, Yosi

    2011-01-01

    Bacterial cells attachment onto solid surfaces and the following growth into mature microbial biofilms may result in highly antibiotic resistant biofilms. Such biofilms may be incidentally formed on tissues or implanted devices, or intentionally formed by directed deposition of microbial sensors on whole-cell bio-chip surface. A new method for electrical characterization of the later on-chip microbial biofilm buildup is presented in this paper. Measurement of impedance vs. frequency in the range of 100 mHz to 400 kHz of Escherichia coli cells attachment to indium-tin-oxide-coated electrodes was carried out while using optical microscopy estimating the electrode area coverage. We show that impedance spectroscopy measurements can be interpreted by a simple electrical equivalent model characterizing both attachment and growth of the biofilm. The correlation of extracted equivalent electrical lumped components with the visual biofilm parameters and their dependence on the attachment and growth phases is confirmed.

  2. Comparison of Enzymatic Assay and Multiple Tube Fermentation Technique in the Assessment of Microbial Quality of the Karoon River

    Directory of Open Access Journals (Sweden)

    Mahnaz Nikaeen

    2010-09-01

    Full Text Available Microbiological monitoring of surface waters designated for use as drinking water is essential by water utilities for the design and operation of drinking water treatment plants. Enzymatic assays have been applied as a rapid alternative approach to assess the microbiological quality of freshwater. In this study, the LMX broth (LMX as an enzymatic assay was compared with the standard method of multiple tube fermentation technique (MTF for the microbial monitoring of the Karoon River. Enumeration of total coliforms and E. coli averaged 9928 and 6684 MPN/ 100 ml by the LMX and 7564 and 6546 MPN/ 100 ml for the MTF, respectively. This difference was statistically significant for TC but the overall analysis revealed no difference between E. coli recoveries on LMX and MTF. In conclusion, LMX can be used for the enumeration of coliforms and E. coli in surface waters as it is less lobar-intensive, yields faster result, and simultaneously detects both total coliforms and E. coli.

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

    Directory of Open Access Journals (Sweden)

    Wennerberg Ann

    2011-03-01

    Full Text Available Abstract 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 μm. 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

  4. Microbial burden of some herbal antimalarials marketed at Elele, Rivers State.

    Science.gov (United States)

    Tatfeng, Y M; Olama, E H; Ojo, T O

    2009-12-30

    Herbal antimalarials still remain an alternative to our traditional communities who can not afford orthodox antimalarials. This study was aimed at investigating the microbial quality of six herbal antimalarials using standard microbiological methods. Of the six preparations analyzed, "schnapps", palm wine and water were the media of preparation; the water base preparations recorded higher microbial load. The mean microbial load was 159.5 × 10(5) cfu/ml and 217.4 × 10(2)cfu/ml in water and alcohol base preparations respectively. The microbial profile of the preparations showed that the schnapps base preparations were predominantly contaminated with Bacillus sp (Aerobic spore bearers) and Mucor spp. The palm wine preparation harboured Bacillus sp, yeasts and Mucor spp while the water base preparations had several isolates such as Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli 0157H7, Proteus mirabilis, Enterococcus feacalis, Serratia marcensces, Staph. aureus, Bacillus spp and Mucor spp. Conclusively, this study underlines the public health importance of these preparations given the high burden of such human pathogen as Ecoli O157H7, Ps aeruginosa, Stahp aureus, etc. in the preparations.

  5. Monitoring of biofilm formation on different material surfaces of medical devices using hyperspectral imaging method

    Science.gov (United States)

    Kim, Do-Hyun; Kim, Moon S.; Hwang, Jeeseong

    2012-03-01

    Contamination of the inner surface of indwelling (implanted) medical devices by microbial biofilm is a serious problem. Some microbial bacteria such as Escherichia coli form biofilms that lead to potentially lifethreatening infections. Other types of medical devices such as bronchoscopes and duodenoscopes account for the highest number of reported endoscopic infections where microbial biofilm is one of the major causes for these infections. We applied a hyperspectral imaging method to detect biofilm contamination on the surface of several common materials used for medical devices. Such materials include stainless steel, titanium, and stainless-steeltitanium alloy. Potential uses of hyperspectral imaging technique to monitor biofilm attachment to different material surfaces are discussed.

  6. Urban Wastewater Impacts on the Spatial Distribution of Solutes and Microbial Constituents in the Musi River, India

    Science.gov (United States)

    Ensink, J.; Scott, C. A.; Cairncross, S.

    2006-05-01

    Wastewater discharge from expanding urban centers deteriorates the quality of receiving waters, a trend that has management and investment implications for cities around the world. This paper presents the results of a 14-month water quality evaluation over a 40-km longitudinal profile downstream of the city of Hyderabad, India (population 7 million) on the Musi River, a tributary to the Krishna River. Upstream to downstream improvements in Musi water quality for microbial constituents (nematode egg, faecal coliform), dissolved oxygen, and nitrate are attributed to natural attenuation processes (dilution, die-off, sedimentation and biological processes) coupled with the effects of in-stream hydraulic infrastructure (weirs and reservoirs). Conversely, upstream to downstream increases in total dissolved solids concentrations are caused by off- stream infrastructure and agricultural water use resulting in crop evapotranspiration and increased solute concentration in the return flow of irrigation diverted upstream in the wastewater system. Future water quality management challenges resulting from rampant urban growth, particularly in developing countries, are discussed.

  7. Biofilm Development

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2015-01-01

    During the past decade we have gained much knowledge about the molecular mechanisms that are involved in initiation and termination of biofilm formation. In many bacteria, these processes appear to occur in response to specific environmental cues and result in, respectively, induction or terminat......During the past decade we have gained much knowledge about the molecular mechanisms that are involved in initiation and termination of biofilm formation. In many bacteria, these processes appear to occur in response to specific environmental cues and result in, respectively, induction...... or termination of biofilm matrix production via the second messenger molecule c-di-GMP. In between initiation and termination of biofilm formation we have defined specific biofilm stages, but the currently available evidence suggests that these transitions are mainly governed by adaptive responses......, and not by specific genetic programs. It appears that biofilm formation can occur through multiple pathways and that the spatial structure of the biofilms is species dependent as well as dependent on environmental conditions. Bacterial subpopulations, e.g., motile and nonmotile subpopulations, can develop...

  8. Microbial water quality in the upper Olifants River catchment: implications for health

    CSIR Research Space (South Africa)

    Le Rouw, Wouter J

    2012-10-01

    Full Text Available indicator counts (E. coli) several pathogens were also monitored for (Table 1). Table 1: Microbial pathogens monitored and the detection method used Determinant Method E. coli Colilert TM Salmonella sp. Real-Time polymerase chain reaction Shigella sp...-Time polymerase chain reaction ? Year 1: E. coli levels were monitored bi-monthly at 11 sampling sites (Figure 1). Pathogens were tested for bimonthly at the sites that exhibited high faecal indicator counts (FIO) counts. Twelve additional sites were monitored...

  9. Biodiversity of the microbial mat of the Garga hot spring.

    Science.gov (United States)

    Rozanov, Alexey Sergeevich; Bryanskaya, Alla Victorovna; Ivanisenko, Timofey Vladimirovich; Malup, Tatyana Konstantinovna; Peltek, Sergey Evgenievich

    2017-12-28

    Microbial mats are a good model system for ecological and evolutionary analysis of microbial communities. There are more than 20 alkaline hot springs on the banks of the Barguzin river inflows. Water temperature reaches 75 °C and pH is usually 8.0-9.0. The formation of microbial mats is observed in all hot springs. Microbial communities of hot springs of the Baikal rift zone are poorly studied. Garga is the biggest hot spring in this area. In this study, we investigated bacterial and archaeal diversity of the Garga hot spring (Baikal rift zone, Russia) using 16S rRNA metagenomic sequencing. We studied two types of microbial communities: (i) small white biofilms on rocks in the points with the highest temperature (75 °C) and (ii) continuous thick phototrophic microbial mats observed at temperatures below 70 °C. Archaea (mainly Crenarchaeota; 19.8% of the total sequences) were detected only in the small biofilms. The high abundance of Archaea in the sample from hot springs of the Baikal rift zone supplemented our knowledge of the distribution of Archaea. Most archaeal sequences had low similarity to known Archaea. In the microbial mats, primary products were formed by cyanobacteria of the genus Leptolyngbya. Heterotrophic microorganisms were mostly represented by Actinobacteria and Proteobacteria in all studied samples of the microbial mats. Planctomycetes, Chloroflexi, and Chlorobi were abundant in the middle layer of the microbial mats, while heterotrophic microorganisms represented mostly by Firmicutes (Clostridia, strict anaerobes) dominated in the bottom part. Besides prokaryotes, we detect some species of Algae with help of detection their chloroplasts 16 s rRNA. High abundance of Archaea in samples from hot springs of the Baikal rift zone supplemented our knowledge of the distribution of Archaea. Most archaeal sequences had low similarity to known Archaea. Metagenomic analysis of microbial communities of the microbial mat of Garga hot spring showed that

  10. Wound biofilms: lessons learned from oral biofilms

    OpenAIRE

    Mancl, Kimberly A.; Kirsner, Robert S.; Ajdic, Dragana

    2013-01-01

    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 relati...

  11. Caenorhabditis elegans BAH-1 is a DUF23 protein expressed in seam cells and required for microbial biofilm binding to the cuticle.

    Directory of Open Access Journals (Sweden)

    Kevin Drace

    2009-08-01

    Full Text Available The cuticle of Caenorhabditis elegans, a complex, multi-layered extracellular matrix, is a major interface between the animal and its environment. Biofilms produced by the bacterial genus Yersinia attach to the cuticle of the worm, providing an assay for surface characteristics. A C. elegans gene required for biofilm attachment, bah-1, encodes a protein containing the domain of unknown function DUF23. The DUF23 domain is found in 61 predicted proteins in C. elegans, which can be divided into three distinct phylogenetic clades. bah-1 is expressed in seam cells, which are among the hypodermal cells that synthesize the cuticle, and is regulated by a TGF-beta signaling pathway.

  12. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Directory of Open Access Journals (Sweden)

    Zhejun Wang

    Full Text Available Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM, peptide 1018 was able to significantly (p50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

  13. PO43- dependence of the tolerance of autotrophic and heterotrophic biofilm communities to copper and diuron.

    Science.gov (United States)

    Tlili, Ahmed; Bérard, Annette; Roulier, Jean-Louis; Volat, Bernadette; Montuelle, Bernard

    2010-06-10

    Pollution-induced community tolerance (PICT) concept is based on the assumption that the toxicant exerts selection pressure on the biological communities when exposure reaches a critical level for a sufficient period of time and therefore sensitive species are eliminated. However, induced tolerance of microbial biofilm communities cannot be attributed solely to the presence of toxicants in rivers but also to various environmental factors, such as amount of nutrients. An experimental study was undertaken to highlight the potential impact of a phosphorus gradient on the sensitivity of periphytic microbial community to Cu and diuron. Biofilms were exposed to real-world levels of chronic environmental contamination of toxicants with a phosphorus gradient. Biofilm sensitivity to Cu and diuron was assessed by performing short-term inhibition tests based on photosynthetic efficiency to target photoautotrophs, extracellular enzyme activity (beta-glucosidase and leucine-aminopeptidase) and substrate-induced respiration activity to target heterotrophs. The impact of P-gradient associated to pollution was evaluated by measuring pesticide concentrations in biofilms, biomass parameters (chla, AFDW), bacterial cell density, photosynthetic efficiency and community structure (using 18S and 16S rDNA gene analysis to target eukaryotes and DGGE and HPLC pigment analysis to target bacteria and photoautotrophs). The obtained results show that depending on the studied toxicant and the used structural or functional parameter, the effect of the phosphorus gradient was variable. This highlights the importance of using a range of parameters that target all the biological communities in the biofilm. The PICT method can be regarded as a good tool for assessing anthropogenic environmental contamination, but it is necessary to dissociate the real impact of toxicants from environmental factors.

  14. Focus on the physics of biofilms

    International Nuclear Information System (INIS)

    Lecuyer, Sigolene; Stocker, Roman; Rusconi, Roberto

    2015-01-01

    Bacteria are the smallest and most abundant form of life. They have traditionally been considered as primarily planktonic organisms, swimming or floating in a liquid medium, and this view has shaped many of the approaches to microbial processes, including for example the design of most antibiotics. However, over the last few decades it has become clear that many bacteria often adopt a sessile, surface-associated lifestyle, forming complex multicellular communities called biofilms. Bacterial biofilms are found in a vast range of environments and have major consequences on human health and industrial processes, from biofouling of surfaces to the spread of diseases. Although the study of biofilms has been biologists’ territory for a long time, a multitude of phenomena in the formation and development of biofilms hinges on physical processes. We are pleased to present a collection of research papers that discuss some of the latest developments in many of the areas to which physicists can contribute a deeper understanding of biofilms, both experimentally and theoretically. The topics covered range from the influence of physical environmental parameters on cell attachment and subsequent biofilm growth, to the use of local probes and imaging techniques to investigate biofilm structure, to the development of biofilms in complex environments and the modeling of colony morphogenesis. The results presented contribute to addressing some of the major challenges in microbiology today, including the prevention of surface contamination, the optimization of biofilm disruption methods and the effectiveness of antibiotic treatments. (editorial)

  15. Identification of active dehalorespiring microbial populations in anoxic river sediment by RNA-based stable isotope probing

    Science.gov (United States)

    Kittelmann, S.; Friedrich, M. W.

    2005-12-01

    Tetrachloroethene (perchloroethylene, PCE), a persistent contaminant in aquifers, soils and sediments, can be reductively dechlorinated by anaerobic microorganisms in a process referred to as dehalorespiration. However, the biodiversity of dehalorespiring microorganisms and their distribution especially in pristine environments is largely unexplored. Therefore, the aim of this study was to detect potentially novel PCE-dehalorespiring microorganisms by using stable isotope probing (SIP), a technique that allows to directly identify the function of uncultivated microbial populations. We simulated a PCE contamination by incubating pristine river sediment in the presence of PCE at a steady, low aqueous concentration (20 μM). Dehalogenation activity in microcosms (20 nmol cis-dichloroethene per ml slurry per day formed) was detected already after 4 weeks at 20°C with sediment indigenous electron donors. The microbial community in sediment incubations was probed with 13C-labelled acetate (0.5 mM) as electron donor and carbon source at 15°C for 3 days. After RNA extraction, "heavy" 13C-rRNA and light 12C-rRNA were separated by isopycnic centrifugation, and Bacteria-related populations in gradient fractions were characterised by terminal restriction fragment length polymorphism analysis and cloning. In heavy gradient fractions from the microcosm with PCE, we detected a prominent 506-bp terminal restriction fragment (T-RF) and a few minor T-RFs only. In contrast, in the control without PCE, Bacteria-specific rRNA was restricted to light gradient fractions, and the prominent T-RFs found in the PCE-dechlorinating microcosm were of minor importance. Apparently, 13C-acetate was incorporated into bacterial rRNA more effectively in PCE-respiring microcosms. Thus, rRNA-SIP provides strong evidence for the presence of PCE-dehalorespiring, 13C-acetate-utilising populations in river sediment microcosms. Cloning/sequencing analysis identified the prominent members of the heavy

  16. Biofilm mediated decontamination of pollutants from the environment

    Directory of Open Access Journals (Sweden)

    Arindam Mitra

    2016-01-01

    Full Text Available In this review, we highlight beneficial use of microbial biofilms in remediation of environmental pollutants by bioremediation. Bioremediation is an environment friendly, cost effective, sustainable technology that utilizes microbes to decontaminate and degrade a wide variety of pollutants into less harmful products. Relative to free-floating planktonic cells, microbes existing in biofilm mode are advantageous for bioremediation because of greater tolerance to pollutants, environmental stress and ability to degrade varied harsh pollutants via diverse catabolic pathways. In biofilm mode, microbes are immobilized in a self-synthesized matrix which offers protection from stress, contaminants and predatory protozoa. Contaminants ranging from heavy metals, petroleum, explosives, pesticides have been remediated using microbial consortia of biofilms. In the industry, biofilm based bioremediation is used to decontaminate polluted soil and groundwater. Here we discuss conventional and newer strategies utilizing biofilms in environmental remediation.

  17. The effect of river water circulation on the distribution and functioning of reservoir microbial communities as determined by a relative distance approach

    Czech Academy of Sciences Publication Activity Database

    Šimek, Karel; Comerma, M.; García, J. C.; Nedoma, Jiří; Marcé, R.; Armengol, J.

    2011-01-01

    Roč. 14, č. 1 (2011), s. 1-14 ISSN 1432-9840 R&D Projects: GA ČR(CZ) GA206/08/0015 Institutional research plan: CEZ:AV0Z60170517 Keywords : canyon-shaped reservoir * ongitudinal gradients * relative distance model * river-reservoir ecosystem * water circulation patterns * plankton succession * microbial dynamics Subject RIV: EE - Microbiology, Virology Impact factor: 3.495, year: 2011

  18. Environmental drivers of soil microbial community structure and function at the Avon River Critical Zone Observatory.

    Science.gov (United States)

    Gleeson, Deirdre; Mathes, Falko; Farrell, Mark; Leopold, Matthias

    2016-11-15

    The Critical Zone is defined as the thin, permeable layer from the tops of the trees to the bottom of the bedrock that sustains terrestrial life on Earth. The geometry and shape of the various weathering zones are known as the critical zone architecture. At the centre of the Critical Zone are soils and the microorganisms that inhabit them. In Western Australia, the million-year-old stable weathering history and more recent lateral erosion during the past hundreds of thousands of years have created a geomorphic setting where deep weathering zones are now exposed on the surface along the flanks of many lateritic hills. These old weathering zones provide diverse physical and chemical properties that influence near surface pedologic conditions and thus likely shape current surface microbiology. Here, we present data derived from a small lateritic hill on the UWA Farm Ridgefield. Spatial soil sampling revealed the contrasting distribution patterns of simple soil parameters such as pH (CaCl2) and electric conductivity. These are clearly linked with underlying changes of the critical zone architecture and show a strong contrast with low values of pH3.3 at the top of the hill to pH5.3 at the bottom. These parameters were identified as major drivers of microbial spatial variability in terms of bacterial and archaeal community composition but not abundance. In addition, we used sensitive (14)C labelling to assess turnover of three model organic nitrogen compounds - an important biogeochemical functional trait relating to nutrient availability. Though generally rapid and in the order of rates reported elsewhere (t½10h). In conclusion, we have shown that the weathering and erosion history of ancient Western Australia affects the surface pedology and has consequences for microbial community structure and function. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Microbial degradation of petroleum hydrocarbons in estuarine sediment of Tama River in Tokyo urban area

    International Nuclear Information System (INIS)

    Yamane, Akiko; Hosomi, Masaaki; Murakami, Akihiko; Sakakibara, Koji

    1997-01-01

    Aerobic and anaerobic biodegradation rates of petroleum hydrocarbons, i.e., hexadecane (HEX), phenanthrene (PHE), and anthracene (ANT), were determined in estuarine sediment of the Tama River in urban Tokyo, followed by estimating their respective degradation potential. While in a sediment slurry, the aerobic biodegradation rates of these petroleum hydrocarbons ranged from 40 to 70 μg.g -1 dry sediment:day -1 . The anaerobic biodegradation rate of HEX was found to be 5 -8 μg.g -1 dry sediment.day -1 , whereas that of PHE and ANT could not be detected following a 2-month incubation. Aerobic degradation of HEX was not affected by coexistence with either PHE or ANT, nor by the salinity level. The number of HEX-, PHE-, or ANT-utilizing bacteria ranged from 5 - 10% of the total number of aerobic heterotrophic bacteria. We calculated their biodegradation potentials using the biomass of naturally existing petroleum hydrocarbon utilizing bacteria present in the sampled sediment, with results for HEX, PHE, and ANT being 1.0 -3.5, 4.2 x 10 -2 , and 1.2 x 10 -2 -9.4 x 10 -1 μg.g -1 dry sediment day -1 , respectively. In the aerobic tidal sediment of the Tama River, the purification potentials of HEX, PHE, and ANT were assessed to be approximately equal to their accumulation potentials occurring at the normal water level. (Author)

  20. Biocorrosion: towards understanding interactions between biofilms and metals.

    Science.gov (United States)

    Beech, Iwona B; Sunner, Jan

    2004-06-01

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

  1. Microbial flora in organic honey samples of africanized honeybees from Parana river islands

    Directory of Open Access Journals (Sweden)

    Maria Josiane Sereia

    2011-06-01

    Full Text Available The purpose of this study was to verify and compare the main contamination sources and the hygienic/sanitary conditions of organic honey samples of Apis mellifera from Parana River islands. Thirty-three (33 samples were analyzed between January 2005 and August 2006. Eleven (11 samples were collected by beekeepers and twenty-two (22 samples were collected and processed in accordance with ideal personal hygiene norms and good manufacturing practices. The samples underwent microbiological analysis in search of coliforms at 35 ºC and 45 ºC, as well as fungi enumeration analysis. As for fungi counting, the samples harvested by beekeepers showed values above the maximum established by Resolution nº 15/94 of Common Market Group - Mercosul. The results showed that secondary contamination sources are responsible for the reduction of organic honey quality.

  2. Aerobic Biofilms Grown from Athabasca Watershed Sediments Are Inhibited by Increasing Concentrations of Bituminous Compounds

    Science.gov (United States)

    Lawrence, John R.; Sanschagrin, Sylvie; Roy, Julie L.; Swerhone, George D. W.; Korber, Darren R.; Greer, Charles W.

    2013-01-01

    Sediments from the Athabasca River and its tributaries naturally contain bitumen at various concentrations, but the impacts of this variation on the ecology of the river are unknown. Here, we used controlled rotating biofilm reactors in which we recirculated diluted sediments containing various concentrations of bituminous compounds taken from the Athabasca River and three tributaries. Biofilms exposed to sediments having low and high concentrations of bituminous compounds were compared. The latter were 29% thinner, had a different extracellular polysaccharide composition, 67% less bacterial biomass per μm2, 68% less cyanobacterial biomass per μm2, 64% less algal biomass per μm2, 13% fewer protozoa per cm2, were 21% less productive, and had a 33% reduced content in chlorophyll a per mm2 and a 20% reduction in the expression of photosynthetic genes, but they had a 23% increase in the expression of aromatic hydrocarbon degradation genes. Within the Bacteria, differences in community composition were also observed, with relatively more Alphaproteobacteria and Betaproteobacteria and less Cyanobacteria, Bacteroidetes, and Firmicutes in biofilms exposed to high concentrations of bituminous compounds. Altogether, our results suggest that biofilms that develop in the presence of higher concentrations of bituminous compounds are less productive and have lower biomass, linked to a decrease in the activities and abundance of photosynthetic organisms likely due to inhibitory effects. However, within this general inhibition, some specific microbial taxa and functional genes are stimulated because they are less sensitive to the inhibitory effects of bituminous compounds or can degrade and utilize some bitumen-associated compounds. PMID:24056457

  3. Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor

    Directory of Open Access Journals (Sweden)

    Marchetti Leonardo

    2006-04-01

    Full Text Available Abstract Background Olive mill wastewater (OMW is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter

  4. Microbial community evolution of black and stinking rivers during in situ remediation through micro-nano bubble and submerged resin floating bed technology.

    Science.gov (United States)

    Sun, Yanmei; Wang, Shiwei; Niu, Junfeng

    2018-06-01

    Microbes play important roles during river remediation and the interaction mechanism illustration between microorganisms and sewage is of great significance to improve restoration technology. In this study, micro-nano bubble and submerged resin floating bed composite technology (MBSR) was firstly used to restore two black and stinking urban rivers. After restoration, the water pollution indices such as dissolved oxygen (DO), ammonia nitrogen (NH 4 + -N), total phosphorous (TP), chemical oxygen demand (COD Cr ), water clarity, and the number of facial coliform were significantly improved. Microbial community composition and relative abundance both varied and more aerobic microbes emerged after remediation. The microbial changes showed correlation with DO, NH 4 + -N, TP and COD Cr of the rivers. In summary, the MBSR treatment improved the physiochemical properties of the two black and stinking urban rivers probably through oxygen enrichment of micro-nano bubble and adsorption of submerged resin floating bed, which thereby stimulated functional microbes to degrade pollutants. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Electrochemical roles of extracellular polymeric substances in biofilms

    DEFF Research Database (Denmark)

    Xiao, Yong; Zhao, Feng

    2017-01-01

    Most microbial cells in nature are surrounded by extracellular polymeric substances (EPS), which are fundamental components and determine the physiochemical properties of a biofilm. This review highlights the EPS properties of conductivity and redox ability from an electrochemical perspective, em...

  6. From biofilm ecology to reactors: a focused review

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  7. Abundance and biomass responses of microbial food web components to hydrology and environmental gradients within a floodplain of the River Danube.

    Science.gov (United States)

    Palijan, Goran

    2012-07-01

    This study investigated the relationships of time-dependent hydrological variability and selected microbial food web components. Samples were collected monthly from the Kopački Rit floodplain in Croatia, over a period of 19 months, for analysis of bacterioplankton abundance, cell size and biomass; abundance of heterotrophic nanoflagellates and nanophytoplankton; and concentration of chlorophyll a. Similar hydrological variability at different times of the year enabled partition of seasonal effects from hydrological changes on microbial community properties. The results suggested that, unlike some other studies investigating sites with different connectivity, bacterioplankton abundance, and phytoplankton abundance and biomass increased during lentic conditions. At increasing water level, nanophytoplankton showed lower sensitivity to disturbance in comparison with total phytoplankton biomass: this could prolong autotrophic conditions within the floodplain. Bacterioplankton biomass, unlike phytoplankton, was not impacted by hydrology. The bacterial biomass less affected by hydrological changes can be an important additional food component for the floodplain food web. The results also suggested a mechanism controlling bacterial cell size independent of hydrology, as bacterial cell size was significantly decreased as nanoflagellate abundance increased. Hydrology, regardless of seasonal sucession, has the potential to structure microbial food webs, supporting microbial development during lentic conditions. Conversely, other components appear unaffected by hydrology or may be more strongly controlled by biotic interactions. This research, therefore, adds to understanding on microbial food web interactions in the context of flood and flow pulses in river-floodplain ecosystems.

  8. Spaceflight promotes biofilm formation by Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Wooseong Kim

    Full Text Available 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.

  9. Geographic variability in amoeboid protists and other microbial groups in the water column of the lower Hudson River Estuary (New York, USA)

    Science.gov (United States)

    Juhl, Andrew R.; Anderson, O. Roger

    2014-12-01

    In comparison to other groups of planktonic microorganisms, relatively little is known about the role of amoeboid protists (amebas) in planktonic ecosystems. This study describes the first geographic survey of the abundance and biomass of amebas in an estuarine water column. Samples collected in the lower Hudson River Estuary were used to investigate relationships between ameba abundance and biomass and hydrographic variables (temperature, salinity, and turbidity), water depth (surface and near bottom), distance from mid-channel to shore, phytoplankton biomass (chlorophyll fluorescence) and the occurrence of other heterotrophic microbial groups (heterotrophic bacteria, nanoflagellates, and ciliates) in the plankton. Although salinity increased significantly towards the mouth of the estuary, there were no significant differences in the abundance or biomass of any microbial group in surface samples collected at three stations separated by 44 km along the estuary's mid-channel. Peak biomass values for all microbial groups were found at the station closest to shore, however, cross-channel trends in microbial abundance and biomass were not statistically significant. Although ameba abundance and biomass in most samples were low compared to other microbial groups, clear patterns in ameba distribution were nevertheless found. Unlike other microbial groups examined, ameba numbers and biomass greatly increased in near bottom water compared to surface samples. Ameba abundance and biomass (in surface samples) were also strongly related to increasing turbidity. The different relationships of ameba abundance and biomass with turbidity suggest a rising contribution of large amebas in microbial communities of the Hudson estuary when turbidity increases. These results, emphasizing the importance of particle concentration as attachment and feeding surfaces for amebas, will help identify the environmental conditions when amebas are most likely to contribute significantly to estuarine

  10. Impact of heavy metal on activity of some microbial enzymes in the riverbed sediments: Ecotoxicological implications in the Ganga River (India).

    Science.gov (United States)

    Jaiswal, Deepa; Pandey, Jitendra

    2018-04-15

    We studied the extracellular enzyme activity (EEA) in the riverbed sediment along a 518km gradient of the Ganga River receiving carbon and nutrient load from varied human sources. Also, we tested, together with substrate-driven stimulation, if the heavy metal accumulated in the sediment inhibits enzyme activities. Because pristine values are not available, we considered Dev Prayag, a least polluted site located 624km upstream to main study stretch, as a reference site. There were distinct increases in enzyme activities in the sediment along the study gradient from Dev Prayag, however, between-site differences were in concordance with sediment carbon(C), nitrogen (N) and phosphorus (P). Fluorescein diacetate hydrolysis (FDAase), β-glucosidase (Glu) and protease activities showed positive correlation with C, N and P while alkaline phosphatase was found negatively correlated with P. Enzyme activities were found negatively correlated with heavy metal, although ecological risk index (E R i ) varied with site and metal species. Dynamic fit curves showed significant positive correlation between heavy metal and microbial metabolic quotient (qCO 2 ) indicating a decrease in microbial activity in response to increasing heavy metal concentrations. This study forms the first report linking microbial enzyme activities to regional scale sediment heavy metal accumulation in the Ganga River, suggests that the microbial enzyme activities in the riverbed sediment were well associated with the proportion of C, N and P and appeared to be a sensitive indicator of C, N and P accumulation in the river. Heavy metal accumulated in the sediment inhibits enzyme activities, although C rich sediment showed relatively low toxicity due probably to reduced bioavailability of the metal. The study has relevance from ecotoxicological as well as from biomonitoring perspectives. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Detecting contaminating microorganism in human food and water from Raman mapping through biofilms

    Science.gov (United States)

    Detecting microbial growth can help experts determine how to prevent the outbreaks especially if human food or water has been contaminated. Biofilms are a group of microbial cells that can either grow on living surfaces or surrounding themselves as they progress. Biofilms are not necessarily uniform...

  12. The electric picnic: synergistic requirements for exoelectrogenic microbial communities

    KAUST Repository

    Kiely, Patrick D; Regan, John M; Logan, Bruce E

    2011-01-01

    (BESs). Analysis of the community profiles of exoelectrogenic microbial consortia in BESs fed different substrates gives a clearer picture of the different microbial populations present in these exoelectrogenic biofilms. Rapid utilization of fermentation

  13. Metabolic versatility of Gram-positive microbial isolates from contaminated river sediments

    International Nuclear Information System (INIS)

    Narancic, Tanja; Djokic, Lidija; Kenny, Shane T.; O’Connor, Kevin E.; Radulovic, Vanja; Nikodinovic-Runic, Jasmina; Vasiljevic, Branka

    2012-01-01

    Highlights: ► Thirty-four isolated Gram-positive bacteria could degrade wide range of aromatic pollutants. ► Nine isolates could grow in the presence of extremely high levels of heavy metals. ► Twelve isolates accumulated polyphosphate, 3 polyhydroxybutyrate, 4 exopolysaccharides. ► The incidence of multiple antibiotic resistance markers among isolates was low. - Abstract: Gram-positive bacteria from river sediments affected by the proximity of a petrochemical industrial site were isolated and characterized with respect to their ability to degrade a wide range of aromatic compounds. In this study we identified metabolically diverse Gram-positive bacteria capable of growth on wide range aromatic compounds in the presence of heavy metals and with the ability to accumulate biopolymers. Thirty-four isolates that were able to use 9 or more common aromatic pollutants, such as benzene, biphenyl, naphthalene etc. as a sole source of carbon and energy included members of Bacillus, Arthrobacter, Rhodococcus, Gordonia, Streptomyces, and Staphylococcus genus. Rhodococcus sp. TN105, Gordonia sp. TN103 and Arthrobacter sp. TN221 were identified as novel strains. Nine isolates were able to grow in the presence of one or more metals (mercury, cadmium, nickel) at high concentration (100 mM). Seven isolates could degrade 15 different aromatic compounds and could grow in the presence of one or more heavy metals. Two of these isolates were resistant to multiple antibiotics including erythromycin and nalidixic acid. One third of isolates could accumulate at least one biopolymer. Twelve isolates (mainly Bacillus sp. and Arthrobacter sp.) accumulated polyphosphate, 3 Bacillus sp. accumulated polyhydroxybutyrate, while 4 isolates could accumulate exopolysaccharides.

  14. Study of the effect of essential oil of Salvia glutinosa L. on microbial biofilm formation by clinical isolates of Acinetobacter baumannii

    Science.gov (United States)

    Tutar, Uǧur

    2016-04-01

    Acinetobacter baumannii is becoming a serious concern in the treatment of infections that can develop resistance to many antibiotics. This persistence may be explained by its capacity to form biofilms. In our study, the essential oil (EO) of the Salvia glutinosa plant, was obtained through the hydrodistillation method. Antimicrobial and antibiofilm activities of the EO on the 20 multi-drug resistant (MDR) A.baumannii isolates were researched. Broth microdilution methods were applied for the determination of the antimicrobial activity. For the determined antibiofilm activity, the Minimal Biofilm Inhibition Concentration (MBIC) test was implemented with the microtiter plate method. Photometric assay was applied for the identification of the antioxidant capacity and colorimetric assay was used to specify the cytotoxicity of the EO of S. glutinosa on L929 cells. In our study, Minimal Inhibition Concentration (MIC) and Minimal Bactericidal Concentration (MBC) values between 1.25-2.5 µl/mL and 5-10 µl/mL respectively. MBIC value of the EO was found as 0.3-2.5 µl/mL. IC50= = 24.4±0.66 µl/mL was found as the antioxidant capacity of the EO. At 25%, 12.5% and 6.25% EO concentrations, no cytotoxicity appeared for the fibroblast cells in terms of the cytotoxic activities (p>0.05). According to the findings obtained in our study, antibiofilm, antimicrobial and antioxidant activities of the S. glutinosa EO seem remarkable. These findings seem promising for the development of potential phytotherapeutic agents in the treatment of the multi-drug resistance (MDR) A.baumannii infections.

  15. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    Directory of Open Access Journals (Sweden)

    Joe A. Lemire

    2015-10-01

    Full Text Available Moving bed biofilm reactors (MBBRs are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR carriers (biofilm support materials, allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that mixed-species biofilms can be harvested from an industrial wastewater inoculum [oil sands process water (OSPW] using the Calgary Biofilm Device (CBD. Moreover, the resultant biofilm communities had the capacity to degrade organic toxins (naphthenic acids—NAs that are found in OSPW. Therefore, we hypothesized that harnessing microbial communities from industrial wastewater, as biofilms, on MBBR carriers may be an effective method to bioremediate industrial wastewater.Here, we detail our methodology adapting the workflow employed for using the CBD, to generate inoculant carriers to seed an MBBR.In this study, OSPW-derived biofilm communities were successfully grown, and their efficacy evaluated, on commercially available MBBR carriers affixed within a modified CBD system. The resultant biofilms demonstrated the capacity to transfer biomass to recipient carriers within a scaled MBBR. Moreover, MBBR systems inoculated in this manner were fully active 2 days post-inoculation, and readily degraded a select population of NAs. Together, these findings suggest that harnessing microbial communities on carriers affixed within a modified CBD system may represent a facile and rapid method for obtaining functional inoculants for use in wastewater MBBR treatment systems.

  16. Hydraulic resistance of biofilms

    KAUST Repository

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

    2013-01-01

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

  17. Quantitative microbial risk assessment (QMRA) shows increased public health risk associated with exposure to river water under conditions of riverbed sediment resuspension.

    Science.gov (United States)

    Abia, Akebe Luther King; Ubomba-Jaswa, Eunice; Genthe, Bettina; Momba, Maggy Ndombo Benteke

    2016-10-01

    Although higher microbial concentrations have been reported in sediments than in the overlying water column, most quantitative microbial risk assessment (QMRA) studies have not clearly indicated the contribution of sediment-borne pathogens to estimated risks. Thus, the present study aimed at determining the public health risk associated with exposure to pathogenic bacteria in polluted river water under undisturbed conditions and conditions of sediment resuspension in the Apies River, Gauteng, South Africa. Microbial pathogens were isolated and identified using culture and molecular methods. The beta-Poisson dose-response model was used to estimate the probability of infection (Pi) with the various pathogens, following accidental/intentional ingestion of 1mL or 100mL (or 50mL) of untreated river water. Mean wet season Escherichia coli counts ranged between 5.8E+01 and 8.8E+04MPN/100mL (water column) and between 2.40E+03 and 1.28E+05MPN/100mL (sediments). Mean dry season E. coli counts ranged between 5.11E+00 and 3.40E+03MPN/100mL (water column) and between 5.09E+00 and 6.30E+03MPN/100mL (sediments). Overall (water and sediments) Vibrio cholerae was the most detected pathogen (58.8%) followed by Salmonella spp. (23.9%) and Shigella (10.1%). Ingestion of 1mL of river water could lead to 0%-4% and 1%-74% Pi with E. coli during the dry and wet season, respectively. During the dry season, the Pi with V. cholerae, Salmonella spp. and Shigella spp. were 0%-1.39%, 0%-4.11% and 0%-0.16% respectively, depending on volume of water ingested. The risks of infections with all microorganisms increased during the wet season. A 2-log increase in water E. coli count following sediments disturbance led to approximately 10 times higher Pi with E. coli than when sediments were undisturbed. Therefore, the use of the untreated water from the Apies River for drinking, household purposes or recreational activities poses a potential health risk to the users of the river. Copyright © 2016

  18. Biofilms in Endodontics—Current Status and Future Directions

    Science.gov (United States)

    Neelakantan, Prasanna; Romero, Monica; Vera, Jorge; Daood, Umer; Khan, Asad U.; Yan, Aixin; Cheung, Gary Shun Pan

    2017-01-01

    Microbiota are found in highly organized and complex entities, known as biofilms, the characteristics of which are fundamentally different from microbes in planktonic suspensions. Root canal infections are biofilm mediated. The complexity and variability of the root canal system, together with the multi-species nature of biofilms, make disinfection of this system extremely challenging. Microbial persistence appears to be the most important factor for failure of root canal treatment and this could further have an impact on pain and quality of life. Biofilm removal is accomplished by a chemo-mechanical process, using specific instruments and disinfecting chemicals in the form of irrigants and/or intracanal medicaments. Endodontic research has focused on the characterization of root canal biofilms and the clinical methods to disrupt the biofilms in addition to achieving microbial killing. In this narrative review, we discuss the role of microbial biofilms in endodontics and review the literature on the role of root canal disinfectants and disinfectant-activating methods on biofilm removal. PMID:28800075

  19. Biofilms in Endodontics-Current Status and Future Directions.

    Science.gov (United States)

    Neelakantan, Prasanna; Romero, Monica; Vera, Jorge; Daood, Umer; Khan, Asad U; Yan, Aixin; Cheung, Gary Shun Pan

    2017-08-11

    Microbiota are found in highly organized and complex entities, known as biofilms, the characteristics of which are fundamentally different from microbes in planktonic suspensions. Root canal infections are biofilm mediated. The complexity and variability of the root canal system, together with the multi-species nature of biofilms, make disinfection of this system extremely challenging. Microbial persistence appears to be the most important factor for failure of root canal treatment and this could further have an impact on pain and quality of life. Biofilm removal is accomplished by a chemo-mechanical process, using specific instruments and disinfecting chemicals in the form of irrigants and/or intracanal medicaments. Endodontic research has focused on the characterization of root canal biofilms and the clinical methods to disrupt the biofilms in addition to achieving microbial killing. In this narrative review, we discuss the role of microbial biofilms in endodontics and review the literature on the role of root canal disinfectants and disinfectant-activating methods on biofilm removal.

  20. Initial evaluations of the use of microbial measures to quantify impact of acid rock drainage on the Finniss River (east branch)

    International Nuclear Information System (INIS)

    Holden, P.J.; Wilde, K.L.; Stone, D.J.; Ben-David, E.A.; Foster, L.J.

    2002-01-01

    Biological measures assessing the impact of pollution on aquatic ecosystems have been increasingly used over the last ten years to examine ecosystem health. The focus, however, has been on diversity and abundance of higher organisms, such as fish, frogs and macroinvertebrates, and it is desirable that such measures be made across all trophic levels of the ecosystem. In this study, phospholipid-fatty acid analysis and microbial carbon substrate utilisation assays (BIOLOG) of sediment and water samples were conducted to evaluate their usefulness as a measure of the effect of acid rock drainage (ARD) on the East Branch of the Finniss River. Both PLFA, and BIOLOG assays, generate data well suited to multivariate analysis and previous studies of the impact of ARD from the Brukunga mine (South Australia) have demonstrated the ability to distinguish between the effect of ARD, nutrients and dry-land salinity on microbial populations

  1. Biofilms in Infections of the Eye

    Directory of Open Access Journals (Sweden)

    Paulo J. M. Bispo

    2015-03-01

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

  2. Roles of ionic strength and biofilm roughness on adhesion kinetics of Escherichia coli onto groundwater biofilm grown on PVC surfaces

    Science.gov (United States)

    Janjaroen, Dao; Ling, Fangqiong; Monroy, Guillermo; Derlon, Nicolas; Mogenroth, Eberhard; Boppart, Stephen A.; Liu, Wen-Tso; Nguyen, Thanh H.

    2013-01-01

    Mechanisms of Escherichia coli attachment on biofilms grown on PVC coupons were investigated. Biofilms were grown in CDC reactors using groundwater as feed solution over a period up to 27 weeks. Biofilm physical structure was characterized at the micro- and meso-scales using Scanning Electron Microscopy (SEM) and Optical Coherence Tomography (OCT), respectively. Microbial community diversity was analyzed with Terminal Restricted Fragment Length Polymorphism (T-RFLP). Both physical structure and microbial community diversity of the biofilms were shown to be changing from 2 weeks to 14 weeks, and became relatively stable after 16 weeks. A parallel plate flow chamber coupled with an inverted fluorescent microscope was also used to monitor the attachment of fluorescent microspheres and E. coli on clean PVC surfaces and biofilms grown on PVC surfaces for different ages. Two mechanisms of E. coli attachment were identified. The adhesion rate coefficients (kd) of E. coli on nascent PVC surfaces and 2-week biofilms increased with ionic strength. However, after biofilms grew for 8 weeks, the adhesion was found to be independent of solution chemistry. Instead, a positive correlation between kd and biofilm roughness as determined by OCT was obtained, indicating that the physical structure of biofilms could play an important role in facilitating the adhesion of E. coli cells. PMID:23497979

  3. Microscopic monitoring of extracellular pH in dental biofilms

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Garcia, Javier; Greve, Matilde

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

  4. Effect of fluoride and chlorhexidine digluconate mouthrinses on plaque biofilms

    DEFF Research Database (Denmark)

    Rabe, Per; Twetman, Svante; Kinnby, Bertil

    2015-01-01

    OBJECTIVE: To develop a model in which to investigate the architecture of plaque biofilms formed on enamel surfaces in vivo and to compare the effects of anti-microbial agents of relevance for caries on biofilm vitality. Materials and Methodology : Enamel discs mounted on healing abutments...... in the pre-molar region were worn by three subjects for 7 days. Control discs were removed before subjects rinsed with 0.1% chlorhexidine digluconate (CHX) or 0.2% sodium fluoride (NaF) for 1 minute. Biofilms were stained with Baclight Live/Dead and z-stacks of images created using confocal scanning laser...... micoscopy. The levels of vital and dead/damaged bacteria in the biofilms, assessed as the proportion of green and red pixels respectively, were analysed using ImageTrak(®) software. Results : The subjects showed individual differences in biofilm architecture. The thickness of the biofilms varied from 28...

  5. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Science.gov (United States)

    Wang, Zhejun; de la Fuente-Núñez, Cesar; Shen, Ya; Haapasalo, Markus; Hancock, Robert E W

    2015-01-01

    Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM), peptide 1018 was able to significantly (pbiofilm formation over 3 days. The activity of the peptide on preformed biofilms was found to be concentration-dependent since more than 60% of the total plaque biofilm cell population was killed by 10 μg/ml of peptide 1018 in 3 days, while at 5 μg/ml 50% of cells were dead and at 1 μg/ml the peptide triggered cell death in around 30% of the total bacterial population, as revealed by confocal microscopy. The presence of saliva did not affect peptide activity, since no statistically significant difference was found in the ability of peptide 1018 to kill oral biofilms using either saliva coated and non-saliva coated hydroxyapatite surfaces. Scanning electron microscopy experiments indicated that peptide 1018 induced cell lysis in plaque biofilms. Furthermore, combined treatment using peptide 1018 and chlorhexidine (CHX) increased the anti-biofilm activity of each compound compared to when these were used alone, resulting in >50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

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

    NARCIS (Netherlands)

    Hayrapetyan, Hasmik

    2017-01-01

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

  8. Impact of Chloramination on the Development of Laboratory-Grown Biofilms Fed with Filter-Pretreated Groundwater

    KAUST Repository

    Ling, Fangqiong

    2013-01-01

    This study evaluated the continuous impact of monochloramine disinfection on laboratory-grown biofilms through the characterization of biofilm architecture and microbial community structure. Biofilm development and disinfection were achieved using CDC (Centers for Disease Control and Prevention) biofilm reactor systems with polyvinyl chloride (PVC) coupons as the substratum and sand filter-pretreated groundwater as the source of microbial seeding and growth nutrient. After 2 weeks of growth, the biofilms were subjected to chloramination for 8 more weeks at concentrations of 7.5±1.4 to 9.1±0.4 mg Cl2 L-1. Control reactors received no disinfection during the development of biofilms. Confocal laser scanning microscopy and image analysis indicated that chloramination could lead to 81.4-83.5% and 86.3-95.6% reduction in biofilm biomass and thickness, respectively, but could not eliminate biofilm growth. 16S rRNA gene terminal restriction fragment length polymorphism analysis indicated that microbial community structures between chloraminated and non-chloraminated biofilms exhibited different successional trends. 16S rRNA gene pyrosequencing analysis further revealed that chloramination could select members of Actinobacteria and Acidobacteria as the dominant populations, whereas natural development leads to the selection of members of Nitrospira and Bacteroidetes as dominant biofilm populations. Overall, chloramination treatment could alter the growth of multi-species biofilms on the PVC surface, shape the biofilm architecture, and select a certain microbial community that can survive or proliferate under chloramination.

  9. STABILITY AND CHANGE IN ESTUARINE BIOFILM BACTERIAL COMMUNITY DIVERSITY

    Science.gov (United States)

    Biofilms develop on all surfaces in aquatic environments and are defined as matrix-enclosed microbial populations adherent to each other and/or surfaces (1, 31). A substantial part of the microbial activity in nature is associated with surfaces (12). Surface association (biofou...

  10. The in vivo biofilm

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Alhede, Maria; Alhede, Morten

    2013-01-01

    Bacteria can grow and proliferate either as single, independent cells or organized in aggregates commonly referred to as biofilms. When bacteria succeed in forming a biofilm within the human host, the infection often becomes very resistant to treatment and can develop into a chronic state. Biofilms...... have been studied for decades using various in vitro models, but it remains debatable whether such in vitro biofilms actually resemble in vivo biofilms in chronic infections. In vivo biofilms share several structural characteristics that differ from most in vitro biofilms. Additionally, the in vivo...... experimental time span and presence of host defenses differ from chronic infections and the chemical microenvironment of both in vivo and in vitro biofilms is seldom taken into account. In this review, we discuss why the current in vitro models of biofilms might be limited for describing infectious biofilms...

  11. Biofilm Formation As a Response to Ecological Competition.

    Directory of Open Access Journals (Sweden)

    Nuno M Oliveira

    2015-07-01

    Full Text Available Bacteria form dense surface-associated communities known as biofilms that are central to their persistence and how they affect us. Biofilm formation is commonly viewed as a cooperative enterprise, where strains and species work together for a common goal. Here we explore an alternative model: biofilm formation is a response to ecological competition. We co-cultured a diverse collection of natural isolates of the opportunistic pathogen Pseudomonas aeruginosa and studied the effect on biofilm formation. We show that strain mixing reliably increases biofilm formation compared to unmixed conditions. Importantly, strain mixing leads to strong competition: one strain dominates and largely excludes the other from the biofilm. Furthermore, we show that pyocins, narrow-spectrum antibiotics made by other P. aeruginosa strains, can stimulate biofilm formation by increasing the attachment of cells. Side-by-side comparisons using microfluidic assays suggest that the increase in biofilm occurs due to a general response to cellular damage: a comparable biofilm response occurs for pyocins that disrupt membranes as for commercial antibiotics that damage DNA, inhibit protein synthesis or transcription. Our data show that bacteria increase biofilm formation in response to ecological competition that is detected by antibiotic stress. This is inconsistent with the idea that sub-lethal concentrations of antibiotics are cooperative signals that coordinate microbial communities, as is often concluded. Instead, our work is consistent with competition sensing where low-levels of antibiotics are used to detect and respond to the competing genotypes that produce them.

  12. Anti-Biofilm Compounds Derived from Marine Sponges

    Directory of Open Access Journals (Sweden)

    Christian Melander

    2011-10-01

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

  13. Implications of Biofilm Formation on Urological Devices

    Science.gov (United States)

    Cadieux, Peter A.; Wignall, Geoffrey R.; Carriveau, Rupp; Denstedt, John D.

    2008-09-01

    Despite millions of dollars and several decades of research targeted at their prevention and eradication, biofilm-associated infections remain the major cause of urological device failure. Numerous strategies have been aimed at improving device design, biomaterial composition, surface properties and drug delivery, but have been largely circumvented by microbes and their plethora of attachment, host evasion, antimicrobial resistance, and dissemination strategies. This is not entirely surprising since natural biofilm formation has been going on for millions of years and remains a major part of microorganism survival and evolution. Thus, the fact that biofilms develop on and in the biomaterials and tissues of humans is really an extension of this natural tendency and greatly explains why they are so difficult for us to combat. Firstly, biofilm structure and composition inherently provide a protective environment for microorganisms, shielding them from the shear stress of urine flow, immune cell attack and some antimicrobials. Secondly, many biofilm organisms enter a metabolically dormant state that renders them tolerant to those antibiotics and host factors able to penetrate the biofilm matrix. Lastly, the majority of organisms that cause biofilm-associated urinary tract infections originate from our own oral cavity, skin, gastrointestinal and urogenital tracts and therefore have already adapted to many of our host defenses. Ultimately, while biofilms continue to hold an advantage with respect to recurrent infections and biomaterial usage within the urinary tract, significant progress has been made in understanding these dynamic microbial communities and novel approaches offer promise for their prevention and eradication. These include novel device designs, antimicrobials, anti-adhesive coatings, biodegradable polymers and biofilm-disrupting compounds and therapies.

  14. Diffuse urban pollution increases metal tolerance of natural heterotrophic biofilms

    International Nuclear Information System (INIS)

    Fechner, Lise C.; Gourlay-Francé, Catherine; Bourgeault, Adeline; Tusseau-Vuillemin, Marie-Hélène

    2012-01-01

    This study is a first attempt to investigate the impact of urban contamination on metal tolerance of heterotrophic river biofilms using a short-term test based on β-glucosidase activity. Tolerance levels to Cu, Cd, Zn, Ni and Pb were evaluated for biofilms collected at three sites along an urban gradient in the Seine river (France). Metallic pollution increased along the river, but concentrations remained low compared to environmental quality standards. Biofilm metal tolerance increased downstream from the urban area. Multivariate analysis confirmed the correlation between tolerance and contamination and between multi-metallic and physico-chemical gradients. Therefore, tolerance levels have to be interpreted in relation to the whole chemical and physical characteristics and not solely metal exposure. We conclude that community tolerance is a sensitive biological response to urban pressure and that mixtures of contaminants at levels lower than quality standards might have a significant impact on periphytic communities. - Highlights: ► A new short-term test based on β-glucosidase activity to assess biofilm metal tolerance. ► Cd, Cu, Ni, Pb and Zn tolerance of natural biofilms collected along an urban gradient. ► Metal tolerance levels increase upstream to downstream the river. ► Community tolerance increases at environmental quality standard exposure concentrations. ► Biofilm tolerance is a sensitive biological response to diffuse urban pollution. - Metal concentrations below environmental quality standards increase tolerance levels of natural, hetetrophic biofilms downstream from an urban area.

  15. Microbiology of dental plaque biofilms and their role in oral health and caries.

    Science.gov (United States)

    Marsh, Philip D

    2010-07-01

    Dental plaque is the biofilm found naturally on teeth. Dental plaque is also implicated in dental caries, which is associated with shifts in the microbial balance of the biofilm resulting in increased proportions of acid producing and acid tolerating bacteria, especially (but not exclusively) mutans streptococci and lactobacilli. The regular intake of fermentable dietary sugars, or impaired saliva flow, produces persistent conditions of low pH within the biofilm, which selects for these cariogenic bacteria. Clinicians should prevent this disruption to the natural microbial balance of the biofilm (relevant approaches are described) rather than merely treating its consequences by restoring cavities. Copyright 2010 Elsevier Inc. All rights reserved.

  16. The effect of feed water dissolved organic carbon concentration and composition on organic micropollutant removal and microbial diversity in soil columns simulating river bank filtration.

    Science.gov (United States)

    Bertelkamp, C; van der Hoek, J P; Schoutteten, K; Hulpiau, L; Vanhaecke, L; Vanden Bussche, J; Cabo, A J; Callewaert, C; Boon, N; Löwenberg, J; Singhal, N; Verliefde, A R D

    2016-02-01

    This study investigated organic micropollutant (OMP) biodegradation rates in laboratory-scale soil columns simulating river bank filtration (RBF) processes. The dosed OMP mixture consisted of 11 pharmaceuticals, 6 herbicides, 2 insecticides and 1 solvent. Columns were filled with soil from a RBF site and were fed with four different organic carbon fractions (hydrophilic, hydrophobic, transphilic and river water organic matter (RWOM)). Additionally, the effect of a short-term OMP/dissolved organic carbon (DOC) shock-load (e.g. quadrupling the OMP concentrations and doubling the DOC concentration) on OMP biodegradation rates was investigated to assess the resilience of RBF systems. The results obtained in this study imply that - in contrast to what is observed for managed aquifer recharge systems operating on wastewater effluent - OMP biodegradation rates are not affected by the type of organic carbon fraction fed to the soil column, in case of stable operation. No effect of a short-term DOC shock-load on OMP biodegradation rates between the different organic carbon fractions was observed. This means that the RBF site simulated in this study is resilient towards transient higher DOC concentrations in the river water. However, a temporary OMP shock-load affected OMP biodegradation rates observed for the columns fed with the river water organic matter (RWOM) and the hydrophilic fraction of the river water organic matter. These different biodegradation rates did not correlate with any of the parameters investigated in this study (cellular adenosine triphosphate (cATP), DOC removal, specific ultraviolet absorbance (SUVA), richness/evenness of the soil microbial population or OMP category (hydrophobicity/charge). Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Difference in initial dental biofilm accumulation between night and day.

    Science.gov (United States)

    Dige, Irene; Schlafer, Sebastian; Nyvad, Bente

    2012-12-01

    The study of initial microbial colonization on dental surfaces is a field of intensive research because of the aetiological role of biofilms in oral diseases. Most previous studies of de novo accumulation and composition of dental biofilms in vivo do not differentiate between biofilms formed during day and night. This study hypothesized that there is a diurnal variation in the rate of accumulation of bacteria on solid surfaces in the oral cavity. In situ biofilm from healthy individuals was collected for 12 h during day and night, respectively, subjected to fluorescent in situ hybridization and visualized using confocal laser scanning microscopy. Analysis of the biofilms using stereological methods and digital image analysis revealed a consistent statistically significant difference between both the total number of bacteria and the biovolume in the two 12-h groups (p = 0.012), with the highest accumulation of bacteria during daytime (a factor of 8.8 and 6.1 higher, respectively). Hybridization with probes specific for streptococci and Actinomyces naeslundii indicated a higher proportion of streptococci in biofilms grown during daytime as compared to night-time. No differences could be observed for A. naeslundii. The degree of microbial coverage and the bacterial composition varied considerably between different individuals. The data provide firm evidence that initial biofilm formation decreases during the night, which may reflect differences in the availability of salivary nutrients. This finding is of significant importance when studying population dynamics during experimental dental biofilm formation.

  18. Proteins with GGDEF and EAL domains regulate Pseudomonas putida biofilm formation and dispersal

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Tolker-Nielsen, Tim

    2006-01-01

    Microbial biofilm formation often causes problems in medical and industrial settings, and knowledge about the factors that are involved in biofilm development and dispersion is useful for creating strategies to control the processes. In this report, we present evidence that proteins with GGDEF...... and EAL domains are involved in the regulation of biofilm formation and biofilm dispersion in Pseudomonas putida. Overexpression in P. putida of the Escherichia coli YedQ protein, which contains a GGDEF domain, resulted in increased biofilm formation. Overexpression in P. putida of the E. coli Yhj......H protein, which contains an EAL domain, strongly inhibited biofilm formation. Induction of YhjH expression in P. putida cells situated in established biofilms led to rapid dispersion of the biofilms. These results support the emerging theme that GGDEF-domain and EAL-domain proteins are involved...

  19. Biofilms in churches built in grottoes

    International Nuclear Information System (INIS)

    Cennamo, Paola; Montuori, Naomi; Trojsi, Giorgio; Fatigati, Giancarlo; Moretti, Aldo

    2016-01-01

    We investigated microorganisms dwelling on rocks, walls and paintings in two votive chapels built in grottoes in the Region of Campania, Italy. One grotto was near the coast in an area with a Mediterranean climate, and the other grotto was inland on a mountain in an area with a cold continental climate. Color and distribution of biofilms in various areas of the grottoes were examined. Microbial components of biofilms were identified by light and electron microscopy and by molecular techniques (DNA analyses and Automatic rRNA Intergenic Spacer Analysis). Biofilms were also analyzed by X-ray diffraction to detect inorganic constituents deriving from rocks in the grottoes and walls of the churches and by X-ray fluorescence to detect the elements that made up the pigments of the mural paintings; optical cross sections were used to observe their relationships with substrata. Species of eubacteria, cyanobacteria and green algae were identified. Some of these species occurred in both grottoes, while others were exclusive to only one of the grottoes. The diversity of species, their common or exclusive occurrence in the grottoes, the relationships among microbial communities and the differences in color and distribution of biofilms were discussed on the basis of the different climatic factors affecting the two grottoes and the different inorganic components of substrata. - Highlights: • Biofilms concur to the degradation of cultural heritage. • Microorganisms cause esthetic and structural damage in votive churches. • Biofilm features vary on different substrata, as limestone, plaster and paintings. • Features of biofilms mainly depend on environmental conditions. • Molecular biology techniques are indispensable in the study of biodegradation.

  20. Biofilms in churches built in grottoes

    Energy Technology Data Exchange (ETDEWEB)

    Cennamo, Paola, E-mail: paola.cennamo@unisob.na.it [Facoltà di Lettere, Università degli Studi Suor Orsola Benincasa di Napoli, Via Santa Caterina da Siena 37, 80135 Naples (Italy); Montuori, Naomi [Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223, 80139 Naples (Italy); Trojsi, Giorgio; Fatigati, Giancarlo [Facoltà di Lettere, Università degli Studi Suor Orsola Benincasa di Napoli, Via Santa Caterina da Siena 37, 80135 Naples (Italy); Moretti, Aldo [Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223, 80139 Naples (Italy)

    2016-02-01

    We investigated microorganisms dwelling on rocks, walls and paintings in two votive chapels built in grottoes in the Region of Campania, Italy. One grotto was near the coast in an area with a Mediterranean climate, and the other grotto was inland on a mountain in an area with a cold continental climate. Color and distribution of biofilms in various areas of the grottoes were examined. Microbial components of biofilms were identified by light and electron microscopy and by molecular techniques (DNA analyses and Automatic rRNA Intergenic Spacer Analysis). Biofilms were also analyzed by X-ray diffraction to detect inorganic constituents deriving from rocks in the grottoes and walls of the churches and by X-ray fluorescence to detect the elements that made up the pigments of the mural paintings; optical cross sections were used to observe their relationships with substrata. Species of eubacteria, cyanobacteria and green algae were identified. Some of these species occurred in both grottoes, while others were exclusive to only one of the grottoes. The diversity of species, their common or exclusive occurrence in the grottoes, the relationships among microbial communities and the differences in color and distribution of biofilms were discussed on the basis of the different climatic factors affecting the two grottoes and the different inorganic components of substrata. - Highlights: • Biofilms concur to the degradation of cultural heritage. • Microorganisms cause esthetic and structural damage in votive churches. • Biofilm features vary on different substrata, as limestone, plaster and paintings. • Features of biofilms mainly depend on environmental conditions. • Molecular biology techniques are indispensable in the study of biodegradation.

  1. In vitro characterization of biofilms formed by Kingella kingae.

    Science.gov (United States)

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

    2017-08-01

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

  2. Influence of invasive Acer negundo leaf litter on benthic microbial abundance and activity in the littoral zone of a temperate river in Lithuania

    Directory of Open Access Journals (Sweden)

    Krevš Alina

    2017-01-01

    Full Text Available Riparian forests are known as important source of allochthonous organic matter entering to water ecosystems via fallen leaves. However, leaf litter, depending on their quality, may create different conditions for benthic microorganisms functioning in littoral zone of water bodies. In order to evaluate the impact of riparian invasive Acer negundo on littoral water zone of the River Neris (Lithuania, we performed physicochemical and microbiological investigations in bottom sediments of three different sites of the river. One sampling site was close by riparian A. negundo, another close by native Alnus glutinosa location and a third zone was near the shore without riparian vegetation. Content of nutrients in the littoral sediments differed between invasive and native trees leaf litter accumulation sites, while not always significantly. The highest microbial densities as well as benthic community respiratory activity (expressed as the rate of organic carbon mineralization occurred in A. negundo leaves accumulation site. In sediments of this site, the most intensive anaerobic terminal organic carbon mineralization process − sulfate reduction and the highest concentration of hydrogen sulfide were also observed. Differences in the intensity of mineralization processes between sites suggest that the replacement of the riparian native species such as dominant A. glutinosa by invasive A. negundo with higher biodegradability leaves may induce local changes in organic matter processing in the littoral zone of the river. The increase of littoral bioproductivity in the accumulation zone of A. negundo leaf litter can occur due to the inflow of available organic matter and its intensive mineralization.

  3. Incorporation of Listeria monocytogenes strains in raw milk biofilms.

    Science.gov (United States)

    Weiler, Christiane; Ifland, Andrea; Naumann, Annette; Kleta, Sylvia; Noll, Matthias

    2013-02-01

    Biofilms develop successively on devices of milk production without sufficient cleaning and originate from the microbial community of raw milk. The established biofilm matrices enable incorporation of pathogens like Listeria monocytogenes, which can cause a continuous contamination of food processing plants. L. monocytogenes is frequently found in raw milk and non-pasteurized raw milk products and as part of a biofilm community in milk meters and bulk milk tanks. The aim of this study was to analyze whether different L. monocytogenes strains are interacting with the microbial community of raw milk in terms of biofilm formation in the same manner, and to identify at which stage of biofilm formation a selected L. monocytogenes strain settles best. Bacterial community structure and composition of biofilms were analyzed by a cloning and sequencing approach and terminal restriction fragment length polymorphism analysis (T-RFLP) based on the bacterial 16S rRNA gene. The chemical composition of biofilms was analyzed by Fourier transform infrared spectroscopy (FTIR), while settled L. monocytogenes cells were quantified by fluorescence in situ hybridization (FISH). Addition of individual L. monocytogenes strains to raw milk caused significant shifts in the biofilm biomass, in the chemical as well as in the bacterial community composition. Biofilm formation and attachment of L. monocytogenes cells were not serotype but strain specific. However, the added L. monocytogenes strains were not abundant since mainly members of the genera Citrobacter and Lactococcus dominated the bacterial biofilm community. Overall, added L. monocytogenes strains led to a highly competitive interaction with the raw milk community and triggered alterations in biofilm formation. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Characterization of Microbial Fuel Cells at Microbially and Electrochemically Meaningful Time scales

    KAUST Repository

    Ren, Zhiyong; Yan, Hengjing; Wang, Wei; Mench, Matthew M.; Regan, John M.

    2011-01-01

    The variable biocatalyst density in a microbial fuel cell (MFC) anode biofilm is a unique feature of MFCs relative to other electrochemical systems, yet performance characterizations of MFCs typically involve analyses at electrochemically relevant

  5. Biofilm Fixed Film Systems

    Directory of Open Access Journals (Sweden)

    Dipesh Das

    2011-09-01

    Full Text Available The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, rotating biological contactors, fluidized bed bioreactors, submerged bed biofilm reactors, biological granular activated carbon, membrane bioreactors, and immobilized cell reactors. Innovative reactors, not easily classified, are then presented, followed by a section on biofilms on sand, soil and sediment.

  6. Biofilm community succession: a neutral perspective.

    Science.gov (United States)

    Woodcock, Stephen; Sloan, William T

    2017-05-22

    Although biofilms represent one of the dominant forms of life in aqueous environments, our understanding of the assembly and development of their microbial communities remains relatively poor. In recent years, several studies have addressed this and have extended the concepts of succession theory in classical ecology into microbial systems. From these datasets, niche-based conceptual models have been developed explaining observed biodiversity patterns and their dynamics. These models have not, however, been formulated mathematically and so remain untested. Here, we further develop spatially resolved neutral community models and demonstrate that these can also explain these patterns and offer alternative explanations of microbial succession. The success of neutral models suggests that stochastic effects alone may have a much greater influence on microbial community succession than previously acknowledged. Furthermore, such models are much more readily parameterised and can be used as the foundation of more complex and realistic models of microbial community succession.

  7. Quantification of biofilm structures by the novel computer program COMSTAT.

    Science.gov (United States)

    Heydorn, A; Nielsen, A T; Hentzer, M; Sternberg, C; Givskov, M; Ersbøll, B K; Molin, S

    2000-10-01

    The structural organization of four microbial communities was analysed by a novel computer program, COMSTAT, which comprises ten features for quantifying three-dimensional biofilm image stacks. Monospecies biofilms of each of the four bacteria, Pseudomonas: putida, P. aureofaciens, P. fluorescens and P. aeruginosa, tagged with the green fluorescent protein (GFP) were grown in flow chambers with a defined minimal medium as substrate. Analysis by the COMSTAT program of four variables describing biofilm structure - mean thickness, roughness, substratum coverage and surface to volume ratio - showed that the four Pseudomonas: strains represent different modes of biofilm growth. P. putida had a unique developmental pattern starting with single cells on the substratum growing into micro-colonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a stronger tendency to form micro-colonies. Finally, the biofilm structures of P. fluorescens had a phenotype intermediate between those of P. putida and P. aureofaciens. Analysis of biofilms of P. aureofaciens growing on 0.03 mM, 0.1 mM or 0.5 mM citrate minimal media showed that mean biofilm thickness increased with increasing citrate concentration. Moreover, biofilm roughness increased with lower citrate concentrations, whereas surface to volume ratio increased with higher citrate concentrations.

  8. An optical microfluidic platform for spatiotemporal biofilm treatment monitoring

    International Nuclear Information System (INIS)

    Kim, Young Wook; Mosteller, Matthew P; Subramanian, Sowmya; Meyer, Mariana T; Ghodssi, Reza; Bentley, William E

    2016-01-01

    Bacterial biofilms constitute in excess of 65% of clinical microbial infections, with the antibiotic treatment of biofilm infections posing a unique challenge due to their high antibiotic tolerance. Recent studies performed in our group have demonstrated that a bioelectric effect featuring low-intensity electric signals combined with antibiotics can significantly improve the efficacy of biofilm treatment. In this work, we demonstrate the bioelectric effect using sub-micron thick planar electrodes in a microfluidic device. This is critical in efforts to develop microsystems for clinical biofilm infection management, including both in vivo and in vitro applications. Adaptation of the method to the microscale, for example, can enable the development of localized biofilm infection treatment using microfabricated medical devices, while augmenting existing capabilities to perform biofilm management beyond the clinical realm. Furthermore, due to scale-down of the system, the voltage requirement for inducing the electric field is reduced further below the media electrolysis threshold. Enhanced biofilm treatment using the bioelectric effect in the developed microfluidic device elicited a 56% greater reduction in viable cell density and 26% further decrease in biomass growth compared to traditional antibiotic therapy. This biofilm treatment efficacy, demonstrated in a micro-scale device and utilizing biocompatible voltage ranges, encourages the use of this method for future clinical biofilm treatment applications. (paper)

  9. Pseudomonas aeruginosa and Saccharomyces cerevisiae Biofilm in Flow Cells

    DEFF Research Database (Denmark)

    Weiss Nielsen, Martin; Sternberg, Claus; Molin, Søren

    2011-01-01

    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......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...... 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...

  10. Pseudomonas aeruginosa and Saccharomyces cerevisiae Biofilm in Flow Cells

    DEFF Research Database (Denmark)

    Weiss Nielsen, Martin; Sternberg, Claus; Molin, Søren

    2011-01-01

    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......). 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...

  11. Control of Biofilms with the Fatty Acid Signaling Molecule cis-2-Decenoic Acid

    Directory of Open Access Journals (Sweden)

    Cláudia N. H. Marques

    2015-11-01

    Full Text Available Biofilms are complex communities of microorganisms in organized structures attached to surfaces. Importantly, biofilms are a major cause of bacterial infections in humans, and remain one of the most significant challenges to modern medical practice. Unfortunately, conventional therapies have shown to be inadequate in the treatment of most chronic biofilm infections based on the extraordinary innate tolerance of biofilms to antibiotics. Antagonists of quorum sensing signaling molecules have been used as means to control biofilms. QS and other cell-cell communication molecules are able to revert biofilm tolerance, prevent biofilm formation and disrupt fully developed biofilms, albeit with restricted effectiveness. Recently however, it has been demonstrated that Pseudomonas aeruginosa produces a small messenger molecule cis-2-decenoic acid (cis-DA that shows significant promise as an effective adjunctive to antimicrobial treatment of biofilms. This molecule is responsible for induction of the native biofilm dispersion response in a range of Gram-negative and Gram-positive bacteria and in yeast, and has been shown to reverse persistence, increase microbial metabolic activity and significantly enhance the cidal effects of conventional antimicrobial agents. In this manuscript, the use of cis-2-decenoic acid as a novel agent for biofilm control is discussed. Stimulating the biofilm dispersion response as a novel antimicrobial strategy holds significant promise for enhanced treatment of infections and in the prevention of biofilm formation.

  12. Microbial Remobilisation on Riverbed Sediment Disturbance in Experimental Flumes and a Human-Impacted River: Implication for Water Resource Management and Public Health in Developing Sub-Saharan African Countries

    Directory of Open Access Journals (Sweden)

    Akebe Luther King Abia

    2017-03-01

    Full Text Available Resuspension of sediment-borne microorganisms (including pathogens into the water column could increase the health risk for those using river water for different purposes. In the present work, we (1 investigated the effect of sediment disturbance on microbial resuspension from riverbed sediments in laboratory flow-chambers and in the Apies River, Gauteng, South Africa; and (2 estimated flow conditions for sediment-borne microorganism entrainment/resuspension in the river. For mechanical disturbance, the top 2 cm of the sediment in flow-chambers was manually stirred. Simulating sudden discharge into the river, water (3 L was poured within 30 s into the chambers at a 45° angle to the chamber width. In the field, sediment was disturbed by raking the riverbed and by cows crossing in the river. Water samples before and after sediment disturbance were analysed for Escherichia coli. Sediment disturbance caused an increase in water E. coli counts by up to 7.9–35.8 times original values. Using Shields criterion, river-flow of 0.15–0.69 m3/s could cause bed particle entrainment; while ~1.57–7.23 m3/s would cause resuspension. Thus, sediment disturbance in the Apies River would resuspend E. coli (and pathogens, with possible negative health implications for communities using such water. Therefore, monitoring surface water bodies should include microbial sediment quality.

  13. Microbial Remobilisation on Riverbed Sediment Disturbance in Experimental Flumes and a Human-Impacted River: Implication for Water Resource Management and Public Health in Developing Sub-Saharan African Countries

    Science.gov (United States)

    Abia, Akebe Luther King; James, Chris; Ubomba-Jaswa, Eunice; Benteke Momba, Maggy Ndombo

    2017-01-01

    Resuspension of sediment-borne microorganisms (including pathogens) into the water column could increase the health risk for those using river water for different purposes. In the present work, we (1) investigated the effect of sediment disturbance on microbial resuspension from riverbed sediments in laboratory flow-chambers and in the Apies River, Gauteng, South Africa; and (2) estimated flow conditions for sediment-borne microorganism entrainment/resuspension in the river. For mechanical disturbance, the top 2 cm of the sediment in flow-chambers was manually stirred. Simulating sudden discharge into the river, water (3 L) was poured within 30 s into the chambers at a 45° angle to the chamber width. In the field, sediment was disturbed by raking the riverbed and by cows crossing in the river. Water samples before and after sediment disturbance were analysed for Escherichia coli. Sediment disturbance caused an increase in water E. coli counts by up to 7.9–35.8 times original values. Using Shields criterion, river-flow of 0.15–0.69 m3/s could cause bed particle entrainment; while ~1.57–7.23 m3/s would cause resuspension. Thus, sediment disturbance in the Apies River would resuspend E. coli (and pathogens), with possible negative health implications for communities using such water. Therefore, monitoring surface water bodies should include microbial sediment quality. PMID:28295001

  14. Microbial Remobilisation on Riverbed Sediment Disturbance in Experimental Flumes and a Human-Impacted River: Implication for Water Resource Management and Public Health in Developing Sub-Saharan African Countries.

    Science.gov (United States)

    Abia, Akebe Luther King; James, Chris; Ubomba-Jaswa, Eunice; Benteke Momba, Maggy Ndombo

    2017-03-15

    Resuspension of sediment-borne microorganisms (including pathogens) into the water column could increase the health risk for those using river water for different purposes. In the present work, we (1) investigated the effect of sediment disturbance on microbial resuspension from riverbed sediments in laboratory flow-chambers and in the Apies River, Gauteng, South Africa; and (2) estimated flow conditions for sediment-borne microorganism entrainment/resuspension in the river. For mechanical disturbance, the top 2 cm of the sediment in flow-chambers was manually stirred. Simulating sudden discharge into the river, water (3 L) was poured within 30 s into the chambers at a 45° angle to the chamber width. In the field, sediment was disturbed by raking the riverbed and by cows crossing in the river. Water samples before and after sediment disturbance were analysed for Escherichia coli. Sediment disturbance caused an increase in water E. coli counts by up to 7.9-35.8 times original values. Using Shields criterion, river-flow of 0.15-0.69 m³/s could cause bed particle entrainment; while ~1.57-7.23 m³/s would cause resuspension. Thus, sediment disturbance in the Apies River would resuspend E. coli (and pathogens), with possible negative health implications for communities using such water. Therefore, monitoring surface water bodies should include microbial sediment quality.

  15. Pseudomonas putida as a microbial cell factory

    DEFF Research Database (Denmark)

    Wigneswaran, Vinoth

    for sustainable production of chemicals, which can be achieved by microbial cell factories. The work presented in this PhD thesis elucidates the application of Pseudomonas putida as a microbial cell factory for production of the biosurfactant rhamnolipid. The rhamnolipid production was achieved by heterologous...... phase. The genomic alterations were identified by genome sequencing and revealed parallel evolution. Glycerol was also shown to be able to support biofilm growth and as a result of this it can be used as an alternative substrate for producing biochemicals in conventional and biofilm reactors. The use...... of biofilm as a production platform and the usage of glycerol as a feedstock show the potential of using microbial cell factories in the transition toward sustainable production of chemicals. Particularly, the applicability of biofilm as a production platform can emerge as a promising alternative...

  16. Stream biofilm responses to flow intermittency: from cells to ecosystems

    OpenAIRE

    Sergi eSabater; Sergi eSabater; Xisca eTimoner; Carles eBorrego; Carles eBorrego; Vicenç eAcuña

    2016-01-01

    Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are eminently microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms) accordingly change their physical structure and community composition. Biofilms experience large decreases on cell densities and biomass, both of bacteria a...

  17. Stream Biofilm Responses to Flow Intermittency: From Cells to Ecosystems

    OpenAIRE

    Sabater, Sergi; Timoner, Xisca; Borrego, Carles; Acuña, Vicenç

    2016-01-01

    Temporary streams are characterized by the alternation of dry and wet hydrological phases, creating both a harsh environment for the biota as well as a high diversity of opportunities for adaptation. These systems are mainly microbial-based during several of these hydrological phases, and those growing on all solid substrata (biofilms) accordingly change their physical structure and community composition. Biofilms experience large decreases in cell densities and biomass, both of bacteria and ...

  18. Shell biofilm-associated nitrous oxide production in marine molluscs

    DEFF Research Database (Denmark)

    Heisterkamp, I.M.; Schramm, Andreas; Larsen, Lone Heimann

    2013-01-01

    Emission of the greenhouse gas nitrous oxide (N2O) from freshwater and terrestrial invertebrates has exclusively been ascribed to N2O production by ingested denitrifying bacteria in the anoxic gut of the animals. Our study of marine molluscs now shows that also microbial biofilms on shell surfaces...... are important sites of N2O production. The shell biofilms of Mytilus edulis, Littorina littorea and Hinia reticulata contributed 18-94% to the total animal-associated N2O emission. Nitrification and denitrification were equally important sources of N2O in shell biofilms as revealed by 15N-stable isotope...... mollusc species. Ammonium excretion by the animals was found to be sufficient to sustain N2O production in the shell biofilm. Apparently, the animals provide a nutrient-enriched microenvironment that stimulates growth and N2O production of the shell biofilm. This animal-induced stimulation...

  19. Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  20. Nanoparticles for Control of Biofilms of Acinetobacter Species

    Directory of Open Access Journals (Sweden)

    Richa Singh

    2016-05-01

    Full Text Available Biofilms are the cause of 80% of microbial infections. Acinetobacter species have emerged as multi- and pan-drug-resistant bacteria and pose a great threat to human health. These act as nosocomial pathogens and form excellent biofilms, both on biotic and abiotic surfaces, leading to severe infections and diseases. Various methods have been developed for treatment and control of Acinetobacter biofilm including photodynamic therapy, radioimmunotherapy, prophylactic vaccines and antimicrobial peptides. Nanotechnology, in the present scenario, offers a promising alternative. Nanomaterials possess unique properties, and multiple bactericidal mechanisms render them more effective than conventional drugs. This review intends to provide an overview of Acinetobacter biofilm and the significant role of various nanoparticles as anti-biofouling agents, surface-coating materials and drug-delivery vehicles for biofilm control and treatment of Acinetobacter infections.

  1. Difference in initial dental biofilm accumulation between night and day

    DEFF Research Database (Denmark)

    Dige, Irene; Schlafer, Sebastian; Nyvad, Bente

    2012-01-01

    formed during day and night. We hypothesised that there is a diurnal variation in the rate of accumulation of bacteria on solid surfaces in the oral cavity. Material and methods. In situ biofilm from healthy individuals was collected for 12 h during day and night, respectively, subjected to fluorescent......Objective. The study of initial microbial colonization on dental surfaces is a field of intensive research because of the aetiological role of biofilms in oral diseases. Most previous studies of de novo accumulation and composition of dental biofilms in vivo do not differentiate between biofilms...... in situ hybridization, and visualized using confocal laser scanning microscopy. Results. Analysis of the biofilms using stereological methods and digital image analysis revealed a consistent statistically significant difference between both the total number of bacteria and the biovolume in the two 12-h...

  2. Involvement of NADH Oxidase in Biofilm Formation in Streptococcus sanguinis.

    Directory of Open Access Journals (Sweden)

    Xiuchun Ge

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

  3. Cold Plasmas for Biofilm Control: Opportunities and Challenges.

    Science.gov (United States)

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

    2018-06-01

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

  4. Pseudomonas aeruginosa Biofilm Infections

    DEFF Research Database (Denmark)

    Rybtke, Morten; Hultqvist, Louise Dahl; Givskov, Michael

    2015-01-01

    Studies of biopsies from infectious sites, explanted tissue and medical devises have provided evidence that biofilms are the underlying cause of a variety of tissue-associated and implant-associated recalcitrant human infections. With a need for novel anti-biofilm treatment strategies, research...... in biofilm infection microbiology, biofilm formation mechanisms and biofilm-associated antimicrobial tolerance has become an important area in microbiology. Substantial knowledge about biofilm formation mechanisms, biofilm-associated antimicrobial tolerance and immune evasion mechanisms has been obtained...... through work with biofilms grown in in vitro experimental setups, and the relevance of this information in the context of chronic infections is being investigated by the use of animal models of infection. Because our current in vitro experimental setups and animal models have limitations, new advanced...

  5. Development of a high-throughput Candida albicans biofilm chip.

    Directory of Open Access Journals (Sweden)

    Anand Srinivasan

    2011-04-01

    Full Text Available We have developed a high-density microarray platform consisting of nano-biofilms of Candida albicans. A robotic microarrayer was used to print yeast cells of C. albicans encapsulated in a collagen matrix at a volume as low as 50 nL onto surface-modified microscope slides. Upon incubation, the cells grow into fully formed "nano-biofilms". The morphological and architectural complexity of these biofilms were evaluated by scanning electron and confocal scanning laser microscopy. The extent of biofilm formation was determined using a microarray scanner from changes in fluorescence intensities due to FUN 1 metabolic processing. This staining technique was also adapted for antifungal susceptibility testing, which demonstrated that, similar to regular biofilms, cells within the on-chip biofilms displayed elevated levels of resistance against antifungal agents (fluconazole and amphotericin B. Thus, results from structural analyses and antifungal susceptibility testing indicated that despite miniaturization, these biofilms display the typical phenotypic properties associated with the biofilm mode of growth. In its final format, the C. albicans biofilm chip (CaBChip is composed of 768 equivalent and spatially distinct nano-biofilms on a single slide; multiple chips can be printed and processed simultaneously. Compared to current methods for the formation of microbial biofilms, namely the 96-well microtiter plate model, this fungal biofilm chip has advantages in terms of miniaturization and automation, which combine to cut reagent use and analysis time, minimize labor intensive steps, and dramatically reduce assay costs. Such a chip should accelerate the antifungal drug discovery process by enabling rapid, convenient and inexpensive screening of hundreds-to-thousands of compounds simultaneously.

  6. IMPACTS OF BIOFILM FORMATION ON CELLULOSE FERMENTATION

    Energy Technology Data Exchange (ETDEWEB)

    Leschine, Susan

    2009-10-31

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

  7. Diagnosis and understanding of chronic biofilm infections

    DEFF Research Database (Denmark)

    Thomsen, Trine Rolighed

    2016-01-01

    Title: Diagnosis and understanding of chronic biofilm infections. Name: Trine Rolighed Thomsen Aalborg University and Danish Technological Institute, Denmark Recent evidence suggests that the microbial community, its spatial distribution and activity play an important role in the prolongation......, anaerobic or unculturable bacteria living in biofilms. Thus, diagnosis of chronic infections is challenged by lack of appropriate sampling strategies and by limitations in microbiological testing methods. The purpose of this study was to improve sampling and diagnosis of chronic infections, especially...... considering the biofilm issue. Systematic and optimized sampling of various specimen types was performed. Extended culture, optimized DNA extraction, quantitative PCR, cloning, next generation sequencing and PNA FISH were applied on different types of specimens for optimized diagnosis. For further...

  8. Actinomyces naeslundii in intial dental biofilm formation

    DEFF Research Database (Denmark)

    Dige, Irene; Raarup, Merete Krog; Nyengaard, Jens Randel

    2009-01-01

    Combined use of Confocal Laser Scanning Microscopy (CLSM) and Fluorescent in situ Hybridization (FISH) offers new opportunities for analysing the spatial relationships and temporal changes of specific members of microbial populations in intact dental biofilms. AIMS: The purpose of this study....... RESULTS: This study confirmed previous work that streptococci are the predominant colonizers of early dental biofilm along with A. naeslundii. There was a notable increase in the total number of bacteria, Streptococcus spp., and A. naeslundii over time with a tendency towards a slower growth rate for A......-layer dental biofilms up to 48 h definitively demonstrated that A. naeslundii preferentially occupied the inner layers. Some A. naeslundii microcolonies extended perpendicularly from the supporting surface surrounded by other bacteria forming chimneys of complex multilayered micro-colonies. CONCLUSIONS...

  9. Application of biofilm bioreactors in white biotechnology.

    Science.gov (United States)

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

    2014-01-01

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

  10. Dental biofilm: ecological interactions in health and disease.

    Science.gov (United States)

    Marsh, P D; Zaura, Egija

    2017-03-01

    The oral microbiome is diverse and exists as multispecies microbial communities on oral surfaces in structurally and functionally organized biofilms. To describe the network of microbial interactions (both synergistic and antagonistic) occurring within these biofilms and assess their role in oral health and dental disease. PubMed database was searched for studies on microbial ecological interactions in dental biofilms. The search results did not lend themselves to systematic review and have been summarized in a narrative review instead. Five hundred and forty-seven original research articles and 212 reviews were identified. The majority (86%) of research articles addressed bacterial-bacterial interactions, while inter-kingdom microbial interactions were the least studied. The interactions included physical and nutritional synergistic associations, antagonism, cell-to-cell communication and gene transfer. Oral microbial communities display emergent properties that cannot be inferred from studies of single species. Individual organisms grow in environments they would not tolerate in pure culture. The networks of multiple synergistic and antagonistic interactions generate microbial inter-dependencies and give biofilms a resilience to minor environmental perturbations, and this contributes to oral health. If key environmental pressures exceed thresholds associated with health, then the competitiveness among oral microorganisms is altered and dysbiosis can occur, increasing the risk of dental disease. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Bacterial biofilms, resistance mechanisms to disinfection; Biopeliculas bacterianas (biofilms), mecanismos de resistencia a la desinfeccion

    Energy Technology Data Exchange (ETDEWEB)

    Codony Iglesias, F.; Morato Farreras, J.

    2002-07-01

    Biofilm is a cell community attached to a support surface, frequently enmeshed within a polymeric matrix secreted by the bacteria. Usually, such structures are developed in a wide range of materials. This development as attached to surfaces or forming suspended aggregates, greatly improve the microbial growth and their survival. This fact may be responsible of adverse effects over equipment and may constitute a public health hazard. In this work are reviewed the basis of the different microbial resistance mechanisms to disinfection from the cellular level to more complex microbial structure. (Author) 16 refs.

  12. The exopolysaccharide matrix: a virulence determinant of cariogenic biofilm.

    Science.gov (United States)

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

    2013-12-01

    Many infectious diseases in humans are caused or exacerbated by biofilms. Dental caries is a prime example of a biofilm-dependent disease, resulting from interactions of microorganisms, host factors, and diet (sugars), which modulate the dynamic formation of biofilms on tooth surfaces. All biofilms have a microbial-derived extracellular matrix as an essential constituent. The exopolysaccharides formed through interactions between sucrose- (and starch-) and Streptococcus mutans-derived exoenzymes present in the pellicle and on microbial surfaces (including non-mutans) provide binding sites for cariogenic and other organisms. The polymers formed in situ enmesh the microorganisms while forming a matrix facilitating the assembly of three-dimensional (3D) multicellular structures that encompass a series of microenvironments and are firmly attached to teeth. The metabolic activity of microbes embedded in this exopolysaccharide-rich and diffusion-limiting matrix leads to acidification of the milieu and, eventually, acid-dissolution of enamel. Here, we discuss recent advances concerning spatio-temporal development of the exopolysaccharide matrix and its essential role in the pathogenesis of dental caries. We focus on how the matrix serves as a 3D scaffold for biofilm assembly while creating spatial heterogeneities and low-pH microenvironments/niches. Further understanding on how the matrix modulates microbial activity and virulence expression could lead to new approaches to control cariogenic biofilms.

  13. Correlative Imaging of Structural and Elemental Composition of Bacterial Biofilms

    International Nuclear Information System (INIS)

    Yang, Y; Heine, R; Xu, F; Helfen, L; Baumbach, T; Suhonen, H; Rosenhahn, A; Gorniak, T; Kirchen, S; Schwartz, T

    2013-01-01

    Synchrotron-based phase contrast tomography (holotomography) and scanning hard X-ray fluorescence microscopy (SXFM) are combined to characterize the three-dimensional (3D) structural and corresponding elemental distribution of bacterial biofilms of Pseudomonas aeruginosa. Samples were fixed without contrast agents or microtomal sectioning. Within an intact microbial community single bacteria are clearly resolved, and their morphology can be directly visualized together with the elemental content. Such 3D set of complementary information at cellular level is essential for gaining a deeper understanding of biofilm evolution aiming to develop potential strategies on biofilm growth control and prevention

  14. Fate of deposited cells in an aerobic binary bacterial biofilm

    International Nuclear Information System (INIS)

    Banks, M.K.

    1989-01-01

    A biofilm is a matrix of microbial cells and their extracellular products that is associated with a solid surface. Previous studies on biofilm development have employed only dissolved compounds as growth limiting substrates, without the influence of microbial species invading from the bulk liquid. The goal of this research project was to quantify the kinetics of processes governing suspended biomass turnover in biofilm systems, and the accompanying effects of suspended cell deposition on biofilm population dynamics. Experiments were conducted with two species of bacteria, Pseudomonas putida ATCC 11172 grown on glucose, and Hyphomicrobium ZV620 grown on methanol. Cryptic growth and particulate hydrolysis studies were evaluated, using combinations of these two bacteria, by measuring the uptake of radiolabelled cell lysis products, under batch conditions. Biofilms studies were performed to investigate bacterial deposition, continual biofilm removal by shear induced erosion, and biofilm ecology. Biofilms were developed in a flow cell reactor, under laminar flow conditions. Bacterial species were differentiated by radioactively labelling each species with their carbon substrate. A mathematical model was developed to predict the biofilm ecology of mixed cultures. The equations developed predict biofilm accumulation, as well as substrate and oxygen consumption. Results indicate that cryptic growth will occur for bacteria growing on their own species soluble lysis products and in some cases, bacteria growing on the soluble lysis products of other species. Particulate hydrolysis only occurred for Pseudomonas putida growing on Pseudomonas putida lysis products, but the lack of particulate hydrolysis occurring in the other studies may have been due to the short experimental period

  15. The Biofilm Challenge

    DEFF Research Database (Denmark)

    Alhede, Maria; Alhede, Morten

    2014-01-01

    The concept of biofilms has emerged in the clinical setting during the last decade. Infections involving biofilms have been documented in all parts of the human body, and it is currently believed that the presence of biofilm-forming bacteria is equivalent to chronic infection. A quick Pubmed search...

  16. Biofilms and mechanics: a review of experimental techniques and findings

    International Nuclear Information System (INIS)

    Gordon, Vernita D; Davis-Fields, Megan; Kovach, Kristin; Rodesney, Christopher A

    2017-01-01

    Biofilms are developmentally-dynamic communities of sessile microbes that adhere to each other and, often, to other structures in their environment. The cohesive mechanical forces binding microbes to each other confer mechanical and structural stability on the biofilm and give rise to biofilm viscoelasticity. The adhesive mechanical forces binding microbes to other structures in their environment can promote biofilm initiation and mechanosensing that leads to changes in biological activity. Thus, physical mechanics is intrinsic to characteristics that distinguish biofilms from free-swimming or free-floating microbes in liquid culture. However, very little is known about the specifics of what mechanical traits characterize different types of biofilms at different stages of development. Even less is known about how mechanical inputs impact microbial biology and how microbes can adjust their mechanical coupling to, and interaction with, their environment. These knowledge gaps arise, in part, from the challenges associated with experimental measurements of microbial and biofilm biomechanics. Here, we review extant experimental techniques and their most-salient findings to date. At the end of this review we indicate areas where significant advances in the state-of-the art are heading. (topical review)

  17. Biofilms and mechanics: a review of experimental techniques and findings

    Science.gov (United States)

    Gordon, Vernita D.; Davis-Fields, Megan; Kovach, Kristin; Rodesney, Christopher A.

    2017-06-01

    Biofilms are developmentally-dynamic communities of sessile microbes that adhere to each other and, often, to other structures in their environment. The cohesive mechanical forces binding microbes to each other confer mechanical and structural stability on the biofilm and give rise to biofilm viscoelasticity. The adhesive mechanical forces binding microbes to other structures in their environment can promote biofilm initiation and mechanosensing that leads to changes in biological activity. Thus, physical mechanics is intrinsic to characteristics that distinguish biofilms from free-swimming or free-floating microbes in liquid culture. However, very little is known about the specifics of what mechanical traits characterize different types of biofilms at different stages of development. Even less is known about how mechanical inputs impact microbial biology and how microbes can adjust their mechanical coupling to, and interaction with, their environment. These knowledge gaps arise, in part, from the challenges associated with experimental measurements of microbial and biofilm biomechanics. Here, we review extant experimental techniques and their most-salient findings to date. At the end of this review we indicate areas where significant advances in the state-of-the art are heading.

  18. Anti-Biofilm Efficacy of Nitric Oxide-Releasing Silica Nanoparticles

    OpenAIRE

    Hetrick, Evan M.; Shin, Jae Ho; Paul, Heather S.; Schoenfisch, Mark H.

    2009-01-01

    The ability of nitric oxide (NO)-releasing silica nanoparticles to kill biofilm-based microbial cells is reported. Biofilms of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans were formed in vitro and exposed to NO-releasing silica nanoparticles. Replicative viability experiments revealed that ≥ 99% of cells from each type of biofilm were killed via NO release, with the greatest efficacy (≥ 99.999% killing) against gram-negative...

  19. Paired methods to measure biofilm killing and removal: a case study with Penicillin G treatment of Staphylococcus aureus biofilm.

    Science.gov (United States)

    Ausbacher, D; Lorenz, L; Pitts, B; Stewart, P S; Goeres, D M

    2018-03-01

    Biofilms are microbial aggregates that show high tolerance to antibiotic treatments in vitro and in vivo. Killing and removal are both important in biofilm control, therefore methods that measure these two mechanisms were evaluated in a parallel experimental design. Kill was measured using the single tube method (ASTM method E2871) and removal was determined by video microscopy and image analysis using a new treatment flow cell. The advantage of the parallel test design is that both methods used biofilm covered coupons harvested from a CDC biofilm reactor, a well-established and standardized biofilm growth method. The control Staphylococcus aureus biofilms treated with growth medium increased by 0·6 logs during a 3-h contact time. Efficacy testing showed biofilms exposed to 400 μmol l -1 penicillin G decreased by only 0·3 logs. Interestingly, time-lapse confocal scanning laser microscopy revealed that penicillin G treatment dispersed the biofilm despite being an ineffective killing agent. In addition, no biofilm removal was detected when assays were performed in 96-well plates. These results illustrate that biofilm behaviour and impact of treatments can vary substantially when assayed by different methods. Measuring both killing and removal with well-characterized methods will be crucial for the discovery of new anti-biofilm strategies. Biofilms are tolerant to antimicrobial treatments and can lead to persistent infections. Finding new anti-biofilm strategies and understanding their mode-of-action is therefore of high importance. Historically, antimicrobial testing has focused on measuring the decrease in viability. While kill data are undeniably important, measuring biofilm disruption provides equally useful information. Starting with biofilm grown in the same reactor, we paired assessment of biofilm removal using a new treatment-flow-cell and real-time microscopy with kill data collected using the single tube method (ASTM E2871). Pairing these two methods

  20. The electric picnic: synergistic requirements for exoelectrogenic microbial communities

    KAUST Repository

    Kiely, Patrick D

    2011-06-01

    Characterization of the various microbial populations present in exoelectrogenic biofilms provides insight into the processes required to convert complex organic matter in wastewater streams into electrical current in bioelectrochemical systems (BESs). Analysis of the community profiles of exoelectrogenic microbial consortia in BESs fed different substrates gives a clearer picture of the different microbial populations present in these exoelectrogenic biofilms. Rapid utilization of fermentation end products by exoelectrogens (typically Geobacter species) relieves feedback inhibition for the fermentative consortia, allowing for rapid metabolism of organics. Identification of specific syntrophic processes and the communities characteristic of these anodic biofilms will be a valuable aid in improving the performance of BESs. © 2011 Elsevier Ltd.

  1. Impact of Medium on the Development and Physiology of Pseudomonas fluorescens Biofilms on Polyurethane Paint

    Science.gov (United States)

    2012-02-01

    can provide nutrients that affect biofilm formation and biodeterioration. Historically, studies of polyurethane biodeterioration have monitored the...microbial growth can accelerate the degradation of fuel tank coatings and cause corrosion of aluminum and stainless steel tanks and pipelines (Passman...conditions are determinants of both biofilm formation /dispersion and the degradative impact of bacteria on PU substrates. For example, the transition of

  2. Occurrence of Legionella pneumophila and Hartmannella vermiformis in fresh water environments and their interactions in biofilms

    NARCIS (Netherlands)

    Kuiper, M.W.

    2006-01-01

    Legionella pneumophila, the causative agent of Legionnaires’ disease, is widespread in natural fresh water environments and is also frequently found in man-made water systems. Microbial biofilms and protozoa are known to play a major role in the proliferation of L. pneumophila. Biofilms provide

  3. DETECTION OF BACTERIAL BIOFILM ON STAINLESS STEEL BY HYPERSPECTRAL FLUORESCENCE IMAGING

    Science.gov (United States)

    In this study, hyperspectral fluorescence imaging techniques were investigated for detection of microbial biofilm on stainless steel plates typically used to manufacture food processing equipment. Stainless steel coupons were immersed in bacterium cultures consisting of nonpathogenic E. coli, Pseudo...

  4. Impacts of Migratory Sandhill Cranes (Grus canadensis) on Microbial Water Quality in the Central Platte River, Nebraska, USA

    Science.gov (United States)

    Wild birds have been shown to be significant sources of numerous types of pathogens that are relevant to humans and agriculture. The presence of large numbers of migratory birds in such a sensitive and important ecosystem as the Platte River in central Nebraska, USA, could potent...

  5. The Effect of Predators on Cholera Biofilms: If it Lyses, We Can Smash It

    Science.gov (United States)

    Kalziqi, Arben; Bernardy, Eryn; Thomas, Jacob; Ratcliff, Will; Hammer, Brian; Yunker, Peter

    Many microbes form biofilms--dense clumps of cells and proteins--on surfaces. Biofilms are complex communities that facilitate the study of biological competition (e.g., two types of microbes may compete to form a biofilm in the same location) and interesting physics (e.g., the source of a biofilm's rigidity). Vibrio cholerae can produce biofilms which have a network-like structure--however, cholera can be genetically engineered to kill other cholera with different genotypes, which leaves behind a structureless ``slime'' rather than such a biofilm. Through mechanical creep testing of both predator-prey and non-predator populations, we found that the predator-prey population responds viscously and decreases in height with repeated compression, whereas the non-predator population responds elastically and maintains its original height. The current work suggests that cell lysis after killing disrupts biofilm formation, preventing microbial colonies from forming rigid networks.

  6. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani, Sahar, E-mail: ssoleima@connect.carleton.ca; Isgor, O. Burkan, E-mail: burkan_isgor@carleton.ca; Ormeci, Banu, E-mail: banu_ormeci@carleton.ca

    2013-11-15

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process.

  7. Monitoring bacterial biofilms with a microfluidic flow chip designed for imaging with white-light interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Brann, Michelle; Suter, Jonathan D.; Addleman, R. Shane; Larimer, Curtis

    2017-07-01

    There is a need for imaging and sensing instrumentation that can monitor transitions in biofilm structure in order to better understand biofilm development and emergent properties such as anti-microbial resistance. Herein, we expanded on our previously reported technique for measuring and monitoring the thickness and topology of live biofilms using white-light interferometry (WLI). A flow cell designed for WLI enabled the use of this non-disruptive imaging method for the capture of high resolution three-dimensional profile images of biofilm growth over time. The fine axial resolution (3 nm) and wide field of view (>1 mm by 1 mm) enabled detection of biofilm formation as early as three hours after inoculation of the flow cell with a live bacterial culture (Pseudomonas fluorescens). WLI imaging facilitated monitoring the early stages of biofilm development and subtle variations in the structure of mature biofilms. Minimally-invasive imaging enabled monitoring of biofilm structure with surface metrology metrics (e.g., surface roughness). The system was used to observe a transition in biofilm structure that occurred in response to expsoure to a common antiseptic. In the future, WLI and the biofilm imaging cell described herein may be used to test the effectiveness of biofilm-specific therapies to combat common diseases associated with biofilm formation such as cystic fibrosis and periodontitis.

  8. Resistance of biofilm-covered mortars to microbiologically influenced deterioration simulated by sulfuric acid exposure

    International Nuclear Information System (INIS)

    Soleimani, Sahar; Isgor, O. Burkan; Ormeci, Banu

    2013-01-01

    Following the reported success of biofilm applications on metal surfaces to inhibit microbiologically influenced corrosion, effectiveness and sustainability of E. coli DH5α biofilm on mortar surface to prevent microbiologically influenced concrete deterioration (MICD) are investigated. Experiments simulating microbial attack were carried out by exposing incrementally biofilm-covered mortar specimens to sulfuric acid solutions with pH ranging from 3 to 6. Results showed that calcium concentration in control reactors without biofilm was 23–47% higher than the reactors with biofilm-covered mortar. Formation of amorphous silica gel as an indication of early stages of acid attack was observed only on the control mortar specimens without biofilm. During acidification, the biofilm continued to grow and its thickness almost doubled from ∼ 30 μm before acidification to ∼ 60 μm after acidification. These results demonstrated that E. coli DH5α biofilm was able to provide a protective and sustainable barrier on mortar surfaces against medium to strong sulfuric acid attack. -- Highlights: •Effectiveness of E.coli DH5α biofilm to prevent MICD was studied. •Conditions that lead to MICD were simulated by chemical acidification. •Biofilm-covered mortar specimens were exposed to sulfuric acid solutions. •The presence of biofilm helped reduce the chemically-induced mortar deterioration. •Biofilm remained alive and continued to grow during the acidification process

  9. [Detection of biofilm formation by selected pathogens relevant to the food industry].

    Science.gov (United States)

    Šilhová-Hrušková, L; Moťková, P; Šilha, D; Vytřasová, J

    2015-09-01

    Detection of biofilm formation by microbial pathogens relevant to the food industry and comparison of biofilm formation under different conditions of culture. The following microorganisms were selected for the study: Staphylococcus aureus, Listeria innocua, Listeria ivanovii, Cronobacter sakazakii, Cronobacter muytjensii, Arcobacter butzleri, Arcobacter cryaerophilus, Campylobacter jejuni, and Campylobacter coli. To detect biofilm formation the microtiter plate assay, as described by Christensen and culture on stainless steel coupons were used. The biofilm forming capacity was confirmed in all microorganisms tested, both on the microtiter plates and stainless steel coupons. Biofilm formation was influenced by the culture medium, material used, and culture duration as well as by the test microorganism. It was found that different species and strains of the same genus differ in biofilm formation. Differences were also found between the collection strains and isolates from the environment. Some bacteria tended to form biofilm more readily on the surface of the polyethylene microtiter plates and less readily on stainless steel coupons while others appeared to have an opposite tendency. Some pathogens were able to increase the planktonic cell density in the initial suspension even by three orders of magnitude within 72 hours while producing plenty of biofilm. The study of biofilm formation by high risk pathogens is of utmost importance, not only to the food industry. From the obtained results, it is evident that bacterial biofilms form rapidly (within 24 hours in the present study). Due to their architecture, these biofilms are difficult to eradicate, and therefore, it is crucial to prevent biofilm formation.

  10. Reduced Efficiency of Chlorine Disinfection of Naegleria fowleri in a Drinking Water Distribution Biofilm.

    Science.gov (United States)

    Miller, Haylea C; Wylie, Jason; Dejean, Guillaume; Kaksonen, Anna H; Sutton, David; Braun, Kalan; Puzon, Geoffrey J

    2015-09-15

    Naegleria fowleri associated with biofilm and biological demand water (organic matter suspended in water that consumes disinfectants) sourced from operational drinking water distribution systems (DWDSs) had significantly increased resistance to chlorine disinfection. N. fowleri survived intermittent chlorine dosing of 0.6 mg/L for 7 days in a mixed biofilm from field and laboratory-cultured Escherichia coli strains. However, N. fowleri associated with an attached drinking water distribution biofilm survived more than 30 times (20 mg/L for 3 h) the recommended concentration of chlorine for drinking water. N. fowleri showed considerably more resistance to chlorine when associated with a real field biofilm compared to the mixed laboratory biofilm. This increased resistance is likely due to not only the consumption of disinfectants by the biofilm and the reduced disinfectant penetration into the biofilm but also the composition and microbial community of the biofilm itself. The increased diversity of the field biofilm community likely increased N. fowleri's resistance to chlorine disinfection compared to that of the laboratory-cultured biofilm. Previous research has been conducted in only laboratory scale models of DWDSs and laboratory-cultured biofilms. To the best of our knowledge, this is the first study demonstrating how N. fowleri can persist in a field drinking water distribution biofilm despite chlorination.

  11. Biofilms on Hospital Shower Hoses: Characterization and ...

    Science.gov (United States)

    Although the source of drinking water used in hospitals is commonly, biofilms on water pipelines are refuge to bacteria that survive different disinfection strategies. Drinking water (DW) biofilms are well known to harbor opportunistic pathogens, however, these biofilm communities remain poorly characterized by culture-independent approaches that circumvent the limitations of conventional monitoring efforts. Hence, the frequency of pathogens in DW biofilms and how biofilm members withstand high doses of disinfectants and/or chlorine residuals in the water supply remain speculative, but directly impact public health. The aim of this study was to characterize the composition of microbial communities growing on five hospital shower hoses using both culture-dependent and culture-independent techniques. Two different sequence-based methods were used to characterize the bacterial fractions: 16S rRNA gene sequencing of bacterial cultures and next generation sequencing of metagenomes. Based on the metagenomic data, we found that Mycobacterium-like species was the abundant bacterial taxa that overlapped among the five samples. We also recovered the draft genome of a novel Mycobacterium species, closely related to opportunistic pathogenic nontuberculous mycobacteria, M. rhodesiae and M. tusciae, in addition to other, less abundant species. In contrast, the cultured fraction was mostly affiliated to Proteobacteria, such as members of the Sphingomonas, Blastomonas and Porph

  12. Advanced Microscopy of Microbial Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Regenberg, Birgitte; Sternberg, Claus

    2011-01-01

    microscopy, super-resolution optical microscopy (STED, SIM, PALM) as well as atomic force microscopy and Raman spectroscopy. Using examples of bistability in microbial populations as well as biofilm development and differentiation in bacterial and yeast consortia, we demonstrate the importance of microscopy...

  13. Removal of Foodborne Pathogen Biofilms by Acidic Electrolyzed Water

    Directory of Open Access Journals (Sweden)

    Qiao Han

    2017-06-01

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

  14. Evidence for biofilm acid neutralization by baking soda.

    Science.gov (United States)

    Zero, Domenick T

    2017-11-01

    The generating of acids from the microbial metabolism of dietary sugars and the subsequent decrease in biofilm pH below the pH at which tooth mineral begins to demineralize (critical pH) are the key elements of the dental caries process. Caries preventive strategies that rapidly neutralize biofilm acids can prevent demineralization and favor remineralization and may help prevent the development of sugar-induced dysbiosis that shifts the biofilm toward increased cariogenic potential. Although the neutralizing ability of sodium bicarbonate (baking soda) has been known for many years, its anticaries potential as an additive to fluoride dentifrice has received only limited investigation. There is evidence that baking soda rapidly can reverse the biofilm pH decrease after a sugar challenge; however, the timing of when it is used in relation to a dietary sugar exposure is critical in that the sooner its used the greater the benefit in preventing a sustained biofilm pH decrease and subsequent demineralization. Furthermore, the effectiveness of baking soda in elevating biofilm pH appears to depend on concentration. Thus, the concentration of baking soda in marketed dentifrice products, which ranges from 10% to 65%, may affect their biofilm pH neutralizing performance. People with hyposalivation particularly may benefit from using fluoride dentifrice containing baking soda because of their diminished ability to clear dietary sugars and buffer biofilm acids. Although promising, there is the need for more evidence that strategies that modify the oral ecology, such as baking soda, can alter the cariogenic (acidogenic and aciduric) properties of biofilm microorganisms. The acid neutralization of dental biofilm by using fluoride dentifrice that contains baking soda has potential for helping counteract modern high-sugar diets by rapidly neutralizing biofilm-generated acid, especially in people with hyposalivation. Copyright © 2017 American Dental Association. Published by

  15. Time to "go large" on biofilm research: advantages of an omics approach.

    Science.gov (United States)

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

    2009-04-01

    In nature, the biofilm mode of life is of great importance in the cell cycle for many microorganisms. Perhaps because of biofilm complexity and variability, the characterization of a given microbial system, in terms of biofilm formation potential, structure and associated physiological activity, in a large-scale, standardized and systematic manner has been hindered by the absence of high-throughput methods. This outlook is now starting to change as new methods involving the utilization of microtiter-plates and automated spectrophotometry and microscopy systems are being developed to perform large-scale testing of microbial biofilms. Here, we evaluate if the time is ripe to start an integrated omics approach, i.e., the generation and interrogation of large datasets, to biofilms--"biofomics". This omics approach would bring much needed insight into how biofilm formation ability is affected by a number of environmental, physiological and mutational factors and how these factors interplay between themselves in a standardized manner. This could then lead to the creation of a database where biofilm signatures are identified and interrogated. Nevertheless, and before embarking on such an enterprise, the selection of a versatile, robust, high-throughput biofilm growing device and of appropriate methods for biofilm analysis will have to be performed. Whether such device and analytical methods are already available, particularly for complex heterotrophic biofilms is, however, very debatable.

  16. Focusing on Environmental Biofilms With Variable-Pressure Scanning Electron Microscopy

    Science.gov (United States)

    Joubert, L.; Wolfaardt, G. M.; Du Plessis, K.

    2006-12-01

    Since the term biofilm has been coined almost 30 years ago, visualization has formed an integral part of investigations on microbial attachment. Electron microscopic (EM) biofilm studies, however, have been limited by the hydrated extracellular matrix which loses structural integrity with conventional preparative techniques, and under required high-vacuum conditions, resulting in a loss of information on spatial relationships and distribution of biofilm microbes. Recent advances in EM technology enable the application of Variable Pressure Scanning Electron Microscopy (VP SEM) to biofilms, allowing low vacuum and hydrated chamber atmosphere during visualization. Environmental biofilm samples can be viewed in situ, unfixed and fully hydrated, with application of gold-sputter-coating only, to increase image resolution. As the impact of microbial biofilms can be both hazardous and beneficial to man and his environment, recognition of biofilms as a natural form of microbial existence is needed to fully assess the potential role of microbial communities on technology. The integration of multiple techniques to elucidate biofilm processes has become imperative for unraveling complex phenotypic adaptations of this microbial lifestyle. We applied VP SEM as integrative technique with traditional and novel analytical techniques to (1)localize lignocellulosic microbial consortia applied for producing alternative bio-energy sources in the mining wastewater industry, (2) characterize and visualize wetland microbial communities in the treatment of winery wastewater, and (3)determine the impact of recombinant technology on yeast biofilm behavior. Visualization of microbial attachment to a lignocellulose substrate, and degradation of exposed plant tissue, gave insight into fiber degradation and volatile fatty acid production for biological sulphate removal from mining wastewater. Also, the 3D-architecture of complex biofilms developing in constructed wetlands was correlated with

  17. A closer look: the complexities of dental biofilm

    OpenAIRE

    Costerton, J.W.; Stoodley, P.

    2003-01-01

    Biofilms are the collections of bacteria and other microorganisms that assemble on surfaces. They are widespread in nature and can colonize natural, nonliving hard surfaces such as river rocks, man-made surfaces like the concrete found in industrial pipelines, and even plant and animal surfaces and, of course, the teeth and gums.Within this broad definition, dental plaque falls into one of many types of different biofilms. Loosely adherent plaque and the denser, more firmly attached plaque ma...

  18. Development of an in vitro Assay, based on the BioFilm Ring Test®, for Rapid Profiling of Biofilm-Growing Bacteria

    Directory of Open Access Journals (Sweden)

    Enea Gino Di Domenico

    2016-09-01

    Full Text Available Microbial biofilm represents a major virulence factor associated with chronic and recurrent infections. Pathogenic bacteria embedded in biofilms are highly resistant to environmental and chemical agents, including antibiotics and therefore difficult to eradicate. Thus, reliable tests to assess biofilm formation by bacterial strains as well as the impact of chemicals or antibiotics on biofilm formation represent desirable tools for a most effective therapeutic management and microbiological risk control. Current methods to evaluate biofilm formation are usually time-consuming, costly, and hardly applicable in the clinical setting.The aim of the present study was to develop and assess a simple and reliable in vitro procedure for the characterization of biofilm-producing bacterial strains for future clinical applications based on the BioFilm Ring Test® (BRT technology. The procedure developed for clinical testing (cBRT can provide an accurate and timely (5 hours measurement of biofilm formation for the most common pathogenic bacteria seen in clinical practice. The results gathered by the cBRT assay were in agreement with the traditional crystal violet (CV staining test, according to the kappa coefficient test (kappa = 0.623. However, the cBRT assay showed higher levels of specificity (92.2% and accuracy (88.1% as compared to CV. The results indicate that this procedure offers an easy, rapid and robust assay to test microbial biofilm and a promising tool for clinical microbiology.

  19. The impact of major earthquakes and subsequent sewage discharges on the microbial quality of water and sediments in an urban river.

    Science.gov (United States)

    Devane, Megan L; Moriarty, Elaine M; Wood, David; Webster-Brown, Jenny; Gilpin, Brent J

    2014-07-01

    A series of large earthquakes struck the city of Christchurch, New Zealand in 2010-2011. Major damage sustained by the sewerage infrastructure required direct discharge of up to 38,000 m(3)/day of raw sewage into the Avon River of Christchurch for approximately six months. This allowed evaluation of the relationship between concentrations of indicator microorganisms (Escherichia coli, Clostridium perfringens and F-RNA phage) and pathogens (Campylobacter, Giardia and Cryptosporidium) in recreational water and sediment both during and post-cessation of sewage discharges. Giardia was the pathogen found most frequently in river water and sediment, although Campylobacter was found at higher levels in water samples. E. coli levels in water above 550 CFU/100 mL were associated with increased likelihood of detection of Campylobacter, Giardia and Cryptosporidium, supporting the use of E. coli as a reliable indicator for public health risk. The strength of the correlation of microbial indicators with pathogen detection in water decreased in the following order: E. coli>F-RNA phage>C. perfringens. All the microorganisms assayed in this study could be recovered from sediments. C. perfringens was observed to accumulate in sediments, which may have confounded its usefulness as an indicator of fresh sewage discharge. F-RNA phage, however, did not appear to accumulate in sediment and in conjunction with E. coli, may have potential as an indicator of recent human sewage discharge in freshwater. There is evidence to support the low-level persistence of Cryptosporidium and Giardia, but not Campylobacter, in river sediments after cessation of sewage discharges. In the event of disturbances of the sediment, it is highly probable that there could be re-mobilisation of microorganisms beyond the sediment-water exchange processes occurring under base flow conditions. Re-suspension events do, therefore, increase the potential risk to human health for those who participate in recreational

  20. Microbial biofilms on silicone facial prostheses

    NARCIS (Netherlands)

    Ariani, Nina

    2015-01-01

    Facial disfigurements can result from oncologic surgery, trauma and congenital deformities. These disfigurements can be rehabilitated with facial prostheses. Facial prostheses are usually made of silicones. A problem of facial prostheses is that microorganisms can colonize their surface. It is hard

  1. Investigation of microbial-mineral interactions by Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Sawicki, J.A.; Brown, D.A.

    1998-01-01

    Moessbauer spectroscopy was used to investigate the reactions of microbes with iron minerals in aqueous solutions and as components of rocks in banded iron formations and granite. A microbial biofilm that formed on a wall of an excavated granite vault in a deep underground laboratory initiated this research. At the aerobic face of the biofilm, iron was found in a form of ferrihydrite; in the anaerobic face against the rock, iron was found as very small siderite particles. Laboratory incubations of the biofilm microbial consortium showed different mineral species could be formed. When the microbial consortium from the biofilm was incubated with magnetite grains, up to about 10% of the iron was altered in three weeks to hematite. The ability of the consortium to precipitate iron both as Fe 2+ and Fe 3+ in close proximity may have a bearing on the deposition of banded iron formations. These reactions could also be important in microbially induced corrosion

  2. Taxonomic and chemical assessment of exceptionally abundant rock mine biofilm

    Directory of Open Access Journals (Sweden)

    Karolina Tomczyk-Żak

    2017-08-01

    Full Text Available Background An exceptionally thick biofilm covers walls of ancient gold and arsenic Złoty Stok mine (Poland in the apparent absence of organic sources of energy. Methods and Results We have characterized this microbial community using culture-dependent and independent methods. We sequenced amplicons of the 16S rRNA gene obtained using generic primers and additional primers targeted at Archaea and Actinobacteria separately. Also, we have cultured numerous isolates from the biofilm on different media under aerobic and anaerobic conditions. We discovered very high biodiversity, and no single taxonomic group was dominant. The majority of almost 4,000 OTUs were classified above genus level indicating presence of novel species. Elemental analysis, performed using SEM-EDS and X-ray, of biofilm samples showed that carbon, sulphur and oxygen were not evenly distributed in the biofilm and that their presence is highly correlated. However, the distribution of arsenic and iron was more flat, and numerous intrusions of elemental silver and platinum were noted, indicating that microorganisms play a key role in releasing these elements from the rock. Conclusions Altogether, the picture obtained throughout this study shows a very rich, complex and interdependent system of rock biofilm. The chemical heterogeneity of biofilm is a likely explanation as to why this oligotrophic environment is capable of supporting such high microbial diversity.

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

    Science.gov (United States)

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

    2012-04-16

    . Even though both the planktonic and biofilm cells were oxidizing lactate and reducing sulfate, the biofilm cells were physiologically distinct compared to planktonic growth states due to altered abundances of genes/proteins involved in carbon/energy flow and extracellular structures. In addition, average expression values for multiple rRNA transcripts and respiratory activity measurements indicated that biofilm cells were metabolically more similar to exponential-phase cells although biofilm cells are structured differently. The characterization of physiological advantages and constraints of the biofilm growth state for sulfate-reducing bacteria will provide insight into bioremediation applications as well as microbially-induced metal corrosion.

  4. EFFECT OF ESSENTIAL OIL ON BIOFILM PRODUCTION BY DIFFERENT LISTERIA MONOCYTOGENES STRAINS

    Directory of Open Access Journals (Sweden)

    G. Comi

    2008-12-01

    Full Text Available The effects of different essential oil (hexanal, 2-(E-hexenal, carvacrol, citron, red orange, thymol and limonene on biofilm production of some Lmonocytogenes strains are evaluated. The formation of biofilm on certain surfaces or on the food, seems to be related with cross-contamination during processing or with the contamination of the final product, with potential risk for the consumer. Many studies were done on the antimicrobial activity of essential oils and their components, but not too much is known about their capacity to influence and reduce the microbial production of biofilm. Our data showed that essential oils can inhibit or limit the biofilm production.

  5. Defining the sources of airborne polychlorinated biphenyls: evidence for the influence of microbially dechlorinated congeners from river sediment?

    Energy Technology Data Exchange (ETDEWEB)

    Chiarenzelli, J. [SUNYat Oswego, NY (United States); Bush, B.; Casey, A.; O' Keefe, P. [SUNY at Albany, School of Public Health, Rensselaer, NY (United States); Barnard, E.; Smith, B. [New York State Dept. of Health, Wadsworth Center for Laboratories and Research, Albany, NY (United States); Gilligan, E. [Syracuse Univ., Dept. of Civil an Environmental Engineering, NY (United States); Johnson, G. [Energy and Geoscience Institute, Dept, of Civil and Environmental Engineering, Salt Lake City, UT (United States)

    2000-07-01

    During sampling in 1993, elevated levels of polychlorinated biphenyls were discovered near three industrial facilities on the Akwesasne Mohawk Nation Reserve along the St. Lawrence River, straddling the Canadian-US. border. Volatilization of Aroclor 1248, which was used extensively at all three sites, was identified as the dominant source, augmented in a minor way by a dechlorinated source, presumably from river sediment and waters. These two sources were found to account for 80 per cent of the contamination. Further, it was established that at a small cove adjacent to an industrial landfill, summer concentrations of PCBs exceeded winter concentrations by a factor of 27. Observation showed the presence of similar congener-specific PCB patterns at all sample sites and an increase in the concentrations of chlorine to biphenyl ratios during the summer months. During the colder months PCB concentrations at all sites declined, nevertheless, PCB levels were still higher than those measured elsewhere in the Great Lakes region during the same time period. Results of this investigation suggest that atmospheric deposition from local contaminant sources can elevate concentrations in produce and vegetative matter, complicating exposure routes and bioaccumulation via modeling of food chain. 22 refs., 4 tabs. 1 fig.

  6. Biofilm is a Major Virulence Determinant in Bacterial Colonization of Chronic Skin Ulcers Independently from the Multidrug Resistant Phenotype

    Directory of Open Access Journals (Sweden)

    Enea Gino Di Domenico

    2017-05-01

    Full Text Available Bacterial biofilm is a major factor in delayed wound healing and high levels of biofilm production have been repeatedly described in multidrug resistant organisms (MDROs. Nevertheless, a quantitative correlation between biofilm production and the profile of antimicrobial drug resistance in delayed wound healing remains to be determined. Microbial identification, antibiotic susceptibility and biofilm production were assessed in 135 clinical isolates from 87 patients. Gram-negative bacteria were the most represented microorganisms (60.8% with MDROs accounting for 31.8% of the total isolates. Assessment of biofilm production revealed that 80% of the strains were able to form biofilm. A comparable level of biofilm production was found with both MDRO and not-MDRO with no significant differences between groups. All the methicillin-resistant Staphylococcus aureus (MRSA and 80% of Pseudomonas aeruginosa MDR strains were found as moderate/high biofilm producers. Conversely, less than 17% of Klebsiella pneumoniae extended-spectrum beta-lactamase (ESBL, Escherichia coli-ESBL and Acinetobacter baumannii were moderate/high biofilm producers. Notably, those strains classified as non-biofilm producers, were always associated with biofilm producer bacteria in polymicrobial colonization. This study shows that biofilm producers were present in all chronic skin ulcers, suggesting that biofilm represents a key virulence determinant in promoting bacterial persistence and chronicity of ulcerative lesions independently from the MDRO phenotype.

  7. Effect of fluoride and chlorhexidine digluconate mouthrinses on plaque biofilms.

    Science.gov (United States)

    Rabe, Per; Twetman, Svante; Kinnby, Bertil; Svensäter, Gunnel; Davies, Julia R

    2015-01-01

    To develop a model in which to investigate the architecture of plaque biofilms formed on enamel surfaces in vivo and to compare the effects of anti-microbial agents of relevance for caries on biofilm vitality. Materials and Methodology : Enamel discs mounted on healing abutments in the pre-molar region were worn by three subjects for 7 days. Control discs were removed before subjects rinsed with 0.1% chlorhexidine digluconate (CHX) or 0.2% sodium fluoride (NaF) for 1 minute. Biofilms were stained with Baclight Live/Dead and z-stacks of images created using confocal scanning laser micoscopy. The levels of vital and dead/damaged bacteria in the biofilms, assessed as the proportion of green and red pixels respectively, were analysed using ImageTrak(®) software. Results : The subjects showed individual differences in biofilm architecture. The thickness of the biofilms varied from 28-96µm although cell density was always the greatest in the middle layers. In control biofilms, the overall levels of vitality were high (71-98%) especially in the area closest to the enamel interface. Rinsing with either CHX or NaF caused a similar reduction in overall vitality. CHX exerted an effect throughout the biofilm, particularly on the surface of cell clusters whereas NaF caused cell damage/death mainly in the middle to lower biofilm layers. Conclusion : We describe a model that allows the formation of mature, undisturbed oral biofilms on human enamel surfaces in vivo and show that CHX and NaF have a similar effect on overall vitality but differ in their sites of action.

  8. Species sorting during biofilm assembly by artificial substrates deployed in a cold seep system

    KAUST Repository

    Zhang, Wei Peng

    2014-10-17

    Studies focusing on biofilm assembly in deep-sea environments are rarely conducted. To examine the effects of substrate type on microbial community assembly, biofilms were developed on different substrates for different durations at two locations in the Red Sea: in a brine pool and in nearby bottom water (NBW) adjacent to the Thuwal cold seep II. The composition of the microbial communities in 51 biofilms and water samples were revealed by classification of pyrosequenced 16S rRNA gene amplicons. Together with the microscopic characteristics of the biofilms, the results indicate a stronger selection effect by the substrates on the microbial assembly in the brine pool compared with the NBW. Moreover, the selection effect by substrate type was stronger in the early stages compared with the later stages of the biofilm development. These results are consistent with the hypotheses proposed in the framework of species sorting theory, which states that the power of species sorting during microbial community assembly is dictated by habitat conditions, duration and the structure of the source community. Therefore, the results of this study shed light on the control strategy underlying biofilm-associated marine fouling and provide supporting evidence for ecological theories important for understanding the formation of deep-sea biofilms.

  9. Species sorting during biofilm assembly by artificial substrates deployed in a cold seep system

    KAUST Repository

    Zhang, Wei Peng; Wang, Yong; Tian, Ren Mao; Bougouffa, Salim; Yang, Bo; Cao, Hui Luo; Zhang, Gen; Wong, Yue Him; Xu, Wei; Batang, Zenon B.; Al-Suwailem, Abdulaziz M.; Zhang, Xixiang; Qian, Pei-Yuan

    2014-01-01

    Studies focusing on biofilm assembly in deep-sea environments are rarely conducted. To examine the effects of substrate type on microbial community assembly, biofilms were developed on different substrates for different durations at two locations in the Red Sea: in a brine pool and in nearby bottom water (NBW) adjacent to the Thuwal cold seep II. The composition of the microbial communities in 51 biofilms and water samples were revealed by classification of pyrosequenced 16S rRNA gene amplicons. Together with the microscopic characteristics of the biofilms, the results indicate a stronger selection effect by the substrates on the microbial assembly in the brine pool compared with the NBW. Moreover, the selection effect by substrate type was stronger in the early stages compared with the later stages of the biofilm development. These results are consistent with the hypotheses proposed in the framework of species sorting theory, which states that the power of species sorting during microbial community assembly is dictated by habitat conditions, duration and the structure of the source community. Therefore, the results of this study shed light on the control strategy underlying biofilm-associated marine fouling and provide supporting evidence for ecological theories important for understanding the formation of deep-sea biofilms.

  10. Silver nanoparticles impede the biofilm formation by Pseudomonas aeruginosa and Staphylococcus epidermidis.

    Science.gov (United States)

    Kalishwaralal, Kalimuthu; BarathManiKanth, Selvaraj; Pandian, Sureshbabu Ram Kumar; Deepak, Venkataraman; Gurunathan, Sangiliyandi

    2010-09-01

    Biofilms are ensued due to bacteria that attach to surfaces and aggregate in a hydrated polymeric matrix. Formation of these sessile communities and their inherent resistance to anti-microbial agents are the source of many relentless and chronic bacterial infections. Such biofilms are responsible play a major role in development of ocular related infectious diseases in human namely microbial keratitis. Different approaches have been used for preventing biofilm related infections in health care settings. Many of these methods have their own demerits that include chemical based complications; emergent antibiotic resistant strains, etc. silver nanoparticles are renowned for their influential anti-microbial activity. Hence the present study over the biologically synthesized silver nanoparticles, exhibited a potential anti-biofilm activity that was tested in vitro on biofilms formed by Pseudomonas aeruginosa and Staphylococcus epidermidis during 24-h treatment. Treating these organisms with silver nanoparticles resulted in more than 95% inhibition in biofilm formation. The inhibition was known to be invariable of the species tested. As a result this study demonstrates the futuristic application of silver nanoparticles in treating microbial keratitis based on its potential anti-biofilm activity. Copyright 2010 Elsevier B.V. All rights reserved.

  11. Mini-review: Biofilm responses to oxidative stress.

    Science.gov (United States)

    Gambino, Michela; Cappitelli, Francesca

    2016-01-01

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

  12. Impact of disinfection on drinking water biofilm bacterial community.

    Science.gov (United States)

    Mi, Zilong; Dai, Yu; Xie, Shuguang; Chen, Chao; Zhang, Xiaojian

    2015-11-01

    Disinfectants are commonly applied to control the growth of microorganisms in drinking water distribution systems. However, the effect of disinfection on drinking water microbial community remains poorly understood. The present study investigated the impacts of different disinfectants (chlorine and chloramine) and dosages on biofilm bacterial community in bench-scale pipe section reactors. Illumina MiSeq sequencing illustrated that disinfection strategy could affect both bacterial diversity and community structure of drinking water biofilm. Proteobacteria tended to predominate in chloraminated drinking water biofilms, while Firmicutes in chlorinated and unchlorinated biofilms. The major proteobacterial groups were influenced by both disinfectant type and dosage. In addition, chloramination had a more profound impact on bacterial community than chlorination. Copyright © 2015. Published by Elsevier B.V.

  13. Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

    Science.gov (United States)

    Zhang, Cheng; Li, Bo; Huang, Xiao; Ni, Yong; Feng, Xi-Qiao

    2016-10-01

    Growing bacterial biofilms exhibit a number of surface morphologies, e.g., concentric wrinkles, radial ridges, and labyrinthine networks, depending on their physiological status and nutrient access. We explore the mechanisms u