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1

Biofilms: Microbial Life on Surfaces  

Microsoft Academic Search

Microorganisms attach to surfaces and develop biofilms. Biofilm-associated cells can be differentiated from their suspended counterparts by generation of an extracellular polymeric substance (EPS) matrix, reduced growth rates, and the up- and down-regulation of specific genes. Attachment is a complex pro- cess regulated by diverse characteristics of the growth medium, substratum, and cell surface. An estab- lished biofilm structure comprises

Rodney M. Donlan

2002-01-01

2

Manipulation of Biofilm Microbial Ecology  

SciTech Connect

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

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

1998-08-15

3

Manipulatiaon of Biofilm Microbial Ecology  

SciTech Connect

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

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

1998-08-09

4

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

5

Cooperation and conflict in microbial biofilms  

PubMed Central

Biofilms, in which cells attach to surfaces and secrete slime (polymeric substances), are central to microbial life. Biofilms are often thought to require high levels of cooperation because extracellular polymeric substances are a shared resource produced by one cell that can be used by others. Here we examine this hypothesis by using a detailed individual-based simulation of a biofilm to investigate the outcome of evolutionary competitions between strains that differ in their level of polymer production. Our model includes a biochemical description of the carbon fluxes for growth and polymer production, and it explicitly calculates diffusion–reaction effects and the resulting solute gradients in the biofilm. An emergent property of these simple but realistic mechanistic assumptions is a strong evolutionary advantage to extracellular polymer production. Polymer secretion is altruistic to cells above a focal cell: it pushes later generations in their lineage up and out into better oxygen conditions, but it harms others; polymer production suffocates neighboring nonpolymer producers. This property, analogous to vertical growth in plants, suggests that polymer secretion provides a strong competitive advantage to cell lineages within mixed-genotype biofilms: global cooperation is not required. Our model fundamentally changes how biofilms are expected to respond to changing social conditions; the presence of multiple strains in a biofilm should promote rather than inhibit polymer secretion. PMID:17210916

Xavier, Joao B.; Foster, Kevin R.

2007-01-01

6

Microbial biofilms: biosurfactants as antibiofilm agents.  

PubMed

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. PMID:25359476

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

2014-12-01

7

Computational Modeling of Synthetic Microbial Biofilms Timothy J. Rudge,,  

E-print Network

Computational Modeling of Synthetic Microbial Biofilms Timothy J. Rudge,,¶ Paul J. Steiner, U.K. Microsoft Research, Cambridge, U.K. *S Supporting Information ABSTRACT: Microbial biofilms environment. These properties make biofilms an attractive target for engineering, particularly

Haseloff, Jim

8

MICROBIAL BIOFILMS AS INDICATORS OF ESTUARINE CONDITION  

EPA Science Inventory

Microbial biofilms are complex communities of bacteria, protozoa, microalgae, and micrometazoa which exist in a polymer matrix on submerged surfaces. Their development is integrative of environmental conditions and is affected by local biodiversity, the availability of organic ma...

9

Microbial biofilms in intertidal systems: an overview  

NASA Astrophysics Data System (ADS)

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

Decho, Alan W.

2000-07-01

10

Microbial Biofilms: Persisters, Tolerance and Dosing  

NASA Astrophysics Data System (ADS)

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

Cogan, N. G.

2005-03-01

11

Chitosan coupling makes microbial biofilms susceptible to antibiotics.  

PubMed

Microbial biofilms, prevalent in nature and inherently resistant to both antimicrobial agents and host defenses, can cause serious problems in the chemical, medical and pharmaceutical industries. Herein we demonstrated that conjugation of an aminoglycoside antibiotic (streptomycin) to chitosan could efficiently damage established biofilms and inhibit biofilm formation. This method was suitable to eradiate biofilms formed by Gram-positive organisms, and it appeared that antibiotic contents, molecular size and positive charges of the conjugate were the key to retain this anti-biofilm activity. Mechanistic insight demonstrated chitosan conjugation rendered streptomycin more accessible into biofilms, thereby available to interact with biofilm bacteria. Thus, this work represent an innovative strategy that antibiotic covalently linked to carbohydrate carriers can overcome antibiotic resistance of microbial biofilms, and might provide a comprehensive solution to combat biofilms in industrial and medical settings. PMID:24284335

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

2013-01-01

12

Microbial biofilm formation and its consequences for the CELSS program  

NASA Technical Reports Server (NTRS)

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

Mitchell, R.

1994-01-01

13

Spatial Distributions of Copper in Microbial Biofilms by Scanning  

E-print Network

Spatial Distributions of Copper in Microbial Biofilms by Scanning Electrochemical Microscopy Z H I was determined in Escherichia coli PHL628 biofilms using a scanning electrochemical microscope (SECM) consisting.7 V (vs Ag/AgCl). The position of the bulk solution-biofilm interface was determined from the change

Houston, Paul L.

14

Proteogenomic studies of natural microbial biofilms  

NASA Astrophysics Data System (ADS)

Acid mine drainage (AMD) forms when rocks rich in pyrite, FeS2, are oxidized upon exposure to air and water. Iron-oxidizing microorganisms accelerate pyrite dissolution by generating ferric iron, an especially effective sulfide oxidant. We have used cultivation-independent methods to study the gene (Tyson et al., 2004) and protein (Ram et al., in review) complements of microbial biofilms from an AMD environment in Richmond, CA. The genomes of the biofilm organisms indicated potential proteins and other small molecules that each organism type can produce. We then used this genome data in combination with 2D LC-MS/MS mass spectrometry to identify proteins within extracellular/periplasmic, soluble, and membrane fractions of the biofilm. This method enabled us to infer the most abundant proteins in each fraction and their general location. In particular, it led us to identify an extracellular/periplasmic cytochrome central to iron oxidation and acid mine drainage, as well as to analyze hypothetical proteins (proteins predicted from the genome with no significant homology to known proteins), some of which are likely to be adaptations by the biofilm organisms for thriving in this unique metal-rich acidic environment.

Ram, R. J.; Verberkmoes, N. C.; Thelen, M. P.; Tyson, G. W.; Baker, B. J.; Shah, M.; Blake, R. C.; Hettich, R. L.; Banfield, J. F.

2005-05-01

15

MICROBIAL BIOFILMS AS INTEGRATIVE SENSORS OF ENVIRONMENTAL QUALITY  

EPA Science Inventory

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...

16

Enhancing Metagenomics Investigations of Microbial Interactions with Biofilm Technology  

PubMed Central

Investigations of microbial ecology and diversity have been greatly enhanced by the application of culture-independent techniques. One such approach, metagenomics, involves sample collections from soil, water, and other environments. Extracted nucleic acids from bulk environmental samples are sequenced and analyzed, which allows microbial interactions to be inferred on the basis of bioinformatics calculations. In most environments, microbial interactions occur predominately in surface-adherent, biofilm communities. In this review, we address metagenomics sampling and biofilm biology, and propose an experimental strategy whereby the resolving power of metagenomics can be enhanced by incorporating a biofilm-enrichment step during sample acquisition. PMID:24284397

McLean, Robert J. C.; Kakirde, Kavita S.

2013-01-01

17

The Biofilm Mode of Life  

Microsoft Academic Search

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

Staffan Kjelleberg; Michael Givskov

18

Early microbial biofilm formation on marine plastic debris  

Microsoft Academic Search

An important aspect of the global problem of plastic debris pollution is plastic buoyancy. There is some evidence that buoyancy is influenced by attached biofilms but as yet this is poorly understood. We submerged polyethylene plastic in seawater and sampled weekly for 3weeks in order to study early stage processes. Microbial biofilms developed rapidly on the plastic and coincided with

Delphine Lobelle; Michael Cunliffe

2011-01-01

19

Peppermint ( Mentha piperita) inhibits microbial biofilms in vitro  

Microsoft Academic Search

Microbial biofilms have become increasingly problematic in the food processing and medical industries where they cause food and surface contamination. Biofilms have also been implicated as the cause of serious infections in humans as their occurrence makes it difficult to treat common infections and the likelihood of recurrent infections is high. Due to emerging resistance, conventional control methods are fast

M. Sandasi; C. M. Leonard; S. F. Van Vuuren; A. M. Viljoen

2011-01-01

20

Dynamic Remodeling of Microbial Biofilms by Functionally Distinct Exopolysaccharides  

E-print Network

Biofilms are densely populated communities of microbial cells protected and held together by a matrix of extracellular polymeric substances. The structure and rheological properties of the matrix at the microscale influence ...

Chew, Su Chuen

21

The biofilm ecology of microbial biofouling, biocide resistance and corrosion  

SciTech Connect

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

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

1997-06-01

22

Evidence for Microbial Biofilms in Cholesteatomas  

Microsoft Academic Search

Background: Sessile bacteria within biofilms are highly resistant to eradication by antimicrobial agents. Previ- ously, we have shown that the most common organisms cultured from experimentally induced cholesteatomas are biofilm formers. Additionally, the keratin \\

Richard A. Chole; Brian T. Faddis

2002-01-01

23

The biofilm matrix – an immobilized but dynamic microbial environment  

Microsoft Academic Search

The biofilm matrix is a dynamic environment in which the component microbial cells appear to reach homeostasis and are optimally organized to make use of all available nutrients. The major matrix components are microbial cells, polysaccharides and water, together with excreted cellular products. The matrix therefore shows great microheterogeneity, within which numerous microenvironments can exist. Although exopolysaccharides provide the matrix

Ian W Sutherland

2001-01-01

24

A mucosal model to study microbial biofilm development and anti-biofilm therapeutics  

PubMed Central

Biofilms are a sessile colony of bacteria which adhere to and persist on surfaces. The ability of bacteria to form biofilms is considered a virulence factor, and in fact is central to the pathogenesis of some organisms. Biofilms are inherently resistant to chemotherapy and host immune responses. Clinically, biofilms are considered a primary cause of a majority of infections, such as otitis media, pneumonia in cystic fibrosis patients and endocarditis. However, the vast majority of the data on biofilm formation comes from traditional microtiter-based or flow displacement assays with no consideration given to host factors. These assays, which have been a valuable tool in high-throughput screening for biofilm-related factors, do not mimic a host-pathogen interaction and may contribute to an inappropriate estimation of the role of some factors in clinical biofilm formation. We describe the development of a novel ex vivo model of biofilm formation on a mucosal surface by an important mucosal pathogen, methicillin resistant S. aureus (MRSA). This model is being used for the identification of microbial virulence factors important in mucosal biofilm formation and novel anti-biofilm therapies. PMID:23246911

Anderson, Michele J.; Parks, Patrick J.; Peterson, Marnie L.

2013-01-01

25

Multimetal resistance and tolerance in microbial biofilms  

Microsoft Academic Search

Geochemical cycling and industrial pollution have made toxic metal ions a pervasive environmental pressure throughout the world. Biofilm formation is a strategy that microorganisms might use to survive a toxic flux in these inorganic compounds. Evidence in the literature suggests that biofilm populations are protected from toxic metals by the combined action of chemical, physical and physiological phenomena that are,

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

2007-01-01

26

The effects of disinfectant foam on microbial biofilms.  

PubMed

This investigation examined the effects of common aqueous biocides and disinfectant foams derived from them on Pseudomonas aeruginosa biofilms. Biofilms were grown on stainless steel coupons under standardised conditions in a reactor supplemented with low concentrations of organic matter to simulate conditions prevalent in industrial systems. Five-day-old biofilms formed under ambient conditions with continuous agitation demonstrated a low coefficient of variation (5.809%) amongst viable biofilm bacteria from independent trials. Scanning electron microscopy revealed biofilms on coupons with viable biofilm bacteria observed by confocal microscopy. An aqueous solution of a common foaming agent amine oxide (AO) produced negligible effects on bacterial viability in biofilms (p>0.05). However, significant biofilm inactivation was noted with aqueous solutions of common biocides (peracetic acid, sodium hypochlorite, sodium ethylenediaminetetraacetic acid) with or without AO (p<0.05). Aereation of a mixture of AO with each of these common biocides resulted in significant reductions in the viability of biofilm bacteria (p<0.05). In contrast, limited effects were noted by foam devoid of biocides. A relationship between microbial inactivation and the concentration of biocide in foam (ranging from 0.1-0.5%) and exposure period were noted (p<0.05). Although, lower numbers of viable biofilm bacteria were recovered after treatment with the disinfectant foam than by the cognate aqueous biocide, significant differences between these treatments were not evident (p>0.05). In summary, the studies revealed significant biofilm inactivation by biocidal foam prepared with common biocides. Validation of foam disinfectants in controlled trials at manufacturing sites may facilitate developments for clean in place applications. Advantages of foam disinfectants include reductions in the volumes of biocides for industrial disinfection and in their disposal after use. PMID:16167393

Sreenivasan, Prem K; Chorny, Roberto C

2005-01-01

27

Embryo fossilization is a biological process mediated by microbial biofilms  

PubMed Central

Fossilized embryos with extraordinary cellular preservation appear in the Late Neoproterozoic and Cambrian, coincident with the appearance of animal body fossils. It has been hypothesized that microbial processes are responsible for preservation and mineralization of organic tissues. However, the actions of microbes in preservation of embryos have not been demonstrated experimentally. Here, we show that bacterial biofilms assemble rapidly in dead marine embryos and form remarkable pseudomorphs in which the bacterial biofilm replaces and exquisitely models details of cellular organization and structure. The experimental model was the decay of cleavage stage embryos similar in size and morphology to fossil embryos. The data show that embryo preservation takes place in 3 distinct steps: (i) blockage of autolysis by reducing or anaerobic conditions, (ii) rapid formation of microbial biofilms that consume the embryo but form a replica that retains cell organization and morphology, and (iii) bacterially catalyzed mineralization. Major bacterial taxa in embryo decay biofilms were identified by using 16S rDNA sequencing. Decay processes were similar in different taphonomic conditions, but the composition of bacterial populations depended on specific conditions. Experimental taphonomy generates preservation states similar to those in fossil embryos. The data show how fossilization of soft tissues in sediments can be mediated by bacterial replacement and mineralization, providing a foundation for experimentally creating biofilms from defined microbial species to model fossilization as a biological process. PMID:19047625

Raff, Elizabeth C.; Schollaert, Kaila L.; Nelson, David E.; Donoghue, Philip C. J.; Thomas, Ceri-Wyn; Turner, F. Rudolf; Stein, Barry D.; Dong, Xiping; Bengtson, Stefan; Huldtgren, Therese; Stampanoni, Marco; Chongyu, Yin; Raff, Rudolf A.

2008-01-01

28

Modelling mechanical characteristics of microbial biofilms by network theory.  

PubMed

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

Ehret, Alexander E; Böl, Markus

2012-10-01

29

Modelling mechanical characteristics of microbial biofilms by network theory  

PubMed Central

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

Ehret, Alexander E.; Bol, Markus

2013-01-01

30

Theoretical Aspects of Antibiotic Diffusion into Microbial Biofilms  

Microsoft Academic Search

Antibiotic penetration into microbial biofilm was investigated theoretically by the solution of mathematical equations describing various combinations of the processes of diffusion, sorption, and reaction. Unsteady material balances on the antibiotic and on a reactive or sorptive biomass constituent, along with associated boundaryandinitialconditions,constitutethemathematicalformulations.Fivecaseswereexamined:diffusion of a noninteracting solute; diffusion of a reversibly sorbing, nonreacting solute; diffusion of an irreversibly sorbing, nonreacting

PHILIP S. STEWART

1996-01-01

31

ORAL MICROBIAL COMMUNITIES: Biofilms, Interactions, and Genetic Systems1  

Microsoft Academic Search

? Abstract Oral microbial-plaque communities are biofilms composed of numer- ous genetically distinct types of bacteria that live in close juxtaposition on host surfaces. These bacteria communicate through physical interactions called coaggregation and coadhesion, as well as other physiological and metabolic interactions. Streptococci and actinomyces are the major initial colonizers of the tooth surface, and the inter- actions between them

Paul E. Kolenbrander

2000-01-01

32

Utilization of microbial biofilms as monitors of bioremediation  

SciTech Connect

A down-well aquifer microbial sampling system was developed using glass wool or Bio-Sep beads as a solid-phase support matrix. Here we describe the use of these devices to monitor the groundwater microbial community dynamics during field bioremediation experiments at the U.S. Department of Energy Natural and Accelerated Bioremediation Research Programs Field Research Center at the Oak Ridge National Laboratory. During the 6-week deployment, microbial biofilms colonized glass wool and bead internal surfaces. Changes in viable biomass, community composition, metabolic status, and respiratory state were reflected in sampler composition, type of donor, and groundwater pH. Biofilms that formed on Bio-Sep beads had 2-13 times greater viable biomass; however, the bead communities were less metabolically active [higher cyclopropane/monoenoic phospholipid fatty acid (PLFA) ratios] and had a lower aerobic respiratory state (lower total respiratory quinone/PLFA ratio and ubiquinone/menaquinone ratio) than the biofilms formed on glass wool. Anaerobic growth in these systems was characterized by plasmalogen phospholipids and was greater in the wells that received electron donor additions. Partial 16S rDNA sequences indicated that Geobacter and nitrate-reducing organisms were induced by the acetate, ethanol, or glucose additions. DNA and lipid biomarkers were extracted and recovered without the complications that commonly plague sediment samples due to the presence of clay or dissolved organic matter. Although microbial community composition in the groundwater or adjacent sediments may differ from those formed on down-well biofilm samplers, the metabolic activity responses of the biofilms to modifications in groundwater geochemistry record the responses of the microbial community to biostimulation while providing integrative sampling and ease of recovery for biomarker analysis.

Peacock, Aaron D. [University of Tennessee; IstokD., Jonathan [Oregon State University, Corvallis; Krumholz, Lee R. [University of Oklahoma; Geyer, Roland [ORNL; Kinsall, Barry Lee [ORNL; Watson, David B [ORNL; Sublette, K. [University of Tulsa; White, David C. [University of Tennessee

2004-03-01

33

Extremophiles Microbial Life Under Extreme  

E-print Network

1 23 Extremophiles Microbial Life Under Extreme Conditions ISSN 1431-0651 Volume 16 Number 3 Extremophiles (2012) 16:553-566 DOI 10.1007/s00792-012-0454-z Life at the hyperarid margin: novel bacterial

34

Biofilm formation by Campylobacter jejuni in controlled mixed-microbial populations  

Microsoft Academic Search

This study was to screen the ability of biofilm formation by Campylobacter jejuni strains found in New Zealand, and investigate the biofilm growth of C. jejuni in a controlled mixed-microbial population that includes five different bacteria. The ability of C. jejuni to form a biofilm in monoculture and mixed-microbial populations was measured in a laboratory assay using a microtiter plate

Koon Hoong Teh; Steve Flint; Nigel French

2010-01-01

35

A unifying hypothesis for the structure of microbial biofilms based on cellular automaton models  

Microsoft Academic Search

A review of the basic structure of microbial biofilm reveals that at least three conceptual models exist: (i) heterogeneous mosaic biofilm, (ii) penetrated water-channel biofilm and (iii) dense confluent biofilm. When consideration is given to the effects of growth resource, it may be that all three variants are correct but form at widely different substrate concentrations. Experimental research with bacterial

Julian W. T. Wimpenny; Ric Colasanti

1997-01-01

36

Kinetics of Microbial Bromate Reduction in a Hydrogen-Oxidizing, Denitrifying Biofilm Reactor  

E-print Network

ARTICLE Kinetics of Microbial Bromate Reduction in a Hydrogen-Oxidizing, Denitrifying Biofilm a hydrogen-based, deni- trifying membrane-biofilm reactor (MBfR) for bromate reduction, and report the first; denitrification; biofilm; hollow-fiber membrane biofilm reactor Introduction Bromate (BrOÃ? 3 ) is an oxidized

Nerenberg, Robert

37

Adhesion and formation of microbial biofilms in complex microfluidic devices  

SciTech Connect

Shewanella oneidensis is a metal reducing bacterium, which is of interest for bioremediation and clean energy applications. S. oneidensis biofilms play a critical role in several situations such as in microbial energy harvesting devices. Here, we use a microfluidic device to quantify the effects of hydrodynamics on the biofilm morphology of S. oneidensis. For different rates of fluid flow through a complex microfluidic device, we studied the spatiotemporal dynamics of biofilms, and we quantified several morphological features such as spatial distribution, cluster formation and surface coverage. We found that hydrodynamics resulted in significant differences in biofilm dynamics. The baffles in the device created regions of low and high flow in the same device. At higher flow rates, a nonuniform biofilm develops, due to unequal advection in different regions of the microchannel. However, at lower flow rates, a more uniform biofilm evolved. This depicts competition between adhesion events, growth and fluid advection. Atomic force microscopy (AFM) revealed that higher production of extra-cellular polymeric substances (EPS) occurred at higher flow velocities.

Kumar, Aloke [ORNL; Karig, David K [ORNL; Neethirajan, Suresh [University of Guelph; Suresh, Anil K [ORNL; Srijanto, Bernadeta R [ORNL; Mukherjee, Partha P [ORNL; Retterer, Scott T [ORNL; Doktycz, Mitchel John [ORNL

2012-01-01

38

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

PubMed

Microbial biofilms play important roles in initiating settlement of marine invertebrate larvae. Given the importance of habitat selection by the motile larval phase, understanding settlement choices is critical if we are to successfully predict the population dynamics of sessile adults. Marine microbial biofilms show remarkable variability in community composition, often mediated by environmental conditions and biofilm age. To determine if biofilm communities were influenced by the time allowed to establish (age) and/or seawater temperature, we manipulated experimental surfaces to firstly determine biofilm community composition and secondly test larval settlement responses for the abundant coral reef sponge Rhopaloeides odorabile. Microbial profiling of biofilms revealed different communities according to both age and temperature. Biofilm community composition, as a result of both elevated seawater temperature and biofilm age, contributed to settlement for sponge larvae with markedly higher numbers of larvae settling to biofilms developed over longer periods (10 d) and at temperatures 2-6°C above ambient. PMID:24518965

Whalan, S; Webster, N S

2014-01-01

39

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

PubMed Central

Microbial biofilms play important roles in initiating settlement of marine invertebrate larvae. Given the importance of habitat selection by the motile larval phase, understanding settlement choices is critical if we are to successfully predict the population dynamics of sessile adults. Marine microbial biofilms show remarkable variability in community composition, often mediated by environmental conditions and biofilm age. To determine if biofilm communities were influenced by the time allowed to establish (age) and/or seawater temperature, we manipulated experimental surfaces to firstly determine biofilm community composition and secondly test larval settlement responses for the abundant coral reef sponge Rhopaloeides odorabile. Microbial profiling of biofilms revealed different communities according to both age and temperature. Biofilm community composition, as a result of both elevated seawater temperature and biofilm age, contributed to settlement for sponge larvae with markedly higher numbers of larvae settling to biofilms developed over longer periods (10?d) and at temperatures 2–6°C above ambient. PMID:24518965

Whalan, S.; Webster, N. S.

2014-01-01

40

Microbial biofilm growth on irradiated, spent nuclear fuel cladding  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

41

Cloth colorization caused by microbial biofilm.  

PubMed

In this study, cloth disfeaturement was investigated biologically. To clarify whether or not microbes can cause cloth disfeaturement, and to identify the microbes causing the disfeaturement, worn cloth samples were incubated on sweat-ingredient agar medium. Non-sterilized cloth samples became yellow-colored during incubation, and bacterial strains belonging to the genera Bacillus, Brevibacterium, Kocuria, Micrococcus and Staphylococcus were isolated from the yellow-colored parts. Two major isolates close to the genera Bacillus and Micrococcus were inoculated separately or together on cloth samples to examine whether or not these isolates can cause colorization. When the isolate close to Micrococcus was inoculated on its own or mixed with the isolate close to Bacillus, the samples turned yellow to a greater extent and a biofilm-like structure was observed by SEM on the colored areas. In contrast, the isolate close to Bacillus alone barely caused any colorization, and no biofilm-like structure was observed. From the yellow-colored samples, bacterial strains with the same 16S rRNA gene sequences as those of the inoculated strains were re-isolated. These results strongly suggest that the bacterial strain belonging to genus Micrococcus causes cloth colorization by forming a biofilm structure. PMID:18359206

Tsuchiya, Yuki; Ohta, Jun; Ishida, Yoshiki; Morisaki, Hisao

2008-07-15

42

Extremophiles Microbial Life Under Extreme  

E-print Network

1 23 Extremophiles Microbial Life Under Extreme Conditions ISSN 1431-0651 Volume 15 Number 4 Extremophiles (2011) 15:473-485 DOI 10.1007/s00792-011-0378- z Bacterial diversity in five Icelandic geothermal

Benning, Liane G.

43

Microbial genomes: Blueprints for life  

SciTech Connect

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

Relman, David A.; Strauss, Evelyn

2000-12-31

44

Life Support Systems Microbial Challenges  

NASA Technical Reports Server (NTRS)

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

Roman, Monserrate C.

2009-01-01

45

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

E-print Network

Time-course correlation of biofilm properties and electrochemical performance in single 2010 Keywords: Microbial fuel cell Electricity Biofilm Electrochemical impedance spectroscopy a b s t r under identical conditions. While voltage stabilized within 4 days, anode biofilms continued growing

Mench, Matthew M.

46

INVESTIGATING THE EFFECT OF MICROBIAL GROWTH AND BIOFILM FORMATION ON SEISMIC WAVE PROPAGATION IN SEDIMENT  

EPA Science Inventory

Previous laboratory investigations have demonstrated that the seismic methods are sensitive to microbially-induced changes in porous media through the generation of biogenic gases and biomineralization. The seismic signatures associated with microbial growth and biofilm formation...

47

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

EPA Science Inventory

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

48

Engineered bidirectional communication mediates a consensus in a microbial biofilm consortium  

E-print Network

Engineered bidirectional communication mediates a consensus in a microbial biofilm consortium Katie, including in a biofilm, where it sustains its response for several days. biological engineering cellular biofilms, and vast reaches of the earth are coated in these living films. In many cases, the microorganisms

Arnold, Frances H.

49

Impact of Initial Biofilm Growth on the Anode Impedance of Microbial Fuel Cells  

E-print Network

ARTICLE Impact of Initial Biofilm Growth on the Anode Impedance of Microbial Fuel Cells Ramaraja P initial biofilm growth in an acetate-fed, two-chamber MFC system with ferricyanide in the cathode. EIS of the anode biofilm, the anode polar- ization resistance was found to decrease by over 70% at open circuit

Mench, Matthew M.

50

Anatomical Evidence of Microbial Biofilms in Tonsillar Tissues A Possible Mechanism to Explain Chronicity  

Microsoft Academic Search

Context: Bacteria within biofilms are resistant to host defenses and antibiotics. The presence of bacterial bio- filmswithinthetissueandcryptsofinflamedtonsilsmay explain the chronicity and recurrent characteristics of some forms of tonsillitis. Objective: To determine if microbial biofilms occur within clinically abnormal tonsils. Design: In this study, we evaluated the histomorpho- logical appearance of 19 human tonsils for evidence of biofilm formation using light

Richard A. Chole; Brian T. Faddis

2003-01-01

51

BIOENERGY AND BIOFUELS Anodic biofilms in microbial fuel cells harbor low numbers  

E-print Network

BIOENERGY AND BIOFUELS Anodic biofilms in microbial fuel cells harbor low numbers of higher this biofilm (Paracoccus denitrificans strain PS-1) produced only 5.6 mW/m2 , whereas the original mixed isolated a strain of Shewanella putrefaciens (strain PS-2) from the same biofilm capable of producing

52

Life Support Systems Microbial Challenges  

NASA Technical Reports Server (NTRS)

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

Roman, Monsi C.

2010-01-01

53

Probing of microbial biofilm communities for coadhesion partners.  

PubMed

Investigations of interbacterial adhesion in dental plaque development are currently limited by the lack of a convenient assay to screen the multitude of species present in oral biofilms. To overcome this limitation, we developed a solid-phase fluorescence-based screening method to detect and identify coadhesive partner organisms in mixed-species biofilms. The applicability of this method was demonstrated using coaggregating strains of type 2 fimbrial adhesin-bearing actinomyces and receptor polysaccharide (RPS)-bearing streptococci. Specific adhesin/receptor-mediated coadhesion was detected by overlaying bacterial strains immobilized to a nitrocellulose membrane with a suspended, fluorescein-labeled bacterial partner strain. Coadhesion was comparable regardless of which cell type was labeled and which was immobilized. Formaldehyde treatment of bacteria, either in suspension or immobilized on nitrocellulose, abolished actinomyces type 2 fimbrial adhesin but not streptococcal RPS function, thereby providing a simple method for assigning complementary adhesins and glycan receptors to members of a coadhering pair. The method's broader applicability was shown by overlaying colony lifts of dental plaque biofilm cultures with fluorescein-labeled strains of type 2 fimbriated Actinomyces naeslundii or RPS-bearing Streptococcus oralis. Prominent coadhesion partners included not only streptococci and actinomyces, as expected, but also other bacteria not identified in previous coaggregation studies, such as adhesin- or receptor-bearing strains of Neisseria pharyngitis, Rothia dentocariosa, and Kingella oralis. The ability to comprehensively screen complex microbial communities for coadhesion partners of specific microorganisms opens a new approach in studies of dental plaque and other mixed-species biofilms. PMID:25107971

Ruhl, Stefan; Eidt, Andreas; Melzl, Holger; Reischl, Udo; Cisar, John O

2014-11-01

54

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

NASA Astrophysics Data System (ADS)

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

Das Gupta, S.; Fang, J.

2008-12-01

55

Iron phosphate precipitation by epilithic microbial biofilms in Arctic Canada K.O. KONHAUSERAND W.S. FYFE  

E-print Network

Iron phosphate precipitation by epilithic microbial biofilms in Arctic Canada K.O. KONHAUSERAND W, in the Canadian Arctic, dark-colored biofilms proliferate on moist surfaces, including exposed grano- diorite outcrops. Transmission electron microscopy of these biofilms indicates that complex epilithic microbial

Konhauser, Kurt

56

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

Microsoft Academic Search

Hyperspectral fluorescence imaging methods were utilized to evaluate the potential detection of pathogenic bacterial biofilm formations on five types of food contact surface materials: stainless steel, high-density polyethylene (HDPE), plastic laminate (Formica), and two variations of polished granite. The main objective of this study was to determine a minimal number of spectral fluorescence bands suitable for detecting microbial biofilms on

Won Jun; Moon S. Kim; Byoung-Kwan Cho; Patricia D. Millner; Kuanglin Chao; Diane E. Chan

2010-01-01

57

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

Microsoft Academic Search

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

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

2009-01-01

58

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

59

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

PubMed Central

The temples of Angkor monuments including Angkor Thom and Bayon in Cambodia and surrounding countries were exclusively constructed using sandstone. They are severely threatened by biodeterioration caused by active growth of different microorganisms on the sandstone surfaces, but knowledge on the microbial community and composition of the biofilms on the sandstone is not available from this region. This study investigated the microbial community diversity by examining the fresh and old biofilms of the biodeteriorated bas-relief wall surfaces of the Bayon Temple by analysis of 16S and 18S rRNA gene sequences. The results showed that the retrieved sequences were clustered in 11 bacterial, 11 eukaryotic and two archaeal divisions with disparate communities (Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria; Alveolata, Fungi, Metazoa, Viridiplantae; Crenarchaeote, and Euyarchaeota). A comparison of the microbial communities between the fresh and old biofilms revealed that the bacterial community of old biofilm was very similar to the newly formed fresh biofilm in terms of bacterial composition, but the eukaryotic communities were distinctly different between these two. This information has important implications for understanding the formation process and development of the microbial diversity on the sandstone surfaces, and furthermore to the relationship between the extent of biodeterioration and succession of microbial communities on sandstone in tropic region. Electronic supplementary material The online version of this article (doi:10.1007/s00248-010-9707-5) contains supplementary material, which is available to authorized users. PMID:20593173

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

2010-01-01

60

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

PubMed

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

Holá, Veronika; Ruzicka, Filip; Horka, Marie

2010-08-01

61

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

62

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

NASA Astrophysics Data System (ADS)

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 suggest that the thermal springs in the Central Alps near Bad Gastein represent a novel and unique habitat for microbial life. Results obtained during these studies revealed reproducibility of Dr. Heinen's micrographs. Hollow reticulated filaments and flat ribbons with parallel hexagonal chambers (web-structures) were found repeatedly. Given the chance that subsurface environments represent a potent opportunity to detect life on planetary bodies it is of big interest to search for representative biosignatures found on earth today. References: 1. Lauwers A. M. & Heinen W. (1985) Mikroskopie (Wien) 42, 94-101. 2. Heinen W. & Lauwers A. M. (1985) Mikroskopie (Wien) 42, 124-134. 3. Weidler G. W., Dornmayr-Pfaffenhuemer M., Gerbl F. W., Heinen W., Stan-Lotter H. (2007) AEM 73, 259-270.

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

2010-05-01

63

New Methods for Analysis of Spatial Distribution and Coaggregation of Microbial Populations in Complex Biofilms  

PubMed Central

In biofilms, microbial activities form gradients of substrates and electron acceptors, creating a complex landscape of microhabitats, often resulting in structured localization of the microbial populations present. To understand the dynamic interplay between and within these populations, quantitative measurements and statistical analysis of their localization patterns within the biofilms are necessary, and adequate automated tools for such analyses are needed. We have designed and applied new methods for fluorescence in situ hybridization (FISH) and digital image analysis of directionally dependent (anisotropic) multispecies biofilms. A sequential-FISH approach allowed multiple populations to be detected in a biofilm sample. This was combined with an automated tool for vertical-distribution analysis by generating in silico biofilm slices and the recently developed Inflate algorithm for coaggregation analysis of microbial populations in anisotropic biofilms. As a proof of principle, we show distinct stratification patterns of the ammonia oxidizers Nitrosomonas oligotropha subclusters I and II and the nitrite oxidizer Nitrospira sublineage I in three different types of wastewater biofilms, suggesting niche differentiation between the N. oligotropha subclusters, which could explain their coexistence in the same biofilms. Coaggregation analysis showed that N. oligotropha subcluster II aggregated closer to Nitrospira than did N. oligotropha subcluster I in a pilot plant nitrifying trickling filter (NTF) and a moving-bed biofilm reactor (MBBR), but not in a full-scale NTF, indicating important ecophysiological differences between these phylogenetically closely related subclusters. By using high-resolution quantitative methods applicable to any multispecies biofilm in general, the ecological interactions of these complex ecosystems can be understood in more detail. PMID:23892743

Almstrand, Robert; Daims, Holger; Persson, Frank; Sorensson, Fred

2013-01-01

64

Microbial interactions in marine water amended by eroded benthic biofilm: A case study from an intertidal mudflat  

NASA Astrophysics Data System (ADS)

In shallow macrotidal ecosystems with large intertidal mudflats, the sediment-water coupling plays a crucial role in structuring the pelagic microbial food web functioning, since inorganic and organic matter and microbial components (viruses and microbes) of the microphytobenthic biofilm can be suspended toward the water column. Two experimental bioassays were conducted in March and July 2008 to investigate the importance of biofilm input for the pelagic microbial and viral loops. Pelagic inocula (< 0.6 ?- and < 10 ? filtrates) were diluted either with < 30 kDa-ultrafiltered seawater or with this ultrafiltrate enriched with the respective size-fractionated benthic biofilm or with < 30 kDa-benthic compounds (BC). The kinetics of heterotrophic nanoflagellates (HNF), bacteria and viruses were assessed together with bacterial and viral genomic fingerprints, bacterial enzymatic activities and viral life strategies. The experimental design allowed us to evaluate the effect of BC modulated by those of benthic size-fractionated microorganisms (virus + bacteria, + HNF). BC presented (1) in March, a positive effect on viruses and bacteria weakened by pelagic HNF. Benthic microorganisms consolidated this negative effect and sustained the viral production together with a relatively diverse and uneven bacterial assemblage structure; (2) in July, no direct impact on viruses but a positive effect on bacteria modulated by HNF, which indirectly enhanced viral multiplication. Both effects were intensified by benthic microorganisms and bacterial assemblage structure became more even. HNF indirectly profited from BC more in March than in July. The microbial loop would be stimulated by biofilm during periods of high resources (March) and the viral loop during periods of depleted resources (July).

Montanié, Hélène; Ory, Pascaline; Orvain, Francis; Delmas, Daniel; Dupuy, Christine; Hartmann, Hans J.

2014-09-01

65

Comparative sensitivity to the fungicide tebuconazole of biofilm and plankton microbial communities in freshwater ecosystems.  

PubMed

Stream and lake ecosystems in agricultural watersheds are exposed to fungicide inputs that can threaten the structure and functioning of aquatic microbial communities. This research analyzes the impact of the triazole fungicide tebuconazole (TBZ) on natural biofilm and plankton microbial communities from sites presenting different degrees of agricultural contamination. Biofilm and plankton communities from less-polluted (LP) and polluted (P) sites were exposed to nominal concentrations of 0 (control), 2 and 20 ?g TBZ L(-1) in 3-week microcosm experiments. Descriptors of microbial community structure (bacterial density and chlorophyll-a concentration) and function (bacterial respiration and production and photosynthesis) were analyzed to chart the effects of TBZ and the kinetics of TBZ attenuation in water during the experiments. The results showed TBZ-induced effects on biofilm function (inhibition of substrate-induced respiration and photosynthetic activity), especially in LP-site communities, whereas plankton communities experienced a transitory stimulation of bacterial densities in communities from both LP and P sites. TBZ attenuation was stronger in biofilm (60-75%) than plankton (15-18%) experiments, probably due to greater adsorption on biofilms. The differences between biofilm and plankton responses to TBZ were likely explained by differences in community structure (presence of extracellular polymeric substances (EPS) matrix) and microbial composition. Biofilm communities also exhibited different sensitivity levels according to their in-field pre-exposure to fungicide, with P-site communities demonstrating adaptation capacities to TBZ. This study indicates that TBZ toxicity to non-targeted aquatic microbial communities essentially composed by microalgae and bacteria was moderate, and that its effects varied between stream and lake microbial communities. PMID:24048021

Artigas, J; Pascault, N; Bouchez, A; Chastain, J; Debroas, D; Humbert, J F; Leloup, J; Tadonleke, R D; ter Halle, A; Pesce, S

2014-01-15

66

Response of Estuarine Biofilm Microbial Community Development to Changes in Dissolved Oxygen and Nutrient Concentrations  

Microsoft Academic Search

The information content and responsiveness of microbial biofilm community structure, as an integrative indicator of water\\u000a quality, was assessed against short-term changes in oxygen and nutrient loading in an open-water estuarine setting. Biofilms\\u000a were grown for 7-day periods on artificial substrates in the Pensacola Bay estuary, Florida, in the vicinity of a wastewater\\u000a treatment plant (WWTP) outfall and a nearby

Andreas Nocker; Joe Eugene Lepo; Linda Lin Martin; Richard Allan Snyder

2007-01-01

67

Role of discontinuous chlorination on microbial production by drinking water biofilms.  

PubMed

Microbial quality in water distribution systems is strongly affected by the development of microbial biofilms. Production and release of microbial cells by the biofilm affect microbial levels in the water column and in some cases this fact constitutes a public health concern. In this study, we attempt to analyze in which way the existence of different episodes of chlorine depletion affects both biofilm formation and microbial load of an artificial laboratory system. The work was carried out using two parallel packed bed reactors both supplied with running tap water. One of the reactors was used as a control and was permanently exposed to the action of chlorine. In the other reactor, chlorine was neutralized at selected times during the experiment and for periods of variable length. During the experiment the concentration of total and viable cells from the effluent was monitored at the exit of each of the reactors. The data obtained were used to estimate microbial production from the biofilms. As an average, release of microbial cells to the water phase increased tenfold in the absence of chlorine. The results also indicate that disinfectant efficiency against the biofilm was not recovered when chlorine returned to normal levels after each event of chlorine neutralization. Cell viability in the water phase in the presence of chlorine was low at the beginning of the experiment but increased 4 orders of magnitude after five neutralization periods. Therefore, subsequent episodes of chlorine depletion may accelerate the development of microbial communities with reduced susceptibility to disinfection in real drinking water systems. PMID:15899288

Codony, Francesc; Morató, Jordi; Mas, Jordi

2005-05-01

68

Significance of microbial biofilms in food industry: a review  

Microsoft Academic Search

Biofilms have been of considerable interest in the context of food hygiene. Of special significance is the ability of microorganisms to attach and grow on food and food-contact surfaces under favourable conditions. Biofilm formation is a dynamic process and different mechanisms are involved in their attachment and growth. Extracellular polymeric substances play an important role in the attachment and colonization

C. Ganesh Kumar; S. K Anand

1998-01-01

69

Biopolymer and water dynamics in microbial biofilm extracellular polymeric substance.  

PubMed

Nuclear magnetic resonance (NMR) is a noninvasive and nondestructive tool able to access several observable quantities in biofilms such as chemical composition, diffusion, and macroscale structure and transport. Pulsed gradient spin echo (PGSE) NMR techniques were used to measure spectrally resolved biomacromolecular diffusion in biofilm biomass, extending previous research on spectrally resolved diffusion in biofilms. The dominant free water signal was nulled using an inversion recovery modification of the traditional PGSE technique in which the signal from free water is minimized in order to view the spectra of components such as the rotationally mobile carbohydrates, DNA, and proteins. Diffusion data for the major constituents obtained from each of these spectral peaks demonstrate that the biomass of the biofilm contains both a fast and slow diffusion component. The dependence of diffusion on antimicrobial and environmental challenges suggests the polymer molecular dynamics measured by NMR are a sensitive indicator of biofilm function. PMID:18665639

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

2008-09-01

70

Viscoelastic properties of Staphylococcus aureus and Staphylococcus epidermidis mono-microbial biofilms  

PubMed Central

Summary The viscoelastic properties of mono?microbial biofilms produced by ocular and reference staphylococcal strains were investigated. The microorganisms were characterized for their haemolytic activity and agr typing and the biofilms, grown on stainless steel surface under static conditions, were analysed by Confocal Laser Scanning Microscopy. Static and dynamic rheometric tests were carried out to determine the steady?flow viscosity and the elastic and viscous moduli. The analysed biofilms showed the typical time?dependent behaviour of viscoelastic materials with considerable elasticity and mechanical stability except for Staphylococcus aureus ATCC 29213 biofilm which showed a very fragile structure. In particular, S. aureus 6ME biofilm was more compact than other staphylococcal biofilms studied with a yield stress ranging between 2 and 3?Pa. The data obtained in this work could represent a starting point for developing new therapeutic strategies against biofilm?associated infections, such as improving the drug effect by associating an antimicrobial agent with a biofilm viscoelasticity modifier. PMID:21255298

Di Stefano, Antonio; D'Aurizio, Eleonora; Trubiani, Oriana; Grande, Rossella; Di Campli, Emanuela; Di Giulio, Mara; Di Bartolomeo, Soraya; Sozio, Piera; Iannitelli, Antonio; Nostro, Antonia; Cellini, Luigina

2009-01-01

71

Composition of EPS fractions from suspended sludge and biofilm and their roles in microbial cell aggregation.  

PubMed

The adhesion and aggregation properties of microbial cell are closely related to extracellular polymeric substances (EPS). In this work, the composition and physicochemical characteristics of EPS in biofilm and suspended sludge (S-sludge) were determined to evaluate their roles in microbial cell aggregation. Raman spectroscopy and three-dimensional fluorescence spectra have been employed to reveal each EPS fraction in different composition. The flocculating capacity of each EPS fraction in the S-sludge shows extraordinary activity, comparing its counterpart in biofilm. Microbial cell surfaces present high hydrophobicity and increased zeta potentials upon EPS extraction. In addition, the respective contribution of EPS to cell aggregating was elucidated. The contribution of combined SEPS and LB-EPS was 23% for S-sludge sample, whereas that was negligible for biofilm sample. The contribution of LB-EPS and TB-EPS were 16% and 30% for S-sludge sample, and -6% and negligible for biofilm sample, respectively. Therefore, EPS promoted the S-sludge cells to aggregate, while in contrast, they showed a negligible or negative effect on the biofilm cells aggregating. PMID:24968163

Zhang, Peng; Fang, Fang; Chen, You-Peng; Shen, Yu; Zhang, Wei; Yang, Ji-Xiang; Li, Chun; Guo, Jin-Song; Liu, Shao-Yang; Huang, Yang; Li, Shan; Gao, Xu; Yan, Peng

2014-12-01

72

Biofilm: the microbial “bunker” for intravascular catheter-related infection  

Microsoft Academic Search

Catheter-related infection in cancer patients remains an important health-care problem with major financial implications. During the last few years a better understanding of the pathogenesis of catheter-related infections and the interaction between microorganisms and catheter surfaces has emerged. Recently the influence of biofilm formation in catheter-related infections has been established. The development of biofilm by the colonizing microbes permits attachment

Manuel Morales; Sebastián Méndez-Alvarez; Juana-Victoria Martín-López; Carmen Marrero; César O. Freytes

2004-01-01

73

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

Microsoft Academic Search

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

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

2000-01-01

74

Dominant Microbial Populations in Limestone-Corroding Stream Biofilms, Frasassi Cave System, Italy  

PubMed Central

Waters from an extensive sulfide-rich aquifer emerge in the Frasassi cave system, where they mix with oxygen-rich percolating water and cave air over a large surface area. The actively forming cave complex hosts a microbial community, including conspicuous white biofilms coating surfaces in cave streams, that is isolated from surface sources of C and N. Two distinct biofilm morphologies were observed in the streams over a 4-year period. Bacterial 16S rDNA libraries were constructed from samples of each biofilm type collected from Grotta Sulfurea in 2002. ?-, ?-, ?-, and ?-proteobacteria in sulfur-cycling clades accounted for ?75% of clones in both biofilms. Sulfate-reducing and sulfur-disproportionating ?-proteobacterial sequences in the clone libraries were abundant and diverse (34% of phylotypes). Biofilm samples of both types were later collected at the same location and at an additional sample site in Ramo Sulfureo and examined, using fluorescence in situ hybridization (FISH). The biomass of all six stream biofilms was dominated by filamentous ?-proteobacteria with Beggiatoa-like and/or Thiothrix-like cells containing abundant sulfur inclusions. The biomass of ?-proteobacteria detected using FISH was consistently small, ranging from 0 to less than 15% of the total biomass. Our results suggest that S cycling within the stream biofilms is an important feature of the cave biogeochemistry. Such cycling represents positive biological feedback to sulfuric acid speleogenesis and related processes that create subsurface porosity in carbonate rocks. PMID:16885314

Macalady, Jennifer L.; Lyon, Ezra H.; Koffman, Bess; Albertson, Lindsey K.; Meyer, Katja; Galdenzi, Sandro; Mariani, Sandro

2006-01-01

75

Interactions between laponite and microbial biofilms in porous media: implications for colloid transport and biofilm stability  

Microsoft Academic Search

Quartz sand columns and sand-filled microscope flow cells were used to investigate the transport characteristics of the clay colloid laponite, and a biofilm-forming bacterium, Pseudomonas aeruginosa SG81. Separate experiments were performed with each particle to determine their individual transport characteristics in clean sand columns. In a second set of experiments, bacterial biofilms were formed prior to introduction of the clay

C. Felipe Leon-Morales; Andrew P. Leis; Martin Strathmann; Hans-Curt Flemming

2004-01-01

76

Shifts in microbial community structure and function in light- and dark-grown biofilms driven by warming.  

PubMed

Biofilms are dynamic players in biogeochemical cycling in running waters and are subjected to environmental stressors like those provoked by climate change. We investigated whether a 2°C increase in flowing water would affect prokaryotic community composition and heterotrophic metabolic activities of biofilms grown under light or dark conditions. Neither light nor temperature treatments were relevant for selecting a specific bacterial community at initial phases (7-day-old biofilms), but both variables affected the composition and function of mature biofilms (28-day-old). In dark-grown biofilms, changes in the prokaryotic community composition due to warming were mainly related to rotifer grazing, but no significant changes were observed in functional fingerprints. In light-grown biofilms, warming also affected protozoan densities, but its effect on prokaryotic density and composition was less evident. In contrast, heterotrophic metabolic activities in light-grown biofilms under warming showed a decrease in the functional diversity towards a specialized use of several carbohydrates. Results suggest that prokaryotes are functionally redundant in dark biofilms but functionally plastic in light biofilms. The more complex and self-serving light-grown biofilm determines a more buffered response to temperature than dark-grown biofilms. Despite the moderate increase in temperature of only 2°C, warming conditions drive significant changes in freshwater biofilms, which responded by finely tuning a complex network of interactions among microbial populations within the biofilm matrix. PMID:24552130

Romaní, Anna M; Borrego, Carles M; Díaz-Villanueva, Verónica; Freixa, Anna; Gich, Frederic; Ylla, Irene

2014-08-01

77

Stratified microbial structure and activity in sulfide- and methane-producing anaerobic sewer biofilms.  

PubMed

Simultaneous production of sulfide and methane by anaerobic sewer biofilms has recently been observed, suggesting that sulfate-reducing bacteria (SRB) and methanogenic archaea (MA), microorganisms known to compete for the same substrates, can coexist in this environment. This study investigated the community structures and activities of SRB and MA in anaerobic sewer biofilms (average thickness of 800 ?m) using a combination of microelectrode measurements, molecular techniques, and mathematical modeling. It was seen that sulfide was mainly produced in the outer layer of the biofilm, between the depths of 0 and 300 ?m, which is in good agreement with the distribution of SRB population as revealed by cryosection-fluorescence in situ hybridization (FISH). SRB had a higher relative abundance of 20% on the surface layer, which decreased gradually to below 3% at a depth of 400 ?m. In contrast, MA mainly inhabited the inner layer of the biofilm. Their relative abundances increased from 10% to 75% at depths of 200 ?m and 700 ?m, respectively, from the biofilm surface layer. High-throughput pyrosequencing of 16S rRNA amplicons showed that SRB in the biofilm were mainly affiliated with five genera, Desulfobulbus, Desulfomicrobium, Desulfovibrio, Desulfatiferula, and Desulforegula, while about 90% of the MA population belonged to the genus Methanosaeta. The spatial organizations of SRB and MA revealed by pyrosequencing were consistent with the FISH results. A biofilm model was constructed to simulate the SRB and MA distributions in the anaerobic sewer biofilm. The good fit between model predictions and the experimental data indicate that the coexistence and spatial structure of SRB and MA in the biofilm resulted from the microbial types and their metabolic transformations and interactions with substrates. PMID:25192994

Sun, Jing; Hu, Shihu; Sharma, Keshab Raj; Ni, Bing-Jie; Yuan, Zhiguo

2014-11-01

78

Implications of in situ calcification for photosynthesis in a ~3.3 Ga-old microbial biofilm from the Barberton greenstone belt, South Africa  

E-print Network

1 Implications of in situ calcification for photosynthesis in a ~3.3 Ga-old microbial biofilm from microbial biofilm Calcification probably due to the activities of a photosynthetic consortium of microorganisms within the biofilm including heterotrophic sulphur reducing bacteria Preservation

Paris-Sud XI, Université de

79

Energy for microbial life on Europa  

Microsoft Academic Search

The planet Jupiter's moon Europa may harbour a subsurface water ocean, but estimates of the available free energy have not been encouraging for supporting life. Here I show that disequilibrium chemistry in the ocean's ice cover, driven by charged particles accelerated in Jupiter's magnetosphere, should produce enough organic and oxidant molecules to fuel a substantial Europan biosphere. Microbial life could

Christopher F. Chyba

2000-01-01

80

The biofilm life cycle and virulence of Pseudomonas aeruginosa are dependent on a filamentous prophage  

Microsoft Academic Search

Mature Pseudomonas aeruginosa biofilms undergo specific developmental events. Using a bacteriophage mutant, generated by deletion of the entire filamentous Pf4 prophage, we show that the phage is essential for several stages of the biofilm life cycle and that it significantly contributes to the virulence of P. aeruginosa in vivo. Here, we show for the first time that biofilms of the

Scott A Rice; Chuan Hao Tan; Per Jensen Mikkelsen; Vanderlene Kung; Jerry Woo; Martin Tay; Alan Hauser; Diane McDougald; Jeremy S Webb; Staffan Kjelleberg

2009-01-01

81

Multi-technique approach to assess the effects of microbial biofilms involved in copper plumbing corrosion.  

PubMed

Microbially influenced corrosion (MIC) is recognized as an unusual and severe type of corrosion that causes costly failures around the world. A microbial biofilm could enhance the copper release from copper plumbing into the water by forming a reactive interface. The biofilm increases the corrosion rate, the mobility of labile copper from its matrix and the detachment of particles enriched with copper under variable shear stress due to flow conditions. MIC is currently considered as a series of interdependent processes occurring at the metal-liquid interface. The presence of a biofilm results in the following effects: (a) the formation of localized microenvironments with distinct pH, dissolved oxygen concentrations, and redox conditions; (b) sorption and desorption of labile copper bonded to organic compounds under changing water chemistry conditions; (c) change in morphology by deposition of solid corrosion by-products; (d) diffusive transport of reactive chemical species from or towards the metal surface; and (e) detachment of scale particles under flow conditions. Using a multi-technique approach that combines pipe and coupon experiments this paper reviews the effects of microbial biofilms on the corrosion of copper plumbing systems, and proposes an integrated conceptual model for this phenomenon supported by new experimental data. PMID:24355512

Vargas, Ignacio T; Alsina, Marco A; Pavissich, Juan P; Jeria, Gustavo A; Pastén, Pablo A; Walczak, Magdalena; Pizarro, Gonzalo E

2014-06-01

82

Growth dynamic of Naegleria fowleri in a microbial freshwater biofilm.  

PubMed

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

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

2012-09-01

83

Microbial Composition and Structure of Aerobic Granular Sewage Biofilms?  

PubMed Central

Aerobic activated sludge granules are dense, spherical biofilms which can strongly improve purification efficiency and sludge settling in wastewater treatment processes. In this study, the structure and development of different granule types were analyzed. Biofilm samples originated from lab-scale sequencing batch reactors which were operated with malthouse, brewery, and artificial wastewater. Scanning electron microscopy, light microscopy, and confocal laser scanning microscopy together with fluorescence in situ hybridization (FISH) allowed insights into the structure of these biofilms. Microscopic observation revealed that granules consist of bacteria, extracellular polymeric substances (EPS), protozoa and, in some cases, fungi. The biofilm development, starting from an activated sludge floc up to a mature granule, follows three phases. During phase 1, stalked ciliated protozoa of the subclass Peritrichia, e.g., Epistylis spp., settle on activated sludge flocs and build tree-like colonies. The stalks are subsequently colonized by bacteria. During phase 2, the ciliates become completely overgrown by bacteria and die. Thereby, the cellular remnants of ciliates act like a backbone for granule formation. During phase 3, smooth, compact granules are formed which serve as a new substratum for unstalked ciliate swarmers settling on granule surfaces. These mature granules comprise a dense core zone containing bacterial cells and EPS and a loosely structured fringe zone consisting of either ciliates and bacteria or fungi and bacteria. Since granules can grow to a size of up to several millimeters in diameter, we developed and applied a modified FISH protocol for the study of cryosectioned biofilms. This protocol allows the simultaneous detection of bacteria, ciliates, and fungi in and on granules. PMID:17704280

Weber, S. D.; Ludwig, W.; Schleifer, K.-H.; Fried, J.

2007-01-01

84

Microbial composition and structure of aerobic granular sewage biofilms.  

PubMed

Aerobic activated sludge granules are dense, spherical biofilms which can strongly improve purification efficiency and sludge settling in wastewater treatment processes. In this study, the structure and development of different granule types were analyzed. Biofilm samples originated from lab-scale sequencing batch reactors which were operated with malthouse, brewery, and artificial wastewater. Scanning electron microscopy, light microscopy, and confocal laser scanning microscopy together with fluorescence in situ hybridization (FISH) allowed insights into the structure of these biofilms. Microscopic observation revealed that granules consist of bacteria, extracellular polymeric substances (EPS), protozoa and, in some cases, fungi. The biofilm development, starting from an activated sludge floc up to a mature granule, follows three phases. During phase 1, stalked ciliated protozoa of the subclass Peritrichia, e.g., Epistylis spp., settle on activated sludge flocs and build tree-like colonies. The stalks are subsequently colonized by bacteria. During phase 2, the ciliates become completely overgrown by bacteria and die. Thereby, the cellular remnants of ciliates act like a backbone for granule formation. During phase 3, smooth, compact granules are formed which serve as a new substratum for unstalked ciliate swarmers settling on granule surfaces. These mature granules comprise a dense core zone containing bacterial cells and EPS and a loosely structured fringe zone consisting of either ciliates and bacteria or fungi and bacteria. Since granules can grow to a size of up to several millimeters in diameter, we developed and applied a modified FISH protocol for the study of cryosectioned biofilms. This protocol allows the simultaneous detection of bacteria, ciliates, and fungi in and on granules. PMID:17704280

Weber, S D; Ludwig, W; Schleifer, K-H; Fried, J

2007-10-01

85

A comparative study of the major microbial biomass of biofilms on exteriors of buildings in Europe and Latin America  

Microsoft Academic Search

Microorganisms in biofilms on building surfaces include algae, bacteria and fungi and cause discolouration and degradation, but definitive information about preferences of microbial groups for given building substrates and how this is affected by environmental conditions is lacking. Major biomass in 230 biofilms from buildings in seven Latin American and six European countries was analysed. Substrates included composites (cement, mortar,

Christine C. Gaylarde; Peter M. Gaylarde

2005-01-01

86

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

NASA Astrophysics Data System (ADS)

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 biofilms and granite surfaces. This investigation demonstrated that biofilm formations on food processing surfaces, even for background materials with heterogeneous fluorescence responses, can be detected. Furthermore, a multispectral approach in developing handheld inspection devices may be needed to inspect surface materials that exhibit non-uniform fluorescence.

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

2009-05-01

87

Microbial diversity in marine biofilms along a water quality gradient on the Great Barrier Reef.  

PubMed

Microbial communities are potential indicators for water quality as they respond rapidly to environmental changes. In the Whitsunday Islands, Australia, microbial biofilm communities from two offshore islands were compared to those from two inshore islands subjected to poor water quality. Biofilm community composition was characterized using three culture-independent molecular techniques. The clone libraries indicated high genetic diversity, with somewhat higher scores in the offshore sites (57%) compared to the inshore sites (41%). The majority of microbes in the biofilms were related to Alphaproteobacteria (39.8%), Gammaproteobacteria (14.1%), Bacteroidetes (13.2%), diatoms (8.3%) and Cyanobacteria (3.9%). Redundancy analysis (RDA) for the CARD-FISH data showed distinct microbial assemblages between offshore and inshore communities. Additionally, 5 out of 13 water quality parameters (DIN, Chla, POP, TSS and POC) explained a significant amount of variation in the microbial communities and high values of these were associated with inshore communities. Analysis of variance (ANOVA) indicated that Cyanobacteria (p=0.01), Bacteroidetes (p=0.04) and to some extent Alphaproteobacteria (p=0.07), were significantly more abundant in the offshore biofilm communities. Principal Component Analysis (PCA) of DGGE data showed clear grouping of cyanobacterial communities into inshore and offshore communities. Reasons for community shifts in the bacterial lineages are currently not resolved. One possible causative factor may be that autotrophic primary producers are more dominant in offshore sites due to the higher light availability as well as the limitation by DIN. The trends found in this study are the bases for more detailed research on microbial indicator species for changes in water quality. PMID:21345635

Kriwy, Pascal; Uthicke, Sven

2011-04-01

88

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

Microsoft Academic Search

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

Filip Ruzicka; Marie Horka; Veronika Hola

89

Microbial Extremophiles in Aspect of Limits of Life  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

90

Extraction of extracellular polymeric substances from extreme acidic microbial biofilms  

Microsoft Academic Search

The efficiency of five extraction methods for extracellular polymeric substances (EPS) was compared on three benthic eukaryotic\\u000a biofilms isolated from an extreme acidic river, Río Tinto (SW, Spain). Three chemical methods (MilliQ water, NaCl, and ethylenediamine\\u000a tetraacetic acid [EDTA]) and two physical methods (Dowex 50.8 and Crown Ether cation exchange resins) were tested. The quality\\u000a and quantity of the EPS

Angeles Aguilera; Virginia Souza-Egipsy; Patxi San Martín-Úriz; Ricardo Amils

2008-01-01

91

Metabolic profiling of biofilm bacteria known to cause microbial influenced corrosion.  

PubMed

This study builds upon previous research that demonstrated the simplicity of obtaining metabolite profiles of bacteria in urban water networks, by using the metabolic profile of bacteria extracted from a reticulation pipe biofilm, which is known to cause microbial influenced corrosion (MIC). The extracellular metabolites of the isolated bacteria, and those bacteria in consortium, were analysed in isolation, and after exposure to low levels of copper. Applying chemometric analytical methodologies to the metabolomic data, we were able to better understand the profile of the isolated biofilm bacteria, which were differentiated according to their activity and copper exposure. It was found that the metabolic activity of the isolated bacteria and the bacteria in consortium varied according to the bacterium's ability to metabolise copper. This demonstrates the power of metabolomic techniques for the discrimination of water reticulation biofilms comprising similar bacteria in consortium, but undergoing different physico-chemical activities, such as corrosion and corrosion inhibition. PMID:24434961

Beale, D J; Morrison, P D; Key, C; Palombo, E A

2014-01-01

92

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

SciTech Connect

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

Not Available

1993-05-01

93

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

PubMed Central

Background Concrete corrosion of wastewater collection systems is a significant cause of deterioration and premature collapse. Failure to adequately address the deteriorating infrastructure networks threatens our environment, public health, and safety. Analysis of whole-metagenome pyrosequencing data and 16S rRNA gene clone libraries was used to determine microbial composition and functional genes associated with biomass harvested from crown (top) and invert (bottom) sections of a corroded wastewater pipe. Results Taxonomic and functional analysis demonstrated that approximately 90% of the total diversity was associated with the phyla Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. The top (TP) and bottom pipe (BP) communities were different in composition, with some of the differences attributed to the abundance of sulfide-oxidizing and sulfate-reducing bacteria. Additionally, human fecal bacteria were more abundant in the BP communities. Among the functional categories, proteins involved in sulfur and nitrogen metabolism showed the most significant differences between biofilms. There was also an enrichment of genes associated with heavy metal resistance, virulence (protein secretion systems) and stress response in the TP biofilm, while a higher number of genes related to motility and chemotaxis were identified in the BP biofilm. Both biofilms contain a high number of genes associated with resistance to antibiotics and toxic compounds subsystems. Conclusions The function potential of wastewater biofilms was highly diverse with level of COG diversity similar to that described for soil. On the basis of the metagenomic data, some factors that may contribute to niche differentiation were pH, aerobic conditions and availability of substrate, such as nitrogen and sulfur. The results from this study will help us better understand the genetic network and functional capability of microbial members of wastewater concrete biofilms. PMID:22727216

2012-01-01

94

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

PubMed

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

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

2014-06-24

95

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

PubMed

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

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

2008-07-01

96

Implications of in situ calcification for photosynthesis in a ~ 3.3 Ga-old microbial biofilm from the Barberton greenstone belt, South Africa  

NASA Astrophysics Data System (ADS)

Timing the appearance of photosynthetic microorganisms is crucial to understanding the evolution of life on Earth. The ability of the biosphere to use sunlight as a source of energy (photoautotrophy) would have been essential for increasing biomass and for increasing the biogeochemical capacity of all prokaryotes across the range of redox reactions that support life. Typical proxies for photosynthesis in the rock record include features, such as a mat-like, laminated morphology (stratiform, domical, conical) often associated with bulk geochemical signatures, such as calcification, and a fractionated carbon isotope signature. However, to date, in situ, calcification related to photosynthesis has not been demonstrated in the oldest known microbial mats. We here use in situ nanometre-scale techniques to investigate the structural and compositional architecture in a 3.3 billion-year (Ga) old microbial biofilm from the Barberton greenstone belt, thus documenting in situ calcification that was most likely related to anoxygenic photosynthesis. The Josefsdal Chert Microbial Biofilm (JCMB) formed in a littoral (photic) environment. It is characterised by a distinct vertical structural and compositional organisation. The lower part is calcified in situ by aragonite, progressing upwards into uncalcified kerogen characterised by up to 1% sulphur, followed by an upper layer that contains intact filaments at the surface. Crystallites of pseudomorphed pyrite are also associated with the biofilm suggesting calcification related to the activity of heterotrophic sulphur reducing bacteria. In this anoxygenic, nutrient-limited environment, the carbon required by the sulphur reducing bacteria could only have been produced by photoautotrophy. We conclude that the Josfsdal Chert Microbial Biofilm was formed by a consortium of anoxygenic microorganisms, including photosynthesisers and sulphur reducing bacteria.

Westall, Frances; Cavalazzi, Barbara; Lemelle, Laurence; Marrocchi, Yves; Rouzaud, Jean-Noël; Simionovici, Alexandre; Salomé, Murielle; Mostefaoui, Smail; Andreazza, Caroline; Foucher, Frédéric; Toporski, Jan; Jauss, Andrea; Thiel, Volker; Southam, Gordon; MacLean, Lachlan; Wirick, Susan; Hofmann, Axel; Meibom, Anders; Robert, François; Défarge, Christian

2011-10-01

97

Extraterrestrial Life in the Microbial Age  

NASA Astrophysics Data System (ADS)

Humankind has long been fascinated with the potential for alien civilizations within the Solar System and beyond (e.g., Crowe and Dowd 2013; Sullivan 2013). Despite the early optimism for life beyond Earth, humankind has yet to make first contact with an alien race. Historical discourse on the topic of alien life can provide some useful input into questions about how the people of Earth today might respond to contact with alien life (e.g., Dick 2013). However, this discourse is primarily devoted to understanding humankind's response to intelligent life. We must recognize that the search for life's potential beyond Earth has dramatically changed since the dawn of the Space Age. We now know that advanced civilizations are not common on planets in our solar system. The search for life on nearby worlds is now limited to non-intelligent, microbial life. Any chance we have of contacting intelligent life lies in receiving transmissions from distant worlds, and contact with such cultures would be greatly limited by the vast expanse of space. This chapter discusses the need for more attention paid to the possible social, economic, and legal ramifications that the discovery of non-intelligent, alien microbial life might bring.

Gronstal, Aaron L.

98

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

PubMed

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

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

2014-01-01

99

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

PubMed

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

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

2012-05-01

100

Impact of flow conditions on ammonium uptake and microbial community structure in benthic biofilms  

NASA Astrophysics Data System (ADS)

Excess nitrogen in surface waters is widely recognized to be a major global problem that adversely affects ecosystems, human health, and the economy. Today, most efforts to understand and model nutrient dynamics at large scales relies on macro-scale parameterization, such as mean channel geometry and velocity with uniform flow assumptions, as well as gross averages of in-situ nutrient transformation rates. However, there is increasing evidence that nutrient transformations in hyporheic zone are regulated by coupling between physical, chemical, and microbiological processes. Ignoring this greatly hinders the estimation of average biochemical transformation rates under the variable flow conditions found in aquatic systems. We used a combination of macro- and micro-scale observations in laboratory flumes to show that interplay between hydrodynamic transport, redox gradients, and microbial metabolism controls ammonium utilization by hyporheic microbial communities. Biofilm structural characteristics were quantified using denaturing gradient gel electrophoresis (DGGE) and real time PCR, while redox and pH gradients were measured using microelectrodes. We found that overlying velocities had profound effect on ammonium uptake due to mass transfer of ammonium from the bulk water to the benthic biofilms, but also due to the delivery of oxygen into the sediment bed. Under laminar flow conditions we didn't observe any change of ammonium uptake as a response to increase in overlying velocity. However, under non-laminar conditions we observe monotonic increase in ammonium uptake, with the greatest uptake under the fastest flow condition. We will discuss ammonium uptake rates results in the context of the different microbial communities and the micro-scale observations that were obtained using the microelectrodes. We anticipate that combined knowledge of the response of the microbial community and bulk nitrogen utilization rates to flow conditions will support the development of improved strategies that rely on biofilm growth to enhance nitrogen removal in natural and engineered systems.

Arnon, Shai; Yanuka, Keren; Nejidat, Ali

2010-05-01

101

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

PubMed

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

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

2014-01-01

102

Identification and characterization of microbial biofilm communities associated with corroded oil pipeline surfaces.  

PubMed

Microbially influenced corrosion (MIC) has long been implicated in the deterioration of carbon steel in oil and gas pipeline systems. The authors sought to identify and characterize sessile biofilm communities within a high-temperature oil production pipeline, and to compare the profiles of the biofilm community with those of the previously analyzed planktonic communities. Eubacterial and archaeal 16S rRNA sequences of DNA recovered from extracted pipeline pieces, termed 'cookies,' revealed the presence of thermophilic sulfidogenic anaerobes, as well as mesophilic aerobes. Electron microscopy and elemental analysis of cookies confirmed the presence of sessile cells and chemical constituents consistent with corrosive biofilms. Mass spectrometry of cookie acid washes identified putative hydrocarbon metabolites, while surface profiling revealed pitting and general corrosion damage. The results suggest that in an established closed system, the biofilm taxa are representative of the planktonic eubacterial and archaeal community, and that sampling and monitoring of the planktonic bacterial population can offer insight into biocorrosion activity. Additionally, hydrocarbon biodegradation is likely to sustain these communities. The importance of appropriate sample handling and storage procedures to oilfield MIC diagnostics is highlighted. PMID:25115517

Lenhart, Tiffany R; Duncan, Kathleen E; Beech, Iwona B; Sunner, Jan A; Smith, Whitney; Bonifay, Vincent; Biri, Bernadette; Suflita, Joseph M

2014-01-01

103

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

PubMed Central

In microbial communities, extracellular polymeric substances (EPS), also called the extracellular matrix, provide the spatial organization and structural stability during biofilm development. One of the major components of EPS is protein, but it is not clear what specific functions these proteins contribute to the extracellular matrix or to microbial physiology. To investigate this in biofilms from an extremely acidic environment, we used shotgun proteomics analyses to identify proteins associated with EPS in biofilms at two developmental stages, designated DS1 and DS2. The proteome composition of the EPS was significantly different from that of the cell fraction, with more than 80% of the cellular proteins underrepresented or undetectable in EPS. In contrast, predicted periplasmic, outer membrane, and extracellular proteins were overrepresented by 3- to 7-fold in EPS. Also, EPS proteins were more basic by ?2 pH units on average and about half the length. When categorized by predicted function, proteins involved in motility, defense, cell envelope, and unknown functions were enriched in EPS. Chaperones, such as histone-like DNA binding protein and cold shock protein, were overrepresented in EPS. Enzymes, such as protein peptidases, disulfide-isomerases, and those associated with cell wall and polysaccharide metabolism, were also detected. Two of these enzymes, identified as ?-N-acetylhexosaminidase and cellulase, were confirmed in the EPS fraction by enzymatic activity assays. Compared to the differences between EPS and cellular fractions, the relative differences in the EPS proteomes between DS1 and DS2 were smaller and consistent with expected physiological changes during biofilm development. PMID:21685158

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

2011-01-01

104

[Analysis on microbial community in biofilm coating onto solid carbon source using the PCR-DGGE technique].  

PubMed

Polylactic acid/Poly (3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PLA/PHBV) granules were used as both carbon source and biofilm carrier for nitrate removal from the contaminated water. The polymerase chain reaction-denature gradient gel electrophoresis (PCR-DGGE) was used to investigate the dynamic change of microbial community in the biofilm coating onto PLA/PHBV granules. The results showed that a decrease in microbial diversity was observed at the initial stage of reactor operation. Shannon-Wiener and Simpson diversity indexes of microbial community in the biofilm slightly changed during the stable period of the reactor running. The major microorganisms in the biofilm were Gram-negative rod bacteria including the genera of Diaphorobacter, Acidovorax, Rubrivivax, Azospira, Thermomonas and Devosia, and all of them belonged to alpha-, beta- and gamma- Proteobacteria, according to the SEM photo of biofilm and 16S rDNA sequences of the DGGE profile. Moreover, the abundance of Diaphorobacter-like genera was the highest in the solid-phase-denitrification biofilm. PMID:24191577

Xu, Ying; Qiu, Tian-Leii; Han, Mei-Lin; Li, Jun; Wang, Xu-Ming

2013-08-01

105

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

PubMed Central

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. PMID:18186940

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

2008-01-01

106

Fate of organo-mineral particles in streams: Microbial degradation by streamwater & biofilm assemblages  

NASA Astrophysics Data System (ADS)

Inland waters are of global biogeochemical importance. They receive carbon inputs of ~ 4.8 Pg C/ y of which, 12 % is buried, 18 % transported to the oceans, and 70 % supports aquatic secondary production. However, the mechanisms that determine the fate of organic matter (OM) in these systems are poorly defined. One aspect of this is the formation of organo-mineral complexes in aquatic systems and their potential as a route for OM transport and burial vs. their use as carbon (C) and nitrogen (N) sources within aquatic systems. Organo-mineral particles form by sorption of dissolved OM to freshly eroded mineral surfaces and may contribute to ecosystem-scale particulate OM fluxes. We experimentally tested the availability of mineral-sorbed OM as a C & N source for streamwater microbial assemblages and streambed biofilms. Organo-mineral particles were constructed in vitro by sorption of 13C:15N-labelled amino acids to hydrated kaolin particles, and microbial degradation of these particles compared with equivalent doses of 13C:15N-labelled free amino acids. Experiments were conducted in 120 ml mesocosms over 7 days using biofilms and water sampled from the Oberer Seebach stream (Austria). Each incubation experienced a 16:8 light:dark regime, with metabolism monitored via changes in oxygen concentrations between photoperiods. The relative fate of the organo-mineral particles was quantified by tracing the mineralization of the 13C and 15N labels and their incorporation into microbial biomass. Here we present the initial results of 13C-label mineralization, incorporation and retention within dissolved organic carbon pool. The results indicate that 514 (× 219) ?mol/ mmol of the 13:15N labeled free amino acids were mineralized over the 7-day incubations. By contrast, 186 (× 97) ?mol/ mmol of the mineral-sorbed amino acids were mineralized over a similar period. Thus, organo-mineral complexation reduced amino acid mineralization by ~ 60 %, with no differences observed between the streamwater and biofilm assemblages. Throughout the incubations, biofilms were observed to leach dissolved organic carbon (DOC). However, within the streamwater assemblage the presence of both organo-mineral particles and kaolin particles was associated with significant DOC removal (-1.7 % and -7.5 % respectively). Consequently, the study demonstrates that mineral and organo-mineral particles can limit the availability of DOC in aquatic systems, providing nucleation sites for flocculation and fresh mineral surfaces, which facilitate OM-sorption. The formation of these organo-mineral particles subsequently restricts microbial OM degradation, potentially altering the transport and facilitating the burial of OM within streams.

Hunter, W. R.; Raich, M.; Wanek, W.; Battin, T. J.

2013-12-01

107

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

PubMed Central

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

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

2009-01-01

108

Denitrification performance and microbial diversity in a packed-bed bioreactor using PCL as carbon source and biofilm carrier.  

PubMed

Polycaprolactone (PCL) was used as both carbon source and biofilm support for denitrifying bacteria in a packed-bed bioreactor. The denitrification performance and microbial diversity were investigated. The microbial community of biofilm developed on the surface of PCL in the reactor was analyzed by pyrosequencing method. The experimental results showed the average nitrate removal efficiency reached 93 % at stable operation. ESEM observation and FTIR analysis were conducted to characterize the PCL structure before and after microbial utilization. For the microbial community, Betaproteobacteria predominated, and most of the PCL-degrading denitrifying bacteria assigned to the family of Comamonadacea. Denitrifying bacteria accounted for more than 20 % in the total population, indicating that PCL is a good carrier and carbon source for biological denitrification. PMID:22555916

Wu, Weizhong; Yang, Luhua; Wang, Jianlong

2013-03-01

109

Microbial biofilms on the sandstone monuments of the Angkor Wat Complex, Cambodia.  

PubMed

Discoloring biofilms from Cambodian temples Angkor Wat, Preah Khan, and the Bayon and West Prasat in Angkor Thom contained a microbial community dominated by coccoid cyanobacteria. Molecular analysis identified Chroococcidiopsis as major colonizer, but low similarity values (<95%) suggested a similar genus or species not present in the databases. In only two of the six sites sampled were filamentous cyanobacteria, Microcoleus, Leptolyngbya, and Scytonema, found; the first two detected by sequencing of 16S rRNA gene library clones from samples of a moist green biofilm on internal walls in Preah Khan, where Lyngbya (possibly synonymous with Microcoleus) was seen by direct microscopy as major colonizer. Scytonema was detected also by microscopy on an internal wall in the Bayon. This suggests that filamentous cyanobacteria are more prevalent in internal (high moisture) areas. Heterotrophic bacteria were found in all samples. DNA sequencing of bands from DGGE gels identified Proteobacteria (Stenotrophomonas maltophilia and Methylobacterium radiotolerans) and Firmicutes (Bacillus sp., Bacillus niacini, Bacillus sporothermodurans, Lysinibacillus fusiformis, Paenibacillus sp., Paenibacillus panacisoli, and Paenibacillus zanthoxyli). Some of these bacteria produce organic acids, potentially degrading stone. Actinobacteria, mainly streptomycetes, were present in most samples; algae and fungi were rare. A dark-pigmented filamentous fungus was detected in internal and external Preah Khan samples, while the alga Trentepohlia was found only in samples taken from external, pink-stained stone at Preah Khan. Results show that these microbial biofilms are mature communities whose major constituents are resistant to dehydration and high levels of irradiation and can be involved in deterioration of sandstone. Such analyses are important prerequisites to the application of control strategies. PMID:22006074

Gaylarde, Christine C; Rodríguez, César Hernández; Navarro-Noya, Yendi E; Ortega-Morales, B Otto

2012-02-01

110

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

PubMed

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. PMID:20890834

Kolter, Roberto

2010-03-01

111

Fossil Biofilms, Microbial Communities and Phosphogenesis in the Paleoproterozoic Baraga Group, Michigan  

NASA Astrophysics Data System (ADS)

Bacteria are important in the phosphorus cycle. They break down organic compounds releasing P, and they can create reducing microenvironments in which P is released from sedimentary oxides. Modern bacteria associated with phosphogenesis store polyphosphate intracellularly under aerobic conditions, which they release when conditions become anoxic. Although bacteria fossils are common in Phanerozoic phosphorite, the nature of their role in phosphogenesis in the Precambrian is unknown. Phosphatic sediments deposited in peritidal environments of the 1.85 Ga Baraga Group, Michigan contain an excellent record of such processes. This succession of marine clastic, iron formation, chert and phosphatic sedimentary rocks accumulated along the Nuna continental margin and ostensibly spans the sulfidic ocean transition. SEM examination of fossil biofilms revealed rod, spherical, and branching filamentous bacteria forms within phosphatic crusts lining fractures and peloids in supratidal to intertidal facies. Pyrite is rare but iron carbonate is abundant in these facies suggesting that these were not sulfate-reducing bacteria. Stromatolites are present in these environments, providing a source of oxygen, but conditions were likely reducing millimeters below the sediment surface. The bacterial communities documented here may have bridged the iron-redox interface. Phosphatized biofilms form meniscal bridges between sediment grains in supratidal facies. Inorganic francolite crystals sometimes engulf the fossils, demonstrating that the bacteria predate later cement crystals. Most prokaryotic life on Earth occurs in biofilms, however, there has been very little documentation of fossil biofilms, with the exception of cyanobacteria-formed stromatolites. Phosphogenesis began at this time because iron ferrihydroxide precursors of hematite and magnetite would have removed and sequestered phosphorus from the oceans, but as iron formation deposition ceased, dissolved P concentrations could have risen leading to phosphogenesis in shallow marine environments. These Proterozoic biofilms and associated fossil benthic communities are the oldest examples preserved within sedimentary phosphate minerals.

Hiatt, E. E.; Edwards, C. T.; Pufahl, P. K.

2009-05-01

112

Microbial Life of North Pacific Oceanic Crust  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

113

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

PubMed

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

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

2014-08-01

114

Metabolic modeling of spatial heterogeneity of biofilms in microbial fuel cells reveals substrate limitations in electrical current generation.  

PubMed

Microbial fuel cells (MFCs) have been proposed as an alternative energy resource for the conversion of organic compounds to electricity. In an MFC, microorganisms such as Geobacter sulfurreducens form an anode-associated biofilm that can completely oxidize organic matter (electron donor) to carbon dioxide with direct electron transfer to the anode (electron acceptor). Mathematical models are useful in analyzing biofilm processes; however, existing models rely on Nernst-Monod type expressions, and evaluate extracellular processes separated from the intracellular metabolism of the microorganism. Thus, models that combine both extracellular and intracellular components, while addressing spatial heterogeneity, are essential for improved representation of biofilm processes. The goal of this work is to develop a model that integrates genome-scale metabolic models with the model of biofilm environment. This integrated model shows the variations of electrical current production and biofilm thickness under the presence/absence of NH4 in the bulk solution, and under varying maintenance energy demands. Further, sensitivity analysis suggested that conductivity is not limiting electrical current generation and that increasing cell density can lead to enhanced current generation. In addition, the modeling results also highlight instances such as the transformation into respiring cells, where the mechanism of electrical current generation during biofilm development is not yet clearly understood. PMID:25113946

Jayasinghe, Nadeera; Franks, Ashley; Nevin, Kelly P; Mahadevan, Radhakrishnan

2014-10-01

115

Biofilms: Online Manual  

NSDL National Science Digital Library

This on-line collection of exercises can be conducted to illustrate the formation and properties of microbial biofilms. Activities include: A Biofilm Primer, An Interesting Paradox, Build a Biofilm Reactor, Bring 'em Back Alive, Buccal Epithelial Cells & Bacterial Cells: Negative Staining, Buried Slide Technique, Dental Biofilms, Flow Through Gram Stain, Microbial Fishing, Pellicle Formation in a Hay Infusion, Rhizosphere Visualization, Microbial Leaching of Copper Ore, Build a Winogradsky Column, Growth of Dental Plaque in vitro, Biofilms from Soil Crumbs, Vinegar Production and Acetic Acid Titration, Isolation of Azospirillum, Observation of the Formation of Biofilms in a Flowing Environment, Measuring Biofilm Depth.

Lennox, John; Altoona, Penn S.

116

The biofilm mode of life boosts the anti-inflammatory properties of Lactobacillus.  

PubMed

The predominant form of life for microorganisms in their natural habitats is the biofilm mode of growth. The adherence and colonization of probiotic bacteria are considered as essential factors for their immunoregulatory function in the host. Here, we show that Lactobacillus casei?ATCC334 adheres to and colonizes the gut of zebrafish larvae. The abundance of pro-inflammatory cytokines and the recruitment of macrophages were low when inflammation was induced in probiotic-fed animals, suggesting that these bacteria have anti-inflammatory properties. We treated human macrophage-differentiated monocytic THP-1 cells with supernatants of L.?casei?ATCC334 grown in either biofilm or planktonic cultures. TNF-? production was suppressed and the NF-?B pathway was inhibited only in the presence of supernatants from biofilms. We identified GroEL as the biofilm supernatant compound responsible, at least partially, for this anti-inflammatory effect. Gradual immunodepletion of GroEL demonstrated that the abundance of GroEL and TNF-? were inversely correlated. We confirmed that biofilm development in other Lactobacillus species affects the immune response. The biofilms supernatants of these species also contained large amounts of GroEL. Thus, our results demonstrate that the biofilm enhances the immunomodulatory effects of Lactobacillus sp. and that secreted GroEL is involved in this beneficial effect. PMID:25052472

Rieu, Aurélie; Aoudia, Nabil; Jego, Gaëtan; Chluba, Johanna; Yousfi, Nadhir; Briandet, Romain; Deschamps, Julien; Gasquet, Benoît; Monedero, Vicente; Garrido, Carmen; Guzzo, Jean

2014-12-01

117

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

PubMed

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

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

2014-07-01

118

Shifts in the microbial community, nitrifiers and denitrifiers in the biofilm in a full-scale rotating biological contactor.  

PubMed

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

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

2014-07-15

119

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

PubMed

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

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

2014-09-01

120

Characterisation of microbial flocs formed from raw textile wastewater in aerobic biofilm reactor (ABR).  

PubMed

Microbial flocs formed from raw textile wastewater in a prototype Aerobic Biofilm Reactor (ABR) system were characterised and studied for their potential use in the treatment of textile wastewater. After 90-100 days of operation, microbial flocs of loose irregular structures were obtained from the reactor with good settling velocity of 33 m/h and sludge volume index (SVI) of 48.2 mL/g. Molecular analysis of the flocs using PCR-amplified 16S rDNA sequence showed 98% homology to those of Bacillus sp, Paenibacillus sp and Acromobacter sp. Detection of Ca(2+)(131 mg/g) and Fe(2+)(131 mg/g) using atomic absorption spectrometer might be implicated with the flocs formation. In addition, presence of Co(2+) and Ni(2+) were indicative of the flocs ability to accumulate at least a fraction of the metals' present in the wastewater. When the flocs were used for the treatment of raw textile wastewater, they showed good removal of COD and colour about 55% and 70% respectively, indicating their potential application. PMID:19657163

Ibrahim, Zaharah; Amin, Mohamad Faiz Mohd; Yahya, Adibah; Aris, Azmi; Umor, Noor Azrimi; Muda, Khalida; Sofian, Nur Shalena

2009-01-01

121

Microbial Life beneath a High Arctic Glacier†  

PubMed Central

The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4°C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4°C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3°C in the dark (to simulate nearly in situ conditions), producing 14CO2 from radiolabeled sodium acetate with minimal organic amendment (?38 ?M C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (??1.8°C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4 beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap. PMID:10919772

Skidmore, Mark L.; Foght, Julia M.; Sharp, Martin J.

2000-01-01

122

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

123

Microbial diversity of supra- and subgingival biofilms on freshly colonized titanium implant abutments in the human mouth.  

PubMed

Supra- and subgingival biofilm formation is considered to be mainly responsible for early implant failure caused by inflammations of periimplant tissues. Nevertheless, little is known about the complex microbial diversity and interindividual similarities around dental implants. An atraumatic assessment was made of the diversity of microbial communities around titanium implants by single strand conformation polymorphism (SSCP) analysis of the 16S rRNA gene amplicons as well as subsequent sequence analysis. Samples of adherent supra- and subgingival periimplant biofilms were collected from ten patients. Additionally, samples of sulcusfluid were taken at titanium implant abutments and remaining teeth. The bacteria in the samples were characterized by SSCP and sequence analysis. A high diversity of bacteria varying between patients and within one patient at different locations was found. Bacteria characteristic for sulcusfluid and supra- and subgingival biofilm communities were identified. Sulcusfluid of the abutments showed higher abundance of Streptococcus species than from residual teeth. Prevotella and Rothia species frequently reported from the oral cavity were not detected at the abutments suggesting a role as late colonizers. Different niches in the human mouth are characterized by specific groups of bacteria. Implant abutments are a very valuable approach to study dental biofilm development in vivo. PMID:20931254

Heuer, W; Stiesch, M; Abraham, W R

2011-02-01

124

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

Microsoft Academic Search

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

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

2000-01-01

125

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

NSF Publications Database

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

126

Continuous nondestructive monitoring of microbial biofilms: A review of analytical techniques  

Microsoft Academic Search

A fundamental requirement for the understanding and control of biofilms is the continuous nondestructive monitoring of biofilm processes. This paper reviews research analytical techniques that monitor biofilm processes in a continuous nondestructive manner and that could also be modified for industrial applications. To be considered ‘continuous’ and ‘nondestructive’ for the purpose of this review a technique must: (a) function in

D E Nivens; RJ Palmer Jr; D C White

1995-01-01

127

Prevalence of microbial biofilms on selected fresh produce and household surfaces  

Microsoft Academic Search

Investigations of biofilms in domestic environments are sparsely represented in the literature. In this study, samples of various household surfaces, including food, laundry and kitchen items, were analyzed for evidence of biofilm presence. Visualization of the surfaces was carried out using cryostage scanning electron microscopy (CSEM) and light microscopy. Qualitative evidence of the presence of biofilm formation was obtained from

Joanna Rayner; Richard Veeh; Janine Flood

2004-01-01

128

Microbial Life in a Liquid Asphalt Desert  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

129

Microbial life in the deep terrestrial subsurface  

SciTech Connect

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

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

1988-12-31

130

Regenerable Microbial Check Valve - Life cycle tests results  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

131

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

Microsoft Academic Search

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

David G. Davies; Claudia N. H. Marques

2009-01-01

132

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

PubMed

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

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

2014-06-01

133

Atmospheres and evolution. [of microbial life on earth  

NASA Technical Reports Server (NTRS)

Studies concerning the regulation of the earth atmosphere and the relation of atmospheric changes to the evolution of microbial life are reviewed. The improbable nature of the composition of the earth atmosphere in light of the atmospheric compositions of Mars and Venus and equilibrium considerations is pointed out, and evidence for the existence of microbial (procaryotic) life on earth as far back as 3.5 billion years ago is presented. The emergence of eucaryotic life in the Phanerozoic due to evolving symbioses between different procaryotic species is discussed with examples given of present-day symbiotic relationships between bacteria and eucaryotes. The idea that atmospheric gases are kept in balance mainly by the actions of bacterial cells is then considered, and it is argued that species diversity is necessary for the maintenance and origin of life on earth in its present form.

Margulis, L.; Lovelock, J. E.

1981-01-01

134

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

135

Evolution of cooperation in microbial biofilms - A stochastic model for the growth and survival of bacterial mats  

NASA Astrophysics Data System (ADS)

Cooperative behavior is essential for microbial biofilms. The structure and composition of a biofilm change over time and thereby influence the evolution of cooperation within the system. In turn, the level of cooperation affects the growth dynamics of the biofilm. Here, we investigate this coupling for an experimentally well-defined situation in which mutants of the Pseudomonas fluorescens strain form a mat at the liquid-air interface by the production of an extra-cellular matrix [1]. We model the occurrence of cooperation in this bacterial population by taking into account the formation of the mat. The presence of cooperators enhances the growth of the mat, but at the same time cheaters can infiltrate the population and put the viability of the mat at risk. We find that the survival time of the mat crucially depends on its initial dynamics which is subject to demographic fluctuations [2]. More generally, our work provides conceptual insights into the requirements and mechanisms for the evolution of cooperation.[1] P. Rainey et al., Nature 425, 72 (2003).[2] A. Melbinger et al., PRL 105, 178101 (2010).

Knebel, Johannes; Cremer, Jonas; Melbinger, Anna; Frey, Erwin

2012-02-01

136

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

PubMed Central

Background Marine epibiotic bacteria produce bioactive compounds effective against microbial biofilms. The study examines antibiofilm ability of a protein obtained from a tropical marine strain of Bacillus licheniformis D1. Methodology/Principal Findings B. licheniformis strain D1 isolated from the surface of green mussel, Perna viridis showed antimicrobial activity against pathogenic Candida albicans BH, Pseudomonas aeruginosa PAO1 and biofouling Bacillus pumilus TiO1 cultures. The antimicrobial activity was lost after treatment with trypsin and proteinase K. The protein was purified by ultrafiltration and size-exclusion chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis revealed the antimicrobial agent to be a 14 kDa protein designated as BL-DZ1. The protein was stable at 75°C for 30 min and over a pH range of 3.0 to 11.0. The sequence alignment of the MALDI-fingerprint showed homology with the NCBI entry for a hypothetical protein (BL00275) derived from B. licheniformis ATCC 14580 with the accession number gi52082584. The protein showed minimum inhibitory concentration (MIC) value of 1.6 µg/ml against C. albicans. Against both P. aeruginosa and B. pumilus the MIC was 3.12 µg/ml. The protein inhibited microbial growth, decreased biofilm formation and dispersed pre-formed biofilms of the representative cultures in polystyrene microtiter plates and on glass surfaces. Conclusion/Significance We isolated a protein from a tropical marine strain of B. licheniformis, assigned a function to the hypothetical protein entry in the NCBI database and described its application as a potential antibiofilm agent. PMID:23691235

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

2013-01-01

137

Influence of tetracycline on the microbial community composition and activity of nitrifying biofilms.  

PubMed

The present work aims to evaluate the bacterial composition and activity (carbon and nitrogen removal) of nitrifying biofilms exposed to 50?gL(-1) of tetracycline. The tetracycline removal efficiency and the occurrence of tetracycline resistance (tet) genes were also studied. Two sequencing batch biofilm reactors (SBBRs) fed with synthetic wastewater were operated without (SBBR1) and with (SBBR2) the antibiotic. Both SBBRs showed similar organic matter biodegradation and nitrification activity. Tetracycline removal was about 28% and biodegradation was probably the principal removal mechanism of the antibiotic. Polymerase chain reaction-denaturing gradient gel electrophoresis analysis of the bacterial community showed shifts leading to not only the fading of some ribotypes, but also the emergence of new ones in the biofilm with tetracycline. The study of the tet genes showed that tet(S) was only detected in the biofilm with tetracycline, suggesting a relationship between its occurrence and the presence of the antibiotic. PMID:25127228

Matos, Maria; Pereira, Maria A; Parpot, Pier; Brito, António G; Nogueira, Regina

2014-12-01

138

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

PubMed

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

Nickzad, A; Déziel, E

2014-05-01

139

Microbial Community Structure and Physiological Status of Different Types of Biofilms in an Acid Mine Drainage Site Determined by Phospholipid Analysis  

NASA Astrophysics Data System (ADS)

A unique aspect of the acid mine drainage (AMD) system at the Green Valley coal mine site (GVS) in western Indiana is the abundance of biofims and biolaminates - stromatolites. Three major types of biofilms have been observed from the AMD site: bright green biofilm dominated by the acidophilic, oxygenic photosynthetic protozoan Euglena mutabilis, olive green biofilm of photosynthetic diatom belonging to the genus Nitzschia, and an olive-green to brownish-green filamentous algae-dominated community. These biofilms are either attached to hard substrata of the effluent channel, or floating at the surface of the effluent with abundant oxygen bubbles, with or without encrusted Fe precipitates. We analyzed lipids (hydrocarbons, wax esters, phospholipids, glycolipids, and neutral lipids) to determine the microbial biomass, community structure and physiological status of biofims collected from the GVS site. Distinctive lipid compositions were observed. The attached, red-crusted biofilms were characterized by abundant wax esters, monounsaturated fatty acids, whereas the floating biofilms by phytadienes, phytanol, polyunsaturated n-alkenes, polyunsaturated fatty acids. The accumulation of abundant wax esters probably reflects the readily available carbon and limitation of nutrients to the biofilm. Alternatively, the wax esters may be the biochemical relics of the anaerobic past of the Earth and the detection of these compounds has important implications for the evolution of eukaryotes and the paleo-environmental conditions on early Earth. This type of biochemical machine may have allowed early eukaryotes to survive recurrent anoxic conditions on early Earth.

Fang, J.

2009-12-01

140

Biofilm Formation by Streptococcus pneumoniae: Role of Choline, Extracellular DNA, and Capsular Polysaccharide in Microbial Accretion?  

PubMed Central

Streptococcus pneumoniae colonizes the human upper respiratory tract, and this asymptomatic colonization is known to precede pneumococcal disease. In this report, chemically defined and semisynthetic media were used to identify the initial steps of biofilm formation by pneumococcus during growth on abiotic surfaces such as polystyrene or glass. Unencapsulated pneumococci adhered to abiotic surfaces and formed a three-dimensional structure about 25 ?m deep, as observed by confocal laser scanning microscopy and low-temperature scanning electron microscopy. Choline residues of cell wall teichoic acids were found to play a fundamental role in pneumococcal biofilm development. The role in biofilm formation of choline-binding proteins, which anchor to the teichoic acids of the cell envelope, was determined using unambiguously characterized mutants. The results showed that LytA amidase, LytC lysozyme, LytB glucosaminidase, CbpA adhesin, PcpA putative adhesin, and PspA (pneumococcal surface protein A) mutants had a decreased capacity to form biofilms, whereas no such reduction was observed in Pce phosphocholinesterase or CbpD putative amidase mutants. Moreover, encapsulated, clinical pneumococcal isolates were impaired in their capacity to form biofilms. In addition, a role for extracellular DNA and proteins in the establishment of S. pneumoniae biofilms was demonstrated. Taken together, these observations provide information on conditions that favor the sessile mode of growth by S. pneumoniae. The experimental approach described here should facilitate the study of bacterial genes that are required for biofilm formation. Those results, in turn, may provide insight into strategies to prevent pneumococcal colonization of its human host. PMID:16936041

Moscoso, Miriam; Garcia, Ernesto; Lopez, Rubens

2006-01-01

141

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

Microsoft Academic Search

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

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

2009-01-01

142

The universe: a cryogenic habitat for microbial life.  

PubMed

Panspermia, an ancient idea, posits that microbial life is ubiquitous in the Universe. After several decades of almost irrational rejection, panspermia is at last coming to be regarded as a serious contender for the beginnings of life on our planet. Astronomical data is shown to be consistent with the widespread distribution of complex organic molecules and dust particles that may have a biological provenance. A minuscule (10(-21)) survival rate of freeze-dried bacteria in space is all that is needed to ensure the continual re-cycling of cosmic microbial life in the galaxy. Evidence that terrestrial life may have come from elsewhere in the solar system has accumulated over the past decade. Mars is seen by some as a possible source of terrestrial life, but some hundreds of billions of comets that enveloped the entire solar system, are a far more likely primordial reservoir of life. Comets would then have seeded Earth, Mars, and indeed all other habitable planetary bodies in the inner regions of the solar system. The implications of this point of view, which was developed in conjunction with the late Sir Fred Hoyle since the 1970s, are now becoming amenable to direct empirical test by studies of pristine organic material in the stratosphere. The ancient theory of panspermia may be on the verge of vindication, in which case the entire universe would be a grand crucible of cryomicrobiology. PMID:15094088

Wickramasinghe, Chandra

2004-04-01

143

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

PubMed Central

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 ?-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. PMID:24552789

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

2014-01-01

144

Modelling the effects of dispersal mechanisms and hydrodynamic regimes upon the structure of microbial communities within fluvial biofilms.  

PubMed

The spatial distribution of microbial taxa is determined primarily by physical and chemical environments and by dispersal. In a homogeneous landscape with limited dispersal, the similarity in abundance of taxa in samples declines with separation distance. We present a one-dimensional model for the spatial autocorrelation in abundances arising from immigration from some remote community and dispersal between environmentally similar landscape patches. Spatial correlation in taxa abundances were calculated from biofilms from the beds of two flumes which differed only in their bedform profiles; one flat and the other a periodic sawtooth shape. The hydraulic regime is approximately uniform over the flat bed, whereas the sawtooth induces fast flow over the peaks and recirculation in the troughs. On the flat bed, the correlation decline between samples was reproduced by a model using one biologically reasonable parameter. A decline was apparent in the other flume; however, a better fit was achieved when dispersal was not assumed constant everywhere. However, analysis of finer-resolution data for the heterogeneous flume suggested even this model did not adequately capture the community's complexity. We conclude that hydrodynamics are a strong driver of taxa-abundance patterns in stream biofilms. However, local adaptability must also be considered to build up a complete mechanistic model. PMID:23240857

Woodcock, Stephen; Besemer, Katharina; Battin, Tom J; Curtis, Thomas P; Sloan, William T

2013-04-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

146

Stabilization of Plutonium in Subsursface Environments via Microbial Reduction and Biofilm Formation  

SciTech Connect

Our work is towards mechanistically understanding interactions of unsaturated bacterial biofilms and their extracellular polymeric substances (EPS) with actinide metals and metal surrogates under vadose zone conditions. Because metal contaminants in the vadose zone co-occur with organic pollutants, some of our work has included experiments with organic pollutants.

Holden, Patricia; Neu, Mary P.

2005-06-01

147

Stabilization of Plutonium in Subsursface Environments via Microbial Reduction and Biofilm Formation  

SciTech Connect

Our work is towards mechanistically understanding interactions of unsaturated bacterial biofilms and their extracellular polymeric substances (EPS) with actinide metals and metal surrogates under vadose zone conditions. Because metal contaminants in the vadose zone co-occur with organic pollutants, some of our work has included experiments with organic pollutants.

Holden, Patricia

2006-06-01

148

Performance and microbial ecology of the hybrid membrane biofilm process for concurrent nitrification  

E-print Network

) is an increasing concern for municipal wastewater, as it can lead to nutrient-induced eutrophication of receiving waters. This research reports on a novel process for TN removal, the hybrid membrane biofilm process, the HMBP membranes supply WaterScience&TechnologyVol55No8­9pp355­362QIWAPublishing2007 355doi: 10.2166/wst

Nerenberg, Robert

149

ADAPTATION OF SUBSURFACE MICROBIAL BIOFILM COMMUNITIES IN RESPONSE TO CHEMICAL STRESSORS  

EPA Science Inventory

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

150

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

USGS Publications Warehouse

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

Cloud, P.; Morrison, K.

1979-01-01

151

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

EPA Science Inventory

Drinking water (DW) biofilm communities influence the survival of opportunistic pathogens, e.g. Legionella pneumophila, via parasitization of free-living amoebae such as Acanthamoebae. Yet knowledge about the microbial composition of DW biofilms developed on common in-premise pl...

152

Immune-mediated diseases and microbial exposure in early life.  

PubMed

The non-communicable disease pandemic includes immune-mediated diseases such as asthma and allergy, which are likely originating in early life where the immature immune system is prone to alterations caused by the exposome. The timing of exposure seems critical for the developing immune system, and certain exposures may have detrimental effects in the earliest life, but no or even beneficial effects later. The human microbiome and infections are candidates as intermediary in the interaction between the host and the environment. The evidence seems inconsistent as infections as well as particular colonization patterns in neonates drive both short-term and long-term asthma symptoms, while, on the other hand, the composition of the microbiome in early life may protect against asthma and allergy in later life. This apparent contradiction may be explained by a deeper disease heterogeneity than we are currently able to discriminate, and in particular, the indiscriminate lumping together of different diseases into one atopic disease category. Also, the microbiome needs a differentiated understanding, considering balance between microbial groups, diversity and microbial genetic capability. Furthermore, the effects of the microbial exposure may only affect individuals with certain susceptibility genes. Few of the observations have been replicated, and publication bias is likely. Therefore, we are still far from understanding, or having proved, causal effects of the human microbiome. Still, the microbiome-gene interaction is a fascinating paradigm that fosters exiting research and promises a breakthrough in the understanding of the mechanisms driving asthma, allergy and eczema, and potentially also other immune-mediated non-communicable diseases. PMID:24533884

Bisgaard, H; Bønnelykke, K; Stokholm, J

2014-04-01

153

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

E-print Network

- idized particles compared to a packed bed control. a r t i c l e i n f o Article history: Received 1 is 951 � 10 mW m�2 , compared to 813 � 2 mW m�2 for the control without stirring (packed bed), and 525 of flowable electrode reactors, where anode biofilms can be electrically charged in a separate storage tank

154

Microsensor measurements of sulfate reduction and sulfide oxidation in compact microbial communities of aerobic biofilms  

SciTech Connect

The microzonation of O{sub 2} respiration, H{sub 2}S oxidation, and SO{sub 4}{sup 2{minus}} reduction in aerobic trickling-filter biofilms was studied by measuring concentration profiles at high spatial resolution (25 to 100 {mu}m) with microsensors for O{sub 2}, S{sup 2{minus}}, and pH. Specific reaction rates were calculated from measured concentration profiles by using a simple one-dimensional diffusion reaction model. The importance of electron acceptor and electron donor availability for the microzonation of respiratory processes and their reaction rates was investigated. Oxygen respiration was found in the upper 0.2 to 0.4 mm of the biofilm, whereas sulfate reduction occurred in deeper, anoxic parts of the biofilm. Sulfate reduction accounted for up to 50% of the total mineralization of organic carbon in the biofilms. All H{sub 2}S produced from sulfate reduction was reoxidized by O{sub 2} in a narrow reaction zone, and no H{sub 2}S escaped to the overlying water. Turnover times of H{sub 2}S and O{sub 2} in the reaction zone were only a few seconds owing to rapid bacterial H{sub 2}S oxidation. Anaerobic H{sub 2}S oxidation with NO{sub 3}{sup {minus}} could be induced by addition of nitrate to the medium. Total sulfate reduction rates increased when the availability of SO{sub 4}{sup 2{minus}} or organic substrate increased as a result of deepening of the sulfate reduction zone or an increase in the sulfate reduction intensity, respectively.

Kuehl, M.; Joergensen, B.B. (Univ. of Aarhus (Denmark))

1992-04-01

155

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

PubMed

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

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

2012-08-01

156

Biofilm Growth Within Porous Media  

NASA Astrophysics Data System (ADS)

Microbial activities in porous medium alter its pore size and permeability. A multispecies biofilm model is utilized to obtain the biofilm dynamic thickness for a common bacterium in biofilm studies, Pseudomonas aeroginosa. Porosity and permeability distribution of the porous network subject to the biofilm formation on the solid surface are obtained using a spherical network along with modified Kozeny-Carman model. The presented model also incorporates the pertinent aspects of macro and micro scales within the biofilm and porous structures.

Shafahi, Maryam

2010-05-01

157

Design of a microfluidic device for the analysis of biofilm behavior in a microbial fuel cell  

E-print Network

This thesis presents design, manufacturing, testing, and modeling of a laminar-flow microbial fuel cell. Novel means were developed to use graphite and other bulk-scale materials in a microscale device without loosing any ...

Jones, A-Andrew D., III (Akhenaton-Andrew Dhafir)

2014-01-01

158

1,5-Anhydro-D-fructose: A natural antibiotic that inhibits the growth of gram-positive bacteria and microbial biofilm formation to prevent nosocomial infection.  

PubMed

Nosocomial infections caused by microbial opportunistic infections or microbial biofilms may occur during hospitalization and increase patient morbidity, mortality and health care costs. Artificial antibiotic agents were initially used to prevent infection; however, the high prevalence of nosocomial infections has resulted in their excessive use, which has led to microbial resistance to these agents. The increase in microbial resistance to antibiotics and the development of antibiotic agents may be the cause of the production of other microbial resistance. Thus, natural compounds that have no adverse side effects would be a preferred treatment modality. Recently, the monosaccharide 1,5-anhydro-D-fructose (1,5-AF), a natural plant compound derived from starch, has been found to have multifunctional properties, including antioxidant, antiplatelet aggregation by thrombin and anti-inflammatory activities. The results of the present study demonstrate that 1,5-AF suppressed the growth of coagulase-negative staphylococci on the hands as well as the growth of Staphylococcus epidermidis, which is a cause of opportunistic infections. Furthermore, 1,5-AF suppressed biofilm formation by the methicillin-resistant Staphylococcus aureus. In conclusion, 1,5-AF is a natural compound that may be effective in preventing nosocomial infections, without causing adverse side effects. PMID:22977551

Meng, Xiaojie; Kawahara, Ko-Ichi; Miyanohara, Hiroaki; Yoshimoto, Yasushi; Yoshinaga, Kazuhiro; Noma, Satoshi; Kikuchi, Kiyoshi; Morimoto, Yoko; Ito, Takashi; Oyama, Yoko; Yoshinaga, Narimasa; Shrestha, Binita; Chandan, Binita; Mera, Kentaro; Tada, Ko-Ichi; Miura, Naoki; Ono, Yoshiko; Takenouchi, Kazunori; Maenosono, Ryuichi; Nagasato, Tomoka; Hashiguchi, Teruto; Maruyama, Ikuro

2011-07-01

159

Biofilm formation and microbial activity in a biofilter system in the presence of MTBE, ETBE and TAME.  

PubMed

Emerging water contaminants derived from unleaded gasoline such as methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME), are in need of effective bioremediation technologies for restoring water resources. In order to design the conditions of a future groundwater bioremediating biofilter, this work assesses the potential use of Acinetobacter calcoaceticus M10, Rhodococcus ruber E10 and Gordonia amicalis T3 for the removal of MTBE, ETBE and TAME in consortia or as individual strains. Biofilm formation on an inert polyethylene support material was assessed with scanning electron microscopy, and consortia were also analysed with fluorescent in situ hybridisation to examine the relation between the strains. A. calcoaceticus M10 was the best coloniser, followed by G. amicalis T3, however, biofilm formation of pair consortia favoured consortium M10-E10 both in formation and activity. However, degradation batch studies determined that neither consortium exhibited higher degradation than individual strain degradation. The physiological state of the three strains was also determined through flow cytometry using propidium iodide and 3'-dihexylocarbocyanine iodide thus gathering information on their viability and activity with the three oxygenates since previous microbial counts revealed slow growth. Strain E10 was observed to have the highest physiological activity in the presence of MTBE, and strain M10 activity with TAME was only maintained for 24 h, thus we believe that biotransformation of MTBE occurs within the active periods established by the cytometry analyses. Viable cell counts and oxygenate removal were determined in the presence of the metabolites tert-butyl alcohol (TBA) and tert-amyl alcohol (TAA), resulting in TBA biotransformation by M10 and E10, and TAA by M10. Our results show that A. calcoaceticus M10 and the consortium M10-E10 could be adequate inocula in MTBE and TAME bioremediating technologies. PMID:21774959

Purswani, Jessica; Juárez, Belén; Rodelas, Belén; Gónzalez-López, Jesús; Pozo, Clementina

2011-10-01

160

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

EPA Science Inventory

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

161

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

PubMed

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

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

2014-06-01

162

Comparison of microbial community assays for the assessment of stream biofilm ecology.  

PubMed

We investigated a range of microbiological community assays performed on scrapes of biofilms formed on artificial diffusing substrates deployed in 8 streams in eastern Scotland, with a view to using them to characterize ecological response to stream water quality. The assays considered were: Multiplex Terminal Restriction Fragment Length Polymorphism or M-TRFLP (a molecular method), Phospholipid Fatty Acid or PLFA analysis (a biochemical method) and MICRORESP™ (a physiological method) alongside TDI, diatom species, and chlorophyll a content. Four of the streams were classified as of excellent status (3-6?g/L Soluble Reactive Phosphorus (SRP)) with respect to soluble P content under the EU Water Framework Directive and four were of borderline good/moderate or moderate status (43-577?g/L SRP). At each site, 3 replicates of 3 solute diffusion treatments were deployed in a Latin square design. Solute diffusion treatments were: KCl (as a control solute), N and P (to investigate the effect of nutrient enrichment), or the herbicide isoproturon (as a "high impact" control, which aimed to affect biofilm growth in a way detectable by all assays). Biofilms were sampled after 4weeks deployment in a low flow period of early summer 2006. The chlorophyll a content of biofilms after 4weeks was 2.0±0.29mg/m(2) (mean±se). Dry matter content was 16.0±13.1g/m(2). The M-TRFLP was successfully used for generating community profiles of cyanobacteria, algae and bacteria and was much faster than diatom identification. The PFLA and TDI were successful after an increase in the sample size, due to low counts. The MICRORESP(™) assays were often below or near detection limit. We estimated the per-sample times for the successful assays as follows: M-TRFLP: 20min, PLFA 40min, TDI 90min. Using MANOVA on the first 5 principal co-ordinates, all the assays except MICRORESP(™) showed significant differences between sites, but none of the assays showed a significant effect of either initial stream trophic status (as classified by the EU Water Framework Directive using chemical standards for soluble P), or of the diffusing solute treatment. Multiple Procrustes analysis on the ordination results showed that the diatom and M-TRFLP data sets hold distinct, though as yet unexplored, information about the ecological factors affecting stream biofilms. The diatom data were subjected to principal components analysis, to identify which taxa were more strongly influenced by site variables, trophic status or treatment effects. These were Acnanthes lanceolata, A. minutissimma, Nitzchia spp., Coccineis spp. and Navicula spp. Further experimentation and data analysis on a larger number of sites, to identify specific M-TRFLP bands that could be used as indicators linked to specific taxa, are desirable. Results highlight the need for a multifactorial approach to understanding controls on stream ecology. PMID:21414363

Vinten, A J A; Artz, R R E; Thomas, N; Potts, J M; Avery, L; Langan, S J; Watson, H; Cook, Y; Taylor, C; Abel, C; Reid, E; Singh, B K

2011-06-01

163

A life detection problem in a High Arctic microbial community  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

164

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

EPA Science Inventory

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...

165

Study casts doubts about chemical process thought to support subterranean microbial life  

E-print Network

other planets was fasci- nating and was accepted by most microbiologists," Lovley says. "UnfortunatelyStudy casts doubts about chemical process thought to support subterranean microbial life) have a c discovered that a critical chemical reaction previously thought to support microbial life deep

Lovley, Derek

166

Putative Role of ?-1,3 Glucans in Candida albicans Biofilm Resistance?  

PubMed Central

Biofilms are microbial communities, embedded in a polymeric matrix, growing attached to a surface. Nearly all device-associated infections involve growth in the biofilm life style. Biofilm communities have characteristic architecture and distinct phenotypic properties. The most clinically important phenotype involves extraordinary resistance to antimicrobial therapy, making biofilm infections very difficulty to cure without device removal. The current studies examine drug resistance in Candida albicans biofilms. Similar to previous reports, we observed marked fluconazole and amphotericin B resistance in a C. albicans biofilm both in vitro and in vivo. We identified biofilm-associated cell wall architectural changes and increased ?-1,3 glucan content in C. albicans cell walls from a biofilm compared to planktonic organisms. Elevated ?-1,3 glucan levels were also found in the surrounding biofilm milieu and as part of the matrix both from in vitro and in vivo biofilm models. We thus investigated the possible contribution of ?-glucans to antimicrobial resistance in Candida albicans biofilms. Initial studies examined the ability of cell wall and cell supernatant from biofilm and planktonic C. albicans to bind fluconazole. The cell walls from both environmental conditions bound fluconazole; however, four- to fivefold more compound was bound to the biofilm cell walls. Culture supernatant from the biofilm, but not planktonic cells, bound a measurable amount of this antifungal agent. We next investigated the effect of enzymatic modification of ?-1,3 glucans on biofilm cell viability and the susceptibility of biofilm cells to fluconazole and amphotericin B. We observed a dose-dependent killing of in vitro biofilm cells in the presence of three different ?-glucanase preparations. These same concentrations had no impact on planktonic cell viability. ?-1,3 Glucanase markedly enhanced the activity of both fluconazole and amphotericin B. These observations were corroborated with an in vivo biofilm model. Exogenous biofilm matrix and commercial ?-1,3 glucan reduced the activity of fluconazole against planktonic C. albicans in vitro. In sum, the current investigation identified glucan changes associated with C. albicans biofilm cells, demonstrated preferential binding of these biofilm cell components to antifungals, and showed a positive impact of the modification of biofilm ?-1,3 glucans on drug susceptibility. These results provide indirect evidence suggesting a role for glucans in biofilm resistance and present a strong rationale for further molecular dissection of this resistance mechanism to identify new drug targets to treat biofilm infections. PMID:17130296

Nett, Jeniel; Lincoln, Leslie; Marchillo, Karen; Massey, Randall; Holoyda, Kathleen; Hoff, Brian; VanHandel, Michelle; Andes, David

2007-01-01

167

Reproducible analyses of microbial food for advanced life support systems.  

PubMed

The use of yeasts in Controlled Ecological Life Support Systems (CELSS) for microbial food regeneration in space required the accurate and reproducible analysis of intracellular carbohydrate and protein levels. The reproducible analysis of glycogen was a key element in estimating overall content of edibles in candidate yeast strains. Typical analytical methods for estimating glycogen in Saccharomyces were not found to be entirely applicable to other candidate strains. Rigorous cell lysis coupled with acid/base fractionation followed by specific enzymatic glycogen analyses were required to obtain accurate results in two strains of Candida. A profile of edible fractions of these strains was then determined. The suitability of yeasts as food sources in CELSS food production processes is discussed. PMID:11541295

Petersen, G R

1988-10-01

168

Response of microbial adhesives and biofilm matrix polymers to chemical treatments as determined by interference reflection microscopy and light section microscopy. [Pseudomonas fluorescens  

SciTech Connect

Both bacterial adhesion to surfaces and the subsequent formation of microbial biofilms have serious implications for a number of industrial applications in aqueous environments. The development of multicellular biofilms on submerged man-made structures such as drilling platforms and ship hulls is the first obvious stage in the fouling of these structures, which can progress to the point where costly cleaning or replacement is needed. On heat exchangers, even thin microbial films cause a serious decrease in efficiency of heat transfer. The polymers involved in the adhesion of Pseudomonas fluorescens H2S to solid surfaces were investigated to determine whether differences between cell surface adhesives and biofilm matrix polymers could be detected. Two optical techniques, i.e., interference reflection microscopy (IRM) and light section microscopy (LSM), were used to compare the responses of the two types of polymer to treatment with electrolytes, dimethyl sulfoxide (DMSO), and Tween 20. Results indicate that both polymers bear acidic groups and thus act electrostatically with cations and are able to enter into hydrophobic interactions. Differences in their response to DMSO could be due to the close proximity of the glass surface or to differences in structure of the two polymers.

Marshall, P.A.; Cowan, M.M.; Fletcher, M. (Univ. of Maryland, Baltimore (USA)); Loeb, G.I. (David Taylor Naval Research Center, Annapolis, MD (USA))

1989-11-01

169

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

PubMed

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

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

2014-04-01

170

Shells of crabs like these may be the key to prolonging the life of microbial fuel cells that  

E-print Network

Shells of crabs like these may be the key to prolonging the life of microbial fuel cells that power) -- Discarded crab and lobster shells may be the key to prolonging the life of microbial fuel cells that power

171

Candida biofilm resistance  

Microsoft Academic Search

Device-related infections in most nosocomial diseases can be traced to the formation of biofilms (microbial communities encased within polysaccharide-rich extracellular matrix) by pathogens on surfaces of these devices. Candida species are the most common fungi isolated from these infections, and biofilms formed by these fungal organisms are associated with drastically enhanced resistance against most antimicrobial agents. This enhanced resistance contributes

Pranab K. Mukherjee; Jyotsna Chandra

2004-01-01

172

Biofilm Susceptibility to Antimicrobials  

Microsoft Academic Search

Microbial biofilms, where organisms are intimately associated with each other and a solid substratum through binding and inclusion within an exopolymer matrix, are widely distributed in nature and disease. In the mouth, multispecies biofilms are associated not only with dental plaque and tooth decay but also with soft tissues of the buccal cavity and with most forms of periodontal disease.

P. Gilbert; J. Das; I. Foley

1997-01-01

173

Determination of Spatial Distributions of Zinc and Active Biomass in Microbial Biofilms by Two-Photon Laser Scanning Microscopy  

Microsoft Academic Search

The spatial distributions of zinc, a representative transition metal, and active biomass in bacterial biofilms were determined using two-photon laser scanning microscopy (2P-LSM). Application of 2P-LSM permits analysis of thicker biofilms than are amenable to observation with confocal laser scanning microscopy and also provides selective excitation of a smaller focal volume with greater depth localization. Thin Escherichia coli PHL628 biofilms

Zhiqiang Hu; Gabriela Hidalgo; Paul L. Houston; Anthony G. Hay; Michael L. Shuler; Hector D. Abruna; William C. Ghiorse; Leonard W. Lion

2005-01-01

174

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

Microsoft Academic Search

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

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

2011-01-01

175

Microbial biofilms on needleless connectors for central venous catheters: comparison of standard and silver-coated devices collected from patients in an acute care hospital.  

PubMed

Microorganisms may colonize needleless connectors (NCs) on intravascular catheters, forming biofilms and predisposing patients to catheter-associated infection (CAI). Standard and silver-coated NCs were collected from catheterized intensive care unit patients to characterize biofilm formation using culture-dependent and culture-independent methods and to investigate the associations between NC usage and biofilm characteristics. Viable microorganisms were detected by plate counts from 46% of standard NCs and 59% of silver-coated NCs (P=0.11). There were no significant associations (P>0.05, chi-square test) between catheter type, side of catheter placement, number of catheter lumens, site of catheter placement, or NC placement duration and positive NC findings. There was an association (P=0.04, chi-square test) between infusion type and positive findings for standard NCs. Viable microorganisms exhibiting intracellular esterase activity were detected on >90% of both NC types (P=0.751), suggesting that a large percentage of organisms were not culturable using the conditions provided in this study. Amplification of the 16S rRNA gene from selected NCs provided a substantially larger number of operational taxonomic units per NC than did plate counts (26 to 43 versus 1 to 4 operational taxonomic units/NC, respectively), suggesting that culture-dependent methods may substantially underestimate microbial diversity on NCs. NC bacterial communities were clustered by patient and venous access type and may reflect the composition of the patient's local microbiome but also may contain organisms from the health care environment. NCs provide a portal of entry for a wide diversity of opportunistic pathogens to colonize the catheter lumen, forming a biofilm and increasing the potential for CAI, highlighting the importance of catheter maintenance practices to reduce microbial contamination. PMID:24371233

Perez, Elizabeth; Williams, Margaret; Jacob, Jesse T; Reyes, Mary Dent; Chernetsky Tejedor, Sheri; Steinberg, James P; Rowe, Lori; Ganakammal, Satishkumar Ranganathan; Changayil, Shankar; Weil, M Ryan; Donlan, Rodney M

2014-03-01

176

Microbial Biofilms on Needleless Connectors for Central Venous Catheters: Comparison of Standard and Silver-Coated Devices Collected from Patients in an Acute Care Hospital  

PubMed Central

Microorganisms may colonize needleless connectors (NCs) on intravascular catheters, forming biofilms and predisposing patients to catheter-associated infection (CAI). Standard and silver-coated NCs were collected from catheterized intensive care unit patients to characterize biofilm formation using culture-dependent and culture-independent methods and to investigate the associations between NC usage and biofilm characteristics. Viable microorganisms were detected by plate counts from 46% of standard NCs and 59% of silver-coated NCs (P = 0.11). There were no significant associations (P > 0.05, chi-square test) between catheter type, side of catheter placement, number of catheter lumens, site of catheter placement, or NC placement duration and positive NC findings. There was an association (P = 0.04, chi-square test) between infusion type and positive findings for standard NCs. Viable microorganisms exhibiting intracellular esterase activity were detected on >90% of both NC types (P = 0.751), suggesting that a large percentage of organisms were not culturable using the conditions provided in this study. Amplification of the 16S rRNA gene from selected NCs provided a substantially larger number of operational taxonomic units per NC than did plate counts (26 to 43 versus 1 to 4 operational taxonomic units/NC, respectively), suggesting that culture-dependent methods may substantially underestimate microbial diversity on NCs. NC bacterial communities were clustered by patient and venous access type and may reflect the composition of the patient's local microbiome but also may contain organisms from the health care environment. NCs provide a portal of entry for a wide diversity of opportunistic pathogens to colonize the catheter lumen, forming a biofilm and increasing the potential for CAI, highlighting the importance of catheter maintenance practices to reduce microbial contamination. PMID:24371233

Perez, Elizabeth; Williams, Margaret; Jacob, Jesse T.; Reyes, Mary Dent; Chernetsky Tejedor, Sheri; Steinberg, James P.; Rowe, Lori; Ganakammal, Satishkumar Ranganathan; Changayil, Shankar; Weil, M. Ryan

2014-01-01

177

Multiple cathodic reaction mechanisms in seawater cathodic biofilms operating in sediment microbial fuel cells.  

PubMed

In this study, multiple reaction mechanisms in cathodes of sediment microbial fuel cells (SMFCs) were characterized by using cyclic voltammetry and microelectrode measurements of dissolved oxygen and pH. The cathodes were acclimated in SMFCs with sediment and seawater from San Diego Bay. Two limiting current regions were observed with onset potentials of approximately +400?mVAg/AgCl for limiting current?I and -120?mVAg/AgCl for limiting current?II. The appearance of two catalytic waves suggests that multiple cathodic reaction mechanisms influence cathodic performance. Microscale oxygen concentration measurements showed a zero surface concentration at the electrode surface for limiting current?II but not for limiting current?I, which allowed us to distinguish limiting current?II as the conventional oxygen reduction reaction and limiting current?I as a currently unidentified cathodic reaction mechanism. Microscale pH measurements further confirmed these results. PMID:25154833

Babauta, Jerome T; Hsu, Lewis; Atci, Erhan; Kagan, Jeff; Chadwick, Bart; Beyenal, Haluk

2014-10-01

178

Kinetics of microbial bromate reduction in a hydrogen-oxidizing, denitrifying biofilm reactor.  

PubMed

Bromate (BrO(3)(-)) is an oxidized contaminant produced from bromide (Br(-)) during ozonation and advanced oxidation of drinking water. Previous research shows that denitrifying bioreactors can reduce bromate to innocuous bromide. We studied a hydrogen-based, denitrifying membrane-biofilm reactor (MBfR) for bromate reduction, and report the first kinetics for a hydrogen-based bromate reduction process. A mixed-culture MBfR reduced up to 1,500 microg/L bromate to below 10 microg/L with a 50-min hydraulic residence time. Kinetics were determined using short-term tests on a completely mixed MBfR at steady state with an influent of 5 mg N/L nitrate plus 100 microg/L bromate. Short-term tests examined the impact of pH, nitrite, nitrate, and bromate on bromate reduction rates in the MBfR. Kinetic parameters for the process were estimated based on the short-term bromate tests. The q(max) for bromate reduction was 0.12 mg BrO(3)(-) x mg(x)(-1) x day(-1), and the K was 1.2 mg BrO(3)(-)/L. This q(max) is 2-3 times higher than reported for heterotrophic enrichments, and the K is the first reported in the literature. Nitrite and nitrate partially inhibited bromate reduction, with nitrite exerting a stronger inhibitory effect. Bromate was self-inhibitory at concentrations above 15 mg/L, but up to 50 mg/L of bromate had no inhibitory effect on denitrification. The optimum pH was approximately 7. We also examined the performance of an MBfR containing pure culture of the denitrifying bacterium Ralstonia eutropha. Under conditions similar to the mixed-culture tests, no bromate reduction was detected, showing that not all denitrifying bacteria are active in bromate reduction. Our results suggest the presence of specialized, dissimilatory bromate-reducing bacteria in the mixed-culture MBfR. PMID:17405178

Downing, Leon S; Nerenberg, Robert

2007-10-15

179

Potential of Biofilms to Harbor Largemouth Bass Virus (LMBV).  

E-print Network

?? Biofilms are surface-attached microbial communities encased by extracellular matrix. This mode of growth enables microbial survival during adverse environmental conditions. In the present study,… (more)

Nath, Shubhankar

2009-01-01

180

Restricting Microbial Exposure in Early Life Negates the Immune Benefits Associated with Gut Colonization in Environments of High Microbial Diversity  

Microsoft Academic Search

BackgroundAcquisition of the intestinal microbiota in early life corresponds with the development of the mucosal immune system. Recent work on caesarean-delivered infants revealed that early microbial composition is influenced by birthing method and environment. Furthermore, we have confirmed that early-life environment strongly influences both the adult gut microbiota and development of the gut immune system. Here, we address the impact

Imke E. Mulder; Bettina Schmidt; Marie Lewis; Margaret Delday; Christopher R. Stokes; Mick Bailey; Rustam I. Aminov; Bhupinder P. Gill; John R. Pluske; Claus-Dieter Mayer; Denise Kelly

2011-01-01

181

Microbial metropolis.  

PubMed

Microorganisms can form tightly knit communities such as biofilms. Many others include marine snow, anaerobic digester granules, the ginger beer plant and bacterial colonies. This chapter is devoted to a survey of the main properties of these communities, with an emphasis on biofilms. We start with attachment to surfaces and the nature of adhesion. The growing community then forms within a matrix, generally of organic macromolecules. Inevitably the environment within such a matrix is different from that outside. Organisms respond by forming crowd-detection and response units; these quorum sensing systems act as switches between planktonic life and the dramatically altered conditions found inside microbial aggregates. The community then matures and changes and may even fail and disappear. Antimicrobial resistance is discussed as an example of multicellular behavior. The multicellular lifestyle has been modeled mathematically and responded to powerful molecular biological techniques. Latterly, microbial systems have been used as models for fundamental evolutionary processes, mostly because of their high rates of reproduction and the ease of genetic manipulation. The life of most microbes is a duality between the yin of the community and the yang of planktonic existence. Sadly far less research has been devoted to adaptation to free-living forms than in the opposite direction. PMID:20943124

Wimpenny, Julian

2009-01-01

182

Microbial Communities that are Concealed Within Mineral Deposits: Expanding our Detection of Life  

NASA Astrophysics Data System (ADS)

In addition to clearly biological microbial mats, lava tubes contain many non-biological appearing mineral deposits that contain life. The discovery that such deposits contain abundant life can help guide our detection of life on other extrater-restrial bodies.

Northup, D. E.; Spilde, M. N.; Hathaway, J. J. M.; Moya, M.; Garcia, M. G.; Boston, P. J.

2010-04-01

183

Influence of the spatial structure on the effective nutrient diffusion in bacterial biofilm  

E-print Network

Influence of the spatial structure on the effective nutrient diffusion in bacterial biofilm T of microbial biofilms. Our approach requires to analyze several experimental spatial structures of biofilms with the biofilm structure. These results suggest that microbial biofilm structures can favour the nutrient access

Boyer, Edmond

184

Effects of the Pt loading side and cathode-biofilm on the performance of a membrane-less and single-chamber microbial fuel cell.  

PubMed

In order to analyze the effect of cathode's Pt loading side on the performance of single-chamber microbial fuel cells (MFCs), power generation of a bamboo charcoal membrane-less air-cathode MFC was examined. The maximum power outputs obtained were 0.144 and 1.16 mW, while the maximum voltage outputs were 0.400 and 0.500 V (external resistance was 500 Omega), respectively, when the Pt loading side facing to the air and to the anode chamber solution; after a long time of operation with the side of cathode loaded Pt facing to anode chamber solution, a biofilm was developed on the inner side of cathode. With the formation of this biofilm, the power outputs of MFC increased first, and then decreased to 0.8 mW; oxidation-reduction potentials (ORP) dropped first, and then achieved the level of stability. Coulombic efficiency (CE) increased at a certain extent. In addition, the impact of cathode-biofilm on the loss of water in anode chamber solution was determined. PMID:18790635

Yang, Shaoqiang; Jia, Boyang; Liu, Hong

2009-02-01

185

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

186

Stabilization of Plutonium in Subsurface Environments via Microbial Reduction and Biofilm Formation  

SciTech Connect

Plutonium has a long half-life (2.4 x 104 years) and is of concern because of its chemical and radiological toxicity, high-energy alpha radioactive decay. A full understanding of its speciation and interactions with environmental processes is required in order to predict, contain, or remediate contaminated sites. Under aerobic conditions Pu is sparingly soluble, existing primarily in its tetravalent oxidation state. To the extent that pentavalent and hexavalent complexes and small colloidal species form they will increase the solubility and resultant mobility from contamination sources. There is evidence that in both marine environments and brines substantial fractions of the plutonium in solution is present as hexavalent plutonyl, PuO2 2+.

Hakim Boukhalfa; Gary A. Icopini; Sean D. Reilly; Mary P. Neu

2007-04-19

187

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

NASA Astrophysics Data System (ADS)

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

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

2004-03-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

189

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

PubMed

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

Picard, Aude; Daniel, Isabelle

2013-12-15

190

Antimicrobial peptides as potential tool to fight bacterial biofilm.  

PubMed

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

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

2014-01-01

191

Energy, ecology and the distribution of microbial life  

PubMed Central

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

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

2013-01-01

192

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

193

Hexacyanoferrate-adapted biofilm enables the development of a microbial fuel cell biosensor to detect trace levels of assimilable organic carbon (AOC) in oxygenated seawater.  

PubMed

A marine microbial fuel cell (MFC) type biosensor was developed for the detection of assimilable organic carbon (AOC) in ocean water for the purpose of online water quality monitoring for seawater desalination plants prone to biofouling of reverse osmosis (RO) membranes. The anodophilic biofilm that developed on the graphite tissue anode could detect acetate as the model AOC to concentrations as low as 5?µM (120?µg/L of AOC), which is sufficiently sensitive as an online biofouling risk sensor. Although the sensor was operated at a higher (+200?±?10?mV) than the usual (-300?mV) anodic potential, the presence of oxygen completely suppressed the electrical signal. In order to overcome this outcompeting effect of oxygen over the anode as electron acceptor by the bacteria, hexacyanoferrate (HCF(III)) was found to enable the development of an adapted biofilm that transferred electrons to HCF(III) rather than oxygen. As the resultant of the reduced HCF(II) could readily transfer electrons to the anode while being re-oxidised to HCF(III), the marine MFC biosensor developed could be demonstrated to work in the presence of oxygen unlike traditional MFC. The possibility of operating the marine MFC in batch or continuous (in-line) mode has been explored by using coulombic or potentiometric interpretation of the signal. Biotechnol. Bioeng. 2014;111: 2412-2420. © 2014 Wiley Periodicals, Inc. PMID:24942462

Cheng, Liang; Quek, Soon Bee; Cord-Ruwisch, Ralf

2014-12-01

194

Effect of oxygen gradients on the activity and microbial community structure of a nitrifying, membrane-aerated biofilm  

Microsoft Academic Search

Shortcut nitrogen removal, that is, removal via formation and reduction of nitrite rather than nitrate, has been observed in membrane-aerated biofilms (MABs), but the extent, the controlling factors, and the kinetics of nitrite formation in MABs are poorly understood. We used a special MAB reactor to systematically study the effects of the dissolved oxygen (DO) concentration at the membrane surface,

Leon S. Downing; Robert Nerenberg

2008-01-01

195

In situ biofilm coupon device  

DOEpatents

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

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

1997-01-01

196

A Self-Produced Trigger for Biofilm Disassembly that Targets  

E-print Network

related poly- amines, prevented biofilm formation by B. subtilis, Escherichia coli, and Staphylococcus such as Staphylococcus aureus and Staphylococcus epidermidis (Bryers, 2008; Otto, 2008). Biofilms have natural life

Gleeson, Joseph G.

197

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

198

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

199

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

PubMed Central

Interaction of microbes with their environment depends on features of the dynamic microbial surface throughout cell growth and division. Surface modifications, whether used to acquire nutrients, defend against other microbes, or resist the pressures of a host immune system, facilitate adaptation to unique surroundings. The release of bioactive membrane vesicles (MVs) from the cell surface is conserved across microbial life, in bacteria, archaea, fungi, and parasites. MV production occurs not only in vitro but also in vivo during infection, underscoring the influence of these surface organelles in microbial physiology and pathogenesis through delivery of enzymes, toxins, communication signals, and antigens recognized by the innate and adaptive immune systems. Derived from a variety of organisms that span kingdoms of life and called by several names (membrane vesicles, outer membrane vesicles [OMVs], exosomes, shedding microvesicles, etc.), the conserved functions and mechanistic strategies of MV release are similar, including the use of ESCRT proteins and ESCRT protein homologues to facilitate these processes in archaea and eukaryotic microbes. Although forms of MV release by different organisms share similar visual, mechanistic, and functional features, there has been little comparison across microbial life. This underappreciated conservation of vesicle release, and the resulting functional impact throughout the tree of life, explored in this review, stresses the importance of vesicle-mediated processes throughout biology. PMID:22409932

Deatherage, Brooke L.

2012-01-01

200

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

National Technical Information Service (NTIS)

Biofilms have played a significant role on the effectiveness of life support hardware on the Space Shuttle and International Space Station (ISS). This presentation will discuss how biofilms impact flight hardware, how on orbit biofilms are analyzed from a...

L. Vega

2013-01-01

201

Interactions of microbial biofilms with toxic trace metals; 2: Prediction and verification of an integrated computer model of lead (II) distribution in the presence of microbial activity  

SciTech Connect

The interfacial interactions of a toxic trace metal, Pb, with a surface modified by a marine film-forming bacterium, Pseudomonas atlantica, were predicted by a structured biofilm model used in conjunction with a chemical speciation model. The validity of the integrated model was tested for batch and continuous operations. Dynamic responses of the biophase due to transient lead concentration increases were also simulated. The reasonable predictions achieved by the model demonstrate its utility in describing trace metal distributions in complex systems where the adsorption properties of inorganic surfaces are modified by adherent bacteria and bacterial production of extracellular polymers.

Hsieh, K.M.; Murgel, G.A.; Lion, L.W.; Shuler, M.L. (Cornell Univ., Ithaca, NY (United States))

1994-06-20

202

Endolithic microbial life in hot and cold deserts  

NASA Technical Reports Server (NTRS)

Endolithic microorganisms (those living inside rocks) occur in hot and cold deserts and exist under extreme environmental conditions. These conditions are discussed on a comparative basis. Quantitative estimates of biomass are comparable in hot and cold deserts. Despite the obvious differences between the hot and cold desert environment, survival strategies show some common features. These endolithic organisms are able to 'switch' rapidly their metabolic activities on and off in response to changes in the environment. Conditions in hot deserts impose a more severe environmental stress on the organisms than in the cold Antarctic desert. This is reflected in the composition of the microbial flora which in hot desert rocks consist entirely of prokaryotic microorganisms, while under cold desert conditions eukaryotes predominate.

Friedmann, E. I.

1980-01-01

203

Metagenomic Analysis of Showerhead Biofilms from a Hospital in Ohio  

EPA Science Inventory

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

204

Methodological approaches for studying the microbial ecology of drinking water distribution systems.  

PubMed

The study of the microbial ecology of drinking water distribution systems (DWDS) has traditionally been based on culturing organisms from bulk water samples. The development and application of molecular methods has supplied new tools for examining the microbial diversity and activity of environmental samples, yielding new insights into the microbial community and its diversity within these engineered ecosystems. In this review, the currently available methods and emerging approaches for characterising microbial communities, including both planktonic and biofilm ways of life, are critically evaluated. The study of biofilms is considered particularly important as it plays a critical role in the processes and interactions occurring at the pipe wall and bulk water interface. The advantages, limitations and usefulness of methods that can be used to detect and assess microbial abundance, community composition and function are discussed in a DWDS context. This review will assist hydraulic engineers and microbial ecologists in choosing the most appropriate tools to assess drinking water microbiology and related aspects. PMID:25105587

Douterelo, Isabel; Boxall, Joby B; Deines, Peter; Sekar, Raju; Fish, Katherine E; Biggs, Catherine A

2014-11-15

205

Engineering biofilm formation and dispersal  

PubMed Central

Anywhere water is in the liquid state, bacteria will exist as biofilms, which are complex communities of cells cemented together. Although frequently associated with disease and biofouling, biofilms are also important for engineering applications, such as bioremediation, biocatalysis and microbial fuel cells. Here we review approaches to alter genetic circuits and cell signaling toward controlling biofilm formation, and emphasize utilizing these tools for engineering applications. Based on a better understanding of the genetic basis of biofilm formation, we find that biofilms may be controlled by manipulating extracellular signals and that they may be dispersed using conserved intracellular signals and regulators. Biofilms could also be formed at specific locations where they might be engineered to make chemicals or treat human disease. PMID:21131080

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

2011-01-01

206

Epistemological issues in the study of microbial life: alternative terran biospheres?  

PubMed

The assumption that all life on Earth today shares the same basic molecular architecture and biochemistry is part of the paradigm of modern biology. This paper argues that there is little theoretical or empirical support for this widely held assumption. Scientists know that life could have been at least modestly different at the molecular level and it is clear that alternative molecular building blocks for life were available on the early Earth. If the emergence of life is, like other natural phenomena, highly probable given the right chemical and physical conditions then it seems likely that the early Earth hosted multiple origins of life, some of which produced chemical variations on life as we know it. While these points are often conceded, it is nevertheless maintained that any primitive alternatives to familiar life would have been eliminated long ago, either amalgamated into a single form of life through lateral gene transfer (LGT) or alternatively out-competed by our putatively more evolutionarily robust form of life. Besides, the argument continues, if such life forms still existed, we surely would have encountered telling signs of them by now. These arguments do not hold up well under close scrutiny. They reflect a host of assumptions that are grounded in our experience with large multicellular organisms and, most importantly, do not apply to microbial forms of life, which cannot be easily studied without the aid of sophisticated technologies. Significantly, the most powerful molecular biology techniques available-polymerase chain reaction (PCR) amplification of rRNA genes augmented by metagenomic analysis-could not detect such microbes if they existed. Given the profound philosophical and scientific importance that such a discovery would represent, a dedicated search for 'shadow microbes' (heretofore unrecognized 'alien' forms of terran microbial life) seems in order. The best place to start such a search is with puzzling (anomalous) phenomena, such as desert varnish, that resist classification as 'biological' or 'nonbiological'. PMID:18053938

Cleland, Carol E

2007-12-01

207

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

PubMed

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

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

2006-10-01

208

Biofilm Roughness Determines Cryptosporidium parvum Retention in Environmental Biofilms  

PubMed Central

The genus Cryptosporidium is a group of waterborne protozoan parasites that have been implicated in significant outbreaks of gastrointestinal infections throughout the world. Biofilms trap these pathogens and can contaminate water supplies through subsequent release. Biofilm microbial assemblages were collected seasonally from three streams in eastern Pennsylvania and used to grow biofilms in laboratory microcosms. Daily oocyst counts in the influx and efflux flow allowed the calculation of daily oocyst retention in the biofilm. Following the removal of oocysts from the influx water, oocyst attachment to the biofilm declined to an equilibrium state within 5 days that was sustained for at least 25 days. Varying the oocyst loading rate for the system showed that biofilm retention could be saturated, suggesting that discrete binding sites determined the maximum number of oocysts retained. Oocyst retention varied seasonally but was consistent across all three sites; however, seasonal oocyst retention was not consistent across years at the same site. No correlation between oocyst attachment and any measured water quality parameter was found. However, oocyst retention was strongly correlated with biofilm surface roughness and roughness varied among seasons and across years. We hypothesize that biofilm roughness and oocyst retention are dependent on environmentally driven changes in the biofilm community rather than directly on water quality conditions. It is important to understand oocyst transport dynamics to reduce risks of human infection. Better understanding of factors controlling biofilm retention of oocysts should improve our understanding of oocyst transport at different scales. PMID:22492449

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

2012-01-01

209

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

EPA Science Inventory

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...

210

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

PubMed

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. PMID:25109340

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

2014-11-01

211

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

EPA Science Inventory

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...

212

Effect of antibacterials on biofilms.  

PubMed

Indwelling catheters are the most common cause of health care-associated bloodstream infections (BSIs). BSIs arise from a bacterial biofilm that consists of bacteria embedded within an extracellular polysaccharide matrix on the catheter surface. The initial step in biofilm formation is adherence of planktonic organisms to the catheter surface. Attached organisms divide to form microcolonies and secrete an extracellular polysaccharide matrix. Under stress conditions, these organisms can detach and become planktonic, resulting in bacteremia that can allow the bacteria to colonize a new site. Systemic antibiotics are able to eliminate planktonic organisms released from the biofilm but are often ineffective in treating infections resulting from biofilm-embedded organisms. Biofilm resistance is usually multifactorial, which makes biofilm eradication difficult, and, thus, most biofilm-related infections require prompt removal of the device. Intervention strategies for biofilm-associated infections include (1) prevention of initial device contamination, (2) minimization of initial microbial cell attachment, (3) use of agents such as high-dose antibiotics or antibiofilm agent in a catheter lock solution to penetrate the biofilm matrix and kill the embedded organisms, and (4) removal of the infected device. Some antibacterials are better than others in treating biofilm-associated bacteria, such as rifampin (in combination with other antibiotics), tigecycline, daptomycin, N-acetylysteine (in combination with tigecycline), and ethanol. PMID:19084156

Aslam, Saima

2008-12-01

213

Bifunctional quaternary ammonium compounds to inhibit biofilm growth and enhance performance for activated carbon air-cathode in microbial fuel cells  

NASA Astrophysics Data System (ADS)

The slow diffusion of hydroxyl out of the catalyst layer as well as the biofouling on the surface of cathode are two problems affecting power for membrane-less air-cathode microbial fuel cells (MFCs). In order to solve both of them simultaneously, here we simply modify activated carbon air-cathode using a bifunctional quaternary ammonium compound (QAC) by forced evaporation. The maximum power density reaches 1041 ± 12 mW m-2 in an unbuffered medium (0.5 g L-1 NaCl), which is 17% higher than the control, probably due to the accelerated anion transport in the catalyst layer. After 2 months, the protein content reduced by a factor of 26 and the power density increases by 33%, indicating that the QAC modification can effectively inhibit the growth of cathodic biofilm and improve the stability of performance. The addition of NaOH and QAC epoxy have a negative effect on power production due to the clogging of pores in catalyst layer.

Li, Nan; Liu, Yinan; An, Jingkun; Feng, Cuijuan; Wang, Xin

2014-12-01

214

"Primers" on Research Techniques Used in Geomicrobiology for Students and Novices from Microbial Life Educational Resources  

NASA Astrophysics Data System (ADS)

Microbial Life Educational Resources (MLER) provides web-based resources and services that support learning about the diversity, ecology and evolution of the (geo)microbial world for students, K-12 teachers, university faculty, as well as for the general public. One of the main goals of MLER is to facilitate integration of modern research techniques and results and effective instructional practices. Two new collections of on-line resources include 1) TechniqueSheets which are 'primers' on analytical techniques commonly used in field and laboratory studies, and 2) focused case studies that demonstrate the use of these techniques in research projects supported by NSF's Microbial Observatory program. TechniqueSheets provide educators and students with essential information about common field and laboratory techniques with image-rich contemporary examples of the employment of these methods in the biogeosciences and microbial life realms. A wide variety of techniques are described including environmental sampling, biogeochemical methods, genomic methods, and microscopy. Every technique includes a general description of what the technique is and how it works, background theory, instrumentation, typical applications and limitations, sampling and sample preparation protocols, data collection, reduction, and representation; interpretations, links to the scientific literature, and collections of related teaching activities. Web-based profiles of the Microbial Observatory projects provide students with case-based learning environments that a) define the "big scientific questions," b) introduce the research teams, c) demonstrate modern research strategies and methodologies, and d) present the key scientific findings. These case studies span a variety of locations from microbial life in the extreme environments of Yellowstone National Park to the diversity of marine sponges in Florida to microbial diversity in Antarctic lakes. The goal of these websites is to help students and other novice-learners to be "critical consumers" of scientific data, to understand how the data were obtained and interpreted, to be able to ask the next important question, to be able to communicate with colleagues in related disciplines, to be able to attend a departmental seminar or read a journal article and be able to comprehend the evidence and interpretations, and ultimately, to provide the foundations that will allow students to design and implement their own research projects employing these techniques. This project was supported by NSF grants 0333402 and 0333363.

Bruckner, M. Z.; Rice, G.; Mogk, D. W.

2007-12-01

215

[Bacteria and biofilm in respiratory tract infections].  

PubMed

Biofilm is a structured community of bacterial cells included in a self-produced polymeric matrix adherent to an inert or living surface. The main property of biofilm consists of making microrganisms more resistant to exogenous insults. Antibiotic therapy typically resolves symptoms determined by planktonic cells released by biofilms but is not able to eradicate and completely clear biofilm. This is why infections sustained by biofilm-producer bacteria are often recurrent, making mandatory repeated antibiotic treatments. The typical conformation of biofilm, the phenotypical and genetical features existing among the different microrganisms confer a natural resistance to a number of antimicrobials so that it is necessary to test antimicrobial activity against the microbial species itself and also against biofilm, when it is present. Comparative studies, performed on quinolones and beta-lactams, evidenced a significant activity against biofilm produced by pneumococci, haemophyli and pseudomonas as well. PMID:19696554

Drago, Lorenzo

2009-07-01

216

Thermodynamic limits to microbial life at high salt concentrations.  

PubMed

Life at high salt concentrations is energetically expensive. The upper salt concentration limit at which different dissimilatory processes occur in nature appears to be determined to a large extent by bioenergetic constraints. The main factors that determine whether a certain type of microorganism can make a living at high salt are the amount of energy generated during its dissimilatory metabolism and the mode of osmotic adaptation used. I here review new data, both from field observations and from the characterization of cultures of new types of prokaryotes growing at high salt concentrations, to evaluate to what extent the theories formulated 12 years ago are still valid, need to be refined, or should be refuted on the basis of the novel information collected. Most data agree well with the earlier theories. Some new observations, however, are not easily explained: the properties of Natranaerobius and other haloalkaliphilic thermophilic fermentative anaerobes, growth of the sulfate-reducing Desulfosalsimonas propionicica with complete oxidation of propionate and Desulfovermiculus halophilus with complete oxidation of butyrate, growth of lactate-oxidizing sulfate reducers related to Desulfonatronovibrio at 346 g l(-1) salts at pH 9.8, and occurrence of methane oxidation in the anaerobic layers of Big Soda Lake and Mono Lake. PMID:21054738

Oren, Aharon

2011-08-01

217

Graywater Treatment Using Biofilm Reactors for Water Recycling in Advanced Life Support  

Microsoft Academic Search

Preliminary experiments for the Bio-Regenerative Environmental Air Treatment for Health (BREATHe) system have been conducted. The BREATHe system is part of a multicomponent life support system and is designed to treat contaminated liquid and gas waste streams simultaneously withing a closed life support system. Experiments focused on the BREATHe I system used for treatment of graywater and waste gas from

Sybil E. Sharvelle; M. Katherine Banks; Katherine Graham; Erin Maloney

2008-01-01

218

Microbial life at high salt concentrations: phylogenetic and metabolic diversity  

PubMed Central

Halophiles are found in all three domains of life. Within the Bacteria we know halophiles within the phyla Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria, Spirochaetes, and Bacteroidetes. Within the Archaea the most salt-requiring microorganisms are found in the class Halobacteria. Halobacterium and most of its relatives require over 100–150 g/l salt for growth and structural stability. Also within the order Methanococci we encounter halophilic species. Halophiles and non-halophilic relatives are often found together in the phylogenetic tree, and many genera, families and orders have representatives with greatly different salt requirement and tolerance. A few phylogenetically coherent groups consist of halophiles only: the order Halobacteriales, family Halobacteriaceae (Euryarchaeota) and the anaerobic fermentative bacteria of the order Halanaerobiales (Firmicutes). The family Halomonadaceae (Gammaproteobacteria) almost exclusively contains halophiles. Halophilic microorganisms use two strategies to balance their cytoplasm osmotically with their medium. The first involves accumulation of molar concentrations of KCl. This strategy requires adaptation of the intracellular enzymatic machinery, as proteins should maintain their proper conformation and activity at near-saturating salt concentrations. The proteome of such organisms is highly acidic, and most proteins denature when suspended in low salt. Such microorganisms generally cannot survive in low salt media. The second strategy is to exclude salt from the cytoplasm and to synthesize and/or accumulate organic 'compatible' solutes that do not interfere with enzymatic activity. Few adaptations of the cells' proteome are needed, and organisms using the 'organic-solutes-in strategy' often adapt to a surprisingly broad salt concentration range. Most halophilic Bacteria, but also the halophilic methanogenic Archaea use such organic solutes. A variety of such solutes are known, including glycine betaine, ectoine and other amino acid derivatives, sugars and sugar alcohols. The 'high-salt-in strategy' is not limited to the Halobacteriaceae. The Halanaerobiales (Firmicutes) also accumulate salt rather than organic solutes. A third, phylogenetically unrelated organism accumulates KCl: the red extremely halophilic Salinibacter (Bacteroidetes), recently isolated from saltern crystallizer brines. Analysis of its genome showed many points of resemblance with the Halobacteriaceae, probably resulting from extensive horizontal gene transfer. The case of Salinibacter shows that more unusual types of halophiles may be waiting to be discovered. PMID:18412960

Oren, Aharon

2008-01-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

220

Biofilms' Role in Planktonic Cell Proliferation  

PubMed Central

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

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

2013-01-01

221

Innovative strategies to overcome biofilm resistance.  

PubMed

We review the recent literature concerning the efficiency of antimicrobial photodynamic inactivation toward various microbial species in planktonic and biofilm cultures. The review is mainly focused on biofilm-growing microrganisms because this form of growth poses a threat to chronically infected or immunocompromised patients and is difficult to eradicate from medical devices. We discuss the biofilm formation process and mechanisms of its increased resistance to various antimicrobials. We present, based on data in the literature, strategies for overcoming the problem of biofilm resistance. Factors that have potential for use in increasing the efficiency of the killing of biofilm-forming bacteria include plant extracts, enzymes that disturb the biofilm structure, and other nonenzymatic molecules. We propose combining antimicrobial photodynamic therapy with various antimicrobial and antibiofilm approaches to obtain a synergistic effect to permit efficient microbial growth control at low photosensitizer doses. PMID:23509680

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

2013-01-01

222

Innovative Strategies to Overcome Biofilm Resistance  

PubMed Central

We review the recent literature concerning the efficiency of antimicrobial photodynamic inactivation toward various microbial species in planktonic and biofilm cultures. The review is mainly focused on biofilm-growing microrganisms because this form of growth poses a threat to chronically infected or immunocompromised patients and is difficult to eradicate from medical devices. We discuss the biofilm formation process and mechanisms of its increased resistance to various antimicrobials. We present, based on data in the literature, strategies for overcoming the problem of biofilm resistance. Factors that have potential for use in increasing the efficiency of the killing of biofilm-forming bacteria include plant extracts, enzymes that disturb the biofilm structure, and other nonenzymatic molecules. We propose combining antimicrobial photodynamic therapy with various antimicrobial and antibiofilm approaches to obtain a synergistic effect to permit efficient microbial growth control at low photosensitizer doses. PMID:23509680

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

2013-01-01

223

Permeabilizing biofilms  

DOEpatents

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

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

2008-02-19

224

Effects of seawater ozonation on biofilm development in aquaculture tanks  

Microsoft Academic Search

Microbial biofilms developing in aquaculture tanks represent a reservoir for opportunistic bacterial pathogens, and procedures to control formation and bacterial composition of biofilms are important for the development of commercially viable aquaculture industries. This study investigated the effects of seawater ozonation on biofilm development on microscope glass slides placed in small-scale aquaculture tanks containing the live feed organism Artemia. Fluorescence

Matthias Wietz; Michael R. Hall; Lone Høj

2009-01-01

225

Formation of aerobic granular sludge biofilms for sustainable wastewater treatment  

E-print Network

ENAC/ Formation of aerobic granular sludge biofilms for sustainable wastewater treatment David G to aerobic granular microbial biofilms (Confocal laser scanning microscopy analysis) Floc viscous bulking) Exopolysaccharide-producing Zoogloea spp. form the early-stage aerobic granular biofilms, and then decline

226

[Urinary catheter biofilm infections].  

PubMed

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

Holá, V; R?zicka, F

2008-04-01

227

Microbial Weathering of Olivine  

NASA Astrophysics Data System (ADS)

Controlled microbial weathering of olivine experiments displays a unique style of nanoetching caused by biofilm attachment to mineral surfaces. We are investigating whether the morphology of biotic nanoetching can be used as a biosignature.

Longazo, T. G.; Wentworth, S. J.; Southam, G.; McKay, D. S.

2002-03-01

228

Detection of in-situ derivatized peptides in microbial biofilms by laser desorption 7.87 eV postionizaton mass spectrometry.  

SciTech Connect

A novel analytical method based on laser desorption postionization mass spectrometry (LDPI-MS) was developed to investigate the competence and sporulation factor-a pentapeptide of amino acid sequence ERGMT-within intact Bacillus subtilis biofilms. Derivatization of the neat ERGMT peptide with quinoline- and anthracene-based tags was separately used to lower the peptide ionization potential and permit direct ionization by 7.87-eV vacuum ultraviolet radiation. The techniques of mass shifting and selective ionization of the derivatized peptide were combined here to permit detection of ERGMT peptide within intact biofilms by LDPI-MS, without any prior extraction or chromatographic separation. Finally, imaging MS specific to the derivatized peptide was demonstrated on an intact biofilm using LDPI-MS. The presence of ERGMT in the biofilms was verified by bulk extraction/LC-MS. However, MALDI imaging MS analyses were unable to detect ERGMT within intact biofilms.

Edirisinghe, P. D.; Moore, J. F.; Skinner-Nemec, K. A.; Lindberg, C.; Giometti, C. S.; Veryovkin, I. V.; Hunt, J. E.; Pellin, M. J.; Hanley, L.; Biosciences Division; Univ. of Illinois at Chicago; MassThink

2007-01-01

229

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

PubMed

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

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

2005-03-01

230

Investigation of multidrug efflux pumps in relation to fluconazole resistance in Candida albicans biofilms  

Microsoft Academic Search

A main characteristic associated with microbial biofilms is their increased resistance to anti- microbial chemotherapies. However, at present very little is known about the phenotypic changes that occur during the transition from the planktonic to the biofilm mode of growth. Candida albicans biofilms displayed an organized three-dimensional structure, and consisted of a dense network of yeasts and filamentous cells deeply

Gordon Ramage; Stefano Bachmann; Thomas F. Patterson; Brian L. Wickes; José L. López-Ribot

2002-01-01

231

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

Microsoft Academic Search

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

Rocco L. Mancinelli

232

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

233

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

PubMed

Deep-sea hypersaline anoxic lakes (DHALs) of the Eastern Mediterranean represent some of the most hostile environments on our planet. We investigated microbial life in the recently discovered Lake Medee, the largest DHAL found to-date. Medee has two unique features: a complex geobiochemical stratification and an absence of chemolithoautotrophic Epsilonproteobacteria, which usually play the primary role in dark bicarbonate assimilation in DHALs interfaces. Presumably because of these features, Medee is less productive and exhibits reduced diversity of autochthonous prokaryotes in its interior. Indeed, the brine community almost exclusively consists of the members of euryarchaeal MSBL1 and bacterial KB1 candidate divisions. Our experiments utilizing cultivation and [(14)C]-assimilation, showed that these organisms at least partially rely on reductive cleavage of osmoprotectant glycine betaine and are engaged in trophic cooperation. These findings provide novel insights into how prokaryotic communities can adapt to salt-saturated conditions and sustain active metabolism at the thermodynamic edge of life. PMID:24352146

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

2013-01-01

234

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

PubMed Central

Deep-sea hypersaline anoxic lakes (DHALs) of the Eastern Mediterranean represent some of the most hostile environments on our planet. We investigated microbial life in the recently discovered Lake Medee, the largest DHAL found to-date. Medee has two unique features: a complex geobiochemical stratification and an absence of chemolithoautotrophic Epsilonproteobacteria, which usually play the primary role in dark bicarbonate assimilation in DHALs interfaces. Presumably because of these features, Medee is less productive and exhibits reduced diversity of autochthonous prokaryotes in its interior. Indeed, the brine community almost exclusively consists of the members of euryarchaeal MSBL1 and bacterial KB1 candidate divisions. Our experiments utilizing cultivation and [14C]-assimilation, showed that these organisms at least partially rely on reductive cleavage of osmoprotectant glycine betaine and are engaged in trophic cooperation. These findings provide novel insights into how prokaryotic communities can adapt to salt-saturated conditions and sustain active metabolism at the thermodynamic edge of life. PMID:24352146

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

2013-01-01

235

Microbial ecology and host-microbiota interactions during early life stages  

PubMed Central

The role of human microbiota has been redefined during recent years and its physiological role is now much more important than earlier understood. Intestinal microbial colonization is essential for the maturation of immune system and for the developmental regulation of the intestinal physiology. Alterations in this process of colonization have been shown to predispose and increase the risk to disease later in life. The first contact of neonates with microbes is provided by the maternal microbiota. Moreover, mode of delivery, type of infant feeding and other perinatal factors can influence the establishment of the infant microbiota. Taken into consideration all the available information it could be concluded that the exposure to the adequate microbes early in gestation and neonatal period seems to have a relevant role in health. Maternal microbial environment affects maternal and fetal immune physiology and, of relevance, this interaction with microbes at the fetal-maternal interface could be modulated by specific microbes administered to the pregnant mother. Indeed, probiotic interventions aiming to reduce the risk of immune-mediated diseases may appear effective during early life. PMID:22743759

Collado, Maria Carmen; Cernada, Maria; Baüerl, Christine; Vento, Máximo; Pérez-Martínez, Gaspar

2012-01-01

236

Characterization of the deep microbial life in the Altmark natural gas reservoir  

NASA Astrophysics Data System (ADS)

Within the framework of the CLEAN project (CO2 Largescale Enhanced gas recovery in the Altmark Natural gas field) technical basics with special emphasis on process monitoring are explored by injecting CO2 into a gas reservoir. Our study focuses on the investigation of the in-situ microbial community of the Rotliegend natural gas reservoir in the Altmark, located south of the city Salzwedel, Germany. In order to characterize the microbial life in the extreme habitat we aim to localize and identify microbes including their metabolism influencing the creation and dissolution of minerals. The ability of microorganisms to speed up dissolution and formation of minerals might result in changes of the local permeability and the long-term safety of CO2 storage. However, geology, structure and chemistry of the reservoir rock and the cap rock as well as interaction with saline formation water and natural gases and the injected CO2 affect the microbial community composition and activity. The reservoir located at the depth of approximately 3500 m, is characterised by high salinity (420 g/l) and temperatures up to 127°C. It represents an extreme environment for microbial life and therefore the main focus is on hyperthermophilic, halophilic anaerobic microorganisms. In consequence of the injection of large amounts of CO2 in the course of a commercial EGR (Enhanced Gas Recovery), the environmental conditions (e.g. pH, temperature, pressure and solubility of minerals) for the autochthonous microorganisms will change. Genetic profiling of amplified 16S rRNA genes are applied for detecting structural changes in the community by using PCR- SSCP (PCR-Single-Strand-Conformation Polymorphism), DGGE (Denaturing Gradient Gel Electrophoresis) and 16S rRNA cloning. First results of the baseline survey indicate the presence of microorganisms similar to representatives from other deep environments. The sequence analyses revealed the presence of several H2-oxidising bacteria (Hydrogenophaga sp., Adicdovorax sp., Ralstonia sp., Pseudomonas sp.), thiosulfate-oxidising bacteria (Diaphorobacter sp.) and biocorrosive thermophilic microorganisms, which have not previously been cultivated. Furthermore, several uncultivated microorganisms were found, that were similar to representatives from other saline, hot, anoxic, deep environments. However, due to the hypersaline and hyperthermophilic reservoir conditions, cell numbers are low, so that the quantification of those microorganisms as well as the determination of microbial activity was not yet possible. Microbial monitoring methods have to be further developed to study microbial activities under these extreme conditions to access their influence on the EGR technique and on enhancing the long term safety of the process by fixation of carbon dioxide by precipitation of carbonates. We thank GDF SUEZ for providing the data for the Rotliegend reservoir, sample material and supporting sampling campaigns. The CLEAN project is funded by the German Federal Ministry of Education and Research (BMBF) in the framework of the GEOTECHNOLOGIEN Program.

Morozova, D.; Alawi, M.; Vieth-Hillebrand, A.; Kock, D.; Krüger, M.; Wuerdemann, H.

2010-12-01

237

DIFFUSION IN BIOFILMS RESPIRING ON ELECTRODES  

PubMed Central

The goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (De) in biofilms respiring on electrodes. Two model electrochemically active biofilms, Geobacter sulfurreducens PCA and Shewanella oneidensis MR-1, were investigated. A novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (PFG-NMR) techniques was used. PFG-NMR allowed noninvasive, nondestructive, high spatial resolution in situ De measurements in living biofilms respiring on electrodes. The electrodes were polarized so that they would act as the sole terminal electron acceptor for microbial metabolism. We present our results as both two-dimensional De heat maps and surface-averaged relative effective diffusion coefficient (Drs) depth profiles. We found that 1) Drs decreases with depth in G. sulfurreducens biofilms, following a sigmoid shape; 2) Drs at a given location decreases with G. sulfurreducens biofilm age; 3) average De and Drs profiles in G. sulfurreducens biofilms are lower than those in S. oneidensis biofilms—the G. sulfurreducens biofilms studied here were on average 10 times denser than the S. oneidensis biofilms; and 4) halting the respiration of a G. sulfurreducens biofilm decreases the De values. Density, reflected by De, plays a major role in the extracellular electron transfer strategies of electrochemically active biofilms. PMID:23420623

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

2013-01-01

238

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

PubMed Central

Biofilms constitute the predominant form of microbial life and a potent reservoir for innate antibiotic resistance in systemic infections. In the spore-forming bacterium Bacillus subtilis, the transition from a planktonic to sessile state is mediated by mutually exclusive regulatory pathways controlling the expression of genes required for flagellum or biofilm formation. Here, we identify mstX and yugO as novel regulators of biofilm formation in B. subtilis. We show that expression of mstX and the downstream putative K+ efflux channel, yugO, is necessary for biofilm development in B. subtilis, and that overexpression of mstX induces biofilm assembly. Transcription of the mstX-yugO operon is under the negative regulation of SinR, a transcription factor that governs the switch between planktonic and sessile states. Furthermore, mstX regulates the activity of Spo0A through a positive autoregulatory loop involving KinC, a histidine kinase that is activated by potassium leakage. The addition of potassium abrogated mstX-mediated biofilm formation. Our findings expand the role of Spo0A and potassium homeostasis in the regulation of bacterial development. PMID:23737939

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

2013-01-01

239

Spatial and temporal variability of biomarkers and microbial diversity reveal metabolic and community flexibility in Streamer Biofilm Communities in the Lower Geyser Basin, Yellowstone National Park.  

PubMed

Detailed analysis of 16S rRNA and intact polar lipids (IPLs) from streamer biofilm communities (SBCs), collected from geochemically similar hot springs in the Lower Geyser Basin, Yellowstone National Park, shows good agreement and affirm that IPLs can be used as reliable markers for the microbial constituents of SBCs. Uncultured Crenarchaea are prominent in SBS, and their IPLs contain both glycosidic and mixed glyco-phospho head groups with tetraether cores, having 0-4 rings. Archaeal IPL contributions increase with increasing temperature and comprise up to one-fourth of the total IPL inventory at >84 °C. At elevated temperatures, bacterial IPLs contain abundant glycosidic glycerol diether lipids. Diether and diacylglycerol (DAG) lipids with aminopentanetetrol and phosphatidylinositol head groups were identified as lipids diagnostic of Aquificales, while DAG glycolipids and glyco-phospholipids containing N-acetylgycosamine as head group were assigned to members of the Thermales. With decreasing temperature and concomitant changes in water chemistry, IPLs typical of phototrophic bacteria, such as mono-, diglycosyl, and sulfoquinovosyl DAG, which are specific for cyanobacteria, increase in abundance, consistent with genomic data from the same samples. Compound-specific stable carbon isotope analysis of IPL breakdown products reveals a large isotopic diversity among SBCs in different hot springs. At two of the hot springs, 'Bison Pool' and Flat Cone, lipids derived from Aquificales are enriched in (13) C relative to biomass and approach values close to dissolved inorganic carbon (DIC) (approximately 0‰), consistent with fractionation during autotrophic carbon fixation via the reversed tricarboxylic acid pathway. At a third site, Octopus Spring, the same Aquificales-diagnostic lipids are 10‰ depleted relative to biomass and resemble stable carbon isotope values of dissolved organic carbon (DOC), indicative of heterotrophy. Other bacterial and archaeal lipids show a similar variance, with values resembling the DIC or DOC pool or a mixture thereof. This variance cannot be explained by hot spring chemistry or temperature alone, but instead, we argue that intermittent input of exogenous organic carbon can result in metabolic shifts of the chemotrophic communities from autotrophy to heterotrophy and vice versa. PMID:23981055

Schubotz, F; Meyer-Dombard, D R; Bradley, A S; Fredricks, H F; Hinrichs, K-U; Shock, E L; Summons, R E

2013-11-01

240

The effects of chlorine, washing and evisceration on microbial population and storage-life of fresh fish  

E-print Network

THE EFFECTS OF CHLORINE, WASHING AND EVISCERATION ON THE MICROBIAL POPULATION AND STORAGE-LIFE OF FRESH FISH A Thesis by CHARLES MADE NEAL Submitted to the Graduate College of Texas ASM Univ rsity in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE Augu t 1977 Major Subject: Food Technology THE EFFECTS OF CHLORINE& WASHING lQ', D EVISCEPATION ON THE MICROBIAL POPULATION AND STORAGE-LIFE OF FRESH FISH A Thesis by CHARLES WADE NEAL Approved as to style and content...

Neal, Charles Wade

2012-06-07

241

Photocatalytic inactivation of biofilms on bioactive dental adhesives.  

PubMed

Biofilms are the most prevalent mode of microbial life in nature and are 10-1000 times more resistant to antibiotics than planktonic bacteria. Persistent biofilm growth associated at the margin of a dental restoration often leads to secondary caries, which remains a challenge in restorative dentistry. In this work, we present the first in vitro evaluation of on-demand photocatalytic inactivation of biofilm on a novel dental adhesive containing TiO2 nanoparticles. Streptococcus mutans biofilm was cultured on this photocatalytic surface for 16 h before photocatalytic treatment with ultraviolet-A (UV-A) light. UV-A doses ranging from 3 to 43 J/cm(2) were applied to the surface and the resulting viability of biofilms was evaluated with a metabolic activity assay incorporating phenol red that provided a quantitative measure of the reduction in viability due to the photocatalytic treatments. We show that an UV-A irradiation dose of 8.4 J/cm(2) leads to one order of magnitude reduction in the number of biofilm bacteria on the surface of the dental adhesives while as much as 5-6 orders of magnitude reduction in the corresponding number can be achieved with a dose of 43 J/cm(2). This material maintains its functional properties as an adhesive in restorative dentistry while offering the possibility of a novel dental procedure in the treatment or prevention of bacterial infections via on-demand UV-A irradiation. Similar materials could be developed for the treatment of additional indications such as peri-implantits. PMID:23847027

Cai, Yanling; Strømme, Maria; Melhus, Asa; Engqvist, Håkan; Welch, Ken

2014-01-01

242

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

NASA Astrophysics Data System (ADS)

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 (< 0.3 µm) were recorded on a unique FIB section (15 x 10 x 3 µm3) of the JCMB. A 300 nm resolution was reached at 2500 eV on the ID21 scanning X-ray microscope (SXM) and a 120x165 (horizontal x vertical) nm at 17450 eV on ID22NI at the European Synchrotron Radiation Facility (ESRF). All maps reveal chemical heterogeneities not previously discernible by scanning the same FIB cut using micron resolution. The feasibility of high-resolution analyses with high flux on rock samples was first shown for samples that had in this respect an ideal hotspot geometry in a uniform silica matrix [3, 4]. Our FIB sample preparation ensures negligible thickness variations so quantitation of all the metals in the JCMB is presently only limited by the important intrinsic heterogeneity of the sample. Methods to deal with micrometer bulk heterogeneity have just been developed by performing redundant volumetric scans in fluorescence tomography to counterbalance the complex sample geometry [5]. An alternative methodology more adapted to the thin slice geometry is tested here. A relationship between the ratio of the Compton to Rayleigh (C-R) scatterings and the average atomic number (Zave), only established with unpolarized X-rays [6], was measured using fully polarized synchrotron beams [7]. C-R peaks measured on thick Astimex standards (1 mm) and those calculated from Monte-Carlo simulations of thick and thin (100 µm and 1 µm) samples having the same compositions were analyzed using a version of the PyMCA software [8] specially optimised for this purpose. The empirical relations of the type Zave = a•(C/R)b obtained for the three analyses sets provide a comprehensive set of calibrations suitable for any sample of any thickness. On the basis of these calibrations, we inferred positions and concentrations of undetected low-Z phases in the JCMB and further corrected the concentrations of the detected metals in the organic phases. 1. Westall F., et al., 2011. Earth & Planet. Sci. Lett., 310, 468-479. 2. Zerkle A L., et al., 2005. Am. J. Science, 305, 467-502. 3. Westphal A. J., et al., 2010. AIP 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.

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

2012-04-01

243

Can nanotechnology deliver the promised benefits without negatively impacting soil microbial life?  

PubMed

Nanotechnology exploits the enhanced reactivity of materials at the atomic scale to improve various applications for humankind. In agriculture, potential nanotechnology applications include crop protection and fertilization. However, such benefits could come with risks for the environment: non-target plants, plant-beneficial soil microbes and other life forms could be impacted if nanoparticles (nanomaterials) contaminate the environment. This review evaluates the impact of the major metallic nanoparticles (Ag, ZnO, CuO, CeO2 , TiO2 , and FeO-based nanoparticles) on soil microbes involved in agricultural processes. The current literature indicate that in addition to population and organismal-scale effects on microbes, other subtle impacts of nanoparticles are seen in the nitrogen cycle, soil enzyme activities, and processes involved in iron metabolism, phytohormone, and antibiotic production. These effects are negative or positive, the outcome being dependent on specific nanoparticles. Collectively, published results suggest that nanotechnology portends considerable, many negative, implications for soil microbes and, thus, agricultural processes that are microbially driven. Nonetheless, the potential of plant and soil microbial processes to mitigate the bioreactivity of nanoparticles also are observed. Whereas the roots of most terrestrial plants are associated with microbes, studies of nanoparticle interactions with plants and microbes are generally conducted separately. The few studies in actual microbe-plant systems found effects of nanoparticles on the functioning of arbuscular mycorrhizal fungi, nitrogen fixation, as well as on the production of microbial siderophores in the plant rhizosphere. It is suggested that a better understanding of the agro-ecological ramifications of nanoparticles would require more in-depth interactive studies in combined plant-microbe-nanoparticle systems. PMID:24913194

Dimkpa, Christian O

2014-09-01

244

Pseudomonas aeruginosa biofilm infections: From molecular biofilm biology to new treatment possibilities.  

PubMed

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, biofilm infections where P. aeruginosa plays an important role are described. Subsequently, current insights into the molecular mechanisms involved in P. aeruginosa biofilm formation and the associated antimicrobial tolerance are reviewed. And finally, based on our knowledge about molecular biofilm biology, a number of therapeutic strategies for combat of P. aeruginosa biofilm infections are presented. PMID:25399808

Tolker-Nielsen, Tim

2014-12-01

245

Structure and function of bacterial biofilms  

SciTech Connect

Two major problems are troubling researchers studying biofilms at microscale: lack of standard procedures and inadequacy of the existing theoretical framework to quantify the observations. As the lack of standard procedures can be, to an extent, mitigated by careful description of experimental protocols and exercising caution when comparing results generated in different laboratories, lack of a proper theoretical framework to interpret the results is a major factor inhibiting progress in understanding biofilm processes. This paper presents examples of microscale biofilm research projects related to the nature of intrabiofilm mass transport and to the nature of electrochemical interactions between biofilms and metals. The selection of topics intended to satisfy two goals (1) to stimulate interest and evoke appreciation for fundamental microscale biofilm research and (2) to demonstrate relevance of microscale biofilm research to Microbially Influenced Corrosion.

Lewandowski, Z. [Montana State Univ., Bozeman, MT (United States). Center for Biofilm Engineering

1998-12-31

246

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

PubMed

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

Merhej, Vicky; Raoult, Didier

2012-01-01

247

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

PubMed Central

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

Merhej, Vicky; Raoult, Didier

2012-01-01

248

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

Microsoft Academic Search

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

Jacek Wierzchos; Carmen Ascaso

2002-01-01

249

A Technique To Quantify the Population Size and Composition of the Biofilm Component in Communities of Bacteria in the Phyllosphere  

Microsoft Academic Search

The presence of microbial biofilms in the phyllosphere of terrestrial plants has recently been demonstrated, but few techniques to study biofilms associated with living plant tissues are available. Here we report a technique to estimate the proportion of the bacterial population on leaves that is assembled in biofilms and to quantitatively isolate bacteria from the biofilm and nonbiofilm (solitary) components

CINDY E. MORRIS; JEAN-MICHEL MONIER; MARIE-AGNES JACQUES

1998-01-01

250

Effects of silver nanoparticles on wastewater biofilms.  

PubMed

The goal of this research is to understand the potential antibacterial effect of silver nanoparticles (Ag-NPs) on biological wastewater treatment processes. It was found that original wastewater biofilms are highly tolerant to the Ag-NP treatment. With an application of 200 mg Ag/L Ag-NPs, the reduction of biofilm bacteria measured by heterotrophic plate counts was insignificant after 24 h. After the removal of loosely bound extracellular polymeric substances (EPS), the viability of wastewater biofilms was reduced when treated under the same conditions. By contrast, when treated as planktonic pure culture, bacteria isolated from the wastewater biofilms were highly vulnerable to Ag-NPs. With a similar initial cell density, most bacteria died within 1 h with the application of 1 mg Ag/L Ag-NPs. The results obtained here indicate that EPS and microbial community interactions in the biofilms play important roles in controlling the antimicrobial effects of Ag-NPs. In addition, slow growth rates may enhance the tolerance of certain bacteria to Ag-NPs. The effects of Ag-NPs on the entire microbial community in wastewater biofilms were analyzed using polymerase chain reaction-denaturing gradient gel electrophoresis, PCR-DGGE. The studies showed that the microbial susceptibility to Ag-NPs is different for each microorganism. For instance, Thiotrichales is more sensitive to Ag-NPs than other biofilm bacteria. PMID:21940033

Sheng, Zhiya; Liu, Yang

2011-11-15

251

Deliberations on Microbial Life in the Subglacial Lake Vostok, East Antarctica  

NASA Astrophysics Data System (ADS)

The objective was to estimate microbial contents of accretion (lake originating) ice from the Lake Vostok buried beneath 4-km thick East Antarctic ice sheet with the ultimate goal to discover microbial life in this extreme icy environment featured by no light, close to freezing point temperature, ultra-low DOC contents, and an excess of oxygen. The PCR based bacterial and archaeal 16S ribosomal RNA gene sequencing constrained by Forensic Biology and Ancient DNA research criteria was used as a main approach. Epifluorescent and confocal microscopies as well as flow cytometry were implemented. DNA study showed that the accretion ice is essentially bacteria- and archaea-free. Up to now, the only accretion ice type 1 featured by mica-clay sediments presence and namely one horizon of four studied (3607m) allowed the recovery a few bacterial phylotypes. This unexpectedly included the chemolithoautotrophic thermophile Hydrogenophilus thermoluteolus and two more unclassified phylotypes all passing numerous contaminant controls. In contrast, the deeper and cleaner accretion ice 2 (three cores) with no sediments presence and near detection limit gas contents gave no reliable signals. The microbes detected in accretion ice 1 are unbelievable to resist an excess of oxygen in the lake water body (700 - 1300 mg O2/l). They are supposed to be thriving in rather warm anoxic sediments in deep faults at the lake bottom and sporadically flushing out along with sediments to the lake veins in a shallow depth bay due to a seismotectonic activity likely operating in the lake environment. A few geophysical and geological evidences support this scenario. In the bay the presence of mica-clay sediments, higher accretion rate due to relief rise and likely oxygen-depleted upper layer of water can provide microbes with a chance to escape the high oxygen tension by the rapid entrapment into accretion ice 1. Sediment-free accretion ice 2, which forms above a deeper part of the lake, shows no evidence for reasonable source for microbe contribution given highly oxygenated lake water environment. Microscopy and flow cytometry trials on strictly decontaminated ice samples gave supporting results. While microscopy failed to reveal cells because the local concentrations were below the detection limit, the flow cytometry succeeded in a preliminary estimate of 9 and 24 cells/ml for accretion 1 (3561m) and control glacial (2054m) ice samples, respectively. However, given the ratio contaminants to indigenous cells is about 10:1 (from PCR results), the genuine microbial contents for both accretion and glacial ice samples is expected to be as low as 1 cell/ml what practically means "sterile" conditions. Thus, the accretion ice from Lake Vostok contains the very low unevenly distributed biomass indicating that the water body (at least upper layer) should also be hosting a highly sparse life, if any. By this, the Lake Vostok for the first time could present the big natural "sterile" water body on Earth providing a unique test area for searching for life on icy moons and planets. The search for life in Lake Vostok is constrained by a high chance of forward-contamination which can be minimized by using of stringent decontamination procedures and comprehensive biological controls.

Bulat, S.; Alekhina, I.; Lipenkov, V.; Lukin, V.; Marie, D.; Petit, J.

2004-12-01

252

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

PubMed Central

Abstract Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai‘i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai‘i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai‘i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies. Key Words: Biosignatures—Astrobiology—Bacteria—Caves—Life detection—Microbial mats. Astrobiology 11, 601–618. PMID:21879833

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

2011-01-01

253

Microfluidics Expanding the Frontiers of Microbial Ecology  

PubMed Central

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

Rusconi, Roberto; Garren, Melissa; Stocker, Roman

2014-01-01

254

Microbial life in cold, sulfur-rich environments: Investigations of an Arctic ecosystem and implications for life detection at Europa  

NASA Astrophysics Data System (ADS)

Exobiological investigations require a detailed understanding of life's interactions with its environment here on Earth before we can confidently recognize signs of these interactions at other worlds such as Europa. Using a cold, sulfur-based ecosystem at Borup Fiord pass in the Canadian High Arctic as a study site, I investigated how the supraglacial non-ice materials are represented across different scales in spectral data, how microbiology is influencing the mineralogy of the site, and whether the products of microbial sulfide oxidation preserve indications of their biogenic origin. A systematic scale-integrated approach was applied to query orbital (Hyperion), field, and laboratory spectra to identify sulfur-rich materials precipitated on a glacier. While sulfur, the main constituent of the deposits, is well represented in Hyperion data, minor constituents such as calcite and gypsum are partially or entirely masked. Absorption features of sulfates, where present, are shifted in wavelength due to the effects of mixing or temperature. Autonomous detection methods were successfully applied to monitor the generation and extent of the deposits, which show spectral similarities to Europa's non-ice materials. Geomicrobiological cultivation of sulfide oxidizing bacteria succeeded in demonstrating that the microbiological community present at the site has the potential to catalyze the generation of sulfur deposits. Sulfur generated in culture is present as biomineralized structures comprised of microbial filaments and sheaths along which sulfur globules are deposited. Consortia producing these structures are dominated by gamma-Proteobacteria closely related to Marinobacter, not previously known to oxidize sulfide. The sulfur structures produced by these consortia are not observed in abiotic controls and have the potential to serve as morphological biosignatures. Investigations into the biogenicity of field deposits reveal mineral assemblages with similar morphologies to those generated in culture. X-ray diffraction analyses show some evidence for rosickyite, a metastable form of biogenic sulfur. Mid-infrared laboratory spectroscopy also indicates the presence of organic functional groups diagnostic of proteins and fatty acids within the sulfur deposits. These combined investigations suggest that sulfur minerals extruded onto Europa's near surface, analogous to those of Borup Fiord pass, have the potential to contain identifiable biosignatures which low-temperature conditions could help stabilize and preserve.

Gleeson, Damhnait Fagan

2009-12-01

255

Microbial community structure across the tree of life in the extreme R?o Tinto  

PubMed Central

Understanding biotic versus abiotic forces that shape community structure is a fundamental aim of microbial ecology. The acidic and heavy metal extreme Río Tinto (RT) in southwestern Spain provides a rare opportunity to conduct an ecosystem-wide biodiversity inventory at the level of all three domains of life, because diversity there is low and almost exclusively microbial. Despite improvements in high-throughput DNA sequencing, environmental biodiversity studies that use molecular metrics and consider entire ecosystems are rare. These studies can be prohibitively expensive if domains are considered separately, and differences in copy number of eukaryotic ribosomal RNA genes can bias estimates of relative abundances of phylotypes recovered. In this study we have overcome these barriers (1) by targeting all three domains in a single polymerase chain reaction amplification and (2) by using a replicated sampling design that allows for incidence-based methods to extract measures of richness and carry out downstream analyses that address community structuring effects. Our work showed that combined bacterial and archaeal richness is an order of magnitude higher than eukaryotic richness. We also found that eukaryotic richness was highest at the most extreme sites, whereas combined bacterial and archaeal richness was highest at less extreme sites. Quantitative community phylogenetics showed abiotic forces to be primarily responsible for shaping the RT community structure. Canonical correspondence analysis revealed co-occurrence of obligate symbionts and their putative hosts that may contribute to biotic forces shaping community structure and may further provide a possible mechanism for persistence of certain low-abundance bacteria encountered in the RT. PMID:20631808

Amaral-Zettler, Linda A; Zettler, Erik R; Theroux, Susanna M; Palacios, Carmen; Aguilera, Angeles; Amils, Ricardo

2011-01-01

256

Minimum information about a biofilm experiment (MIABiE): standards for reporting experiments and data on sessile microbial communities living at interfaces.  

PubMed

The minimum information about a biofilm experiment (MIABiE) initiative has arisen from the need to find an adequate and scientifically sound way to control the quality of the documentation accompanying the public deposition of biofilm-related data, particularly those obtained using high-throughput devices and techniques. Thereby, the MIABiE consortium has initiated the identification and organization of a set of modules containing the minimum information that needs to be reported to guarantee the interpretability and independent verification of experimental results and their integration with knowledge coming from other fields. MIABiE does not intend to propose specific standards on how biofilms experiments should be performed, because it is acknowledged that specific research questions require specific conditions which may deviate from any standardization. Instead, MIABiE presents guidelines about the data to be recorded and published in order for the procedure and results to be easily and unequivocally interpreted and reproduced. Overall, MIABiE opens up the discussion about a number of particular areas of interest and attempts to achieve a broad consensus about which biofilm data and metadata should be reported in scientific journals in a systematic, rigorous and understandable manner. PMID:24478124

Lourenço, Anália; Coenye, Tom; Goeres, Darla M; Donelli, Gianfranco; Azevedo, Andreia S; Ceri, Howard; Coelho, Filipa L; Flemming, Hans-Curt; Juhna, Talis; Lopes, Susana P; Oliveira, Rosário; Oliver, Antonio; Shirtliff, Mark E; Sousa, Ana M; Stoodley, Paul; Pereira, Maria Olivia; Azevedo, Nuno F

2014-04-01

257

Detection of Microbial Life in Glacial Samples - Laboratories Studies and Development for Field use  

NASA Astrophysics Data System (ADS)

Adenosine triphosphate (ATP) is frequently used as a proxy for bulk microbial biomass in environmental sciences and, in the food and health industries. Despite successful ATP detection in a variety of ecosystems, very little data are available on ATP levels in the glacial system. In this study, protocols for ATP detection on glacial ice and sediment samples are investigated, in order to aid in the development of a single-use device for in-field life detection, and also to increase the available data on biomass estimates in the cryosphere. ATP detection in two glacial samples reveals concentrations indistinguishable from internal blanks. Therefore, the samples were centrifuged and their particulate loads were subjected to four different extraction processes. Applying these extraction methods resulted in higher ATP concentration than samples with no extraction process; the different techniques increase the ATP detected between 5 and 15 times (also relative to an internal standard). Concurrent with the laboratory based development of extraction protocols is the development of a single-use device for the detection of ATP at the sampling site, in icy environments. The device is microfluidic-based, using commercially available reagents for the detection of ATP by bioluminescence. In order to produce a robust measure of biomass, both laboratory and field based analyses need to be carried out. This work shows the potential of ATP detection in glacial samples and the early development of a device for in situ life detection. The quantification of ATP in microfluidic format is being developed as the preliminary target for an integrated life detection and characterisation device.

Barnett, M. J.; Cullen, D. C.; Telling, J.; Wadham, J. L.; Holt, J.; Sims, M.

2007-12-01

258

Saturated hydraulic conductivity and biofilms: A theoretical approach linking pore and pedon scale  

NASA Astrophysics Data System (ADS)

The fate of active substances in the soil environment is shaped by soil physical properties as well as microbial life. Microorganisms degrading those substances occur in soil pores either in suspension or as biofilms on grain surfaces. At the same scale, i.e. pore scale, the soil physical properties texture, density, porosity, and water content have an impact on transport behaviour of active substances. Macroscopic parameters describe these processes at pedon scale; e.g. hydraulic conductivity summarizes the effect of named pore scale parameters. Narsilio et al. [2009] derived a relationship between the saturated hydraulic conductivity and pore scale water velocity fields based on Navier-Stokes equation for incompressible fluids. However, they did not analyse the influence of heterogeneity and microbial activity, whereas microorganisms, especially biofilms, do have an impact on hydraulic conductivity [Vandevivere and Baveye, 1992]. Biofilms alter the pore geometry while growing. This alteration directly influences the soil water flow field and hence the convective transport of active substances. Here, we present a way to couple the saturated hydraulic conductivity at macro scale to biomass population dynamics and pore space. The hydraulic conductivity will be analysed with regard to heterogeneous soils. The model combining fluid flow, reactive transport, and biofilm dynamics is applied to investigate the degradation and transport behaviour of pesticides in heterogeneous soils.

Richter, M.; Moenickes, S.; Richter, O.; Schröder, T.

2012-04-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

260

Staphylococcal Biofilms  

Microsoft Academic Search

\\u000a Staphylococcus epidermidis and Staphylococcus aureus are the most frequent causes of nosocomial infections and infections on indwelling medical devices, which characteristically\\u000a involve biofilms. Recent advances in staphylococcal molecular biology have provided more detailed insight into the basis of\\u000a biofilm formation in these opportunistic pathogens. A series of surface proteins mediate initial attachment to host matrix\\u000a proteins, which is followed by

M. Otto

261

Natural Microbial Assemblages Reflect Distinct Organismal and Functional Partitioning  

NASA Astrophysics Data System (ADS)

The ability to link microbial community structure to function has long been a primary focus of environmental microbiology. With the advent of community genomic and proteomic techniques, along with advances in microscopic imaging techniques, it is now possible to gain insights into the organismal and functional makeup of microbial communities. Biofilms growing within highly acidic solutions inside the Richmond Mine (Iron Mountain, Redding, California) exhibit distinct macro- and microscopic morphologies. They are composed of microorganisms belonging to the three domains of life, including archaea, bacteria and eukarya. The proportion of each organismal type depends on sampling location and developmental stage. For example, mature biofilms floating on top of acid mine drainage (AMD) pools exhibit layers consisting of a densely packed bottom layer of the chemoautolithotroph Leptospirillum group II, a less dense top layer composed mainly of archaea, and fungal filaments spanning across the entire biofilm. The expression of cytochrome 579 (the most highly abundant protein in the biofilm, believed to be central to iron oxidation and encoded by Leptospirillum group II) is localized at the interface of the biofilm with the AMD solution, highlighting that biofilm architecture is reflected at the functional gene expression level. Distinct functional partitioning is also apparent in a biological wastewater treatment system that selects for distinct polyphosphate accumulating organisms. Community genomic data from " Candidatus Accumulibacter phosphatis" dominated activated sludge has enabled high mass-accuracy shotgun proteomics for identification of key metabolic pathways. Comprehensive genome-wide alignment of orthologous proteins suggests distinct partitioning of protein variants involved in both core-metabolism and specific metabolic pathways among the dominant population and closely related species. In addition, strain- resolved proteogenomic analysis of the AMD biofilms also highlights the importance of strain heterogeneity for the maintenance of community structure and function. These findings explain the importance of genetic diversity in facilitating the stable performance of complex microbial processes. Furthermore, although very different in terms of habitat, both microbial communities exhibit distinct functional compartmentalization and demonstrate its role in sustaining microbial community structure.

Wilmes, P.; Andersson, A.; Kalnejais, L. H.; Verberkmoes, N. C.; Lefsrud, M. G.; Wexler, M.; Singer, S. W.; Shah, M.; Bond, P. L.; Thelen, M. P.; Hettich, R. L.; Banfield, J. F.

2007-12-01

262

Impairment of the Bacterial Biofilm Stability by Triclosan  

PubMed Central

The accumulation of the widely-used antibacterial and antifungal compound triclosan (TCS) in freshwaters raises concerns about the impact of this harmful chemical on the biofilms that are the dominant life style of microorganisms in aquatic systems. However, investigations to-date rarely go beyond effects at the cellular, physiological or morphological level. The present paper focuses on bacterial biofilms addressing the possible chemical impairment of their functionality, while also examining their substratum stabilization potential as one example of an important ecosystem service. The development of a bacterial assemblage of natural composition – isolated from sediments of the Eden Estuary (Scotland, UK) – on non-cohesive glass beads (<63 µm) and exposed to a range of triclosan concentrations (control, 2 – 100 µg L?1) was monitored over time by Magnetic Particle Induction (MagPI). In parallel, bacterial cell numbers, division rate, community composition (DGGE) and EPS (extracellular polymeric substances: carbohydrates and proteins) secretion were determined. While the triclosan exposure did not prevent bacterial settlement, biofilm development was increasingly inhibited by increasing TCS levels. The surface binding capacity (MagPI) of the assemblages was positively correlated to the microbial secreted EPS matrix. The EPS concentrations and composition (quantity and quality) were closely linked to bacterial growth, which was affected by enhanced TCS exposure. Furthermore, TCS induced significant changes in bacterial community composition as well as a significant decrease in bacterial diversity. The impairment of the stabilization potential of bacterial biofilm under even low, environmentally relevant TCS levels is of concern since the resistance of sediments to erosive forces has large implications for the dynamics of sediments and associated pollutant dispersal. In addition, the surface adhesive capacity of the biofilm acts as a sensitive measure of ecosystem effects. PMID:22523534

Hubas, Cedric; Behrens, Sebastian; Ricciardi, Francesco; Paterson, David M.

2012-01-01

263

Wetlands for Wastewater: a Visual Approach to Microbial Dynamics  

NASA Astrophysics Data System (ADS)

The complex character of distillery wastewater comprises high concentrations of sugars, lignins, hemicelluloses, dextrans, resins, polyphenols and organic acids which are recalcitrant to biodegradation. Microorganisms play a key role in the production and degradation of organic matter, environmental pollutants, and cycling of nutrients and metals. Due to their short life cycles microbes respond rapidly to external nutrient loading, with major consequences for the stability of biological systems. We evaluated the feasibility of wetlands to treat winery and distillery effluents in experimental systems based on constructed wetlands, including down-scaled on-site distillery wetlands, small-scale controlled greenhouse systems, and bench-scale mesocosms. Chemical, visual and molecular fingerprinting (t-RFLP) techniques were applied to study the dynamics of planktonic and attached (biofilm) communities at various points in wetlands of different size, retention time and geological substrate, and under influence of shock nutrient loadings. Variable- Pressure Scanning Electron Microscopy (VP-SEM) was applied to visualize microbial colonization, morphotype diversity and distribution, and 3D biofilm architecture. Cross-taxon and predator-prey interactions were markedly influenced by organic loading, while the presence of algae affected microbial community composition and biofilm structure. COD removal varied with geological substrate, and was positively correlated with retention time in gravel wetlands. Planktonic and biofilm communities varied markedly in different regions of the wetland and over time, as indicated by whole-community t-RFLP and VP-SEM. An integrative visual approach to community dynamics enhanced data retrieval not afforded by molecular techniques alone. The high microbial diversity along spatial and temporal gradients, and responsiveness to the physico-chemical environment, suggest that microbial communities maintain metabolic function by modifying species composition in response to fluctuations in their environment. It seems apparent that microbial community plasticity may indeed be the distinguishing characteristic of a successful wetland system.

Joubert, L.; Wolfaardt, G.; Du Plessis, K.

2007-12-01

264

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

NASA Technical Reports Server (NTRS)

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

Rothschild, L. J.

1995-01-01

265

Sulfate reducing bacteria in microbial mats: Changing paradigms, new discoveries  

E-print Network

: Sulfate-reducing bacteria; Biofilms; Carbonate precipitation; Lithification; Stromatolites; Microbial mats's 4.6 Ga history (Shen and Buick, 2004). Isotopic evidence indicates that sulfate reduction evolved

266

Performances and microbial features of a granular activated carbon packed-bed biofilm reactor capable of an efficient anaerobic digestion of olive mill wastewaters  

Microsoft Academic Search

Anaerobic digestion of olive mill wastewaters is generally performed in anaerobic contact bioreactors where the removal of toxic phenols is often unsatisfactory. In the present work we show that a granular activated carbon packed-bed biofilm reactor can be successfully used to achieve effective and reproducible wastewater decontamination even at high organic loads. A comparison of 16S rRNA gene sequences of

Lorenzo Bertin; Maria Chiara Colao; Maurizio Ruzzi; Fabio Fava

2004-01-01

267

The essential role of hydrodynamic shear force in the formation of biofilm and granular sludge  

Microsoft Academic Search

Biofilm and granular sludge processes are promising biotechnology for wastewater treatment. The formation, structure and metabolism of immobilized microbial community are associated very closely with hydrodynamic shear force in reactors. Therefore, this paper attempts to review the essential role of shear force in the formation and performance of biofilm and granular sludge. More compact, stable and denser biofilms, aerobic and

Yu Liu; Joo-Hwa Tay

2002-01-01

268

Dispersion as an Important Step in the Candida albicans Biofilm Developmental Cycle  

Microsoft Academic Search

Biofilms are dynamic microbial communities in which transitions between planktonic and sessile modes of growth occur interchangeably in response to different environmental cues. In the last decade, early events associated with C. albicans biofilm formation have received considerable attention. However, very little is known about C. albicans biofilm dispersion or the mechanisms and signals that trigger it. This is important

Priya Uppuluri; Ashok K. Chaturvedi; Anand Srinivasan; Mohua Banerjee; Anand K. Ramasubramaniam; Julia R. Köhler; David Kadosh; Jose L. Lopez-Ribot

2010-01-01

269

cDNA Microarray Analysis of Differential Gene Expression in Candida albicans Biofilm Exposed to Farnesol  

Microsoft Academic Search

Candida albicans biofilms are structured microbial communities with high levels of drug resistance. Farnesol, a quorum-sensing molecule that inhibits hyphal formation in C. albicans, has been found to prevent biofilm formation by C. albicans. There is limited information, however, about the molecular mechanism of farnesol against biofilm formation. We used cDNA microarray analysis to identify the changes in the gene

Ying-Ying Cao; Yong-Bing Cao; Zheng Xu; Kang Ying; Yao Li; Yi Xie; Zhen-Yu Zhu; Wan-Sheng Chen; Yuan-Ying Jiang

2005-01-01

270

Power output and columbic efficiencies from biofilms of Geobacter sulfurreducens comparable to mixed  

E-print Network

Power output and columbic efficiencies from biofilms of Geobacter sulfurreducens comparable the process of electron transfer on anode biofilms. To further evaluate this, Geobacter sulfurre- ducens for a microbial fuel cell. Geobacter sulfurre- ducens formed relatively uniform biofilms 3­18 mm thick

Lovley, Derek

271

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

PubMed

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

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

2010-05-01

272

Quantification of biofilm structures by the novel computer program COMSTAT  

Microsoft Academic Search

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

Arne Heydorn; Alex Toftgaard Nielsen; Morten Hentzer; Claus Sternberg; Michael Givskov; Bjarne Kjær Ersbøll; Søren Molin

2000-01-01

273

Resistance of bacterial biofilms to disinfectants: a review  

Microsoft Academic Search

A biofilm can be defined as a community of microorganisms adhering to a surface and surrounded by a complex matrix of extrapolymeric substances. It is now generally accepted that the biofilm growth mode induces microbial resistance to disinfection that can lead to substantial economic and health concerns. Although the precise origin of such resistance remains unclear, different studies have shown

A. Bridier; R. Briandet; V. Thomas; F. Dubois-Brissonnet

2011-01-01

274

Bacterial biofilms: from the Natural environment to infectious diseases  

Microsoft Academic Search

Biofilms — matrix-enclosed microbial accretions that adhere to biological or non-biological surfaces — represent a significant and incompletely understood mode of growth for bacteria. Biofilm formation appears early in the fossil record (?3.25 billion years ago) and is common throughout a diverse range of organisms in both the Archaea and Bacteria lineages, including the 'living fossils' in the most deeply

Luanne Hall-Stoodley; J. William Costerton; Paul Stoodley

2004-01-01

275

Catheter lock solutions influence staphylococcal biofilm formation on abiotic surfaces  

Microsoft Academic Search

Background. Microbial biofilms form on central venous catheters and may be associated with systemic infections as well as decreased dialysis efficiency due to catheter thrombosis. The most widely used anticoagulant catheter lock solution in the US is sodium heparin. We have previously shown that sodium heparin in clinically relevant concentrations enhances Staphylococcus aureus biofilm formation. In the present study, we

Robert M. Q. Shanks; Jennifer L. Sargent; Raquel M. Martinez; Martha L. Graber; George A. O'Toole

2006-01-01

276

Biofilms: an extra hurdle for effective antimicrobial therapy.  

PubMed

Since the 1960's much research has focused on biofilms, i.e. microbial-derived populations irreversibly attached to a surface and embedded in a self-produced polymeric matrix. In this matrix, microbial cells are protected from detrimental external factors such as heat, UV radiation and the host immune system. The most relevant biofilm-related property is the unusual high resistance to antimicrobial therapy, although the origin of this extreme resistance is still the subject of debate. Besides an overview of the main characteristics of biofilms, this review discusses the different resistance mechanisms that lead to increased biofilm-related morbidity and mortality. Adherent communities are involved in at least 65% of all human bacterial infections, particularly in cystic fibrosis and several nosocomial device- related infections. Even in healthy immunocompetent individuals, biofilm infections are rarely resolved and usually persist until the colonized surface is removed from the body. Fundamental research aiming to develop new anti-biofilm strategies will largely depend on the availability of appropriate in vitro models for production and quantification of biofilms. This review describes the most frequently used in vitro biofilm models with respect to the different pitfalls that can emerge from in vitro biofilm research. Despite extensive efforts, no antimicrobial drug has yet been found that completely eradicates adherent microbial populations. The advantages and disadvantages of the currently available therapies are described with a particular focus on antibiotics and biocides. The options and benefits of future antibiofilm therapies are discussed. PMID:20433417

Cos, P; Toté, K; Horemans, T; Maes, L

2010-01-01

277

Microscale Confinement features in microfluidic devices can affect biofilm  

SciTech Connect

Biofilms are aggregations of microbes that are encased by extra-cellular polymeric substances (EPS) and adhere to surfaces and interfaces. Biofilm development on abiotic surfaces is a dynamic process, which typically proceeds through an initial phase of adhesion of plankntonic microbes to the substrate, followed by events such as growth, maturation and EPS secretion. However, the coupling of hydrodynamics, microbial adhesion and biofilm growth remain poorly understood. Here, we investigate the effect of semiconfined features on biofilm formation. Using a microfluidic device and fluorescent time-lapse microscopy, we establish that confinement features can significantly affect biofilm formation. Biofilm dynamics change not only as a function of confinement features, but also of the total fluid flow rate, and our combination of experimental results and numerical simulations reveal insights into the link between hydrodynamics and biofilm formation.

Kumar, Aloke [ORNL] [ORNL; Karig, David K [ORNL] [ORNL; Neethirajan, Suresh [University of Guelph] [University of Guelph; Acharya, Rajesh K [ORNL] [ORNL; Mukherjee, Partha P [ORNL] [ORNL; Retterer, Scott T [ORNL] [ORNL; Doktycz, Mitchel John [ORNL] [ORNL

2013-01-01

278

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

PubMed Central

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

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

2014-01-01

279

Battling Bacterial Biofilms with Gas Discharge Plasma  

NASA Astrophysics Data System (ADS)

Most studies dealing with growth and physiology of bacteria have been carried out using free-living cells. However, most bacteria live in communities referred to as biofilms where cooperative interactions among their members make conventional methods of controlling microbial growth often ineffective. The use of gas discharge plasmas represents an alternative to traditional decontamination/sterilization methods. We studied biofilms using two organisms, Chromobacterium violaceum and Pseudomonas aeruginosa. With the first organism we demonstrated almost complete loss of cell culturability after a 5-min plasma treatment. However, additional determinations showed that non-culturable cells were still alive after short exposure times. We have recently reported the effect of plasma on P. aeruginosa biofilms grown on borosilicate coupons. In this paper, we present results for plasma treatments of 1-, 3-, and 7-day old P. aeruginosa biofilms grown on polycarbonate or stainless-steel coupons. Results indicate nearly 100% of ­biofilm inactivation after 5 min of exposure with similar inactivation kinetics for 1-, 3-, and 7-day-old biofilms, and for both materials used. The inactivation kinetics is similar for both organisms, suggesting that the method is useful regardless of the type of biofilm. AFM images show changes in biofilm structure for various plasma exposure times.

Zelaya, Anna; Vandervoort, Kurt; Brelles-Mariño, Graciela

280

Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor  

PubMed Central

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, enriched significantly in the biofilter throughout the treatment. Conclusion The silica-bead packed bed biofilm reactor developed and characterized in this study was able to significantly decontaminate anaerobically digested OMWs. Therefore, the application of an integrated anaerobic-aerobic process resulted in an improved system for valorization and decontamination of OMWs. PMID:16595023

Bertin, Lorenzo; Colao, Maria Chiara; Ruzzi, Maurizio; Marchetti, Leonardo; Fava, Fabio

2006-01-01

281

Lava cave microbial communities within mats and secondary mineral deposits: implications for life detection on other planets.  

PubMed

Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai'i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai'i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai'i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies. PMID:21879833

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

2011-09-01

282

Attachment and biofilm formation by foodborne bacteria in meat processing environments: causes, implications, role of bacterial interactions and control by alternative novel methods.  

PubMed

Attachment of potential spoilage and pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent serious challenges to the meat industry, since these may lead to cross-contamination of the products, resulting in lowered-shelf life and transmission of diseases. In meat processing environments, microorganisms are sometimes associated to surfaces in complex multispecies communities, while bacterial interactions have been shown to play a key role in cell attachment and detachment from biofilms, as well as in the resistance of biofilm community members against antimicrobial treatments. Disinfection of food contact surfaces in such environments is a challenging task, aggravated by the great antimicrobial resistance of biofilm associated bacteria. In recent years, several alternative novel methods, such as essential oils and bacteriophages, have been successfully tested as an alternative means for the disinfection of microbial-contaminated food contact surfaces. In this review, all these aspects of biofilm formation in meat processing environments are discussed from a microbial meat-quality and safety perspective. PMID:23747091

Giaouris, Efstathios; Heir, Even; Hébraud, Michel; Chorianopoulos, Nikos; Langsrud, Solveig; Møretrø, Trond; Habimana, Olivier; Desvaux, Mickaël; Renier, Sandra; Nychas, George-John

2014-07-01

283

3D-fluorescence in situ hybridization of intact, anaerobic biofilm.  

PubMed

FISH (fluorescence in situ hybridization) is a valuable technique to visualize and quantify localization of different microbial species within biofilms. Biofilm conformation can be altered during typical sample preparation for FISH, which can impact observations in multispecies biofilms, including the relative positions of cells. Here, we describe methods to preserve 3-D structure during FISH for visualization of an anaerobic coculture biofilm of Desulfovibrio vulgaris Hildenborough and Methanococcus maripaludis. PMID:24838887

Brileya, Kristen A; Camilleri, Laura B; Fields, Matthew W

2014-01-01

284

Biofilms and planktonic cells of Deinococcus geothermalis in extreme environments  

NASA Astrophysics Data System (ADS)

In addition to the several extreme environments on Earth, Space can be considered as just another exceptional environment with a unique mixture of stress factors comprising UV radiation, vacuum, desiccation, temperature, ionizing radiation and microgravity. Life that processes in these environments can depend on the life forms and their state of living. The question is whether there are different strategies for individual microorganisms compared to communities of the same organisms to cope with the different factors of their surroundings. Comparative studies of the survi-val of these communities called biofilms and planktonic cell samples of Deinococcus geothermalis stand at the focal point of the presented investigations. A biofilm is a structured community of microorganisms that live encapsulated in a matrix of extracellular polymeric substances on a surface. Microorganisms living in a biofilm usually have significantly different properties to cooperate than individually living microorganisms of the same species. An advantage of the biofilm is increased resistance to various chemical and physical effects, while the dense extracellular matrix and the outer layer of the cells protect the interior of the microbial consortium. The space experiment BOSS (Biofilm organisms surfing Space) as part the ESA experimental unit EXPOSE R-2 with a planned launch date in July 2014 will be subsequently mounted on the Russian Svesda module outside the ISS. An international team of scientists coordinated by Dr. P. Rettberg will investigate the hypothesis whether microorganisms organized as biofilm outmatch the same microorganisms exposed individually in the long-term survival of the harsh environmental conditions as they occur in space and on Mars. Another protective function in the samples could be dust par-ticles for instance Mars regolith simulant contained inside the biofilms or mixed with the planktonic cells, as additional shelter especially against the extraterrestrial UV radiation. D. geothermalis besides others, like co-cultures of Halomonas muralis and Halococcus morrhuae, Bacillus horneckiae, Chroococcidiopsis CCMEE 029 and Streptomyces + Polaromonas and Arthrobacter strains from volcanic rocks, was involved in the several preparatory test runs at the Planetary and Space Simulation facilities at the German Aerospace Center in Cologne. Results of the already carried out EVTs (Experiment Verification Test) and the SVT (Science verification test) as EXPOSE-R2 mission pre-paration tests, where investigated parameters like dehydration, temperature extremes, extraterrestrial UV radiation, simulated Martian atmosphere, and a Mars-like UV climate were tested individually as well as in combination will be presented. Following exposure to the parameters listed above, the survival of both biofilms and planktonic cells of D. geothermalis was assessed in terms of (i) culturability by colony counts on R2A medium, (ii) membrane integrity by using the Live/Dead differential staining kit, (iii) ATP content by using a commercial luminometric assay, and (iv) the presence of 16S rRNA by fluorescence in situ hybridization. So far, the results suggest that Deinococcus geothermalis remains viable in the desiccated state over weeks to months, whereas culturability, intracellular ATP levels, and membrane integrity were preserved in biofilm cells at a significantly higher level than in planktonic cells. Furthermore, cells of both sample types were able to survive simulated space and Martian conditions and showed high resistance after irradiation with monochromatic and polychromatic UV. The results will contribute to the fundamental understanding of the opportunities and limitations of viability of microorganisms organized in biofilms or as planktonic cells under the extreme environ-mental conditions of space or other planets.

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

285

Marine bacterial isolates inhibit biofilm formation and disrupt mature biofilms of Pseudomonas aeruginosa PAO1  

Microsoft Academic Search

According to the Centers for Disease Control and Prevention, biofilms cause 65% of infections in developed countries. Pseudomonas aeruginosa biofilm cause life threatening infections in cystic fibrosis infection and they are 1,000 times more tolerant to antibiotic\\u000a than the planktonic cells. As quorum sensing, hydrophobicity index and extracellular polysaccharide play a crucial role in\\u000a biofilm formation, extracts from 46 marine

Chari Nithya; Mansur Farzana Begum; Shunmugiah Karutha Pandian

2010-01-01

286

Life in Oligotropic Desert Environments: Contrasting Taxonomic and Functional Diversity of Two Microbial Mats with Metagenomics  

NASA Astrophysics Data System (ADS)

The metagenomic analysis of two microbial mats from the oligotrophic waters in the Cuatrociéngas basin reveals large differences both at taxonomic and functional level. These are explained in terms of environmental stability and nutrient availability.

Bonilla-Rosso, G.; Peimbert, M.; Olmedo, G.; Alcaraz, L. D.; Eguiarte, L. E.; Souza, V.

2010-04-01

287

Oh What a Tangled Biofilm Web Bacteria Weave  

MedlinePLUS

... a Tangled Biofilm Web Bacteria Weave Inside Life Science View All Articles | Inside Life Science Home Page Oh What a Tangled Biofilm Web ... Conversations Learning from Bacterial Chatter This Inside Life Science article also appears on LiveScience . Learn about related ...

288

Microbial profiles of commercial, vacuum-packaged, fresh pork of normal or short storage life  

Microsoft Academic Search

The microbial ecology of fresh vacuum-packed pork cuts during storage at ?1.5 °C for up to 45 days was examined to characterize rates of microbial growth and pH changes in commercially prepared products of normal storage quality. Pork loins in commercial distribution with odour defects were also studied to determine a possible cause of the defects and avoid future problems.

Richard A. Holley; Michael D. Peirson; Jocelyn Lam; Kit Bee Tan

2004-01-01

289

A novel planar flow cell for studies of biofilm heterogeneity and flow-biofilm interactions  

PubMed Central

Biofilms are microbial communities growing on surfaces, and are ubiquitous in nature, in bioreactors, and in human infection. Coupling between physical, chemical, and biological processes is known to regulate the development of biofilms; however, current experimental systems do not provide sufficient control of environmental conditions to enable detailed investigations of these complex interactions. We developed a novel planar flow cell that supports biofilm growth under complex two-dimensional fluid flow conditions. This device provides precise control of flow conditions and can be used to create well-defined physical and chemical gradients that significantly affect biofilm heterogeneity. Moreover, the top and bottom of the flow chamber are transparent, so biofilm growth and flow conditions are fully observable using non-invasive confocal microscopy and high-resolution video imaging. To demonstrate the capability of the device, we observed the growth of Pseudomonas aeruginosa biofilms under imposed flow gradients. We found a positive relationship between patterns of fluid velocity and biofilm biomass because of faster microbial growth under conditions of greater local nutrient influx, but this relationship eventually reversed because high hydrodynamic shear leads to the detachment of cells from the surface. These results reveal that flow gradients play a critical role in the development of biofilm communities. By providing new capability for observing biofilm growth, solute and particle transport, and net chemical transformations under user-specified environmental gradients, this new planar flow cell system has broad utility for studies of environmental biotechnology and basic biofilm microbiology, as well as applications in bioreactor design, environmental engineering, biogeochemistry, geomicrobiology, and biomedical research. PMID:21656713

Zhang, Wei; Sileika, Tadas S.; Chen, Cheng; Liu, Yang; Lee, Jisun; Packman, Aaron I.

2012-01-01

290

COAGGREGATION OCCURS AMONGST BACTERIA WITHIN AND BETWEEN DOMESTIC SHOWERHEAD BIOFILMS  

PubMed Central

Showerheads support the development multi-species biofilms that can be unsightly, produce malodor, and may harbor pathogens. The outer surface spray plates of many showerheads support visible biofilms that likely contain a mixture of bacteria from freshwater and potentially from human users. Coaggregation, a mechanism by which genetically distinct bacteria specifically recognize one another, may contribute to the retention and enrichment of different species within these biofilms. The aim of this work was to identify the bacterial composition of outer spray plate biofilms of three domestic shower heads and to determine the inter- and intra-biofilm coaggregation ability of each culturable isolate. The bacterial composition of the three biofilms was determined by using bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) and by culturing on R2A medium. An average of 31 genera per biofilm were identified using bTEFAP and a total of 30 isolates were cultured. Even though the microbial diversity of each showerhead biofilm differed, every cultured isolate was able to coaggregate with at least one other isolate from the same or different showerhead biofilm. Promiscuous coaggregating isolates belonged to the genera Brevundimonas, Micrococcus, and Lysobacter. This work suggests that coaggregation may be a common feature of showerhead biofilms. Characterization of the mechanisms mediating coaggregation, and the inter-species interactions they facilitate, may allow for novel strategies to inhibit biofilm development. PMID:23194413

Vornhagen, Jay; Stevens, Michael; McCormick, David; Dowd, Scot E.; Eisenberg, Joseph N.S.; Boles, Blaise R.; Rickard, Alexander H.

2014-01-01

291

Biofilm Formation Avoids Complement Immunity and Phagocytosis of Streptococcus pneumoniae  

PubMed Central

Streptococcus pneumoniae is a frequent member of the microbiota of the human nasopharynx. Colonization of the nasopharyngeal tract is a first and necessary step in the infectious process and often involves the formation of sessile microbial communities by this human pathogen. The ability to grow and persist as biofilms is an advantage for many microorganisms, because biofilm-grown bacteria show reduced susceptibility to antimicrobial agents and hinder recognition by the immune system. The extent of host protection against biofilm-related pneumococcal disease has not been determined yet. Using pneumococcal strains growing as planktonic cultures or as biofilms, we have investigated the recognition of S. pneumoniae by the complement system and its interactions with human neutrophils. Deposition of C3b, the key complement component, was impaired on S. pneumoniae biofilms. In addition, binding of C-reactive protein and the complement component C1q to the pneumococcal surface was reduced in biofilm bacteria, demonstrating that pneumococcal biofilms avoid the activation of the classical complement pathway. In addition, recruitment of factor H, the downregulator of the alternative pathway, was enhanced by S. pneumoniae growing as biofilms. Our results also show that biofilm formation diverts the alternative complement pathway activation by a PspC-mediated mechanism. Furthermore, phagocytosis of pneumococcal biofilms was also impaired. The present study confirms that biofilm formation in S. pneumoniae is an efficient means of evading both the classical and the PspC-dependent alternative complement pathways the host immune system. PMID:23649097

Domenech, Mirian; Ramos-Sevillano, Elisa; Garcia, Ernesto

2013-01-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

293

Rediscovering Biology - Unit 4: Microbial Diversity  

NSDL National Science Digital Library

This page is the jumping-off point for an educational unit on microbial diversity. There are links to a course outline and classroom activity worksheets, a 30-minute video, an online textbook chapter, images and animations that supplement the chapter, transcripts of interviews with five experts featured in the video, and a glossary and bibliography. The video and chapter cover the three domains (archaea, bacteria, eukaryotes), methods of studying the tree of life, the diversity of microbial metabolic systems, biofilms, and the role of microbes in global carbon and nitrogen cycling and human health. The course outline provides a structure for incorporating the video, the textbook chapter, and four classroom activities into a 2hr session appropriate for high school or undergraduate students.

Broadcasting, Oregon P.; Learner.org, Annenberg M.

294

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

NASA Astrophysics Data System (ADS)

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

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

1997-07-01

295

Measurement of microbial activity in soil by colorimetric observation of in situ dye reduction: an approach to detection of extraterrestrial life  

Microsoft Academic Search

BACKGROUND: Detecting microbial life in extraterrestrial locations is a goal of space exploration because of ecological and health concerns about possible contamination of other planets with earthly organisms, and vice versa. Previously we suggested a method for life detection based on the fact that living entities require a continual input of energy accessed through coupled oxidations and reductions (an electron

Ronald L Crawford; Andrzej Paszczynski; Qingyong Lang; Daniel P Erwin; Lisa Allenbach; Giancarlo Corti; Tony J Anderson; I Francis Cheng; Chien Wai; Bruce Barnes; Richard Wells; Touraj Assefi; Mohammad Mojarradi

2002-01-01

296

Tracking the autochthonous carbon transfer in stream biofilm food webs.  

PubMed

Food webs in the rhithral zone rely mainly on allochthonous carbon from the riparian vegetation. However, autochthonous carbon might be more important in open canopy streams. In streams, most of the microbial activity occurs in biofilms, associated with the streambed. We followed the autochthonous carbon transfer toward bacteria and grazing protozoa within a stream biofilm food web. Biofilms that developed in a second-order stream (Thuringia, Germany) were incubated in flow channels under climate-controlled conditions. Six-week-old biofilms received either ¹³C- or ¹²C-labeled CO?, and uptake into phospholipid fatty acids was followed. The dissolved inorganic carbon of the flow channel water became immediately labeled. In biofilms grown under 8-h light/16-h dark conditions, more than 50% of the labeled carbon was incorporated in biofilm algae, mainly filamentous cyanobacteria, pennate diatoms, and nonfilamentous green algae. A mean of 29% of the labeled carbon reached protozoan grazer. The testate amoeba Pseudodifflugia horrida was highly abundant in biofilms and seemed to be the most important grazer on biofilm bacteria and algae. Hence, stream biofilms dominated by cyanobacteria and algae seem to play an important role in the uptake of CO? and transfer of autochthonous carbon through the microbial food web. PMID:22067054

Risse-Buhl, Ute; Trefzger, Nicolai; Seifert, Anne-Gret; Schönborn, Wilfried; Gleixner, Gerd; Küsel, Kirsten

2012-01-01

297

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

298

Ecology and life history of an amoebomastigote, Paratetramitus jugosus, from a microbial mat: new evidence for multiple fission  

NASA Technical Reports Server (NTRS)

Five microbial habitats (gypsum crust, gypsum photosynthetic community, Microcoleus mat, Thiocapsa scum, and black mud) were sampled for the presence of the euryhaline, rapidly growing amoebomastigote, Paratetramitus jugosus. Field investigations of microbial mats from Baja California Norte, Mexico, and Salina Bido near Matanzas, Cuba, reveal that P. jugosus is most frequently found in the Thiocapsa layer of microbial mats. Various stages of the life history were studied using phase-contrast, differential-interference, and transmission electron microscopy. Mastigote stages were induced and studied by electron microscopy; mastigotes that actively feed on bacteria bear two or more undulipodia. A three-dimensional drawing of the kinetid ("basal apparatus") based on electron micrographs is presented. Although promitoses were occasionally observed, it is unlikely that they can account for the rapid growth of P. jugosus populations on culture media. Dense, refractile, spherical, and irregular-shaped bodies were seen at all times in all cultures along with small mononucleate (approximately 2-7 micrometers diameter) amoebae. Cytochemical studies employing two different fluorescent stains for DNA (DAPI, mithramycin) verified the presence of DNA in these small bodies. Chromatin-like material seen in electron micrographs within the cytoplasm and blebbing off nuclei were interpreted to the chromatin bodies. Our interpretation, consistent with the data but not proven, is that propagation by multiple fission of released chromatin bodies that become small amoebae may occur in Paratetramitus jugosus. These observations are consistent with descriptions of amoeba propagules in the early literature (Hogue, 1914).

Enzien, M.; McKhann, H. I.; Margulis, L.

1989-01-01

299

Microbial Weathering of Olivine  

NASA Technical Reports Server (NTRS)

Controlled microbial weathering of olivine experiments displays a unique style of nanoetching caused by biofilm attachment to mineral surfaces. We are investigating whether the morphology of biotic nanoetching can be used as a biosignature. Additional information is contained in the original extended abstract.

McKay, D. S.; Longazo, T. G.; Wentworth, S. J.; Southam, G.

2002-01-01

300

Conflicts of interest in biofilms  

Microsoft Academic Search

High cell density and close proximity of diverse species of microorganisms are typical of life in natural biofilms. These conditions give ample opportunity for both competitive and cooperative interactions between individuals of the same and different species. Cooperative behaviour benefits the group of neighbouring microbes but comes at a fitness cost for the cooperating individuals. This creates a conflict of

J.-U. Kreft

2005-01-01

301

Effects of the Pt loading side and cathode-biofilm on the performance of a membrane-less and single-chamber microbial fuel cell  

Microsoft Academic Search

In order to analyze the effect of cathode’s Pt loading side on the performance of single-chamber microbial fuel cells (MFCs), power generation of a bamboo charcoal membrane-less air-cathode MFC was examined. The maximum power outputs obtained were 0.144 and 1.16mW, while the maximum voltage outputs were 0.400 and 0.500V (external resistance was 500?), respectively, when the Pt loading side facing

Shaoqiang Yang; Boyang Jia; Hong Liu

2009-01-01

302

Uranium Immobilization by Sulfate-reducing Biofilms  

SciTech Connect

Hexavalent uranium [U(VI)] was immobilized using biofilms of the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans G20. The biofilms were grown in flat-plate continuous-flow reactors using lactate as the electron donor and sulfate as the electron acceptor. U(VI) was continuously fed into the reactor for 32 weeks at a concentration of 126 íM. During this time, the soluble U(VI) was removed (between 88 and 96% of feed) from solution and immobilized in the biofilms. The dynamics of U immobilization in the sulfate-reducing biofilms were quantified by estimating: (1) microbial activity in the SRB biofilm, defined as the hydrogen sulfide (H2S) production rate and estimated from the H2S concentration profiles measured using microelectrodes across the biofilms; (2) concentration of dissolved U in the solution; and (3) the mass of U precipitated in the biofilm. Results suggest that U was immobilized in the biofilms as a result of two processes: (1) enzymatically and (2) chemically, by reacting with microbially generated H2S. Visual inspection showed that the dissolved sulfide species reacted with U(VI) to produce a black precipitate. Synchrotron-based U L3-edge X-ray absorption near edge structure (XANES) spectroscopy analysis of U precipitated abiotically by sodium sulfide indicated that U(VI) had been reduced to U(IV). Selected-area electron diffraction pattern and crystallographic analysis of transmission electron microscope lattice-fringe images confirmed the structure of precipitated U as being that of uraninite.

Beyenal, Haluk; Sani, Rajesh K.; Peyton, Brent M.; Dohnalkova, Alice; Amonette, James E.; Lewandowski, Zbigniew

2004-04-01

303

Update on the challenging role of biofilms in peritoneal dialysis.  

PubMed

Biofilms are commonly associated with an increased risk of patient infection. In peritoneal dialysis (PD), catheter associated infection, especially peritonitis, remains a clinically relevant problem. Although the presence of a biofilm is recognized in relapsing, repeat, and catheter-related peritonitis, it remains poorly characterized. In this review, an update on the role of biofilms in PD infections is presented. The emerging concept that host cells and tissue associated biofilms, in addition to the biofilms on the catheters themselves, contribute to the recalcitrance of infections is discussed. Furthermore, the evidence of biofilms on PD catheters, their developmental stages, and the possible influence of the PD environment are reviewed. The focus is given to ex vivo and in vitro studies that contribute to the elucidation of the interplay between host, microbial, and dialysis factors. The key issues that are still to be answered and the challenges to clinical practice are discussed. PMID:23998251

Martins, Margarida; Rodrigues, Anabela; Pedrosa, Jorge M; Carvalho, Maria J; Cabrita, António; Oliveira, Rosário

2013-09-01

304

The Impact of Microbially Influenced Corrosion on Spent Nuclear Fuel and Storage Life  

SciTech Connect

A study was performed to evaluate if microbial activity could be considered a threat to spent nuclear fuel integrity. The existing data regarding the impact of microbial influenced corrosion (MIC) on spent nuclear fuel storage does not allow a clear assessment to be made. In order to identify what further data are needed, a literature survey on MIC was accomplished with emphasis on materials used in nuclear fuel fabrication, e.g., A1, 304 SS, and zirconium. In addition, a survey was done at Savannah River, Oak Ridge, Hanford, and the INEL on the condition of their wet storage facilities. The topics discussed were the SNF path forward, the types of fuel, ramifications of damaged fuel, involvement of microbial processes, dry storage scenarios, ability to identify microbial activity, definitions of water quality, and the use of biocides. Information was also obtained at international meetings in the area of biological mediated problems in spent fuel and high level wastes. Topics dis cussed included receiving foreign reactor research fuels into existing pools, synergism between different microbes and other forms of corrosion, and cross contamination.

J. H. Wolfram; R. E. Mizia; R. Jex; L. Nelson; K. M. Garcia

1996-10-01

305

Impact of chloramination on the development of laboratory-grown biofilms fed with filter-pretreated groundwater.  

PubMed

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. PMID:23124766

Ling, Fangqiong; Liu, Wen-Tso

2013-01-01

306

The impact of culture medium on the development and physiology of biofilms of Pseudomonas fluorescens formed on polyurethane paint.  

PubMed

Microbial biofilms cause the deterioration of polymeric coatings such as polyurethanes (PUs). In many cases, microbes have been shown to use the PU as a nutrient source. The interaction between biofilms and nutritive substrata is complex, since both the medium and the substratum can provide nutrients that affect biofilm formation and biodeterioration. Historically, studies of PU biodeterioration have monitored the planktonic cells in the medium surrounding the material, not the biofilm. This study monitored planktonic and biofilm cell counts, and biofilm morphology, in long-term growth experiments conducted with Pseudomonas fluorescens under different nutrient conditions. Nutrients affected planktonic and biofilm cell numbers differently, and neither was representative of the system as a whole. Microscopic examination of the biofilm revealed the presence of intracellular storage granules in biofilms grown in M9 but not yeast extract salts medium. These granules are indicative of nutrient limitation and/or entry into stationary phase, which may impact the biodegradative capability of the biofilm. PMID:23697763

Crookes-Goodson, Wendy J; Bojanowski, Caitlin L; Kay, Michelle L; Lloyd, Pamela F; Blankemeier, Andrew; Hurtubise, Jennifer M; Singh, Kristi M; Barlow, Daniel E; Ladouceur, Harold D; Matt Eby, D; Johnson, Glenn R; Mirau, Peter A; Pehrsson, Pehr E; Fraser, Hamish L; Russell, John N

2013-01-01

307

The development and succession of microbial communities in 90-day Bioregenerative Life Support Experiment in the Lunar Palace 1  

NASA Astrophysics Data System (ADS)

Lunar Palace 1, as an integrative experiment facility for permanent astrobase life-support artificial closed ecosystem, is an artificial ecosystem which consists of plant cultivation, animal breeding and waste treatment units. It has been used to carry out a 90-day bioregenerative life support experiment with three crew members. Apparently, it’s hard to prevent the growth of microorganisms in such closed ecosystem for their strong adaptive capacity. Original microorganisms in the cabin, microbes in the course of loads delivery and the autologous microorganism by crew members and animals themselves are all the main source of the interior microorganisms, which may grow and regenerate in air, water and plants. Therefore, if these microorganisms could not be effectively monitored and controlled, it may cause microbial contamination and even lead to the unsteadiness of the whole closed ecosystem. In this study, the development and succession of the microbial communities of air, water system, plant system, and key facilities surfaces in Lunar Palace 1 were continuously monitored and analyzed by using plate counting method and molecular biological method during the 90-day experiment. The results were quite useful for the controlling of internal microorganisms and the safe operation of the whole system, and could also reveal the succession rules of microorganisms in an artificial closed ecosystem.

Sun, Yi; Liu, Hong; Fu, Yuming; Liu, Bojie; Su, Qiang; Xie, Beizhen; Qin, Youcai; Dong, Chen; Liu, Guanghui

308

STABILITY AND CHANGE IN ESTUARINE BIOFILM BACTERIAL COMMUNITY DIVERSITY  

EPA Science Inventory

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...

309

Structure, composition, and strength of nitrifying membrane-aerated biofilms.  

PubMed

Membrane-aerated biofilm reactors (MABRs) are a novel technology based on the growth of biofilms on oxygen-permeable membranes. Hereby, MABRs combine all the advantages of biofilm growth with a more flexible and efficient control of the oxygen load. In the present work, MABR flow cells were operated to achieve full nitrification. MABR biofilms had a significantly different structure than co-diffusion biofilms reported in the literature. Different levels of shear stress and oxygen loading during MABR operation also affected the biofilm parameters. Furthermore, reactor operation at higher oxygen loads resulted in an increased biofilm cohesiveness, which depended on the EPS mass in the biofilms and the type of stress applied (more cohesive against normal than shear stresses). The EPS in the strongest biofilms had a higher content of proteins and a lower level of carbohydrates. Staining analyses revealed that the outermost EPS in the stronger biofilm regions was of hydrophilic nature and distributed around dense microbial aggregates, whereas it was homogeneously distributed in the weaker strata. Overall, the obtained results provide input parameters to future modelling efforts and operating conditions to support more robust autotrophic N conversions in MABRs. PMID:24721662

Pellicer-Nàcher, Carles; Smets, Barth F

2014-06-15

310

Electrochemically active biofilms: facts and fiction. A review  

PubMed Central

This review examines the electrochemical techniques used to study extracellular electron transfer in the electrochemically active biofilms that are used in microbial fuel cells and other bioelectrochemical systems. Electrochemically active biofilms are defined as biofilms that exchange electrons with conductive surfaces: electrodes. Following the electrochemical conventions, and recognizing that electrodes can be considered reactants in these bioelectrochemical processes, biofilms that deliver electrons to the biofilm electrode are called anodic, ie electrode-reducing, biofilms, while biofilms that accept electrons from the biofilm electrode are called cathodic, ie electrode-oxidizing, biofilms. How to grow these electrochemically active biofilms in bioelec-trochemical systems is discussed and also the critical choices made in the experimental setup that affect the experimental results. The reactor configurations used in bioelectrochemical systems research are also described and the authors demonstrate how to use selected voltammetric techniques to study extracellular electron transfer in bioelectrochemical systems. Finally, some critical concerns with the proposed electron transfer mechanisms in bioelectrochemical systems are addressed together with the prospects of bioelectrochemical systems as energy-converting and energy-harvesting devices. PMID:22856464

Babauta, Jerome; Renslow, Ryan; Lewandowski, Zbigniew; Beyenal, Haluk

2014-01-01

311

Anti-Biofilm Compounds Derived from Marine Sponges  

PubMed Central

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. PMID:22073007

Stowe, Sean D.; Richards, Justin J.; Tucker, Ashley T.; Thompson, Richele; Melander, Christian; Cavanagh, John

2011-01-01

312

Antibody-Guided Alpha Radiation Effectively Damages Fungal Biofilms  

PubMed Central

The use of indwelling medical devices—pacemakers, prosthetic joints, catheters—is rapidly growing and is often complicated by infections with biofilm-forming microbes that are resistant to antimicrobial agents and host defense mechanisms. We investigated for the first time the use of microbe-specific monoclonal antibodies (MAbs) as delivery vehicles for targeting biofilms with cytocidal radiation. MAb 18B7 (immunoglobulin G1 [IgG1]), which binds to capsular polysaccharides of the human pathogenic fungus Cryptococcus neoformans, penetrated cryptococcal biofilms, as shown by confocal microscopy. When the alpha radiation-emitter 213-Bismuth (213Bi) was attached to MAb 18B7 and the radiolabeled MAb was added to C. neoformans biofilms, there was a 50% reduction in biofilm metabolic activity. In contrast, when the IgM MAb 13F1 labeled with 213Bi was used there was no penetration of the fungal biofilm and no damage. Unlabeled 18B7, 213Bi-labeled nonspecific MAbs, and gamma and beta types of radiation did not have an effect on biofilms. The lack of efficacy of gamma and beta radiation probably reflects the radioprotective properties of polysaccharide biofilm matrix. Our results indicate that C. neoformans biofilms are susceptible to treatment with antibody-targeted alpha radiation, suggesting a novel option for the prevention or treatment of microbial biofilms on indwelling medical devices. PMID:16723575

Martinez, L. R.; Bryan, R. A.; Apostolidis, C.; Morgenstern, A.; Casadevall, A.; Dadachova, E.

2006-01-01

313

Riddle of Biofilm Resistance  

Microsoft Academic Search

A biofilm is a population of cells growing on a surface and enclosed in an exopolysaccharide matrix. Biofilms are notori- ously difficult to eradicate and are a source of many recalci- trant infections. The nature of bacterial biofilm resistance to antimicrobials is the subject of the present minireview. Patho- genic yeast such as Candida albicans also form recalcitrant biofilms, and

KIM LEWIS

2001-01-01

314

Patterns of biofilm formation in intermittent and permanent streams: analysis of biofilm structure and metabolism  

NASA Astrophysics Data System (ADS)

The development and functioning of benthic microbial communities in streams is largely dependent on the hydrological conditions. Climate change projections predict that the hydrological characteristics will probably be affected because of the rainfall regime. Hence, rivers from the Mediterranean region will become more similar to those draining arid or desert regions, while temperate streams will suffer of higher water flow fluctuations. In this study, we compared the process of biofilm formation between an intermittent (the Fuirosos, Mediterranean) and a permanent (the Walzbach, Central European) stream. Specifically, we analyzed the succession of bacterial and algal populations in the biofilm through bacterial rDNA sequences analysis (16S rDNA and 16S-23S intergenic sequence) and diatom taxa identification over a 60-days colonization experiment. Moreover, changes in biofilm structural (microbial biomass and extracellular polysaccharide content) and metabolic (extracellular enzyme activities) parameters were also analyzed. The successional patterns of microbial populations in the Fuirosos showed clear discontinutities coinciding with flood episodes while at the Walzbach the time sequence was more gradual. Although both study sites were forested, greater microbial biomass standing stock (algal and bacterial) and greater species biodiversity was detected during biofilm development at the Mediterranean site. The higher bacterial biodiversity may be related to the potential effect of flooding episodes in reducing biological interactions in complex microbial communities, such as the competitive exclusion of species. Moreover, the presence of rapid colonizing diatom species might be an adaptation to hydrological changes. In contrast, species competition could define the more stable environments, such as that observed in the Central European stream. Overall, the hystorical evolutionary pressure from the different bioclimatic regions could be also affecting the microbial community composition. Further, the analysis of the whole biofilm colonization sequence showed a greater EPS development and a higher potential extracellular enzyme activity rates in the Mediterranean stream. The higher EPS reflected a functional response of the biofilms to avoid detachment during high flow episodes and the higher enzyme activities were according to the low water nutrient concentration available for microbes. However, the higher nutrient conditions (higher nitrate and phosphate concentrations) at the Central European stream was not reflected on higher biomass standing stock in biofilms. Likely, the biomass accrual of biofilms was related to the differences in climatic conditions between study sites (e. g. daily insulation, temperature oscillation). The results suggest that microbial community development and functioning is primarily related to the physical characteristics of the different sites (specially the stream hydrology, but also the light regime).

Artigas, J.; Schwartz, T.; Kirchen, S.; Romaní, A. M.; Fund, K.; Obst, U.; Sabater, S.

2009-04-01

315

A Microbial Oasis in the Hypersaline Atacama Subsurface Discovered by a Life Detector Chip: Implications for the Search for Life on Mars  

PubMed Central

Abstract The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5?m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2?m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5?g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260?g kg?1) and perchlorate (41.13??g g?1 maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14??g g?1) or formate (76.06??g g?1) as electron donors, and sulfate (15875??g g?1), nitrate (13490??g g?1), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars. Key Words: Atacama Desert—Life detection—Biosensor—Biopolymers—In situ measurement. Astrobiology 11, 969–996. PMID:22149750

de Diego-Castilla, Graciela; Moreno-Paz, Mercedes; Blanco, Yolanda; Cruz-Gil, Patricia; Rodriguez-Manfredi, Jose A.; Fernandez-Remolar, David; Gomez, Felipe; Gomez, Manuel J.; Rivas, Luis A.; Demergasso, Cecilia; Echeverria, Alex; Urtuvia, Viviana N.; Ruiz-Bermejo, Marta; Garcia-Villadangos, Miriam; Postigo, Marina; Sanchez-Roman, Monica; Chong-Diaz, Guillermo; Gomez-Elvira, Javier

2011-01-01

316

Implications of Biofilm Formation on Urological Devices  

NASA Astrophysics Data System (ADS)

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.

Cadieux, Peter A.; Wignall, Geoffrey R.; Carriveau, Rupp; Denstedt, John D.

2008-09-01

317

Oil biodegradation. Water droplets in oil are microhabitats for microbial life.  

PubMed

Anaerobic microbial degradation of hydrocarbons, typically occurring at the oil-water transition zone, influences the quality of oil reservoirs. In Pitch Lake, Trinidad and Tobago--the world's largest asphalt lake--we found that microorganisms are metabolically active in minuscule water droplets (1 to 3 microliters) entrapped in oil. Pyrotag sequencing of individual droplet microbiomes revealed complex methanogenic microbial communities actively degrading the oil into a diverse range of metabolites, as shown by nuclear magnetic resonance and Fourier transform ion cyclotron resonance mass spectrometry. High salinity and water-stable isotopes of the droplets indicate a deep subsurface origin. The 13.5% water content and the large surface area of the droplets represent an underestimated potential for biodegradation of oil away from the oil-water transition zone. PMID:25104386

Meckenstock, Rainer U; von Netzer, Frederick; Stumpp, Christine; Lueders, Tillmann; Himmelberg, Anne M; Hertkorn, Norbert; Schmitt-Kopplin, Philipp; Harir, Mourad; Hosein, Riad; Haque, Shirin; Schulze-Makuch, Dirk

2014-08-01

318

Geochemistry of late Archaean stromatolites from Zimbabwe: evidence for microbial life in restricted epicontinental seas  

Microsoft Academic Search

We report comprehensive trace element and Sr-isotope data for microbial carbonates from the Archaean Mushandike limestone, Masvingo Greenstone Belt, Zimbabwe. The stromatolites have very coherent REE+Y patterns and share the essential shale-normalised characteristics of other Archaean marine precipitates (positive La and Gd anomalies, absence of a negative Ce anomaly and a strongly superchondritic Y\\/Ho ratio). Mixing models constrain the maximum

Balz S Kamber; Robert Bolhar; Gregory E Webb

2004-01-01

319

Community-Level Assessment of the Effects of the Broad-Spectrum Antimicrobial Chlorhexidine on the Outcome of River Microbial Biofilm Development?  

PubMed Central

Chlorhexidine is a common-use antibacterial agent found in a range of personal-care products. We used rotating annular reactors to cultivate river biofilms under the influence of chlorhexidine or its molar equivalent in nutrients. Studies of the degradation of [14C]chlorhexidine demonstrated that no mineralization of the compound occurred. During studies with 100 ?g liter?1 chlorhexidine, significant changes were observed in the protozoan and micrometazoan populations, the algal and cyanobacterial biomass, the bacterial biomass, and carbon utilization. Denaturing gradient gel electrophoresis (DGGE) in combination with statistical analyses showed that the communities developing under control and 100 ?g liter?1 chlorhexidine were significantly different. At 10 ?g liter?1 chlorhexidine, there was significantly increased algal and cyanobacterial biomass while the bacterial biomass was not significantly affected (P < 0.05). No significant effects on protozoan or metazoan grazing were detected at the 10-?g liter?1 chlorhexidine level. Fluorescent in situ hybridization indicated a significant reduction in the abundance of betaproteobacteria and gammaproteobacteria (P < 0.05). Archaeal cell counts were significantly reduced by both chlorhexidine and nutrient treatments. DGGE and statistical analyses indicated that 10 ?g liter?1 chlorhexidine and molar equivalent nutrient treatments were significantly different from control communities. In contrast to community level observations, toxicological testing with a panel of cyanobacteria, algae, and protozoa indicated no detectable effects at 10, 50, and 100 ?g liter?1 chlorhexidine. Thus, community level assessment indicated a risk of low levels of chlorhexidine in aquatic habitats while conventional approaches did not. PMID:18378652

Lawrence, J. R.; Zhu, B.; Swerhone, G. D. W.; Topp, E.; Roy, J.; Wassenaar, L. I.; Rema, T.; Korber, D. R.

2008-01-01

320

Inactivation kinetics of anaerobic wastewater biofilms by free nitrous acid.  

PubMed

Recent studies have shown that free nitrous acid (FNA) is biocidal to a broad range of microorganisms. Microorganisms residing in anaerobic sewer biofilms were found to be inactivated after a short (6-24 h) exposure to FNA. In this study, we investigate the inactivation kinetics of anaerobic sewer biofilms grown in real wastewater. Microbial viability of biofilms was determined using LIVE/DEAD staining. A two-fraction kinetic model was developed to simulate the inactivation of mixed culture in biofilms. The kinetic parameters were estimated by using Bayesian statistics. Model simulation found that a fraction (85 %) of the biofilm community was highly sensitive to FNA with a high inactivation rate, and a fraction (15 %) was tolerant to FNA and persisted after FNA treatment. This different susceptibility to FNA treatment was likely due to the diverse microbial community and biofilm protection. The fact that nearly 85 % microbes were inactivated confirmed that FNA is a strong biocide to mixed-culture biofilms. It was found that the inactivation rate constant was not affected by pH levels. The kinetic model was successfully used to optimize FNA dosage for sulfide control in sewer biofilms. Also, results suggest that a high FNA concentration is preferred than long exposure time to reduce the total chemical consumption. PMID:23775272

Jiang, Guangming; Yuan, Zhiguo

2014-02-01

321

Characterization of biofilm formed by human-derived nanoparticles  

PubMed Central

Aim Microbial biofilm matrix contains polysaccharides and proteins and can require extracellular nucleic acids for initial formation. Experiments were designed to identify infectious pathogens in human aneurysms and to characterize biofilm formed by calcified human arterial-derived nanoparticles. Materials & method A total of 26 different microbial pathogens were isolated from 48 inflammatory aneurysms. Consistent amounts (0.49 McFarland units) of nanoparticles derived from similar tissue were seeded into 24-well plates and cultured for 21 days in the absence (control) or presence of RNase, tetracycline or gentamicin. Results Control biofilm developed within 14 days, as detected by concanavalin A and BacLight™ Green staining. The formation of biofilm in wells treated with RNase was not different from the control; however, gentamicin partially inhibited and tetracycline completely inhibited biofilm formation. Therefore, nanoparticle biofilm retains some characteristics of conventional bacterial biofilm and requires protein–calcium interactions, although extracellular RNA is not required. Conclusion This model system may also allow study of nanosized vesicles derived from donor tissue, including any microbes present, and could provide a useful tool for in vitro investigation of nanoparticle biofilm formation. PMID:19958229

Schwartz, Maria K; Hunter, Larry W; Huebner, Marianne; Lieske, John C; Miller, Virginia M

2011-01-01

322

Microbial Life in the Subseafloor at Mid-Ocean Ridges: A Key to Understanding Ancient Ecosystems on Earth and Elsewhere?  

NASA Astrophysics Data System (ADS)

Some planets and moons in our solar system were similar to Earth in their geological properties during the first few hundred million years after accretion. This is the period when life arose and became established on Earth. It follows that understanding the geophysical and geochemical characteristics of early Earth could provide insight into life-supporting environments on other solar bodies that have not evolved "Garden of Eden" conditions. Hydrothermal systems are primordial and their emergence coincided with the accumulation of liquid water on Earth. The interactions of water and rock associated with hydrothermal systems result in predictable suites of dissolved elements and volatiles. While the concentrations of these chemicals vary at different vent locations and were certainly different during the early Archaean, the overall chemical composition of aqueous hydrothermal fluid is likely to be the same because of the basaltic nature of oceanic crust. In present-day hydrothermal systems, those environments not contaminated by electron acceptors produced from pelagic photosynthesis would most closely mimic the earliest conditions on Earth. These conditions include the subseafloor and high temperature, anaerobic environments associated with hydrothermal systems. The microorganisms associated with these environments derive energy from sulfur, iron, hydrogen and organic compounds. New seafloor eruptions and diffuse flow vents provide unprecedented access to deep subseafloor microbial communities. For example, 12 new eruptions have occurred in the past 15 years including five in the Northeast Pacific. Hyperthermophiles were isolated from 5-30oC diffuse vent fluids from new eruption sites at CoAxial within months of the June, 1993 eruption and from the 1998 eruption at Axial Volcano, and from plume fluids within days of the February, 1996 eruption at the N. Gorda Ridge. The presence of such organisms in fluids that are 20 to 50°C below their minimum growth temperature indicates that they originated from a hot subseafloor habitat. Based on the 16S rRNA sequences and the RFLP patterns of the 500 base sequence between the 16S and 23S rRNA genes (intergenic spacer region), these heterotrophic archaea represent new species, and a new genus, within the Thermococcales (Summit and Baross, 1998; 2001). These isolates grow over an unusually wide temperature range and in low levels of organic material. While Thermococcus and Methanococcus species are the most commonly isolated species of hyperthermophiles from subseafloor biotopes, preliminary phylogenetic analyses based on 16S rRNA sequences of microbial communities in the diffuse flow fluids at new eruption sites show a high diversity of archaea that are not related to cultured organisms. Results to date support the hypothesis that subseafloor microbes associated with hydrothermal systems have nutritional, physiological and bioenergetic characteristics that reflect the physical and geochemical properties of their habitat. Moreover, we propose that deep-sea subsurface environments are analogs of ecosystems on other solar bodies. Thus, by examining the chemical and microbial ecology and energetics of the subsurface, and particularly the subsurface associated with hydrothermal systems, a framework for studying the prospects of extraterrestrial life can be developed. It is predicted that if there were life on other hydrothermally active solar bodies, the same energy sources would fuel microbial metabolism even though the molecular characteristics of these life forms may not resemble Earth organisms having identical metabolisms.

Baross, J. A.; Delaney, J. R.

2001-12-01

323

Laser-induced fluorescence emission (L.I.F.E.): in situ nondestructive detection of microbial life in the ice covers of Antarctic lakes.  

PubMed

Laser-induced fluorescence emission (L.I.F.E.) images were obtained in situ following 532 nm excitation of cryoconite assemblages in the ice covers of annual and perennially frozen Antarctic lakes during the 2008 Tawani International Expedition to Schirmacher Oasis and Lake Untersee in Dronning Maud Land, Antarctica. Laser targeting of a single millimeter-scale cryoconite results in multiple neighboring excitation events secondary to ice/air interface reflection and refraction in the bubbles surrounding the primary target. Laser excitation at 532 nm of cyanobacteria-dominated assemblages produced red and infrared autofluorescence activity attributed to the presence of phycoerythrin photosynthetic pigments. The method avoids destruction of individual target organisms and does not require the disruption of either the structure of the microbial community or the surrounding ice matrix. L.I.F.E. survey strategies described may be of interest for orbital monitoring of photosynthetic primary productivity in polar and alpine glaciers, ice sheets, snow, and lake ice of Earth's cryosphere. The findings open up the possibility of searching from either a rover or from orbit for signs of life in the polar regions of Mars and the frozen regions of exoplanets in neighboring star systems. PMID:19778277

Storrie-Lombardi, Michael C; Sattler, Birgit

2009-09-01

324

Laser Induced Fluorescence Emission (L.I.F.E.): In Situ Non-Destructive Detection of Microbial Life on Supraglacial Environments  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence emission (L.I.F.E.) is an in situ laser scanning technique to detect photoautotrophic pigments such as phycoerythrin of an ice ecosystem such as supraglacial environments without contamination. The sensitivity of many psychrophiles to even moderate changes in temperature, and the logistical difficulties associated with either in situ analysis or sampling makes it difficult to study microbial metabolism in ice ecosystems in a high resolution. Surface communities of cold ecosystems are highly autotrophic and therefor ideal systems for L.I.F.E examinations. 532nm green lasers excite photopigments in cyanobacteria and produce multiple fluorescence signatures between 550nm and 750nm including carotenoids, phycobiliproteins which would enable a non-invasive in-situ measurement. The sensitivity of many psychrophiles to even moderate changes in temperature, and the logistical difficulties associated with either in situ analysis or sampling makes it difficult to study these cryosphere ecosystems. In general, the ice habitat has to be disrupted using techniques that usually include coring, sawing, and melting. Samples are also often chosen blindly, with little indication of probable biomass. The need for an in situ non-invasive, non-destructive technique to detect, localize, and sample cryosphere biomass in the field is therefore of considerable importance. L.I.F.E has already been tested in remote ecosystems like Antarctica (Lake Untersee, Lake Fryxell), supraglacial environments in the Kongsfjord region in the High Arctic and High Alpine glaciers but until now no calibration was set to convert the L.I.F.E. signal into pigment concentration. Here we describe the standardization for detection of Phycobiliproteins (Phycoerythrine) which are found in red algae, cyanobacteria, and cryptomonads. Similar methods are already used for detection of phytoplankton in liquid systems like oceans and lakes by NASÁs Airborne Oceanographic LIDAR since 1979. The possibility to use L.I.F.E. in ice though is a novelty and provides a promising tool to monitor vanishing ice systems like retreating glaciers.

Sattler, B.; Tilg, M.; Storrie-Lombardi, M.; Remias, D.; Psenner, R.

2012-04-01

325

Azolla-Anabaena symbionts and microbial mat as nitrogen-fixing biocatalysts for bioregenerative space life support.  

PubMed

This study was conducted to characterize the responses of selected nitrogen-fixing biocatalysts to various environmental parameters that are likely to be encountered in a scaled-up nitrogen-fixing bioregenerative unit for use in a biologically based life support system (BLSS). The results showed that while both Azolla filiculoides and Azolla nilotica thrived on standard nitrogen-free liquid media, only Azolla filiculoides maintained its growth rate in the presence of 50% by volume of aerobic-bioreactor potato effluent (ABPE) in its liquid medium. The growth rate and Anabaena cavity population of Azolla filiculoides also remained undiminished in the presence of as much as 10 mM of NO3- in its liquid medium. The tolerance of Azolla filiculoides for NO3- however, lay somewhere between 10 and 20 mM of NO3-. Azolla filiculoides failed to grow at 5 mM or greater concentrations of NH4+. The growth rate of the Oscillatoria-dominated microbial mat was significantly elevated by increased silage loading density (16 g/L) as well as by adding 5 mM of NO3- into its liquid medium. Neither the growth rate of Azolla filiculoides nor that of the microbial mat was affected by three levels of photosynthetic photon flux (PPF) (520, 265, and 125 micromoles m-2 s-1) under high-pressure sodium or cool fluorescent lamps. PMID:11871445

Cuello, J L; Rodriguez-Eaton, S; Stryjewski, E C; Sager, J C

1998-01-01

326

Measuring the microbiome: perspectives on advances in DNA-based techniques for exploring microbial life  

PubMed Central

This article reviews recent advances in ‘microbiome studies’: molecular, statistical and graphical techniques to explore and quantify how microbial organisms affect our environments and ourselves given recent increases in sequencing technology. Microbiome studies are moving beyond mere inventories of specific ecosystems to quantifications of community diversity and descriptions of their ecological function. We review the last 24 months of progress in this sort of research, and anticipate where the next 2 years will take us. We hope that bioinformaticians will find this a helpful springboard for new collaborations with microbiologists. PMID:22308073

Bunge, John; Gilbert, Jack A.; Moore, Jason H.

2012-01-01

327

Synthetic Biology and Microbial Fuel Cells: Towards Self-Sustaining Life Support Systems  

NASA Technical Reports Server (NTRS)

NASA ARC and the J. Craig Venter Institute (JCVI) collaborated to investigate the development of advanced microbial fuels cells (MFCs) for biological wastewater treatment and electricity production (electrogenesis). Synthetic biology techniques and integrated hardware advances were investigated to increase system efficiency and robustness, with the intent of increasing power self-sufficiency and potential product formation from carbon dioxide. MFCs possess numerous advantages for space missions, including rapid processing, reduced biomass and effective removal of organics, nitrogen and phosphorus. Project efforts include developing space-based MFC concepts, integration analyses, increasing energy efficiency, and investigating novel bioelectrochemical system applications

Hogan, John Andrew

2014-01-01

328

Animal models to investigate fungal biofilm formation.  

PubMed

Microbial biofilms play an essential role in several infectious diseases and are defined as extensive communities of sessile organisms irreversibly associated with a surface, encased within a polysaccharide-rich extracellular matrix (ECM), and exhibiting enhanced resistance to antimicrobial drugs. Forming a biofilm provides the microbes protection from environmental stresses due to contaminants, nutritional depletion, or imbalances, but is dangerous to human health due to their inherent robustness and elevated resistance.The use of indwelling medical devices (e.g., central venous catheters, CVCs) in current therapeutic practice is associated with 80-90 % of hospital-acquired bloodstream and deep tissue infections. Most cases of catheter-related bloodstream infections (CRBSIs) involve colonization of microorganisms on catheter surfaces where they form a biofilm. Additionally, Fusarium solani and F. oxysporum were the causative organisms of the 2005/2006 outbreak of contact lens-associated fungal keratitis in the United States, Europe, the UK, and Singapore, and these infections involved formation of biofilms on contact lens. Fungal biofilm formation is studied using a number of techniques, involving the use of a wide variety of substrates and growth conditions. In vitro techniques involving the use of confocal scanning laser/scanning electron microscopy, metabolic activity assay, dry weight measurements, and antifungal susceptibility assays are increasingly used by investigators to quantify and evaluate biofilm morphology. However, there are not many in vivo models used to validate biofilm-associated infections. In this protocol, we describe a clinically relevant rabbit model of C. albicans biofilm-associated catheter infection to evaluate the morphology, topography, and architecture of fungal biofilms. We also describe a murine model of contact lens-associated Fusarium keratitis.Evaluation of the formation of fungal biofilms on catheters in vivo, their analysis using scanning electron microscopy (SEM) and quantitative catheter culture (QCC), and treatment of biofilms using antimicrobial lock therapy can be completed in ~20-25 days using the described methods. The rabbit model has utility in evaluating the efficacy of lock solutions. In addition, the murine model of contact lens-associated Fusarium keratitis enables characterizing/comparing the formation of Fusarium biofilms on contact lenses in vitro and determining their role in vivo. PMID:24664831

Chandra, Jyotsna; Pearlman, Eric; Ghannoum, Mahmoud A

2014-01-01

329

Use of 70% alcohol for the routine removal of microbial hard surface bioburden in life science cleanrooms.  

PubMed

ABSTRACT? Alcohol-based disinfectants are used for the removal of microbial hard surface bioburden in Life science Cleanrooms. Evidence for using formulations containing 70% alcohol has been lost over time but probably originates from historical observations of the activity of 60-70% alcohol. Tradition is no longer adequate to inform contemporary cleaning practice. We evaluated the efficacy of ethanol, isopropanol and trade-specific denatured alcohol 7 against vegetative Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Enterococcus hirae using standardized European Suspension and Hard Surface tests. All three alcohols were effective at lower concentrations than the 70% standard. This constitutes the first evaluation of disinfectant formulations containing ?70% alcohol using standard methodology. The utility of trade-specific denatured alcohol #7 and evidence-based cleanroom practice warrant further validation. PMID:25405882

Salvage, Richard; Hull, Claire M; Kelly, Diane E; Kelly, Steven L

2014-10-01

330

Microbial Contamination of Allende and Murchison Carbonaceous Chondrites; Developing a Protocol for Life Detection in Extraterrestrial Materials Using Biotechnology  

NASA Technical Reports Server (NTRS)

The arguments used to refute the McKay et al., (1996) hypothesis of possible Martian life in ALH84001 failed to use contamination of the meteorite as a source. This has worrying implications for our ability to detect terrestrial microbiota in meteorites and therefore any potential extraterrestrial biosignatures in both meteorites and possible returned samples. We report on imaging and microbial culturing of both Allende and Murchison carbonaceous chondrites and on the use of molecular biology techniques on a sample of Allende. Contaminating fungi and bacteria were observed (in the case of Murchison) and cultured from both meteorites. DNA was successfully extracted and subsequent PCR showed the presence of both bacterial and fungal DNA although no Archaea were detected. These results show that it is possible to use molecular biological techniques on very small quantities (300 mg) of extraterrestrial material.

Steele, A.; Whitby, C.; Griffin, C.; Toporski, J. K. W.; Westall, F.; Saunders, J. R.; McKay, D. S.

2001-01-01

331

Desiccation tolerance of iron bacteria biofilms on Mars regolith simulants  

NASA Astrophysics Data System (ADS)

Iron oxidizing bacteria play an important role in the geological redox cycling of iron on earth. The redox change between Fe(II) and Fe(III) can be used for biological energy production [1]. Therefore iron oxidation in the iron rich martian soils may be or may have been microbially mediated. The microbial conversion of iron is considered to be an ancient form of metabolism [2], so it might have evolved on Mars as well. However, to exist in recent martian soils, bacteria must be able to endure dry and cold conditions. Neutrophilic iron oxidizers can be found in various iron rich aquatic environments, where they lead to the precipitation of insoluble ferric hydroxides. Some of these environments fall temporarily dry, what could have led to an adaptation to desiccation by bacteria, existing there. One strategy of iron bacteria to endure drought stress might be the formation of biofilms by excreting Extracellular Polymeric Substances (EPS). The deposition of iron hydroxides could enable them to endure dry conditions as well. For our experiments, neutrophilic iron oxidizing bacteria have been isolated from a creek in Bad Salzhausen/Hesse and temporarily drying out pools in Tierra del Fuego. Strains from aquatic environments in the national park "Unteres Odertal" and from water wells in Berlin/Brandenburg are included in the tests as well. In desiccation experiments, the capability of iron bacteria to tolerate dry conditions are investigated. The aim of our first experiment is the adaptation to dry conditions. Biofilms of 15 strains are grown on ceramic beads in liquid medium containing complexed Fe(II), established biofilms contain Fe(III) precipitates. The cultures are desiccated in a sterile airflow until the weight of the cultures remained constant. After a desiccation period of 9 h up to 7 d, the beads are transferred to fresh liquid medium. Adapted strains are used in further desiccation experiments, where biofilms are grown on two martian regolith simulants. These mineral mixtures were developed and produced by the Naturkundemuseum Berlin according to recent data of Mars research missions [3, 4, 5, 6, 7]. The minerals are attached to object slides with potassium silicate and biofilms are grown on the mineral surface. The biofilms are quantified by cell counting and the structure is evaluated by epifluorescence microscopy. After desiccation in a sterile airflow, the survival of cells is determined by fluorescence staining. Acknowledgements This research was supported by the Helmholtz Association through the research alliance "Planetary Evolution and Life". References [1] Weber, K. A. et al. (2006). Microorganisms pumping iron: anaerobic microbial iron oxidation and reduction. Nature Reviews Microbiology 4: 752-764. [2] Vargas, M. et al. (1998). Microbiological evidence for Fe(III) reduction on early Earth. Nature 395: 65-67. [3] Bibring, J.-P., Y. Langevin, et al. (2005). Mars surface diversity as revealed by the OMEGA/Mars express observations. Science 307(5715): 1576-1581. [4] Bibring, J.-P., S. W. Squyres, et al. (2006). Merging Views on Mars. Science 313(5795): 1899-1901. [5] Chevrier, V. and P. E. Mathé (2007). Mineralogy and evolution of the surface of Mars: A review. Planetary and Space Science 55(3): 289-314. [6] McCollom, T. M. and B. M. Hynek (2005). A volcanic environment for bedrock diagenesis at Meridiani Planum on Mars. Nature 438(7071): 1129-1131. [7] Poulet, F., J. P. Bibring, et al. (2005). Phyllosilicates on Mars and implications for early martian climate. Nature 438(7068): 623-627.

Feyh, Nina; Szewzyk, Ulrich

2010-05-01

332

Life in extreme environments: microbial diversity in Great Salt Lake, Utah.  

PubMed

Great Salt Lake (GSL) represents one of the world's most hypersaline environments. In this study, the archaeal and bacterial communities at the North and South arms of the lake were surveyed by cloning and sequencing the 16S rRNA gene. The sampling locations were chosen for high salt concentration and the presence of unique environmental gradients, such as petroleum seeps and high sulfur content. Molecular techniques have not been systematically applied to this extreme environment, and thus the composition and the genetic diversity of microbial communities at GSL remain mostly unknown. This study led to the identification of 58 archaeal and 42 bacterial operational taxonomic units. Our phylogenetic and statistical analyses displayed a high biodiversity of the microbial communities in this environment. In this survey, we also showed that the majority of the 16S rRNA gene sequences within the clone library were distantly related to previously described environmental halophilic archaeal and bacterial taxa and represent novel phylotypes. PMID:24682608

Tazi, Loubna; Breakwell, Donald P; Harker, Alan R; Crandall, Keith A

2014-05-01

333

The Microbial Community on Marine Plastic Debris: Life in the "Plastisphere"  

NASA Astrophysics Data System (ADS)

Plastic debris is an abundant substrate of anthropogenic origin in the marine environment that is receiving increased attention. We documented the bacterial (V6-V4) and eukaryotic (V9) communities on open ocean plastic debris samples using 454 amplicon sequencing of small-subunit rRNA hypervariable regions and Scanning Electron Microscopy (SEM). Parametric alpha diversity measures of plastic samples showed considerable species richness comparable to the surrounding seawater with many Operational Taxonomic Units (OTUs) unique to the plastic substrates. We also found that while all samples contained an OTU assigned to SAR 11 (Candidatus Pelagibacter), considered to be one of most abundant heterotrophic bacteria in the ocean, this was not the most abundant OTU in our samples. Quite surprisingly, the most abundant OTU found in our polypropylene sample was an OTU assigned to the genus Vibrio. Although endemic to the marine environment, the genus Vibrio has several members that are human and animal pathogens. Our samples also included representatives from many protist groups and fungi. Sequences recovered were dominated by heterotrophs including an unidentified sequence related to colonial radiolaria and suctorian ciliates, but many photosynthetic groups including dinoflagellates, diatoms, and green, brown, and red algae were also present. SEM images revealed a complex landscape of microbes on the surface of the plastic; rich bacterial biofilms included diatoms and stalked suctorian ciliates covered with what appeared to be bacterial epibionts. The fact that these communities are distinct from the surrounding surface water suggests that plastic surfaces may serve as a unique new ecological habitat in the open ocean and warrant further investigation. We have proposed the term "Plastisphere" to describe the community of organisms closely associated with plastic debris in aquatic systems.

Amaral-Zettler, L. A.; Zettler, E. R.; Mincer, T. J.

2011-12-01

334

A Reproducible Oral Microcosm Biofilm Model for Testing Dental Materials  

PubMed Central

Aims Most studies of biofilm effects on dental materials use single-species biofilms, or consortia. Microcosm biofilms grown directly from saliva or plaque are much more diverse, but difficult to characterize. We used the Human Oral Microbial Identification Microarray (HOMIM) to validate a reproducible oral microcosm model. Methods and Results Saliva and dental plaque were collected from adults and children. Hydroxyapatite and dental composite disks were inoculated with either saliva or plaque, and microcosm biofilms were grown in a CDC biofilm reactor. In later experiments, the reactor was pulsed with sucrose. DNA from inoculums and microcosms were analyzed by HOMIM for 272 species. Microcosms included about 60% of species from the original inoculum. Biofilms grown on hydroxyapatite and composites were extremely similar. Sucrose-pulsing decreased diversity and pH, but increased the abundance of Streptococcus and Veilonella. Biofilms from the same donor, grown at different times, clustered together. Conclusions This model produced reproducible microcosm biofilms that were representative of the oral microbiota. Sucrose induced changes associated with dental caries. Significance and Impact of the Study This is the first use of HOMIM to validate an oral microcosm model that can be used to study the effects of complex biofilms on dental materials. PMID:22925110

Rudney, J.D.; Chen, R.; Lenton, P.; Li, J.; Li, Y.; Jones, R.S.; Reilly, C.; Fok, A.S.; Aparicio, C.

2012-01-01

335

In situ imaging of biofilm within opaque porous media (Invited)  

NASA Astrophysics Data System (ADS)

Microbial biofilms are observed in both natural and engineered subsurface environments and can dramatically alter the physical properties of porous media. Current understanding of biofilm formation and the associated impacts to structural and hydrodynamic properties of porous media are limited by our ability to observe changes to pore morphology in situ. Imaging biofilm within opaque porous media has historically presented a significant challenge. Synchrotron-based x-ray computed microtomography has been a long standing tool for the non-destructive imaging of porous media; however, traditional contrast agents used in tomography research diffuse readily into both the aqueous phase as well as the porous media associated biofilm, thereby preventing easy delineation of the two phases. Two new methods for imaging biofilm within porous media using x-ray microtomography will be presented. The first method utilizes silver-coated glass microspheres as a surface attached contrast agent for delineating the biofilm-aqueous phase interface within porous media. The second method introduces a barium sulfate suspension to the aqueous phase which is excluded from the biofilm matrix. The use of these contrast agents allow for direct segmentation of the solid, biofilm and aqueous phases. Imaging results using both of these methods will be presented along with the respective advantages and limitations. Quantitative analysis of biofilm formation and changes to macropore morphology will be presented, along with potential applications for these methods.

Iltis, G.; Davit, Y.; Wood, B. D.; Wildenschild, D.

2010-12-01

336

Monitoring biofilm attachment on medical devices surfaces using hyperspectral imaging  

NASA Astrophysics Data System (ADS)

Microbial biofilm is a colony of single bacteria cells (planktonic) that attached to surfaces, attract other microorganisms to attach and grow, and together they build an extracellular matrix composed of polysaccharides, protein, and DNA. Eventually, some cells will detach and spread to other surface. Biofilm on medical devices can cause severe infection to all age ranges from infant to adult. Therefore, it is important to detect biofilm in a fast and efficient manner. Hyperspectral imaging was utilized for distinguishing wide area of biofilm coverage on various materials and on different textures of stainless steeltest coupons. Not only is the coverage of biofilm important, but also the shear stress of biofilm on the attached surfaces is significant. This study investigates the effects of shear stress on the adhesion of biofilms on common medical device surfaces such as glass, polycarbonate, polytetrafluoroethylene, and stainless steel with different textures. Biofilm was grown using Ps. aeruginosa and growth was monitored after 24 and 48 hours at 37° C. The coupons covered with biofilm were tilted at 45 degrees and 90 degrees for 30 seconds to induce shear stress and Hyperspectral images were taken. We hypothesize that stronger attachment on rough surface would be able to withstand greater shear stress compared to smooth surface.

Le, Hanh N. D.; Hitchins, Victoria M.; Ilev, Ilko K.; Kim, Do-Hyun

2014-02-01

337

Form and Function of Clostridium thermocellum Biofilms  

PubMed Central

The importance of bacterial adherence has been acknowledged in microbial lignocellulose conversion studies; however, few reports have described the function and structure of biofilms supported by cellulosic substrates. We investigated the organization, dynamic formation, and carbon flow associated with biofilms of the obligately anaerobic cellulolytic bacterium Clostridium thermocellum 27405. Using noninvasive, in situ fluorescence imaging, we showed biofilms capable of near complete substrate conversion with a characteristic monolayered cell structure without an extracellular polymeric matrix typically seen in biofilms. Cell division at the interface and terminal endospores appeared throughout all stages of biofilm growth. Using continuous-flow reactors with a rate of dilution (2 h?1) 12-fold higher than the bacterium's maximum growth rate, we compared biofilm activity under low (44 g/liter) and high (202 g/liter) initial cellulose loading. The average hydrolysis rate was over 3-fold higher in the latter case, while the proportions of oligomeric cellulose hydrolysis products lost from the biofilm were 13.7% and 29.1% of the total substrate carbon hydrolyzed, respectively. Fermentative catabolism was comparable between the two cellulose loadings, with ca. 4% of metabolized sugar carbon being utilized for cell production, while 75.4% and 66.7% of the two cellulose loadings, respectively, were converted to primary carbon metabolites (ethanol, acetic acid, lactic acid, carbon dioxide). However, there was a notable difference in the ethanol-to-acetic acid ratio (g/g), measured to be 0.91 for the low cellulose loading and 0.41 for the high cellulose loading. The results suggest that substrate availability for cell attachment rather than biofilm colonization rates govern the efficiency of cellulose conversion. PMID:23087042

Dumitrache, Alexandru; Allen, Grant; Liss, Steven N.; Lynd, Lee R.

2013-01-01

338

Evidence of Ancient Microbial Life in an Impact Structure and Its Implications for Astrobiology  

Microsoft Academic Search

The search for present and past life on Mars has drawn major attention from the scientific community, as well as from national\\u000a and international space agencies. A major reason for focusing the search for life on Mars is that, apart from being the closest\\u000a planetary body of major astrobiological interest, Mars may have shared a number of environmental features with

Tomas Hode; Sherry L. Cady; Ilka Dalwigk; Per Kristiansson

339

Cell growth and protein expression of Shewanella oneidensis in biofilms and hydrogel-entrapped cultures.  

PubMed

The performance of biofilm-based bioprocesses is difficult to predict and control because of the intrinsic heterogeneous and dynamic properties of microbial biofilms. Biofilm mimics, such as microbial cells entrapped in polymeric scaffolds that are permeable for nutrients, have been proposed to replace real biofilms to achieve long-term robust performance in engineering applications. However, the physiological differences between cells that are physically entrapped in a synthetic polymeric matrix and biofilm cells that are encased in a self-produced polymeric matrix remain unknown. In this study, using Shewanella oneidensis as a model organism and alginate hydrogel as a model synthetic matrix, we compared the cell growth and protein expression in entrapped cultures and biofilms. The hydrogel-entrapped cultures were found to exhibit a growth rate comparable with biofilms. There was no substantial difference in cell viability, surface charge, as well as hydrophobicity between the cells grown in alginate hydrogel and those grown in biofilms. However, the gel-entrapped cultures were found to be physiologically different from biofilms. The gel-entrapped cultures had a higher demand for metabolic energy. The siderophore-mediated iron uptake was repressed in the gel-entrapped cells. The presence of the hydrogel matrix decreased the expression of proteins involved in biofilm formation, while inducing the production of extracellular DNA (eDNA) in the gel-entrapped cultures. These results advance the fundamental understanding of the physiology of hydrogel-entrapped cells, which can lead to more efficient biofilm mimic-based applications. PMID:24626808

Zhang, Yingdan; Ng, Chun Kiat; Cohen, Yehuda; Cao, Bin

2014-05-01

340

Ice Shelf Microbial Ecosystems in the High Arctic and Implications for Life on Snowball Earth  

NASA Astrophysics Data System (ADS)

The Ward Hunt Ice Shelf (83°N, 74°W) is the largest remaining section of thick (>10m) landfast sea ice along the northern coastline of Ellesmere Island, Canada. Extensive meltwater lakes and streams occur on the surface of the ice and are colonized by photosynthetic microbial mat communities. This High Arctic cryo-ecosystem is similar in several of its physical, biological and geochemical features to the McMurdo Ice Shelf in Antarctica. The ice-mats in both polar regions are dominated by filamentous cyanobacteria but also contain diatoms, chlorophytes, flagellates, ciliates, nematodes, tardigrades and rotifers. The luxuriant Ward Hunt consortia also contain high concentrations (107-108cm-2) of viruses and heterotrophic bacteria. During periods of extensive ice cover, such as glaciations during the Proterozoic, cryotolerant mats of the type now found in these polar ice shelf ecosystems would have provided refugia for the survival, growth and evolution of a variety of organisms, including multicellular eukaryotes.

Vincent, W. F.; Gibson, J. A. E.; Pienitz, R.; Villeneuve, V.; Broady, P. A.; Hamilton, P. B.; Howard-Williams, C.

341

Biofilms on tracheoesophageal voice prostheses: a confocal laser scanning microscopy demonstration of mixed bacterial and yeast biofilms.  

PubMed

The aim of this study was to demonstrate the presence of yeast and bacterial biofilms on the surface of tracheoesophageal voice prostheses (TVPs) by a double-staining technique with confocal laser scanning microscopy (CLSM). Biofilms of 12 removed TVPs were visualized by scanning electron microscopy, then stained with ConA-FITC and propidium iodide for CLSM. Microbial identification was by partial 16S rRNA gene analysis and ITS-2 sequence analysis. Microbial biofilms on the TVPs consisted of bacteria and filamentous cells. Bacterial cells were attached to the filamentous and unicellular yeast cells, thus forming a network. Sequence analyses of six voice prostheses identified the presence of a variety of bacterial and yeast species. In vivo studies showed that Klebsiella oxytoca and Micrococcus luteus efficiently attached to Candida albicans. CLSM with double fluorescence staining can be used to demonstrate biofilm formations composed of a mixture of yeast and bacterial cells on the surface of TVPs. PMID:20473799

Kania, Romain E; Lamers, Gerda E M; van de Laar, Nicole; Dijkhuizen, Marloes; Lagendijk, Ellen; Huy, Patrice Tran Ba; Herman, Philippe; Hiemstra, Pieter; Grote, Jan J; Frijns, Johan; Bloemberg, Guido V

2010-07-01

342

Submarine water-rock interactions and microbial life: a theoretical approach  

NASA Astrophysics Data System (ADS)

Mass and energy balances coupled with thermodynamic calculations indicate that a large amount of energy in the form of chemical work (about 100 Petajoule/yr) is transported to the seafloor by hydrothermal vent fluids. A similar amount of energy is tied to the affinity of reduced components in seafloor rocks and minerals for oxidation. Chemolithoautotrophic microorganisms harness an unknown fraction of that energy to produce primary biomass in the deep sea. The specific magmatic and fluid-rock interaction processes taking place within the geological system control what metabolic reactions can support chemolithoautotrophy-based microbial ecosystems at the seafloor. It turns out that basement composition, magmatic degassing, and subseafloor mineralization impose a first-order control on vent fluid chemistry. We used thermodynamic calculations to assess how much energy hot rocks can provide in different geotectonic setting to support biomass production by chemolithoautotrophic microorganisms. The dominant energy source varies greatly between vents in different submarine settings, from hydrogen sulfide in basalt-hosted systems to dihydrogen and methane in peridotite-hosted systems to Fe and S in felsic rock systesm in island arcs. The dihydrogen fluxes related to serpentinization are at least one order of magnitude greater than those related to global magmatism, and hydrogen consumption could be one of the most important catabolic reactions in deep-sea chemolithoautotrophy. In one example we show that peridotite-water interactions release quantities of hydrogen that are sufficient for methanogens and sulfate reducers to thrive under a range of temperature and fluid flux conditions. In contrast, hydrogen production within basaltic aquifers is barely enough under the best of circumstances to allow for growth of methanogens and sulfate reducers. This prediction appears to be corroborated by sulfur isotope compositions of hydrothermally altered peridotites and basalts, where only the former show a distinct mode centered around light (microbial) isotopic ratios.

Bach, W.; Hentscher, M.

2009-04-01

343

A genetic basis for Pseudomonas aeruginosa biofilm antibiotic resistance  

Microsoft Academic Search

Biofilms are surface-attached microbial communities with characteristic architecture and phenotypic and biochemical properties distinct from their free-swimming, planktonic counterparts. One of the best-known of these biofilm-specific properties is the development of antibiotic resistance that can be up to 1,000-fold greater than planktonic cells. We report a genetic determinant of this high-level resistance in the Gram-negative opportunistic pathogen, Pseudomonas aeruginosa. We

Thien-Fah Mah; Betsey Pitts; Brett Pellock; Graham C. Walker; Philip S. Stewart; George A. O'Toole

2003-01-01

344

Microstructure and mechanical properties of in situ Streptococcus mutans biofilms.  

PubMed

Insight into live microbial biofilm microstructure and mechanical properties and their interactions with the underlying substrate can lead to the development of new remedial strategies and/or materials. Here we report mechanical properties of dental pathogenic Streptococcus mutans biofilms, grown on a polystyrene-coated plate of a shear rheometer in physiologically relevant conditions, precisely controlled in a custom built bioreactor. In situ measurements demonstrated the importance of microstructure and composition of extracellular polymeric substances on the biofilm modulus. The biofilms behave like a weak gel with storage moduli higher than loss moduli. The simple but robust experimental technique presented here can easily be extended to other biofilm-material systems. PMID:24351115

Waters, Michael S; Kundu, Santanu; Lin, Nancy J; Lin-Gibson, Sheng

2014-01-01

345

Discrete nanoparticles induce loss of Legionella pneumophila biofilms from surfaces.  

PubMed

Nanoparticles (NPs) have been shown to induce dispersal events in microbial biofilms but the mechanism of the dispersal is unknown. Biofilms contaminate many man-made aquatic systems such as cooling towers, spas and dental lines. Within these biofilms, Legionella pneumophila is a primary pathogen, leading to these environments serving as sources for disease outbreaks. Here we show a reduction in biofilm bio-volume upon treatment with citrate-coated 6-nm platinum NPs, polyethylene glycol (PEG)-coated 11-nm gold NPs, and PEG-coated 8-nm iron oxide NPs. Treatment with citrate-coated 8-nm silver NPs, however, did not reduce biomass. The synthesis of NPs that remain dispersed and resist irreversible aggregation in the exposure media appears to be a key factor in the ability of NPs to induce biofilm dispersal. PMID:23586422

Raftery, Tara D; Kerscher, Petra; Hart, Ashley E; Saville, Steven L; Qi, Bin; Kitchens, Christopher L; Mefford, Olin Thompson; McNealy, Tamara L

2014-08-01

346

Biofilm Shows Spatially Stratified Metabolic Responses to Contaminant Exposure  

SciTech Connect

The objective of this study was to elucidate the spatiotemporal responses of live S. oneidensis MR-1 biofilms to U(VI) (uranyl, UO22+) and Cr(VI) (chromate, CrO42-), important environmental contaminants at DOE contaminated sites. Toward this goal, we applied noninvasive nuclear magnetic resonance (NMR) imaging, diffusion, relaxation and spectroscopy techniques to monitor in situ spatiotemporal responses of S. oneidensis biofilms to U(VI) and Cr(VI) exposure in terms of changes in biofilm structures, diffusion properties, and cellular metabolism. Exposure to U(VI) or Cr(VI) did not appear to change the overall biomass distribution but caused changes in the physicochemical microenvironments inside the biofilm as indicated by diffusion measurements. Changes in the diffusion properties of the biofilms in response to U(VI) and Cr(VI) exposure imply a novel function of the extracellular polymeric substances (EPS) affecting the biotransformation and transport of contaminants in the environment. In the presence of U(VI) or Cr(VI), the anaerobic metabolism of lactate was inhibited significantly, although the biofilms were still capable of reducing U(VI) and Cr(VI). Local concentrations of Cr(III)aq in the biofilm suggested relatively high Cr(VI) reduction activities at the top of the biofilm, near the medium-biofilm interface. The depth-resolved metabolic activities of the biofilm suggested higher diversion effects of gluconeogenesis and C1 metabolism pathways at the bottom of the biofilm and in the presence of U(VI). This study provides a noninvasive means to investigate spatiotemporal responses of biofilms, including surface-associated microbial communities in engineering, natural and medical settings, to various environmental perturbations including exposure to environmental contaminants and antimicrobials.

Cao, Bin; Majors, Paul D.; Ahmed, B.; Renslow, Ryan S.; Sylvia, Crystal P.; Shi, Liang; Kjelleberg, Staffan; Fredrickson, Jim K.; Beyenal, Haluk

2012-11-01

347

Viable halobacteria from Permo-Triassic salt deposits and the possibility of extraterrestrial microbial life  

NASA Astrophysics Data System (ADS)

The range of physico-chemical parameters for the presence of life is ever expanding, making it conceivable to search in seemingly inhospitable environments for extraterrestrial forms of life. Extremely halophilic archaebacteria (haloarchaea) were isolated from ancient salt deposits, adding another dimension - potentially exorbitant longevity - to the unusual characteristics of prokaryotic life. Distribution of haloarchaea in salt sediments appears to be world-wide; one particular strain, Halococcus salifodinae, was found in Alpine and Zechstein sediments. By using amplification of 16S rRNA genes with DNA extracted from rock salt, we obtained evidence for numerous haloarchaea, which have not been cultivated yet. Phylogenetic analysis revealed novel taxa within known lineages of haloarchaea. The results could be of relevance for astrobiology: together with the recent findings of halite, sylvite and water in some meteorites, it is intriguing to consider a specific search for extreme halophiles in Mars return samples or other materials from celestial bodies.

Stan-Lotter, H.; Radax, C.; Gruber, C.; Legat, A.; Pfaffenhuemer, M.; Wieland, H.

2001-08-01

348

The exopolysaccharide matrix: a virulence determinant of cariogenic biofilm.  

PubMed

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. PMID:24045647

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

2013-12-01

349

Effect of light and temperature on biomass, photosynthesis and capsular polysaccharides in cultured phototrophic biofilms  

Microsoft Academic Search

Phototrophic biofilms seem to be suitable candidates for tertiary wastewater treatment due to their high uptake capacity for\\u000a nutrients and other pollutants, also taking into account the time and cost savings derived from easy procedures for biomass\\u000a harvesting. Biomass accrual, structure, and physiology of biofilms affect the efficiency of nutrient removal by its microbial\\u000a community. Here, we construct a biofilm

Francesca Di Pippo; Neil Tomas William Ellwood; Antonella Guzzon; Luisa Siliato; Ernesto Micheletti; Roberto De Philippis; Patrizia B. Albertano

350

Marine Biofilms as Mediators of Colonization by Marine Macroorganisms: Implications for Antifouling and Aquaculture  

Microsoft Academic Search

In the marine environment, biofilms on submerged surfaces can promote or discourage the settlement of invertebrate larvae\\u000a and macroalgal spores. The settlement-mediating effects of biofilms are believed to involve a variety of biofilm attributes\\u000a including surface chemistry, micro-topography, and a wide range of microbial products from small-molecule metabolites to high-molecular\\u000a weight extracellular polymers. The settled organisms in turn can modify

P.-Y. Qian; S. C. K. Lau; H.-U. Dahms; S. Dobretsov; T. Harder

2007-01-01

351

A “cryptic” microbial mat: A new model ecosystem for extant life on Mars  

Microsoft Academic Search

If life were present on Mars today, it would face potentially lethal environmental conditions such as a lack of water, frigid temperatures, ultraviolet radiation, and soil oxidants. In addition, the Viking missions did not detect near-surface organic carbon available for assimilation. Autotrophic organisms that lived under a protective layer of sand or gravel would be able to circumvent the ultraviolet

L. J Rothschild

1995-01-01

352

Tracking the cellulolytic activity of Clostridium thermocellum biofilms  

PubMed Central

Background Microbial cellulose conversion by Clostridium thermocellum 27405 occurs predominantly through the activity of substrate-adherent bacteria organized in thin, primarily single cell-layered biofilms. The importance of cellulosic surface exposure to microbial hydrolysis has received little attention despite its implied impact on conversion kinetics. Results We showed the spatial heterogeneity of fiber distribution in pure cellulosic sheets, which made direct measurements of biofilm colonization and surface penetration impossible. Therefore, we utilized on-line measurements of carbon dioxide (CO2) production in continuous-flow reactors, in conjunction with confocal imaging, to observe patterns of biofilm invasion and to indirectly estimate microbial accessibility to the substrate’s surface and the resulting limitations on conversion kinetics. A strong positive correlation was found between cellulose consumption and CO2 production (R2?=?0.996) and between surface area and maximum biofilm activity (R2?=?0.981). We observed an initial biofilm development rate (0.46 h-1, 0.34 h-1 and 0.33 h-1) on Whatman sheets (#1, #598 and #3, respectively) that stabilized when the accessible surface was maximally colonized. The results suggest that cellulose conversion kinetics is initially subject to a microbial limitation period where the substrate is in excess, followed by a substrate limitation period where cellular mass, in the form of biofilms, is not limiting. Accessible surface area acts as an important determinant of the respective lengths of these two distinct periods. At end-point fermentation, all sheets were digested predominantly under substrate accessibility limitations (e.g., up to 81% of total CO2 production for Whatman #1). Integration of CO2 production rates over time showed Whatman #3 underwent the fastest conversion efficiency under microbial limitation, suggestive of best biofilm penetration, while Whatman #1 exhibited the least recalcitrance and the faster degradation during the substrate limitation period. Conclusion The results showed that the specific biofilm development rate of cellulolytic bacteria such as C. thermocellum has a notable effect on overall reactor kinetics during the period of microbial limitation, when ca. 20% of cellulose conversion occurs. The study further demonstrated the utility of on-line CO2 measurements as a method to assess biofilm development and substrate digestibility pertaining to microbial solubilization of cellulose, which is relevant when considering feedstock pre-treatment options. PMID:24286524

2013-01-01

353

Microbial life in Champagne Pool, a geothermal spring in Waiotapu, New Zealand.  

PubMed

Surveys of Champagne Pool, one of New Zealand's largest terrestrial hot springs and rich in arsenic ions and compounds, have been restricted to geological and geochemical descriptions, and a few microbiological studies applying culture-independent methods. In the current investigation, a combination of culture and culture-independent approaches were chosen to determine microbial density and diversity in Champagne Pool. Recovered total DNA and adenosine 5'-triphosphate (ATP) content of spring water revealed relatively low values compared to other geothermal springs within New Zealand and are in good agreement with low cell numbers of 5.6 +/- 0.5 x 10(6) cells/ml obtained for Champagne Pool water samples by 4',6-diamidino-2-phenylindole (DAPI) staining. Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rRNA (small-subunit ribosomal nucleic acid) gene clone library analyses of environmental DNA indicated the abundance of Sulfurihydrogenibium, Sulfolobus, and Thermofilum-like populations in Champagne Pool. From these results, media were selected to target the enrichment of hydrogen-oxidizing and sulfur-dependent microorganisms. Three isolates were successfully obtained having 16S rRNA gene sequences with similarities of approximately 98% to Thermoanaerobacter tengcongensis, 94% to Sulfurihydrogenibium azorense, and 99% to Thermococcus waiotapuensis, respectively. PMID:17426919

Hetzer, Adrian; Morgan, Hugh W; McDonald, Ian R; Daughney, Christopher J

2007-07-01

354

Microbial life at -13 ?C in the brine of an ice-sealed Antarctic lake  

PubMed Central

The permanent ice cover of Lake Vida (Antarctica) encapsulates an extreme cryogenic brine ecosystem (?13 °C; salinity, 200). This aphotic ecosystem is anoxic and consists of a slightly acidic (pH 6.2) sodium chloride-dominated brine. Expeditions in 2005 and 2010 were conducted to investigate the biogeochemistry of Lake Vida’s brine system. A phylogenetically diverse and metabolically active Bacteria dominated microbial assemblage was observed in the brine. These bacteria live under very high levels of reduced metals, ammonia, molecular hydrogen (H2), and dissolved organic carbon, as well as high concentrations of oxidized species of nitrogen (i.e., supersaturated nitrous oxide and ?1 mmol?L?1 nitrate) and sulfur (as sulfate). The existence of this system, with active biota, and a suite of reduced as well as oxidized compounds, is unusual given the millennial scale of its isolation from external sources of energy. The geochemistry of the brine suggests that abiotic brine-rock reactions may occur in this system and that the rich sources of dissolved electron acceptors prevent sulfate reduction and methanogenesis from being energetically favorable. The discovery of this ecosystem and the in situ biotic and abiotic processes occurring at low temperature provides a tractable system to study habitability of isolated terrestrial cryoenvironments (e.g., permafrost cryopegs and subglacial ecosystems), and is a potential analog for habitats on other icy worlds where water-rock reactions may cooccur with saline deposits and subsurface oceans. PMID:23185006

Murray, Alison E.; Kenig, Fabien; Fritsen, Christian H.; McKay, Christopher P.; Cawley, Kaelin M.; Edwards, Ross; Kuhn, Emanuele; McKnight, Diane M.; Ostrom, Nathaniel E.; Peng, Vivian; Ponce, Adrian; Priscu, John C.; Samarkin, Vladimir; Townsend, Ashley T.; Wagh, Protima; Young, Seth A.; Yung, Pung To; Doran, Peter T.

2012-01-01

355

Listeria monocytogenes EGD-e Biofilms: No Mushrooms but a Network of Knitted Chains  

Microsoft Academic Search

Listeria monocytogenes is a food pathogen that can attach on most of the surfaces encountered in the food industry. Biofilms are three-dimensional microbial structures that facilitate the persistence of pathogens on surfaces, their resistance toward antimicrobials, and the final contamination of processed goods. So far, little is known about the structural dynamics of L. monocytogenes biofilm formation and its regulation.

Aurelie Rieu; Romain Briandet; Olivier Habimana; Dominique Garmyn; Jean Guzzo; Pascal Piveteau

2008-01-01

356

Fate of terrestrial DOC within stream biofilm communities: a stable isotope approach (Invited)  

Microsoft Academic Search

Heterotrophic members of the biofilm community play a critical ecological role in lotic ecosystems. They take up, degrade, and mineralize organic carbon, often dominate community respiration, and are a critical link to higher trophic levels through the microbial loop. The goal of our study was to identify who within the stream biofilm community actively metabolizes stream dissolved organic carbon (DOC)

T. N. Wiegner; L. Kaplan; S. E. Ziegler; R. H. Findlay

2010-01-01

357

Synergistic Activity of Dispersin B and Cefamandole Nafate in Inhibition of Staphylococcal Biofilm Growth on Polyurethanes  

Microsoft Academic Search

isms. In the last two decades, several strategies to prevent microbial adhesion and biofilm formation on the surfaces of medical devices, based mainly on the use of antiadhesive, antiseptic, and antibiotic coatings on polymer surfaces, have been developed. More recent alternative approaches are based on molecules able to interfere with quorum-sensing phenomena or to dissolve biofilms. Interestingly, a newly purified

G. Donelli; I. Francolini; D. Romoli; E. Guaglianone; A. Piozzi; C. Ragunath; J. B. Kaplan

2007-01-01

358

Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates  

Microsoft Academic Search

This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs\\/aggregates (also called granules) without use of chemicals and form thick layers of cells known as \\

Nasib Qureshi; Bassam A Annous; Thaddeus C Ezeji; Patrick Karcher; Ian S Maddox

2005-01-01

359

Mathematical Medicine and Biology (2004) 21, 147166 The role of the biofilm matrix in structural development  

E-print Network

of swelling, may induce the formation of isolated towers or mushroom clusters by spatial variation in EPS to anti-microbial agents, have made biofilm research an active area in the past three decades. As more

Keener, James P.

360

EFFECT OF VARYING FLOW REGIMES ON BIOFILM DENSITIES IN A DISTRIBUTION SYSTEM SIMULATOR  

EPA Science Inventory

Maintenance of a free chlorine residual within water distribution systems is used to reduce the possibility of microbial contamination. However, it has been demonstrated that biofilms within water distribution systems can harbor coliforms. In laboratory scale studies, others have...

361

Role of efflux pumps in the antibiotic resistance of bacteria embedded in a biofilm  

PubMed Central

Biofilms are complex microbial associations anchored to abiotic or biotic surfaces, embedded in extracellular matrix produced by the biofilms themselves where they interact with each other and the environment. One of the main properties of biofilms is their capacity to be more resistant to antimicrobial agents than planktonic cells. Efflux pumps have been reported as one of the mechanisms responsible for the antimicrobial resistance in biofilm structures. Evidence of the role of efflux pump in biofilm resistance has been found in several microorganisms such as Pseudomonas aeruginosa, Escherichia coli and Candida albicans. However, in spite of the studies on the importance of efflux pumps in biofilm growth and about their relevance in antimicrobial resistance forming biofilm, the exact role of these efflux systems has not been determined as yet. PMID:23380871

Soto, Sara M.

2013-01-01

362

Predation Response of Vibrio fischeri Biofilms to Bacterivorus Protists  

PubMed Central

Vibrio fischeri proliferates in a sessile, stable community known as a biofilm, which is one alternative survival strategy of its life cycle. Although this survival strategy provides adequate protection from abiotic factors, marine biofilms are still susceptible to grazing by bacteria-consuming protozoa. Subsequently, grazing pressure can be controlled by certain defense mechanisms that confer higher biofilm antipredator fitness. In the present work, we hypothesized that V. fischeri exhibits an antipredator fitness behavior while forming biofilms. Different predators representing commonly found species in aquatic populations were examined, including the flagellates Rhynchomonas nasuta and Neobodo designis (early biofilm feeders) and the ciliate Tetrahymena pyriformis (late biofilm grazer). V. fischeri biofilms included isolates from both seawater and squid hosts (Euprymna and Sepiola species). Our results demonstrate inhibition of predation by biofilms, specifically, isolates from seawater. Additionally, antiprotozoan behavior was observed to be higher in late biofilms, particularly toward the ciliate T. pyriformis; however, inhibitory effects were found to be widespread among all isolates tested. These results provide an alternative explanation for the adaptive advantage and persistence of V. fischeri biofilms and provide an important contribution to the understanding of defensive mechanisms that exist in the out-of-host environment. PMID:23144127

Chavez-Dozal, Alba; Gorman, Clayton; Erken, Martina; Steinberg, Peter D.; McDougald, Diane

2013-01-01

363

Micron-scale Fe 2+/Fe 3+, intermediate sulfur species and O 2 gradients across the biofilm-solution-sediment interface control biofilm organization  

NASA Astrophysics Data System (ADS)

We measured micron-scale Fe 2+/Fe 3+ and intermediate sulfur species gradients across the biofilm-solution interface and defined the microbial community composition in natural and bioreactor-cultivated acid mine drainage biofilms to investigate how community organization correlated with geochemical conditions. Intermediate sulfur species concentrations were also measured in associated sediments. Under initial conditions of high Fe 2+ and O 2 concentrations, the first biofilm colonists were Leptospirillum Group II, UBA genotype, and a few Archaea. Cytochrome 579 concentration in early formed biofilms was high, correlating with rapid Fe 2+ oxidation. As biofilm thickness increased, O 2 concentrations in the middle of biofilms decreased, indicating that diffusion limitation of O 2 may control activity levels of aerobic organisms. Calculated low O 2 and high Fe 3+ concentrations in the interior regions of biofilms may explain the previously reported suppression of the UBA genotype in mature biofilms. Instead, Leptospirillum Group II, 5-way CG genotype, dominated under these conditions. Leptospirillum Group III and eukaryotes appeared in the community as the biofilm thickened and Fe 3+/Fe 2+ increased. In mature biofilms, the architecture changed from planar to crenulated, perhaps to increase the surface area of biofilms and decrease O 2 diffusion limitation. In thick, mature biofilms, layering is associated with segregation of Leptospirillum Group II and Archaea and the concentration of cytochrome 579 is lower. The accumulation of Archaea close to the biofilm-air interface may facilitate their aerobic metabolism of waste carbon compounds. Sulfite, thiosulfate and polysulfides were detected in AMD sediments and thiosulfate was detected in solution. These compounds indicate the redox status of the system and represent potential energy sources. Temporal and spatial heterogeneity in community structure correlate with heterogeneity in geochemical conditions, implying active feedbacks between geochemical conditions and microbial species distribution and activity.

Ma, Shufen; Banfield, Jillian F.

2011-06-01

364

New life in old reservoirs - the microbial conversion of oil to methane  

NASA Astrophysics Data System (ADS)

Since almost 20 years it is known from stable isotope studies that large amounts of biogenic methane are formed in oil reservoirs. The investigation of this degradation process and of the underlying biogeochemical controls are of economical and social importance, since even under optimal conditions, not more than 30-40 % of the oil in a reservoir is actually recovered. The conversion of parts of this non-recoverable oil via an appropriate biotechnological treatment into easily recoverable methane would provide an extensive and ecologically sound energy resource. Laboratory mesocosm as well as high pressure autoclave experiments with samples from different geosystems showed high methane production rates after the addition of oils, single hydrocarbons or coals. The variation of parameters, like temperature, pressure or salinity, showed a broad tolerance to environmental conditions. The fingerprinting of the microbial enrichments with DGGE showed a large bacterial diversity while that of Archaea was limited to three to four dominant species. The Q-PCR results showed the presence of high numbers of Archaea and Bacteria. To analyse their function, we measured the abundances of genes indicative of metal reduction (16S rRNA gene for Geobacteraceae), sulphate reduction (sulphate reductase, dsr), and methanogenesis (methyl coenzyme M-reductase, mcrA). The methanogenic consortia will be further characterised to determine enzymatic pathways and the individual role of each partner. Degradation pathways for different compounds will be studied using 13C-labelled substrates and molecular techniques. Our stable isotope data from both, methane produced in our incubations with samples from various ecosystems and field studies, implies a common methanogenic biodegradation mechanism, resulting in consistent patterns of hydrocarbon alteration.

Gründger, Friederike; Feisthauer, Stefan; Richnow, Hans Hermann; Siegert, Michael; Krüger, Martin

2010-05-01

365

Focusing on Environmental Biofilms With Variable-Pressure Scanning Electron Microscopy  

NASA Astrophysics Data System (ADS)

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 molecular fingerprints of wetland communities using tRFLP (Terminal Restriction Fragment Length Polymorphism) - and gave evidence of temporal and spatial variation in a wetland system, to potentially be applied as management tool in wastewater treatment. Visualization of differences in biofilm development by wild and recombinant yeast strains furthermore supported real-time quantitative data of biofilm development by Cryptococcus laurentii and Saccharomyces yeast strains. In all cases VP SEM allowed a more holistic interpretation of biofilm processes than afforded by quantitative empirical data only.

Joubert, L.; Wolfaardt, G. M.; Du Plessis, K.

2006-12-01

366

Simulation of batch-operated experimental wetland mesocosms in AQUASIM biofilm reactor compartment.  

PubMed

In this study, a mathematical biofilm reactor model based on the structure of the Constructed Wetland Model No.1 (CWM1) coupled to AQUASIM's biofilm reactor compartment has been used to reproduce the sequence of transformation and degradation of organic matter, nitrogen and sulphur observed in a set of constructed wetland mesocosms and to elucidate the development over time of microbial species as well as the biofilm thickness of a multispecies bacterial biofilm in a subsurface constructed wetland. Experimental data from 16 wetland mesocosms operated under greenhouse conditions, planted with three different plant species (Typha latifolia, Carex rostrata, Schoenoplectus acutus) and an unplanted control were used in the calibration of this mechanistic model. Within the mesocosms, a thin (predominantly anaerobic) biofilm was simulated with an initial thickness of 49 ?m (average) and in which no concentration gradients developed. The biofilm density and area, and the distribution of the microbial species within the biofilm were evaluated to be the most sensitive biofilm properties; while the substrate diffusion limitations were not significantly sensitive to influence the bulk volume concentrations. The simulated biofilm density ranging between 105,000 and 153,000 gCOD/m(3) in the mesocosms was observed to vary with temperature, the presence as well as the species of macrophyte. The biofilm modeling was found to be a better tool than the suspended bacterial modeling approach to show the influence of the rhizosphere configuration on the performance of the constructed wetlands. PMID:24468449

Mburu, Njenga; Rousseau, Diederik P L; Stein, Otto R; Lens, Piet N L

2014-02-15

367

Investigation of biofilms  

SciTech Connect

Drinking water systems, wastewater operations, and even groundwater and surface water, have in common the presence of cellular colonies called biofilms. Until now the means for studying biofilms have been limited. The present text provides the first in-depth assessment of current and experimental ways of studying biofilms, both in sample form and in situ. It shows how sensors, microscopy, lasers, and calorimetry, among other tools, can be used to obtain data on the morphology and metabolism of biofilms. In clarifying the way biofilms are studied, the book offers new insights into biofilms themselves. At the same time the text applies the techniques of inquiry to many problems confronting the environmental specialist, notably, the control of corrosion and biofouling, and the improvement of fixed-biofilm reactors in wastewater treatment.

Flemming, H.C.; Griebe, T.; Szewzyk, U.

1999-07-01

368

Opportunistic pathogens enriched in showerhead biofilms  

PubMed Central

The environments we humans encounter daily are sources of exposure to diverse microbial communities, some of potential concern to human health. In this study, we used culture-independent technology to investigate the microbial composition of biofilms inside showerheads as ecological assemblages in the human indoor environment. Showers are an important interface for human interaction with microbes through inhalation of aerosols, and showerhead waters have been implicated in disease. Although opportunistic pathogens commonly are cultured from shower facilities, there is little knowledge of either their prevalence or the nature of other microorganisms that may be delivered during shower usage. To determine the composition of showerhead biofilms and waters, we analyzed rRNA gene sequences from 45 showerhead sites around the United States. We find that variable and complex, but specific, microbial assemblages occur inside showerheads. Particularly striking was the finding that sequences representative of non-tuberculous mycobacteria (NTM) and other opportunistic human pathogens are enriched to high levels in many showerhead biofilms, >100-fold above background water contents. We conclude that showerheads may present a significant potential exposure to aerosolized microbes, including documented opportunistic pathogens. The health risk associated with showerhead microbiota needs investigation in persons with compromised immune or pulmonary systems. PMID:19805310

Feazel, Leah M.; Baumgartner, Laura K.; Peterson, Kristen L.; Frank, Daniel N.; Harris, J. Kirk; Pace, Norman R.

2009-01-01

369

Organic acid based sanitizers and free chlorine to improve the microbial quality and shelf-life of sugar snaps.  

PubMed

A screening in a sugar snap packaging company showed a converged build-up of aerobic psychrotrophic plate count (APC) (ca. 6.5 log CFU/100mL), yeasts and molds (Y&M), and lactic acid bacteria (LAB) (both ca. 4.5 log CFU/100mL) in the wash water in the absence of water sanitizer, and a low build-up of chemical oxygen demand (30 ± 5 mg O2/L) and turbidity (5.2 ± 1.1 NTU). Decontamination experiments were performed in the lab with Purac FCC 80® (80% L(+) lactic acid), two other commercial water sanitizers based on organic acids (NATRApHASe-ABAV®, and NATRApHASe-FVS®) and chlorine to evaluate their performance in reduction of the sugar snap microbial load as well as their functionality as disinfectant of the wash water to avoid cross-contamination. An additional 1 log reduction of APC on the sugar snaps was achieved with lactic acid in the range 0.8 to 1.6%, ABAV 0.5%, and free chlorine 200mg/L when compared to a water wash, while no significant difference in the numbers of Y&M was obtained when washing in sanitizer compared to water. There was no significant influence of the studied concentration and contact time on decontamination efficiency. Treatment with lactic acid 0.8% resulted in a lower APC contamination on the sugar snaps than on the untreated and water washed samples for 10 days. Chlorine 200mg/L was the only treatment able to maintain the Y&M load lower than the untreated samples throughout the entire storage duration. The use of water sanitizers could not extend the sensorial shelf-life. Microbial loads were not indicative/predictive of visual microbial spoilage (shelf-life limiting factor), whereas maturity and amount of damage at the calyx end of the pods were. The APC wash water contamination (5.2 log CFU/100mL) was reduced significantly by chlorine 20 to 200mg/L (to 1.4 log CFU/100mL), ABAV 0.5 to 1.5% (to 2.7 log CFU/100mL), FVS 0.5% (to 2.7 log CFU/100mL) and lactic acid 0.8 to 1.6% (to 3.4 log CFU/100mL). Only the use of chlorine enabled the reduction of the Y&M wash water contamination significantly (from 3.4 to 1.4 log CFU/100mL). The low physicochemical build-up of the sugar snap wash water during the industrial washing process makes free chlorine attractive as a water disinfectant to prevent bacterial and fungal cross-contamination, whereas the sanitizers based on organic acids are not, due to their weak water disinfection efficiency. PMID:24135672

Van Haute, Sam; Uyttendaele, Mieke; Sampers, Imca

2013-10-15

370

Rock physics models for constraining quantitative interpretation of ultrasonic data for biofilm growth and development  

NASA Astrophysics Data System (ADS)

This study examines the use of rock physics modeling for quantitative interpretation of seismic data in the context of microbial growth and biofilm formation in unconsolidated sediment. The impetus for this research comes from geophysical experiments by Davis et al. (2010) and Kwon and Ajo-Franklin et al. (2012). These studies observed that microbial growth has a small effect on P-wave velocities (VP) but a large effect on seismic amplitudes. Davis et al. (2010) and Kwon and Ajo-Franklin et al. (2012) speculated that the amplitude variations were due to a combination of rock mechanical changes from accumulation of microbial growth related features such as biofilms. A more definite conclusion can be drawn by developing rock physics models that connect rock properties to seismic amplitudes. The primary objective of this work is to provide an explanation for high amplitude attenuation due to biofilm growth. The results suggest that biofilm formation in the Davis et al. (2010) experiment exhibit two growth styles: a loadbearing style where biofilm behaves like an additional mineral grain and a non-loadbearing mode where the biofilm grows into the pore spaces. In the loadbearing mode, the biofilms contribute to the stiffness of the sediments. We refer to this style as "filler." In the non-loadbearing mode, the biofilms contribute only to change in density of sediments without affecting their strength. We refer to this style of microbial growth as "mushroom." Both growth styles appear to be changing permeability more than the moduli or the density. As the result, while the VP velocity remains relatively unchanged, the amplitudes can change significantly depending on biofilm saturation. Interpreting seismic data from biofilm growths in term of rock physics models provide a greater insight into the sediment-fluid interaction. The models in turn can be used to understand microbial enhanced oil recovery and in assisting in solving environmental issues such as creating bio-barriers to prevent water contamination or CO2 leakage.

Alhadhrami, Fathiya Mohammed

371

[Adaptation study for biofilm of the urinary tract via highly complicated bladder model (biofilm model of the urinary tract)--experimental study using automatic simulator of the urinary antimicrobial agent concentration].  

PubMed

With the view of making an adaptation study for biofilm of the urinary tract, we devised a computer-controlled highly complicated bladder model (biofilm model of the urinary tract) that allowed the simulation of time-course changes in the urinary concentration of antimicrobial agents. Clarithromycin (CAM), which is reported to have an anti-biofilm action, was examined at urinary levels approximating clinical concentrations and its effect on biofilm was determined. The following results were obtained. 1) Ofloxacin (OFLX, 200 mg x 2/day, MIC; 8 micrograms/ml), which is active against Pseudomonas aruginosa, caused apparent microbial elimination from the model at 42 hours, but bacterial regrowth occurred 4 hours after withdrawal of this agent. No disappearance of the biofilm was noted with OFLX suggesting that this was the cause of bacterial regrowth. 2) The combination of OFLX (200 mg x 2/day) and CAM (MIC; > 128 micrograms/ml, 200 mg x 2/day) on anti-biofilm agent, with no effect on P. aeruginosa, eliminated bacteria from the bladder model more rapidly and prolonged the regrowth time to 10 hours after withdrawal of the antimicrobial agents. Disappearance of most of the biofilm and only slight microbial adhesion was noted. 3) The combination of OFLX (200 mg x 2/day) and CAM (400 mg x 3/day) caused microbial elimination from the bladder model with no regrowth at 30 hours after withdrawal of the antimicrobial agents. The biofilm disappeared completely and no microbial adhesion was noted. 4) CAM alone (400 mg x 3/day) allowed microbial recovery to the initial level within 48 hours after withdrawal, but led to disappearance of the biofilm and the adhesion of microbes without a glycocalyx. 5) These results suggest that the anti-biofilm action of CAM is dose-dependent, and that combined use of an appropriate antimicrobial agent and anti-biofilm agent like CAM may be effective for biofilm infections of the urinary tract. PMID:8089557

Sano, M; Kumamoto, Y; Nishimura, M; Hirose, T; Ohya, S

1994-07-01

372

Sulfate- and Sulfur-Reducing Bacteria as Terrestrial Analogs for Microbial Life on Jupiter's Satellite Io  

NASA Technical Reports Server (NTRS)

Observations from the Voyager and Galileo spacecraft have revealed Jupiter's moon Io to be the most volcanically active body of our Solar System. The Galileo Near Infrared Imaging Spectrometer (NIMS) detected extensive deposits of sulfur compounds, elemental sulfur and SO2 frost on the surface of Io. There are extreme temperature variations on Io's surface, ranging from -130 C to over 2000 C at the Pillan Patera volcanic vent. The active volcanoes, fumaroles, calderas, and lava lakes and vast sulfur deposits on this frozen moon indicate that analogs of sulfur- and sulfate-reducing bacteria might inhabit Io. Hence Io may have great significance to Astrobiology. Earth's life forms that depend on sulfur respiration are members of two domains: Bacteria and Archaea. Two basic links of the biogeochemical sulfur cycle of Earth have been studied: 1) the sulfur oxidizing process (occurring at aerobic conditions) and 2) the process of sulfur-reduction to hydrogen sulfide (anaerobic conditions). Sulfate-reducing bacteria (StRB) and sulfur-reducing bacteria (SrRB) are responsible for anaerobic reducing processes. At the present time the systematics of StRB include over 112 species distributed into 35 genera of Bacteria and Archaea. Moderately thermophilic and mesophilic SrRB belong to the Bacteria. The hyperthermophilic SrRB predominately belong to the domain Archaea and are included in the genera: Pyrodictium, Thermoproteus, Pyrobaculum, Thermophilum, Desulfurococcus, and Thermodiscus. The StRB and SrRB use a wide spectrum of substrates as electron donors for lithotrophic and heterotrophic type nutrition. The electron acceptors for the StRB include: sulfate, thiosulfate, sulfite, sulfur, arsenate, dithionite, tetrathionate, sulfur monoxide, iron, nitrite, selenite, fumarate, oxygen, carbon dioxide, and chlorine-containing phenol compounds. The Sulfate- and Sulfur-reducing bacteria are widely distributed in anaerobic ecosystems, including extreme environments like hot springs, deepsea hydrothermal vents, soda and high salinity lakes, and cryo-environments. Furthermore, the StRB and SrRB have Astrobiological significance as these anaerobic extremophiles may represent the dominant relic life forms that inhabited our planet during the extensive volcanic activity in the Earth's early evolutionary period.

Pikuta, Elena V.; Hoover, Richard B.; Six, N. Frank (Technical Monitor)

2001-01-01

373

Nature of Phosphorus Compounds Fueling Microbial Life in Deep-Sea Sediments at North Pond  

NASA Astrophysics Data System (ADS)

Phosphorus is an essential nutrient that can be limiting in some environments. Despite its critical importance for life, many components of its cycle, including phosphorus uptake and cycling in deep-sea sediments, remain unclear. Understanding phosphorus cycling in open ocean sediments is crucial, since a significant portion of Earth's prokaryotes thrives in this environment. However, little is known about the nature of phosphorus compounds these microorganisms are taking up or the mechanisms used. This study aims to identify the specific phosphorus forms within the labile and refractory sedimentary phosphorus pools that "fuel" the deep biosphere at North Pond, an isolated sediment pond on the western flank of the Mid-Atlantic ridge. Sediment samples were collected from four boreholes drilled during the IODP expedition 336. Sedimentary phosphorus compounds are characterized using sequential extractions (SEDEX), which separate them into distinct reservoirs. In addition, solution phase 31P nuclear magnetic resonance spectroscopy is used to further characterize phosphorus forms. We hypothesize that phosphorus in deep sub-seafloor sediments has low bioavailability and is mainly present in mineral phases.

Defforey, D.; Paytan, A.

2012-12-01

374

Micron-scale Fe2+/Fe3+, intermediate sulfur species and O2 gradients across the biofilm - water - sediment interface control biofilm organization  

NASA Astrophysics Data System (ADS)

We measured micron-scale Fe2+/Fe3+ and intermediate sulfur species gradients across the biofilm - water interface and defined the microbial community composition in natural and bioreactor-cultivated acid mine drainage biofilms to investigate how community organization correlated with geochemical conditions. Intermediate sulfur species concentrations were also measured in associated sediments. Under initial conditions of high Fe2+ and O2 concentrations, the first biofilm colonists were Leptospirillum Group II, UBA genotype, and a few archaea. Cytochrome concentration in early-formed biofilms was high, correlating with rapid Fe oxidation. As biofilm thickness increased, O2 concentrations in the middle of biofilms decreased, indicating that diffusion limitation of O2 may control activity levels of aerobic species. Calculated low O2 and high Fe3+ concentrations in the interior regions of biofilms may explain the previously reported suppression of the UBA genotype in more mature biofilms. Instead, Leptospirillum Group II, 5-way CG genotype, dominated under these conditions. Leptospirillum Group III and eukaryotes appeared in the community as Fe3+/Fe2+ increased. In mature biofilms, the architecture changed from planar to convoluted, perhaps to increase the surface area of biofilms and decrease O2 diffusion limitation. In thick, mature biofilms, layering was associated with segregation of Leptospirillum Group II and archaea and the cytochrome concentration was lower. The accumulation of Archaea close to the biofilm-air interface may facilitate their aerobic metabolism of waste carbon compounds. Sulfite, thiosulfate and polysulfides were detected in AMD sediments and thiosulfate was detected in solution. These compounds indicate the redox status of the system and provide potential energy sources. Temporal and spatial heterogeneity in community structure correlate with heterogeneity in geochemical conditions, implying that geochemical conditions dictate microbial species organization.

Ma, S.; Banfield, J. F.

2010-12-01

375

Biofouling and microbial communities in membrane distillation and reverse osmosis.  

PubMed

Membrane distillation (MD) is an emerging desalination technology that uses low-grade heat to drive water vapor across a microporous hydrophobic membrane. Currently, little is known about the biofilms that grow on MD membranes. In this study, we use estuarine water collected from Long Island Sound in a bench-scale direct contact MD system to investigate the initial stages of biofilm formation. For comparison, we studied biofilm formation in a bench-scale reverse osmosis (RO) system using the same feedwater. These two membrane desalination systems expose the natural microbial community to vastly different environmental conditions: high temperatures with no hydraulic pressure in MD and low temperature with hydraulic pressure in RO. Over the course of 4 days, we observed a steady decline in bacteria concentration (nearly 2 orders of magnitude) in the MD feed reservoir. Even with this drop in planktonic bacteria, significant biofilm formation was observed. Biofilm morphologies on MD and RO membranes were markedly different. MD membrane biofilms were heterogeneous and contained several colonies, while RO membrane biofilms, although thicker, were a homogeneous mat. Phylogenetic analysis using next-generation sequencing of 16S rDNA showed significant shifts in the microbial communities. Bacteria representing the orders Burkholderiales, Rhodobacterales, and Flavobacteriales were most abundant in the MD biofilms. On the basis of the results, we propose two different regimes for microbial community shifts and biofilm development in RO and MD systems. PMID:25295386

Zodrow, Katherine R; Bar-Zeev, Edo; Giannetto, Michael J; Elimelech, Menachem

2014-11-18

376

Modeling phototrophic biofilms in a plug-flow reactor.  

PubMed

The use of phototrophic biofilms in wastewater treatment has been recognized as a potential option for development of new reactor configurations. For better understanding of these systems, a numerical model was developed including relevant microbial processes. As a novelty, this model was implemented in COMSOL Multiphysics, a modern computational environment for complex dynamic models. A two-dimensional biofilm model was used to study the spatial distribution of microbial species within the biofilm and along the length of the reactor. The biofilm model was coupled with a one-dimensional plug-flow bulk liquid model. The impact of different operational conditions on the chemical oxygen demand (COD) and ammonia conversions was assessed. The model was tuned by varying two parameters: the half-saturation coefficient for light use by phototrophs and the oxygen mass transfer coefficient. The mass transfer coefficient was found to be determining for the substrate conversion rate. Simulations indicate that heterotrophs would overgrow nitrifiers and phototrophs within the biofilm until a low biodegradable COD value in the wastewater is reached (organic loading rate <2.32 gCOD/(m(2) d)). This limits the proposed positive effect of treating wastewater with a combination of algae and heterotrophs/autotrophs. Mechanistic models like this one are made for understanding the microbial interactions and their influence on the reactor performance. PMID:25325552

Muñoz Sierra, J D; Picioreanu, C; van Loosdrecht, M C M

2014-01-01

377

Coaggregation occurs amongst bacteria within and between biofilms in domestic showerheads.  

PubMed

Showerheads support the development of multi-species biofilms that can be unsightly, produce malodor, and may harbor pathogens. The outer-surface spray-plates of many showerheads support visible biofilms that likely contain a mixture of bacteria from freshwater and potentially from human users. Coaggregation, a mechanism by which genetically distinct bacteria specifically recognize one another, may contribute to the retention and enrichment of different species within these biofilms. The aim of this work was to describe the bacterial composition of outer spray-plate biofilms of three domestic showerheads and to determine the intra- and inter-biofilm coaggregation ability of each culturable isolate. The bacterial composition of the three biofilms was determined by using bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) and by culturing on R2A medium. An average of 31 genera per biofilm were identified using bTEFAP and a total of 30 isolates were cultured. Even though the microbial diversity of each showerhead biofilm differed, every cultured isolate was able to coaggregate with at least one other isolate from the same or different showerhead biofilm. Promiscuous coaggregating isolates belonged to the genera Brevundimonas, Micrococcus, and Lysobacter. This work suggests that coaggregation may be a common feature of showerhead biofilms. Characterization of the mechanisms mediating coaggregation, and the inter-species interactions they facilitate, may allow for novel strategies to inhibit biofilm development. PMID:23194413

Vornhagen, Jay; Stevens, Michael; McCormick, David W; Dowd, Scot E; Eisenberg, Joseph N S; Boles, Blaise R; Rickard, Alexander H

2013-01-01

378

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

PubMed Central

Background Desulfovibrio vulgaris Hildenborough is a sulfate-reducing bacterium (SRB) that is intensively studied in the context of metal corrosion and heavy-metal bioremediation, and SRB populations are commonly observed in pipe and subsurface environments as surface-associated populations. In order to elucidate physiological changes associated with biofilm growth at both the transcript and protein level, transcriptomic and proteomic analyses were done on mature biofilm cells and compared to both batch and reactor planktonic populations. The biofilms were cultivated with lactate and sulfate in a continuously fed biofilm reactor, and compared to both batch and reactor planktonic populations. Results The functional genomic analysis demonstrated that biofilm cells were different compared to planktonic cells, and the majority of altered abundances for genes and proteins were annotated as hypothetical (unknown function), energy conservation, amino acid metabolism, and signal transduction. Genes and proteins that showed similar trends in detected levels were particularly involved in energy conservation such as increases in an annotated ech hydrogenase, formate dehydrogenase, pyruvate:ferredoxin oxidoreductase, and rnf oxidoreductase, and the biofilm cells had elevated formate dehydrogenase activity. Several other hydrogenases and formate dehydrogenases also showed an increased protein level, while decreased transcript and protein levels were observed for putative coo hydrogenase as well as a lactate permease and hyp hydrogenases for biofilm cells. Genes annotated for amino acid synthesis and nitrogen utilization were also predominant changers within the biofilm state. Ribosomal transcripts and proteins were notably decreased within the biofilm cells compared to exponential-phase cells but were not as low as levels observed in planktonic, stationary-phase cells. Several putative, extracellular proteins (DVU1012, 1545) were also detected in the extracellular fraction from biofilm cells. Conclusions 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. PMID:22507456

2012-01-01

379

Species sorting during biofilm assembly by artificial substrates deployed in a cold seep system  

PubMed Central

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. PMID:25323200

Zhang, Wei Peng; Wang, Yong; Tian, Ren Mao; Bougouffa, Salim; Yang, Bo; Cao, Hui Luo; Zhang, Gen; Wong, Yue Him; Xu, Wei; Batang, Zenon; Al-Suwailem, Abdulaziz; Zhang, Xi Xiang; Qian, Pei-Yuan

2014-01-01

380

Species sorting during biofilm assembly by artificial substrates deployed in a cold seep system.  

PubMed

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. PMID:25323200

Zhang, Wei Peng; Wang, Yong; Tian, Ren Mao; Bougouffa, Salim; Yang, Bo; Cao, Hui Luo; Zhang, Gen; Wong, Yue Him; Xu, Wei; Batang, Zenon; Al-Suwailem, Abdulaziz; Zhang, Xi Xiang; Qian, Pei-Yuan

2014-01-01

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