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Letteratura scientifica selezionata sul tema "Microbial mat communities"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 1 febbraio 2022

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Articoli di riviste sul tema "Microbial mat communities"

Tice, Michael M., Daniel C. O. Thornton, Michael C. Pope, Thomas D. Olszewski e Jian Gong. "Archean Microbial Mat Communities". Annual Review of Earth and Planetary Sciences 39, n. 1 (30 maggio 2011): 297–319. http://dx.doi.org/10.1146/annurev-earth-040809-152356.

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Franks, Jonathan, e John F. Stolz. "Flat laminated microbial mat communities". Earth-Science Reviews 96, n. 3 (ottobre 2009): 163–72. http://dx.doi.org/10.1016/j.earscirev.2008.10.004.

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Rothschild, Lynn J., e Lorraine J. Giver. "Photosynthesis below the surface in a cryptic microbial mat". International Journal of Astrobiology 1, n. 4 (ottobre 2002): 295–304. http://dx.doi.org/10.1017/s1473550403001320.

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The discovery of subsurface communities has encouraged speculation that such communities might be present on planetary bodies exposed to harsh surface conditions, including the early Earth. While the astrobiology community has focused on the deep subsurface, near-subsurface environments are unique in that they provide some protection while allowing partial access to photosynthetically active radiation. Previously we identified near-surface microbial communities based on photosynthesis. Here we assess the productivity of such an ecosystem by measuring in situ carbon fixation rates in an intertidal marine beach through a diurnal cycle, and find them surprisingly productive. Gross fixation along a transect (99×1 m) perpendicular to the shore was highly variable and depended on factors such as moisture and mat type, with a mean of ~41 mg C fixed m−2 day−1. In contrast, an adjacent well-established cyanobacterial mat dominated by Lyngbya aestuarii was ~12 times as productive (~500 mg C fixed m−2 day−1). Measurements made of the Lyngbya mat at several times per year revealed a correlation between total hours of daylight and gross daily production. From these data, annual gross fixation was estimated for the Lyngbya mat and yielded a value of ~1.3×105 g m−2 yr−1. An analysis of pulse-chase data obtained in the study in conjunction with published literature on similar ecosystems suggests that subsurface interstitial mats may be an overlooked endogenous source of organic carbon, mostly in the form of excreted fixed carbon.

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Revsbech, Niels Peter, Erik Trampe, Mads Lichtenberg, David M. Ward e Michael Kühl. "In SituHydrogen Dynamics in a Hot Spring Microbial Mat during a Diel Cycle". Applied and Environmental Microbiology 82, n. 14 (6 maggio 2016): 4209–17. http://dx.doi.org/10.1128/aem.00710-16.

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ABSTRACTMicrobes can produce molecular hydrogen (H2) via fermentation, dinitrogen fixation, or direct photolysis, yet the H2dynamics in cyanobacterial communities has only been explored in a few natural systems and mostly in the laboratory. In this study, we investigated the dielin situH2dynamics in a hot spring microbial mat, where various ecotypes of unicellular cyanobacteria (Synechococcussp.) are the only oxygenic phototrophs. In the evening, H2accumulated rapidly after the onset of darkness, reaching peak values of up to 30 μmol H2liter−1at about 1-mm depth below the mat surface, slowly decreasing to about 11 μmol H2liter−1just before sunrise. Another pulse of H2production, reaching a peak concentration of 46 μmol H2liter−1, was found in the early morning under dim light conditions too low to induce accumulation of O2in the mat. The light stimulation of H2accumulation indicated that nitrogenase activity was an important source of H2during the morning. This is in accordance with earlier findings of a distinct early morning peak in N2fixation and expression ofSynechococcusnitrogenase genes in mat samples from the same location. Fermentation might have contributed to the formation of H2during the night, where accumulation of other fermentation products lowered the pH in the mat to less than pH 6 compared to a spring source pH of 8.3.IMPORTANCEHydrogen is a key intermediate in anaerobic metabolism, and with the development of a sulfide-insensitive microsensor for H2, it is now possible to study the microdistribution of H2in stratified microbial communities such as the photosynthetic microbial mat investigated here. The ability to measure H2profiles within the mat compared to previous measurements of H2emission gives much more detailed information about the sources and sinks of H2in such communities, and it was demonstrated that the high rates of H2formation in the early morning when the mat was exposed to low light intensities might be explained by nitrogen fixation, where H2is formed as a by-product.

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Nübel, Ulrich, Ferran Garcia-Pichel, Michael Kühl e Gerard Muyzer. "Quantifying Microbial Diversity: Morphotypes, 16S rRNA Genes, and Carotenoids of Oxygenic Phototrophs in Microbial Mats". Applied and Environmental Microbiology 65, n. 2 (1 febbraio 1999): 422–30. http://dx.doi.org/10.1128/aem.65.2.422-430.1999.

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ABSTRACT We quantified the diversity of oxygenic phototrophic microorganisms present in eight hypersaline microbial mats on the basis of three cultivation-independent approaches. Morphological diversity was studied by microscopy. The diversity of carotenoids was examined by extraction from mat samples and high-pressure liquid chromatography analysis. The diversity of 16S rRNA genes from oxygenic phototrophic microorganisms was investigated by extraction of total DNA from mat samples, amplification of 16S rRNA gene segments from cyanobacteria and plastids of eukaryotic algae by phylum-specific PCR, and sequence-dependent separation of amplification products by denaturing-gradient gel electrophoresis. A numerical approach was introduced to correct for crowding the results of chromatographic and electrophoretic analyses. Diversity estimates typically varied up to twofold among mats. The congruence of richness estimates and Shannon-Weaver indices based on numbers and proportional abundances of unique morphotypes, 16S rRNA genes, and carotenoids unveiled the underlying diversity of oxygenic phototrophic microorganisms in the eight mat communities studied.

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Jesser, Kelsey J., Heather Fullerton, Kevin W. Hager e Craig L. Moyer. "Quantitative PCR Analysis of Functional Genes in Iron-Rich Microbial Mats at an Active Hydrothermal Vent System (Lō'ihi Seamount, Hawai'i)". Applied and Environmental Microbiology 81, n. 9 (13 febbraio 2015): 2976–84. http://dx.doi.org/10.1128/aem.03608-14.

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ABSTRACTThe chemolithotrophicZetaproteobacteriarepresent a novel class ofProteobacteriawhich oxidize Fe(II) to Fe(III) and are the dominant bacterial population in iron-rich microbial mats.Zetaproteobacteriawere first discovered at Lō'ihi Seamount, located 35 km southeast off the big island of Hawai'i, which is characterized by low-temperature diffuse hydrothermal venting. Novel nondegenerate quantitative PCR (qPCR) assays for genes associated with microbial nitrogen fixation, denitrification, arsenic detoxification, Calvin-Benson-Bassham (CBB), and reductive tricarboxylic acid (rTCA) cycles were developed using selected microbial mat community-derived metagenomes. Nitrogen fixation genes were not detected, but all other functional genes were present. This suggests that arsenic detoxification and denitrification processes are likely cooccurring in addition to two modes of carbon fixation. Two groups of microbial mat community types were identified by terminal restriction fragment length polymorphism (T-RFLP) and were further described based on qPCR data for zetaproteobacterial abundance and carbon fixation mode preference. qPCR variance was associated with mat morphology but not with temperature or sample site. Geochemistry data were significantly associated with sample site and mat morphology. Together, these qPCR assays constitute a functional gene signature for iron microbial mat communities across a broad array of temperatures, mat types, chemistries, and sampling sites at Lō'ihi Seamount.

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Shen, Yan, Volker Thiel, Pablo Suarez-Gonzalez, Sebastiaan W. Rampen e Joachim Reitner. "Sterol preservation in hypersaline microbial mats". Biogeosciences 17, n. 3 (7 febbraio 2020): 649–66. http://dx.doi.org/10.5194/bg-17-649-2020.

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Abstract. Microbial mats are self-sustaining benthic ecosystems composed of highly diverse microbial communities. It has been proposed that microbial mats were widespread in Proterozoic marine environments, prior to the emergence of bioturbating organisms at the Precambrian–Cambrian transition. One characteristic feature of Precambrian biomarker records is that steranes are typically absent or occur in very low concentrations. This has been explained by low eukaryotic source inputs, or degradation of primary produced sterols in benthic microbial mats (“mat-seal effect”). To better understand the preservational pathways of sterols in microbial mats, we analyzed freely extractable and carbonate-bound lipid fractions as well as decalcified extraction residues in different layers of a recent calcifying mat (∼1500 years) from the hypersaline Lake 2 on the island of Kiritimati, central Pacific. A variety of C27–C29 sterols and distinctive C31 4α-methylsterols (4α-methylgorgosterol and 4α-methylgorgostanol, biomarkers for dinoflagellates) were detected in freely extractable and carbonate-bound lipid pools. These sterols most likely originated from organisms living in the water column and the upper mat layers. This autochthonous biomass experienced progressive microbial transformation and degradation in the microbial mat, as reflected by a significant drop in total sterol concentrations, up to 98 %, in the deeper layers, and a concomitant decrease in total organic carbon. Carbonate-bound sterols were generally low in abundance compared to the freely extractable portion, suggesting that incorporation into the mineral matrix does not play a major role in the preservation of eukaryotic sterols in this mat. Likewise, pyrolysis of extraction residues suggested that sequestration of steroid carbon skeletons into insoluble organic matter was low compared to hopanoids. Taken together, our findings argue for a major mat-seal effect affecting the distribution and preservation of steroids in the mat studied. This result markedly differs from recent findings made for another microbial mat growing in the nearby hypersaline Lake 22 on the same island, where sterols showed no systematic decrease with depth. The observed discrepancies in the taphonomic pathways of sterols in microbial mats from Kiritimati may be linked to multiple biotic and abiotic factors including salinity and periods of subaerial exposure, implying that caution has to be exercised in the interpretation of sterol distributions in modern and ancient microbial mat settings.

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Brooks, Chequita N., e Erin K. Field. "Iron Flocs and the Three Domains: Microbial Interactions in Freshwater Iron Mats". mBio 11, n. 6 (15 dicembre 2020): e02720-20. http://dx.doi.org/10.1128/mbio.02720-20.

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ABSTRACTFreshwater iron mats are dynamic geochemical environments with broad ecological diversity, primarily formed by the iron-oxidizing bacteria. The community features functional groups involved in biogeochemical cycles for iron, sulfur, carbon, and nitrogen. Despite this complexity, iron mat communities provide an excellent model system for exploring microbial ecological interactions and ecological theories in situ. Syntrophies and competition between the functional groups in iron mats, how they connect cycles, and the maintenance of these communities by taxons outside bacteria (the eukaryota, archaea, and viruses) have been largely unstudied. Here, we review what is currently known about freshwater iron mat communities, the taxa that reside there, and the interactions between these organisms, and we propose ways in which future studies may uncover exciting new discoveries. For example, the archaea in these mats may play a greater role than previously thought as they are diverse and widespread in iron mats based on 16S rRNA genes and include methanogenic taxa. Studies with a holistic view of the iron mat community members focusing on their diverse interactions will expand our understanding of community functions, such as those involved in pollution removal. To begin addressing questions regarding the fundamental interactions and to identify the conditions in which they occur, more laboratory culturing techniques and coculture studies, more network and keystone species analyses, and the expansion of studies to more freshwater iron mat systems are necessary. Increasingly accessible bioinformatic, geochemical, and culturing tools now open avenues to address the questions that we pose herein.

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Griffiths, Robert P., Bruce A. Caldwell, Kermit Cromack Jr. e Richard Y. Morita. "Douglas-fir forest soils colonized by ectomycorrhizal mats. I. Seasonal variation in nitrogen chemistry and nitrogen cycle transformation rates". Canadian Journal of Forest Research 20, n. 2 (1 febbraio 1990): 211–18. http://dx.doi.org/10.1139/x90-030.

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Monthly samples of ectomycorrhizal mat soils from a maturing Douglas-fir forest and adjacent nonmat soils were collected and analyzed for respiration, acetylene reduction activity, denitrification rates, extractable ammonium, nitrogen mineralization, microbial biomass, temperature, pH, percent moisture, total phosphate, nitrogen, and carbon. Seasonal patterns suggested complex interactions among the host tree, ectomycorrhizal fungus, and the mat microbial community as influenced by seasonal changes in moisture, temperature, and light availability. The most dramatic changes in rates were found during moisture-temperature transition periods in the spring and fall. Respiration within the mat community was highest during the period when tree growth is normally the greatest (in the spring and fall). In addition, there was a major respiration peak observed in the winter that we hypothesize was caused by the utilization of labile carbon by microheterotrophs. Differences were also observed between mat and nonmat soils in respiration rates, microbial biomass carbon, acetylene reduction activity, and levels of mineralizable nitrogen, which were all generally higher in the mat soils, and pH and denitrification rates, which were generally lower in nonmat soils. There is also evidence that suggests that nitrogen is very tightly coupled within the mat communities.

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Jungblut, Anne D., Ian Hawes, Tyler J. Mackey, Megan Krusor, Peter T. Doran, Dawn Y. Sumner, Jonathan A. Eisen, Colin Hillman e Alexander K. Goroncy. "Microbial Mat Communities along an Oxygen Gradient in a Perennially Ice-Covered Antarctic Lake". Applied and Environmental Microbiology 82, n. 2 (13 novembre 2015): 620–30. http://dx.doi.org/10.1128/aem.02699-15.

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ABSTRACTLake Fryxell is a perennially ice-covered lake in the McMurdo Dry Valleys, Antarctica, with a sharp oxycline in a water column that is density stabilized by a gradient in salt concentration. Dissolved oxygen falls from 20 mg liter−1to undetectable over one vertical meter from 8.9- to 9.9-m depth. We provide the first description of the benthic mat community that falls within this oxygen gradient on the sloping floor of the lake, using a combination of micro- and macroscopic morphological descriptions, pigment analysis, and 16S rRNA gene bacterial community analysis. Our work focused on three macroscopic mat morphologies that were associated with different parts of the oxygen gradient: (i) “cuspate pinnacles” in the upper hyperoxic zone, which displayed complex topography and were dominated by phycoerythrin-rich cyanobacteria attributable to the genusLeptolyngbyaand a diverse but sparse assemblage of pennate diatoms; (ii) a less topographically complex “ridge-pit” mat located immediately above the oxic-anoxic transition containingLeptolyngbyaand an increasing abundance of diatoms; and (iii) flat prostrate mats in the upper anoxic zone, dominated by a green cyanobacterium phylogenetically identified asPhormidium pseudopriestleyiand a single diatom,Diadesmis contenta. Zonation of bacteria was by lake depth and by depth into individual mats. Deeper mats had higher abundances of bacteriochlorophylls and anoxygenic phototrophs, includingChlorobiandChloroflexi. This suggests that microbial communities form assemblages specific to niche-like locations. Mat morphologies, underpinned by cyanobacterial and diatom composition, are the result of local habitat conditions likely defined by irradiance and oxygen and sulfide concentrations.

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Più fonti

Tesi sul tema "Microbial mat communities"

Bottos, Eric. "Biodiversity and activity of microbial mat communities from Canadian high Arctic ice shelf ecosystems". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100776.

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Microbial mats exist in freshwater pools atop the Ward Hunt and Markham ice shelves in the Canadian high Arctic. In this study, culture-dependent and culture-independent techniques were used to describe the microbial diversity and activity of these mat communities.Bacterial and archaeal 16S rRNA gene clone libraries were constructed from Markham and Ward Hunt mat samples. Bacterial libraries from both mats had high diversity, though the Markham library appeared more diverse than the Ward Hunt library. Over 95% of sequences in both bacterial libraries, and all isolates from both mats, grouped within the phyla Bacteroidetes, Proteobacteria, and Actinobacteria. Archaeal diversity appeared low in both mats. Only one phylotype, potentially representing a novel Euryarchaeota, was observed in both archaeal libraries. Populations in both communities showed activity at subzero temperatures, with growth of isolates at -5°C and detectable metabolic activity at -10°C, measured by radiorespiration assays of mat microcosms.

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Allen, Michelle Ann Biotechnology &amp Biomolecular Sciences Faculty of Science UNSW. "An astrobiology-focused analysis of Microbial Mat communities from Hamelin Pool, Shark Bay, Western Australia". Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences, 2006. http://handle.unsw.edu.au/1959.4/26194.

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A unique opportunity to study both benthic microbial mats and modern stromatolites from a common niche is presented by the hypersaline environment of Hamelin Pool, Shark Bay, Australia. However, prior to this study, the microbial mat communities have not been well characterised. To investigate the taxonomic and functional diversity of Hamelin Pool pustular and smooth mats, and their similarity to Hamelin Pool stromatolites, culturing, culture-independent, and lipid analysis methods were employed. The cultured isolates obtained included heterotrophic bacteria similar to those obtained from other hypersaline environments, and 19 strains of cyanobacteria including potentially novel species. For the first time archaeal isolates were obtained from the pustular and smooth mats, and further characterisation of two strains indicated they might represent novel species of the genus Haloferax. Total DNA was extracted from the mats and 16S rRNA gene clone libraries were generated targeting the bacteria, cyanobacteria, archaea and eukarya. Both the pustular and smooth mat bacterial clone libraries were highly diverse, with 11 bacterial divisions represented, and Chao1 estimates of total species richness indicating ~3000 ??? 6000 species. Cyanobacterial and archaeal clone libraries revealed unique phylotypes associated with sediments of differing morphology. Statistically significant differences between the mat populations and Hamelin Pool stromatolite communities were identified using !-LIBSHUFF, a program designed to compare two 16S rRNA gene libraries. Signature lipid biomarkers were assessed for the pustular and smooth mats and an intertidal stromatolite from Hamelin Pool. Fatty acids (as methyl esters), wax esters, hydrocarbons, ether-bound lipids, hopanoids and sterols indicated the presence of oxygenic phototrophs, anoxygenic phototrophs, sulfate-reducing bacteria, sulfur-oxidising bacteria, heterotrophic bacteria and archaea in each of the sediment types. Limited contributions from diatoms, bivalves and their dinoflagellate symbionts, and from higher plant aerosols were also detected. Significantly, 2-methyl hopanoids and eight pseudohomologous series of branched alkanes with quaternary carbon centers were identified in the mats and stromatolites. Although differing in lithification status and precise microbial composition, the pustular and smooth mats are excellent analogues for the extant stromatolites of Hamelin Pool, and by corollary, provide a fascinating link to Precambrian microbial communities.

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Louvado, António Miguel de Oliveira. "Oil descontamination by benthic microbial communities". Doctoral thesis, Universidade de Aveiro, 2018. http://hdl.handle.net/10773/23525.

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Doutoramento em Biologia
Os sedimentos marinhos são um reservatório de hidrocarbonetos petrogénicos libertados naturalmente ou acidentalmente para o ambiente marinho. Nos sedimentos marinhos, os hidrocarbonetos são usados como fonte de carbono e energia por comunidades bacterianas complexas. Contudo, a eficiência de biodegradação poderá ser limitada por fatores ambientais. Este trabalho aborda o previsível impacto das condições particulares do mar profundo, da acidificação dos oceanos e da adição de dispersantes químicos nos processos de biodegradação de hidrocarbonetos em ambientes marinhos. Numa primeira fase, a função de destoxificação primária das bactérias degradadoras de hidrocarbonetos aromáticos policíclicos (HAP) nos sedimentos do mar profundo foi avaliado através de uma compilação de informação disponível na literatura científica e também através de uma análise dependente do cultivo envolvendo culturas de enriquecimento de sedimentos de vulcões de lama do mar profundo. Posteriormente, o impacto interativo da acidificação do oceano e da contaminação por hidrocarbonetos petrogénicos em comunidades bacterianas bênticas foi avaliado, em experiências de simulação multifatorial em sistema de microcosmo previamente executadas, com sedimentos subsuperficiais estuarinos. Finalmente, foi executado uma experiência multifatorial em sistema de microcosmos para avaliar o impacto da aplicação de dispersantes químicos em situações simuladas de derrame de hidrocarbonetos em sedimentos estuarinos portuários. Os resultados obtidos, através da análise da fração cultivável, indicam que nos sedimentos do mar profundo a comunidade bacteriana degradadora de HAP é distinta da encontrada noutros sedimentos marinhos devido à predominância de bactérias relacionadas com o género Bacillus. Nos ensaios de microcosmos, apesar das diferenças entre os cenários testados, as comunidades bacterianas revelaram-se em geral, estáveis. Nos sedimentos subsuperficiais estuarinos, as alterações abióticas impostas foram provavelmente atenuadas pela barreira sedimentar sobrejacente e a comunidade bacteriana pareceu ser estável em termos de estrutura e atividade. Do mesmo modo, a dispersão química de hidrocarbonetos petrogénicos, apesar de aumentar a biodisponibilidade de PAH, não alterou significativamente a composição das comunidades bacteriana de sedimentos superficiais estuarinos. Possivelmente, a exposição prévia do sedimento portuário a poluição por hidrocarbonetos poderá ter condicionado a resposta da comunidade bêntica bacteriana à contaminação por petróleo. Em conclusão, a degradação bacteriana de hidrocarbonetos é um processo ubíquo em sedimentos marinhos e as comunidades bacterianas degradadoras revelam elevada estabilidade relativamente à variação de fatores ambientais.
The marine sediment compartment is a key sink for naturally and accidentally released oil hydrocarbons in the marine environment. Here, complex communities of interacting bacterial species will efficiently use oil hydrocarbons as sources of carbon and energy. However, the efficiency of the biodegradation process can be limited by some near-future scenarios. This work addresses different environmental scenarios regarding oil hydrocarbon biodegradation in marine sediments. First, the role of bacteria as primary detoxifiers of polycyclic aromatic hydrocarbons in deep-sea sediments was evaluated through the compilation of available data and through a culture-dependent analysis of enrichment cultures derived mud volcano sediments. Next, the impact of the interactive effects of ocean acidification and oil hydrocarbon contamination was further analyzed in subsurface estuarine sediments. Finally, the impact of chemically dispersed oil in estuarine port sediments is evaluated through a multi-factorial microcosm simulation. Results show that , in deep sea mud volcano sediments, the culturable fraction of the PAH-degrading bacterial community seems distinct from other environments, with a predominance of Bacillus-like bacteria. In the microcosmbased assays, despite the differences between them, the overall bacterial community exhibit a reliable stability. In subsurface sediments, abiotic changes tested were possibly attenuated by the superficial sediment barrier and bacterial seem stable to environmental changes. Also, the chemical dispersion of oil, despite enhancing PAH concentration, did not impose significant alterations to the bacterial community composition at the marine sediment surface. The potential pre-exposure of the port sediment to oil hydrocarbon pollution may have preconditioned the response of the benthic bacterial communities to oil contamination. In conclusion, oil-hydrocarbon biodegradation is ubiquitous and communities exhibit a structural stability to environmental changes.

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Jeanbille, Mathilde. "Réponse des consortia microbiens benthiques à une contamination chronique aux hydrocarbures". Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3043/document.

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Les communautés microbiennes procèdent au recyclage des nutriments et à la degradation de la matière organique, et sont ainsi essentielles aux cycles biogéochimiques dans le sédiment et plus largement dans les océans. La contamination chronique aux hydrocarbures représente près de 80% des déversements totaux dans les océans. Toutefois, en comparaison des marées noires, son impact sur les communautés microbiennes est encore mal compris. Dans cette étude, nous avons d’abord utilisé une approche de type méta-analyse pour élucider l’effet global de la contamination aux hydrocarbures dans différents habitats. La réponse des communautés bactériennes à la contamination s’est révélée être dépendante du type d’habitat, les sols étant plus impactés que d’autres habitats, comme par exemple les sédiments marins. Nous nous sommes ensuite intéressés aux communautés microbiennes des trois domaines du vivant de sédiments côtiers provenant des côtes méditerranéennes et atlantiques. La contamination chronique n’influençait que marginallement les communautés benthiques, et la diversité alpha n’était pas réduite dans les sédiments contaminés. Cedendant, la comparaison des réseaux de co-occurrence des échantillons contaminés et non-contaminés a montré que le réseau des communautés contaminées présentait une topologie différente, indiquant une vulnérabilité plus importante à d’éventuelles perturbations environnementales. Des indicateurs potentiels de la contamination identifiés avec la méta-analyse ont été ciblés pour étudier l’impact de la contamination chronique aux hydrocarbures sur les services écologiques qu’ils assurent (i.e. la dégradation de la matière organique et des hydrocarbures) en utillisant la technique de Micro-FISH
Within the sediment, microbial communities play a pivotal role by driving essential processes such as nutrient cycling and organic matter degradation. Chronic hydrocarbons contamination represents almost 80% of the total input in the oceans. However, as compared to oil spills, its impact on microbial communities remains poorly understood. In this study, we first used a meta-analysis approach to decipher the global effect of hydrocarbons contamination in different habitats. Bacterial community response to the contamination was found to be dependant of the habitat studied, with soils being more impacted than other habitats, like marine sediments. Because bacteria are in interactions with other important members of microbial communities such as Archaea and Eukaryotes, we focused on microbial communities from the three domains of life in coastal marine sediments from the Mediterrranean and the French Atlantic coasts. Independently of the domains of life, chronic hydrocarbons contamination appeared to be a poor driver of communities structuration, and alpha diversity was not reduced in contaminated sediments. However, the comparison of co-occurences networks of contaminated and non-contaminated samples showed that the network from the contaminated samples exhibited a different topology, which suggests a higher vulnerability to eventual environmental perturbations. Potential indicators species identified using the meta-analysis approach were targeted to study the impact of chronic contamination on the ecological services they provide (i.e. organic matter and hydrocarbons degradation) using the Micro-FISH method

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Jungblut, Anne Dorothee Biotechnology &amp Biomolecular Sciences Faculty of Science UNSW. "Characterisation of microbial Mat communities in meltwater ponds of the McMurdo ice shelf, Antarctica". 2007. http://handle.unsw.edu.au/1959.4/40496.

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The investigation presented in this thesis examined the microbial and functional diversity of the meltwater ponds Fresh, Orange and Salt Ponds on the McMurdo Ice Shelf, near Bratina Island, Antarctica. These sites were chosen because of the ecological importance and absence of detailed characterisations of their diversity and function as part of Antarctica?s largest wetland. Particular focus was on cyanobacterial diversity, nitrogen fixation and secondary metabolite production. Using 16S rRNA gene and morphological analysis a large diversity of cyanobacteria (more than 22 phylotypes) was identified with high phylogenetic similarities (up to 99% sequence identity) to cyanobacteria from mats in other regions of Antarctica. In addition biogeographical distributions were identified including potentially endemic and cosmopolitan cyanobacteria. High salinities were also connected to the change and reduction of diversity. Lipid marker analyses were performed targeting hydrocarbons, ether-linked hydrocarbons, methylated fatty acid esters (FAME), wax esters, hopanols and sterols. Lipid biomarker profiles were similar to typical cyanobacteria dominated mats with major input from microorganisms including oxygenic and anoxygenic phototrophs, obligate aerobic and anaerobic heterotrophs that conduct the metabolic processes of fermentation, sulphate reduction, sulphate and iron-oxidation, methanogeneses. Signature lipids indicative of Chloroflexus and archaea, as well as branched aliphatic alkanes with quaternary substituted carbon atoms (BAQCs), were identified for the first time in Fresh, Orange and Salt Ponds. Based on nifH gene analysis, the nitrogen fixing diversity characterised in Orange Pond consisted of cyanobacterial Nostoc sp. as well as firmicutes, beta-, gamma- and delta-proteobacteria. Acetylene reduction assays and nifH gene RNA transcript diversity identified Nostoc sp. as a main contributor of nitrogenase activity in these ponds. Furthermore, analytical methods were used to identify the cyanobacterial secondary metabolites microcystins, although the genetic basis for this production and the toxin producer could not been identified. However non-ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) genes were identified which could be the genetic basis for novel bioactives. The use of a multi-disciplinary approach synthesis and subsequent results significantly increased our understanding of the diversity and function of microbial mat communities in the unique meltwater ponds of the McMurdo Ice shelf, Antarctica.

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Bilyj, Michael. "A Study on the Phototrophic Microbial Mat Communities of Sulphur Mountain Thermal Springs and their Association with the Endangered, Endemic Snail Physella johnsoni". 2011. http://hdl.handle.net/1993/4787.

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The seasonal population fluctuation of anoxygenic phototrophs and the diversity of cyanobacteria at the Sulphur Mountain thermal springs of Banff, Canada were investigated and compared to the drastic population changes of the endangered snail Physella johnsoni. A new species and two strains of Rhodomicrobium were taxonomically characterized in addition to new species of Rhodobacter and Erythromicrobium. Major mat-forming organisms included Thiothrix-like species, oxygenic phototrophs of genera Spirulina, Oscillatoria, and Phormidium and purple nonsulfur bacteria Rhodobacter, Rhodopseudomonas and Rhodomicrobium. Aerobic anoxygenic phototrophs comprised upwards of 9.6 x 104 CFU/cm2 of mat or 18.9% of total aerobic heterotrophic bacterial isolates at certain sites, while maximal purple nonsulfur and purple sulfur bacteria were quantified at 3.2 x 105 and 2.0 x 106 CFU/cm2 of mat, respectively. Photosynthetic activity measurements revealed incredibly productive carbon fixation rates averaging 40.5 mg C/cm2/24 h. A temporal mismatch was observed for mat area and prokaryote-based organics to P. johnsoni population flux in a “tracking inertia” manner.

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Hesse, Cedar N. "Characterization of fungal and bacterial communities associated with mat-forming ectomycorrhizal fungi from old-growth stands in the H.J. Andrews Experimental Forest". Thesis, 2012. http://hdl.handle.net/1957/30044.

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Mat-forming ectomycorrhizal (EcM) fungi represent a prevalent constituent of many temperate forest ecosystems and create dramatic changes in soil structure and chemistry. EcM mat soil have been shown to have increased microbial respiration rates and have been hypothesized to harbor unique assemblages of fungi and bacteria. The objectives of this dissertation were to characterize and examine the fungal and bacterial communities associated with EcM mats in old-growth forests of the H.J. Andrews Experimental Forest located in the Oregon Cascades. Additionally, this work assessed the application of traditional, emerging, and novel molecular sampling techniques for determining microbial communities of environmental samples. This research investigated the microbial communities associated with two common EcM mat genera found in old-growth Douglas fir stands in the Pacific Northwest; Piloderma (Atheliales, Basidiomycota) and Ramaria (Gomphales, Basidiomycota). Soil samples were collected from Piloderma and Ramaria mats and surrounding non- mat soil for molecular analysis of nucleic acids. First, a comparative study was conducted to determine the most appropriate rDNA molecular sampling technique for microbial community characterization. Two next-generation sequencing methods, Roche 454 pyrosequencing and Illumina-based environmental sequencing, the latter developed by the author, were compared to a more traditional sequencing approach, i.e., Sanger sequencing of clone libraries. These findings informed the subsequent sampling of the fungal ITS and bacterial 16S rDNA fragment with 454 pyrosequencing to determine the microbial communities within mat and non-mat soils. Second, this work utilized a pyrosequencing approach to explore fungal community structure in EcM mat and non-mat soils. This work concluded that differences in microbial communities do exist between Piloderma mat, Ramaria mat, and non-mat soils, but the differences are largely quantitative with relatively few distinct taxonomic shifts in microbial constituents. Piloderma, Ramaria and Russula, in addition to being the dominant taxa found on mycorrhizal root tips, were found to be the most abundant taxa in bulk soils within their respective mat types or non-mat sample. The background fungal communities within the EcM mats in this study exhibited considerable taxonomic overlap with the exception of Piloderma vs. non-mat comparisons; Russula species dominated nonmat soils but tended to be excluded or significantly underrepresented in Piloderma mats. Lastly, this study explored the bacterial communities associated with Piloderma and Ramaria mats using lower- coverage 454-Jr pyrosequencing. Bacterial communities exhibited significant structure as a function of mat-type, soil horizon and pH, but this finding should be interpreted with respect to the nonrandom distribution of Piloderma-mats in the O- horizon and the Ramaria-mats in the A-horizon, and the tendancy for EcM mats to be more acidic than surrounding soils. Nonetheless, the total microbial (bacterial and fungal) community was typically dominated by the mat-forming taxa, or Russula, in the case of non-mat soils. While the presence of Piloderma mats did enrich or restrict some bacterial groups, soil pH was also found to be a significant driver of bacterial richness and taxonomic diversity. Fungal and bacterial richness were also found to be positively related to one another, regardless of soil horizon or EcM mat type. This work, taken together, contributes to the understanding of hyperdiversity and heterogeneity of microbial communities of temperate forest soils and highlights the potential for fungal and bacterial communities to be influenced by the presence of EcM mats.
Graduation date: 2012

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"Improving Cyanobacterial Hydrogen Production through Bioprospecting of Natural Microbial Communities". Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.20988.

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abstract: Some cyanobacteria can generate hydrogen (H2) under certain physiological conditions and are considered potential agents for biohydrogen production. However, they also present low amounts of H2 production, a reaction reversal towards H2 consumption, and O2 sensitivity. Most attempts to improve H2 production have involved genetic or metabolic engineering approaches. I used a bio-prospecting approach instead to find novel strains that are naturally more apt for biohydrogen production. A set of 36, phylogenetically diverse strains isolated from terrestrial, freshwater and marine environments were probed for their potential to produce H2 from excess reductant. Two distinct patterns in H2 production were detected. Strains displaying Pattern 1, as previously known from Synechocystis sp. PCC 6803, produced H2 only temporarily, reverting to H2 consumption within a short time and after reaching only moderately high H2 concentrations. By contrast, Pattern 2 cyanobacteria, in the genera Lyngbya and Microcoleus, displayed high production rates, did not reverse the direction of the reaction and reached much higher steady-state H2 concentrations. L. aestuarii BL J, an isolate from marine intertidal mats, had the fastest production rates and reached the highest steady-state concentrations, 15-fold higher than that observed in Synechocystis sp. PCC 6803. Because all Pattern 2 strains originated in intertidal microbial mats that become anoxic in dark, it was hypothesized that their strong hydrogenogenic capacity may have evolved to aid in fermentation of the photosynthate. When forced to ferment, these cyanobacteria display similarly desirable characteristics of physiological H2 production. Again, L. aestuarii BL J had the fastest specific rates and attained the highest H2 concentrations during fermentation, which proceeded via a mixed-acid pathway to yield acetate, ethanol, lactate, H2, CO2 and pyruvate. The genome of L. aestuarii BL J was sequenced and bioinformatically compared to other cyanobacterial genomes to ascertain any potential genetic or structural basis for powerful H2 production. The association hcp exclusively in Pattern 2 strains suggests its possible role in increased H2 production. This study demonstrates the value of bioprospecting approaches to biotechnology, pointing to the strain L. aestuarii BL J as a source of useful genetic information or as a potential platform for biohydrogen production.
Dissertation/Thesis
Ph.D. Molecular and Cellular Biology 2013

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Grover, Heather D. "Carbon isotopic fractionation in Methanosarcina barkeri and the study of anaerobic microbial communities of saline springs in West Central Manitoba". Thesis, 2005. http://hdl.handle.net/1993/96.

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Stable carbon isotope fractionation during methanogenesis is affected by the availability of substrates. The effects of different substrates on methanogen biomass, total lipid extract, biomarkers and methane under both abundant and limiting substrate conditions were studied. Methanosarcina barkeri was grown with methanol, acetate, trimethylamine (TMA) and H2/CO2, and carbon isotope fractionation in methane production was greatest with methanol, followed by H2/CO2, TMA and acetate. In contrast, biomass was isotopically lightest in M.barkeri grown on methanol, followed by TMA, H2/CO2 and acetate. Generally, fractionation was greater in cultures grown with abundant substrate availability as compared to those supplied with limiting substrate. During autotrophic growth, fractionation was greatest during slower growth for both methane and biomass production. The results of these fractionation studies under controlled laboratory conditions can be applied to the interpretation of isotopic signatures for methane and methanogen biomarkers, and ecological processes, in marine environments. Several hypersaline springs off the western shore of Lake Winnipegosis, MB support unique microbial mat communities. These low temperature springs contain water with a mean salinity as high as 6.1%. Studies were undertaken to contrast the anaerobic microbial communities of these springs, specifically the methanogens and sulphate-reducing bacteria (SRB), and their contributions to biogeochemical cycling in these mats. Comparisons of lipid profiles revealed changes in the proportions of the dominant fatty acids related to the amount of mat growth. Cultures of SRB and methanogens were established with six different substrates. Methanogenic cultures grew best on TMA and methanol, but could use formate, H2/CO2 and glycine betaine as well. In contrast, H2/CO2 was the preferred substrate of the SRB enrichment cultures, which were also able to use formate, but not TMA, the breakdown product of the compatible solute glycine betaine. Maximum methane production occurred at 5% salinity. The lipid composition of the mats, including methanogen biomarkers, and the results of the enrichments on different substrates and at different salinities, suggest that methanogenesis in these springs is supported by compatible solutes whereas sulphate reduction is linked to availability of hydrogen and formate.
February 2005

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Franks, Jonathan. "Confocal and TEM analysis of microbial communities in modern stromatolites at Highborne Cay, Bahamas". 2007. http://digital.library.duq.edu/u?/etd,115967.

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Libri sul tema "Microbial mat communities"

Klotz, Martin G., Donald A. Bryant, Jim K. Fredrickson, William P. Inskeep e Michael Kühl, a cura di. Systems Biology and Ecology of Microbial Mat Communities. Frontiers Media SA, 2016. http://dx.doi.org/10.3389/978-2-88919-793-4.

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Yehuda, Cohen, Rosenberg Eugene, American Society for Microbiology e Batsheva de Rothschild Foundation for the Advancement of Science in Israel., a cura di. Microbial mats: Physiological ecology of benthic microbial communities. Washington, D.C: American Society for Microbiology, 1989.

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Kirchman, David L. Microbial growth, biomass production, and controls. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0008.

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Soon after the discovery that bacteria are abundant in natural environments, the question arose as to whether or not they were active. Although the plate count method suggested that they were dormant if not dead, other methods indicated that a large fraction of bacteria and fungi are active, as discussed in this chapter. It goes on to discuss fundamental equations for exponential growth and logistic growth, and it describes phases of growth in batch cultures, continuous cultures, and chemostats. In contrast with measuring growth in laboratory cultures, it is difficult to measure in natural environments for complex communities with co-occurring mortality. Among many methods that have been suggested over the years, the most common one for bacteria is the leucine approach, while for fungi it is the acetate-in ergosterol method. These methods indicate that the growth rate of the bulk community is on the order of days for bacteria in their natural environment. It is faster in aquatic habitats than in soils, and bacteria grow faster than fungi in soils. But bulk rates for bacteria appear to be slower than those for phytoplankton. All of these rates for natural communities are much slower than rates measured for most microbes in the laboratory. Rates in subsurface environments hundreds of meters from light-driven primary production and high organic carbon conditions are even lower. Rates vary greatly among microbial taxa, according to data on 16S rRNA. Copiotrophic bacteria grow much faster than oligotrophic bacteria, but may have low growth rates when conditions turn unfavorable. Some of the factors limiting heterotrophic bacteria and fungi include temperature and inorganic nutrients, but the supply of organic compounds is perhaps most important in most environments.

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Kirchman, David L. The ecology of viruses. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0010.

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In addition to grazing, another form of top-down control of microbes is lysis by viruses. Every organism in the biosphere is probably infected by at least one virus, but the most common viruses are thought to be those that infect bacteria. Viruses come in many varieties, but the simplest is a form of nucleic acid wrapped in a protein coat. The form of nucleic acid can be virtually any type of RNA or DNA, single or double stranded. Few viruses in nature can be identified by traditional methods because their hosts cannot be grown in the laboratory. Direct count methods have found that viruses are very abundant, being about ten-fold more abundant than bacteria, but the ratio of viruses to bacteria varies greatly. Viruses are thought to account for about 50% of bacterial mortality but the percentage varies from zero to 100%, depending on the environment and time. In addition to viruses of bacteria and cyanobacteria, microbial ecologists have examined viruses of algae and the possibility that viral lysis ends phytoplankton blooms. Viruses infecting fungi do not appear to lyse their host and are transmitted from one fungus to another without being released into the external environment. While viral lysis and grazing are both top-down controls on microbial growth, they differ in several crucial respects. Unlike grazers, which often completely oxidize prey organic material to carbon dioxide and inorganic nutrients, viral lysis releases the organic material from hosts more or less without modification. Perhaps even more important, viruses may facilitate the exchange of genetic material from one host to another. Metagenomic approaches have been used to explore viral diversity and the dynamics of virus communities in natural environments.

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Capitoli di libri sul tema "Microbial mat communities"

Bebout, Brad M., Hans W. Paerl, James E. Bauer, Donald E. Canfield e David J. Des Marais. "Nitrogen cycling in microbial mat communities: The quantitative importance of N-fixation and other sources of N for primary productivity". In Microbial Mats, 265–71. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78991-5_27.

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Oren, Aharon, Uri Fischel, Zeev Aizenshtat, Eitan B. Krein e Robert H. Reed. "Osmotic adaptation of microbial communities in hypersaline microbial mats". In Microbial Mats, 125–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78991-5_14.

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Esteve, Isabel, Dolores Ceballos, Maira Martínez-Alonso, Núria Gaju e Ricardo Guerrero. "Development of versicolored microbial mats: Succession of microbial communities". In Microbial Mats, 415–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78991-5_42.

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Stahl, David A., e William C. Capman. "Application of molecular genetics to the study of microbial communities". In Microbial Mats, 193–206. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78991-5_20.

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Wimpenny, Julian, Sarah Kinniment, Liese Ganderton e David Stickler. "New cultivation techniques and laboratory model systems for investigating the growth of stratified microbial communities". In Microbial Mats, 229–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78991-5_24.

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Muyzer, Gerard, e Ellen C. de Waal. "Determination of the genetic diversity of microbial communities using DGGE analysis of PCR-amplified 16S rDNA". In Microbial Mats, 207–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78991-5_21.

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Lee, Sang In, Sun Ae Kim, Si Hong Park e Steven C. Ricke. "Molecular and New-Generation Techniques for Rapid Detection of Foodborne Pathogens and Characterization of Microbial Communities in Poultry Meat". In Food Safety in Poultry Meat Production, 235–60. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05011-5_11.

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Nierychlo, Marta, Jeppe Lund Nielsen e Per Halkjær Nielsen. "Studies of the Ecophysiology of Single Cells in Microbial Communities by (Quantitative) Microautoradiography and Fluorescence In Situ Hybridization (MAR-FISH)". In Springer Protocols Handbooks, 115–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/8623_2015_66.

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Pierson, Beverly K., John Bauld, Richard W. Castenholz, Elisa D'Amelio, David J. Des Marais, Jack D. Farmer, John P. Grotzinger et al. "Modern Mat-Building Microbial Communities: a Key to the Interpretation of Proterozoic Stromatolitic Communities". In The Proterozoic Biosphere, 245–342. Cambridge University Press, 1992. http://dx.doi.org/10.1017/cbo9780511601064.008.

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Castenholz, Richard W., Elisa D'Amelio, Jack D. Farmer, Bo Barker Jøgensen, Anna C. Palmisano, Beverly K. Pierson e David M. Ward. "Modern Mat-Building Microbial Communities: Methods of Investigation and Supporting Data". In The Proterozoic Biosphere, 821–54. Cambridge University Press, 1992. http://dx.doi.org/10.1017/cbo9780511601064.022.

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Atti di convegni sul tema "Microbial mat communities"

Spilde, Michael N., Diana E. Northup, Nicole A. Caimi, Penelope J. Boston, Frederick D. Stone e Stephen Smith. "MICROBIAL MAT COMMUNITIES IN HAWAIIAN LAVA CAVES". In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-283965.

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Campbell, M. A., M. J. L. Coolen, P. T. Visscher, R. Bush, B. P. Burns e K. Grice. "Sulfur Metabolising Bacteria within Hypersaline Microbial Mat Communities". In 29th International Meeting on Organic Geochemistry. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201902997.

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Turner, Christina A., e Craig Moyer. "TAXONOMIC AND FUNCTIONAL ANALYSIS OF MICROBIAL MAT COMMUNITIES OF MARIANA REGION HYDROTHERMAL VENTS". In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-308566.

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Charlson, Emily S., Jen Chen, Rebecca Custers-Allen, Kyle Bittinger, Hongzhe Li, Rohini Sinha, Jennifer Hwang, Frederic D. Bushman e Ronald G. Collman. "Disordered Microbial Communities In The Upper Respiratory Tract Of Cigarette Smokers". In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a1766.

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Fujimura, Kei, Christine C. Johnson, Dennis R. Ownby, Michael J. Cox, Eoin Brodie, Edward Zoratti, Kimberly Woodcroft et al. "The Impact Of Pet Ownership On Microbial Communities In Settled House Dust". In American Thoracic Society 2010 International Conference, May 14-19, 2010 • New Orleans. American Thoracic Society, 2010. http://dx.doi.org/10.1164/ajrccm-conference.2010.181.1_meetingabstracts.a5634.

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Sulaiman, I., B. Wu, J. C. Tsay, Y. Li, M. Sauthoff, A. S. Scott, K. Gershner et al. "Functional Microbiomic Approaches Using Lower Airway Samples Identify a Subset of Lung Microbial Communities with Evidence of Active Microbial Metabolism". In American Thoracic Society 2020 International Conference, May 15-20, 2020 - Philadelphia, PA. American Thoracic Society, 2020. http://dx.doi.org/10.1164/ajrccm-conference.2020.201.1_meetingabstracts.a4246.

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Zakharkina, TI, C. Herr, OA Yildirim, M. Friedrich e R. Bals. "Terminal Restriction Fragment Length Polymorphism Is a Representative Tool To Study Pulmonary Microbial Communities." In American Thoracic Society 2009 International Conference, May 15-20, 2009 • San Diego, California. American Thoracic Society, 2009. http://dx.doi.org/10.1164/ajrccm-conference.2009.179.1_meetingabstracts.a3249.

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Yang, J. S. W., D. A. Ngan, J. Leung, D. D. Sin e S. F. P. Man. "Investigation of Microbial Communities in the Gut-Lung Axis of Human Immunodeficiency Virus-Infected Donors". In American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a5186.

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Garcia, Alfonso, Trevor Place, Michael Holm, Jennifer Sargent e Andrew Oliver. "Pipeline Sludge Sampling for Assessing Internal Corrosion Threat". In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33113.

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Internal corrosion sometimes occurs under deposits of solid particles on the bottom of transmission pipelines. The solids trap water with soluble products and other nutrients which can support the development of microbial communities and may lead to Microbiologically Influenced Corrosion (MIC). Corrosion processes associated with the metabolic activities of specific bacteria have been discussed elsewhere, but the simple presence of large microbial populations may increase the risk of internal corrosion owing to the ability of biofilms to extract and concentrate water at the pipe floor. As a method to monitor the internal corrosion threat in transmission pipelines and recommend mitigating activities for corrosion management, reliable microbial content and corrosion activity correlations are desired. Sludge samples have been obtained from cleaning pigs at the pipe trap and analyzed using Biological Activity Reaction Test (BART™) (or serial dilution test), Dean-Stark analysis, XRD and EDX. These tests provide information about certain bacterial populations, water / solid / hydrocarbon content, and crystalline/elemental composition of these solids, respectively. Despite best efforts, bacterial population/activity of pipeline sludge samples exhibit high variability and are difficult to correlate to actual internal corrosion in a pipeline. Considering that bacterial populations in pipeline sludge may be a meaningful representation of the internal corrosion threat to a transmission pipeline, a more rigorous approach on the sludge sampling procedure is necessary to improve the accuracy and reliability of the bacterial assays. It is also important to control such variables as storage temperature of the samples, exposure to air, and storage duration prior to enumeration — as these may affect the viability of the sample and enumeration results. This report presents historical pipeline sludge analysis data and suggests a method to evaluate data containing high variability. Practical recommendations to reduce data variability through handling and storage of sludge samples are also discussed.

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Nettles, R., L. Yang, B. Methe, S. Qin, J. S. Bednash, A. Fitch, J. Evankovich et al. "Metagenomic Sequencing of Respiratory Microbial Communities for Detection of Etiologic Pathogens of Pneumonia in Mechanically-Ventilated Adult Patients". In American Thoracic Society 2019 International Conference, May 17-22, 2019 - Dallas, TX. American Thoracic Society, 2019. http://dx.doi.org/10.1164/ajrccm-conference.2019.199.1_meetingabstracts.a3675.

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Rapporti di organizzazioni sul tema "Microbial mat communities"

Bebout, Brad. A Systems biology approach to energy flow in H2 producing microbial communities: Microbial mats. Office of Scientific and Technical Information (OSTI), marzo 2018. http://dx.doi.org/10.2172/1425657.

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