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Metagenome of Amazon forest conversion: impacts on soil-borne microbial diversity and functions; Metagenoma da conversão da floresta Amazônica: impactos na diversidade taxonômica e funcional dos micro-organismos do solo

Mendes, Lucas William
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/04/2014 EN
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56.41%
The Amazon rainforest is considered the world's largest reservoir of plant and animal biodiversity, but in recent years has been subjected to high rates of deforestation for the conversion of native areas into agricultural fields and pasture. The understanding of the effects of land-use change on soil microbial communities is essential, taking into account the importance that these organisms play in the ecosystem. In this context, this thesis evaluated the effect of these changes on microorganism communities in soils under different land-use systems. In the first study, the microbial communities were analyzed using the nextgeneration sequencing Illumina Hiseq2000, considering samples from native forest, deforested area, agriculture and pasture. From the analysis of approximately 487 million sequences was possible to show that microbial communities respond differently in each landuse system, with changes in both taxonomic and functional diversity. Also, we suggested that ecosystem function in forest soils is maintained by the abundance of microorganisms, while in disturbed areas such functioning is maintained by high diversity and functional redundancy. In the second study, we assessed the extent to which a particular plant species...

The influence of microbial ecology of drinking water biofilms on their resistance to disinfection

Simões, Lúcia C.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
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66.27%
The knowledge of the role of microbial ecology of drinking water (DW) biofilms on disinfection might help to improve our understanding of their resistance mechanisms and allow the development of effective strategies to apply in drinking water distribution systems (DWDS). In this study six opportunistic bacteria (Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata and Staphylococcus sp.) isolated from a DWDS were used to form single and multispecies biofilms. Those biofilms were exposed to sodium hypochlorite (SHC) at different oncentrations for 1 h and biofilm control was assessed in terms of mass removal and metabolic activity, cultivability and viability reduction. Biofilm recovery was also assessed 24 h after SHC treatment. The results demonstrate that total biofilm mass removal (single and multispecies biofilms) was not achieved for the SHC concentrations tested. Total biofilm inactivation was only achieved for A. calcoaceticus and Staphylococcus sp. single species biofilms and for multispecies biofilms without A. calcoaceticus, when exposed to high SHC concentrations. From the single species biofilms, Methylobacterium sp. and M. mucogenicum had the highest resistance to SHC...

Molecular Tools in Microbial Ecology

Oliveira, Solange; Laranjo, Marta; Alexandre, Ana
Fonte: Nova Science Publishers, Inc. Publicador: Nova Science Publishers, Inc.
Tipo: Parte de Livro Formato: 51341 bytes; application/pdf
ENG
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Editors: Laia Diaz and Marta Perez Book Description: The new book presents the latest research on ecology which is the study of the interrelationships between organisms and their environment, including the biotic and abiotic components. There are at least six kinds of ecology: ecosystem, physiological, behavioral, population, and community. Specific topics include: Acid Deposition, Acid Rain Revisited, Biodiversity, Biocomplexity, and Carbon Sequestration in Soils, Coral Reefs, Ecosystem Services, Environmental Justice, Fire Ecology, Floods, Global Climate Change, Hypoxia, and Invasion.

Reconsidering rumen microbial consortia to enhance feed efficiency and reduce environmental impact of ruminant livestock production systems

Firkins,Jeffrey Lynn
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2010 EN
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56.38%
Because cultivation-based approaches to assess rumen microbiology assess only the minority of microbial groups and can miss opportunities to assess important functions, molecular-based approaches have flourished in microbial ecology and have been adapted to the rumen. Current approaches are described herein, specifically for a robust adaptation to nutrition studies or future opportunities. These included automated profiling techniques, density gradient gel electrophoresis, and future adaption of microarray or high-throughput sequencing technologies. Based on current knowledge, a more holistic approach is needed to describe various functional groups of microbes within the context of how they influence, and are influenced by, the whole consortium (combination of microbial groups). Such a perspective is applied to issues related to increasing fiber digestibility when feeding concentrate or unsaturated fats to high producing beef and dairy cattle. These same microbial populations should help to provide growth factors for fibrolytic bacteria while competing against the hyperammonia-producing bacteria such that there would be less need for excessive rumen-degraded protein as a safety factor. Moreover, these same dietary conditions influence the processes of biohydrogenation and methanogenesis. After accounting for population structures of bacteria...

RNA Stable Isotope Probing, a Novel Means of Linking Microbial Community Function to Phylogeny

Manefield, Mike; Whiteley, Andrew S.; Griffiths, Robert I.; Bailey, Mark J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /11/2002 EN
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56.26%
Identifying microorganisms responsible for recognized environmental processes remains a great challenge in contemporary microbial ecology. Only in the last few years have methodological innovations provided access to the relationship between the function of a microbial community and the phylogeny of the organisms accountable for it. In this study stable-isotope-labeled [13C]phenol was fed into a phenol-degrading community from an aerobic industrial bioreactor, and the 13C-labeled RNA produced was used to identify the bacteria responsible for the process. Stable-isotope-labeled RNA was analyzed by equilibrium density centrifugation in concert with reverse transcription-PCR and denaturing gradient gel electrophoresis. In contradiction with findings from conventional methodologies, this unique approach revealed that phenol degradation in the microbial community under investigation is dominated by a member of the Thauera genus. Our results suggest that this organism is important for the function of this bioreactor.

The Environment and the Microbial Ecology of Human Skin

McBride, Mollie E.; Duncan, W. Christopher; Knox, J. M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1977 EN
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56.38%
Microbial flora of the skin of three human population groups representing different natural environments was examined quantitatively and qualitatively to determine whether environmental differences in temperature and humidity can influence the microbial flora of normal skin. Five anatomical skin sites - hands, back, axillae, groin, and feet - were sampled from 10 subjects working in a high-humidity, high-temperature environment, 10 subjects from a low-temperature, high-humidity environment, and 10 subjects working in a moderate-temperature and low-humidity environment. Bacterial populations were significantly larger from the back, axillae, and feet in individuals from the high-temperature and high-humidity environment as compared to the moderate-temperature, low-humidity environment. High humidity and low temperature had no significant effect on total populations, but this group showed a higher frequency of isolation of fungi, and gram-negative bacteria from the back and feet. Although there was an indication that increase in the environmental humidity could result in an increased frequency of isolation of gram-negative bacteria, there was no evidence that an increase in either temperature or humidity altered the relative proportions of gram-negative bacteria in the predominantly gram-positive microbial flora found on normal skin. It was concluded that...

Phosphoglycerides of Trichophyton terrestre and One Phenotype Selected from the Apollo 16 Microbial Ecology Evaluation Device

Sawyer, R. T.; Deskins, D. C.; Volz, P. A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1975 EN
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66.27%
Total lipid extracted from wild-type Trichophyton terrestre CDC-X285 was found to be 2.0% of the dry cell weight. The total lipid contained the following phospholipid components identified by silicic acid-impregnated thin-layer and paper chromatography: phosphatidyl inositol, phosphatidyl choline, phosphatidyl serine, and phosphatidic acid. The total lipid extracted from the phenotype T. terrestre 7048-1 isolated from the Apollo 16 Microbial Ecology Evaluation Device (MEED) was found to vary according to the time at which the phospholipids were extracted. The Trichophyton phenotype was selected from a cuvette housed in the MEED exposed to specific space parameters including ultraviolet light of known wavelengths and energy levels in deep space. The phospholipid components identified in the phenotype were phosphatidyl ethanolamine and cardiolipin. The major lipid fraction was composed of digalactosyl diglyceride and monogalactosyl diglyceride. An unusual lipid was detected in the phenotype, which appeared to be sterol glycoside.

Characterization of Microbial Communities in Gas Industry Pipelines

Zhu, Xiang Y.; Lubeck, John; Kilbane, John J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2003 EN
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56.26%
Culture-independent techniques, denaturing gradient gel electrophoresis (DGGE) analysis, and random cloning of 16S rRNA gene sequences amplified from community DNA were used to determine the diversity of microbial communities in gas industry pipelines. Samples obtained from natural gas pipelines were used directly for DNA extraction, inoculated into sulfate-reducing bacterium medium, or used to inoculate a reactor that simulated a natural gas pipeline environment. The variable V2-V3 (average size, 384 bp) and V3-V6 (average size, 648 bp) regions of bacterial and archaeal 16S rRNA genes, respectively, were amplified from genomic DNA isolated from nine natural gas pipeline samples and analyzed. A total of 106 bacterial 16S rDNA sequences were derived from DGGE bands, and these formed three major clusters: beta and gamma subdivisions of Proteobacteria and gram-positive bacteria. The most frequently encountered bacterial species was Comamonas denitrificans, which was not previously reported to be associated with microbial communities found in gas pipelines or with microbially influenced corrosion. The 31 archaeal 16S rDNA sequences obtained in this study were all related to those of methanogens and phylogenetically fall into three clusters: order I...

Selected Nucleic Acid Precursors in Studies of Aquatic Microbial Ecology

Karl, David M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1982 EN
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66.31%
The use of radiolabeled nucleosides and nucleic acid bases to estimate the rates of RNA and DNA synthesis in naturally occurring microbial assemblages requires numerous assumptions, several of which are evaluated herein. Comparative time series analyses of the uptake and incorporation, labeling specificity, and extent of catabolism of [2-3H]adenine, [methyl-3H]thymidine, and [5-3H]uridine were performed with pure bacterial and algal cultures, as well as with environmental samples. [3H]thymidine yielded the most variable results, especially with regard to the extent of nonspecific macromolecular labeling. The pathways of [3H]thymidine and [3H]adenine metabolism were further evaluated by isotope dilution methods and by comparing incorporation patterns of thymidine labeled at different sites of the molecule. The advantages, uncertainties, and limitations of the use of radiolabeled nucleic acid precursors in studies of aquatic microbial ecology are discussed and a prospectus for future studies presented.

Effects of Physical Properties of Feed on Microbial Ecology and Survival of Salmonella enterica Serovar Typhimurium in the Pig Gastrointestinal Tract

Mikkelsen, Lene Lind; Naughton, Patrick J.; Hedemann, Mette S.; Jensen, Bent Borg
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2004 EN
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56.23%
A two-by-two factorial experiment with pigs was conducted to study the effect of feed grinding (fine and coarse) and feed processing (pelleted and nonpelleted) on physicochemical properties, microbial populations, and survival of Salmonella enterica serovar Typhimurium DT12 in the gastrointestinal tracts of pigs. Results demonstrated a strong effect of diet on parameters measured in the stomachs of the pigs, whereas the effect was less in the other parts of the gastrointestinal tract. Pigs fed the coarse nonpelleted (C-NP) diet showed more solid gastric content with higher dry matter content than pigs fed the fine nonpelleted (F-NP), coarse pelleted (C-P), or fine pelleted (F-P) diet. Pigs fed the C-NP diet also showed significantly increased number of anaerobic bacteria (P < 0.05), increased concentrations of organic acids, and reduced pH in the stomach. In addition, pigs fed the C-NP diet showed increased in vitro death rate of S. enterica serovar Typhimurium DT12 in content from the stomach (P < 0.001). Pigs fed the C-NP diet had a significantly higher concentration of undissociated lactic acid in gastric content than pigs fed the other diets (P < 0.001). A strong correlation between the concentration of undissociated lactic acid and the death rate of S. enterica serovar Typhimurium DT12 was found. In the distal small intestine...

Integration of Microbial Ecology and Statistics: a Test To Compare Gene Libraries

Schloss, Patrick D.; Larget, Bret R.; Handelsman, Jo
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2004 EN
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56.23%
Libraries of 16S rRNA genes provide insight into the membership of microbial communities. Statistical methods help to determine whether differences in library composition are artifacts of sampling or are due to underlying differences in the communities from which they are derived. To contribute to a growing statistical framework for comparing 16S rRNA libraries, we present a computer program, ∫-LIBSHUFF, which calculates the integral form of the Cramér-von Mises statistic. This implementation builds upon the LIBSHUFF program, which uses an approximation of the statistic and makes a number of modifications that improve precision and accuracy. Once ∫-LIBSHUFF calculates the P values, when pairwise comparisons are tested at the 0.05 level, the probability of falsely identifying a significant P value is 0.098 for a study with two libraries, 0.265 for three libraries, and 0.460 for four libraries. The potential negative effects of making the multiple pairwise comparisons necessitate correcting for the increased likelihood that differences between treatments are due to chance and do not reflect biological differences. Using ∫-LIBSHUFF, we found that previously published 16S rRNA gene libraries constructed from Scottish and Wisconsin soils contained different bacterial lineages. We also analyzed the published libraries constructed for the zebrafish gut microflora and found statistically significant changes in the community during development of the host. These analyses illustrate the power of ∫-LIBSHUFF to detect differences between communities...

Use of 16S rRNA and rpoB Genes as Molecular Markers for Microbial Ecology Studies▿

Case, Rebecca J.; Boucher, Yan; Dahllöf, Ingela; Holmström, Carola; Doolittle, W. Ford; Kjelleberg, Staffan
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
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66.36%
Several characteristics of the 16S rRNA gene, such as its essential function, ubiquity, and evolutionary properties, have allowed it to become the most commonly used molecular marker in microbial ecology. However, one fact that has been overlooked is that multiple copies of this gene are often present in a given bacterium. These intragenomic copies can differ in sequence, leading to identification of multiple ribotypes for a single organism. To evaluate the impact of such intragenomic heterogeneity on the performance of the 16S rRNA gene as a molecular marker, we compared its phylogenetic and evolutionary characteristics to those of the single-copy gene rpoB. Full-length gene sequences and gene fragments commonly used for denaturing gradient gel electrophoresis were compared at various taxonomic levels. Heterogeneity found between intragenomic 16S rRNA gene copies was concentrated in specific regions of rRNA secondary structure. Such “heterogeneity hot spots” occurred within all gene fragments commonly used in molecular microbial ecology. This intragenomic heterogeneity influenced 16S rRNA gene tree topology, phylogenetic resolution, and operational taxonomic unit estimates at the species level or below. rpoB provided comparable phylogenetic resolution to that of the 16S rRNA gene at all taxonomic levels...

Phylogenetic Composition of Rocky Mountain Endolithic Microbial Ecosystems▿

Walker, Jeffrey J.; Pace, Norman R.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
56.28%
The endolithic environment, the pore space in rocks, is a ubiquitous microbial habitat. Photosynthesis-based endolithic communities inhabit the outer few millimeters to centimeters of rocks exposed to the surface. Such endolithic ecosystems have been proposed as simple, tractable models for understanding basic principles in microbial ecology. In order to test previously conceived hypotheses about endolithic ecosystems, we studied selected endolithic communities in the Rocky Mountain region of the United States with culture-independent molecular methods. Community compositions were determined by determining rRNA gene sequence contents, and communities were compared using statistical phylogenetic methods. The results indicate that endolithic ecosystems are seeded from a select, global metacommunity and form true ecological communities that are among the simplest microbial ecosystems known. Statistical analysis showed that biogeographical characteristics that control community composition, such as rock type, are more complex than predicted. Collectively, results of this study support the idea that patterns of microbial diversity found in endolithic communities are governed by principles similar to those observed in macroecological systems.

Effect of Carbohydrate Composition in Barley and Oat Cultivars on Microbial Ecophysiology and Proliferation of Salmonella enterica in an In Vitro Model of the Porcine Gastrointestinal Tract▿ †

Pieper, Robert; Bindelle, Jérôme; Rossnagel, Brian; Van Kessel, Andrew; Leterme, Pascal
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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56.28%
The influence of the carbohydrate (CHO) composition of cereal cultivars on microbial ecophysiology was studied using an in vitro model of the porcine gastrointestinal tract. Ten hull-less barley cultivars, six barley cultivars with hulls, six oat cultivars, and six oat groats that differed in β-glucan, nonstarch polysaccharide (NSP), and starch contents and starch type were hydrolyzed enzymatically and incubated for 72 h with pig feces. Fermentation kinetics were modeled, and microbial compositions and short-chain fatty acid (SCFA) profiles were analyzed using terminal restriction fragment length polymorphism and gas chromatography. Cluster analysis and canonical ordination revealed different effects on fermentation and microbial ecology depending on the type of CHO and cultivar. First, in cultivars of barley with hulls and oats, the cellulose and insoluble NSP contents (i) increased Ruminococcus flavefaciens-like and Clostridium xylanolyticum-like phylotypes, (ii) increased acetate production, and (iii) decreased fermentation activity. Second, in hull-less barley cultivars the β-glucan, amylose, amylopectin, crude protein, and soluble NSP contents determined the microbial community composition and activity as follows: (i) the amylose contents of the hull-less barley varieties increased the butyrate production and the abundance of Clostridium butyricum-like phylotypes...

Lineage-Specific Responses of Microbial Communities to Environmental Change

Youngblut, Nicholas D.; Shade, Ashley; Read, Jordan S.; McMahon, Katherine D.; Whitaker, Rachel J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2013 EN
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56.26%
A great challenge facing microbial ecology is how to define ecologically relevant taxonomic units. To address this challenge, we investigated how changing the definition of operational taxonomic units (OTUs) influences the perception of ecological patterns in microbial communities as they respond to a dramatic environmental change. We used pyrosequenced tags of the bacterial V2 16S rRNA region, as well as clone libraries constructed from the cytochrome oxidase C gene ccoN, to provide additional taxonomic resolution for the common freshwater genus Polynucleobacter. At the most highly resolved taxonomic scale, we show that distinct genotypes associated with the abundant Polynucleobacter lineages exhibit divergent spatial patterns and dramatic changes over time, while the also abundant Actinobacteria OTUs are highly coherent. This clearly demonstrates that different bacterial lineages demand different taxonomic definitions to capture ecological patterns. Based on the temporal distribution of highly resolved taxa in the hypolimnion, we demonstrate that change in the population structure of a single genotype can provide additional insight into the mechanisms of community-level responses. These results highlight the importance and feasibility of examining ecological change in microbial communities across taxonomic scales while also providing valuable insight into the ecological characteristics of ecologically coherent groups in this system.

Proteomic tools to decipher microbial community structure and functioning

Arsène-Ploetze, Florence; Bertin, Philippe N.; Carapito, Christine
Fonte: Springer Berlin Heidelberg Publicador: Springer Berlin Heidelberg
Tipo: Artigo de Revista Científica
EN
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56.26%
Recent advances in microbial ecology allow studying microorganisms in their environment, without laboratory cultivation, in order to get access to the large uncultivable microbial community. With this aim, environmental proteomics has emerged as an appropriate complementary approach to metagenomics providing information on key players that carry out main metabolic functions and addressing the adaptation capacities of living organisms in situ. In this review, a wide range of proteomic approaches applied to investigate the structure and functioning of microbial communities as well as recent examples of such studies are presented.

Microbial Co-occurrence Relationships in the Human Microbiome

Faust, Karoline; Sathirapongsasuti, Jarupon Fah; Izard, Jacques Georges; Segata, Nicola; Gevers, Dirk; Raes, Jeroen; Huttenhower, Curtis
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
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56.3%
The healthy microbiota show remarkable variability within and among individuals. In addition to external exposures, ecological relationships (both oppositional and symbiotic) between microbial inhabitants are important contributors to this variation. It is thus of interest to assess what relationships might exist among microbes and determine their underlying reasons. The initial Human Microbiome Project (HMP) cohort, comprising 239 individuals and 18 different microbial habitats, provides an unprecedented resource to detect, catalog, and analyze such relationships. Here, we applied an ensemble method based on multiple similarity measures in combination with generalized boosted linear models (GBLMs) to taxonomic marker (16S rRNA gene) profiles of this cohort, resulting in a global network of 3,005 significant co-occurrence and co-exclusion relationships between 197 clades occurring throughout the human microbiome. This network revealed strong niche specialization, with most microbial associations occurring within body sites and a number of accompanying inter-body site relationships. Microbial communities within the oropharynx grouped into three distinct habitats, which themselves showed no direct influence on the composition of the gut microbiota. Conversely...

Microbial Reprogramming Inhibits Western Diet-Associated Obesity

Poutahidis, Theofilos; Kleinewietfeld, Markus; Smillie, Christopher; Levkovich, Tatiana; Perrotta, Alison; Bhela, Siddheshvar; Varian, Bernard J.; Ibrahim, Yassin M.; Lakritz, Jessica R.; Kearney, Sean M.; Chatzigiagkos, Antonis; Hafler, David A.; Alm, Er
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
56.28%
A recent epidemiological study showed that eating ‘fast food’ items such as potato chips increased likelihood of obesity, whereas eating yogurt prevented age-associated weight gain in humans. It was demonstrated previously in animal models of obesity that the immune system plays a critical role in this process. Here we examined human subjects and mouse models consuming Westernized ‘fast food’ diet, and found CD4+ T helper (Th)17-biased immunity and changes in microbial communities and abdominal fat with obesity after eating the Western chow. In striking contrast, eating probiotic yogurt together with Western chow inhibited age-associated weight gain. We went on to test whether a bacteria found in yogurt may serve to lessen fat pathology by using purified Lactobacillus reuteri ATCC 6475 in drinking water. Surprisingly, we discovered that oral L. reuteri therapy alone was sufficient to change the pro-inflammatory immune cell profile and prevent abdominal fat pathology and age-associated weight gain in mice regardless of their baseline diet. These beneficial microbe effects were transferable into naïve recipient animals by purified CD4+ T cells alone. Specifically, bacterial effects depended upon active immune tolerance by induction of Foxp3+ regulatory T cells (Treg) and interleukin (Il)-10...

Microbial Ecology of an Extreme Acidic Environment, the Tinto River

González-Toril, E.; Llobet-Brossa, E.; Casamayor, E. O.; Amann, R.; Amils, R.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2003 EN
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56.27%
The Tinto River (Huelva, southwestern Spain) is an extreme environment with a rather constant acidic pH along the entire river and a high concentration of heavy metals. The extreme conditions of the Tinto ecosystem are generated by the metabolic activity of chemolithotrophic microorganisms thriving in the rich complex sulfides of the Iberian Pyrite Belt. Molecular ecology techniques were used to analyze the diversity of this microbial community. The community's composition was studied by denaturing gradient gel electrophoresis (DGGE) using 16S rRNA and by 16S rRNA gene amplification. A good correlation between the two approaches was found. Comparative sequence analysis of DGGE bands showed the presence of organisms related to Leptospirillum spp., Acidithiobacillus ferrooxidans, Acidiphilium spp., “Ferrimicrobium acidiphilum,” Ferroplasma acidiphilum, and Thermoplasma acidophilum. The different phylogenetic groups were quantified by fluorescent in situ hybridization with a set of rRNA-targeted oligonucleotide probes. More than 80% of the cells were affiliated with the domain Bacteria, with only a minor fraction corresponding to Archaea. Members of Leptospirillum ferrooxidans, Acidithiobacillus ferrooxidans, and Acidiphilium spp....

Diversidad y ecología de las comunidades microbiológicas de las lagunas pampeanas; Diversity and ecology of microbial communities from shallow lakes from the Pampa plain

Llames, María Eugenia del Rosario
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2011 SPA
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56.31%
Las bacterias son los organismos más abundantes de la Tierra y son los encargados de mediar en una multitud de procesos críticos para el medio ambiente. En los sistemas acuáticos, el bacterioplancton incluye organismos autótrofos y heterótrofos, de amplia distribución cuya producción y biomasa pueden llegar a constituir un alto porcentaje de la producción primaria total del sistema. Dado su rol central en procesos ecológicos básicos del ecosistema resulta de gran importancia conocer sus patrones de distribución, su dinámica poblacional y los factores más relevantes en la determinación de la estructura y el funcionamiento de esta comunidad, aspectos hasta ahora desconocidos para las comunidades bacterianas de las lagunas pampeanas. Los primeros estudios en microbiología acuática se realizaron mediante técnicas de cultivo tradicionales. Luego, la introducción de técnicas provenientes de la biología molecular ha permitido avanzar enormemente en el conocimiento de las comunidades microbiológicas. Estas técnicas han permitido estudiar no sólo la identidad, sino también la actividad y la genómica microbiana. Actualmente existen numerosas especies procariotas descriptas formalmente, sin embargo, aun no existe un consenso en la sistemática bacteriana para definir la unidad biológica fundamental de diversidad. En consecuencia...