Project description:Tibet is one of the most threatened regions by climate warming, thus understanding how its microbial communities function may be of high importance for predicting microbial responses to climate changes. Here, we report a study to profile soil microbial structural genes, which infers functional roles of microbial communities, along four sites/elevations of a Tibetan mountainous grassland, aiming to explore potential microbial responses to climate changes via a strategy of space-for-time substitution. Using a microarray-based metagenomics tool named GeoChip 4.0, we showed that microbial communities were distinct for most but not all of the sites. Substantial variations were apparent in stress, N and C cycling genes, but they were in line with the functional roles of these genes. Cold shock genes were more abundant at higher elevations. Also, gdh converting ammonium into urea was more abundant at higher elevations while ureC converting urea into ammonium was less abundant, which was consistent with soil ammonium contents. Significant correlations were observed between N-cycling genes (ureC, gdh and amoA) and nitrous oxide flux, suggesting that they contributed to community metabolism. Lastly, we found by CCA, Mantel tests and the similarity tests that soil pH, temperature, NH4+–N and vegetation diversity accounted for the majority (81.4%) of microbial community variations, suggesting that these four attributes were major factors affecting soil microbial communities. Based on these observations, we predict that climate changes in the Tibetan grasslands are very likely to change soil microbial community functional structure, with particular impacts on microbial N cycling genes and consequently microbe-mediated soil N dynamics.
Project description:Tibet is one of the most threatened regions by climate warming, thus understanding how its microbial communities function may be of high importance for predicting microbial responses to climate changes. Here, we report a study to profile soil microbial structural genes, which infers functional roles of microbial communities, aiming to explore potential microbial responses to climate changes via a strategy of space-for-time substitution. Using a microarray-based metagenomics tool named GeoChip 4.0, we showed that microbial communities were distinct for most but not all of the sites. Substantial variations were apparent in stress, N and C cycling genes, but they were in line with the functional roles of these genes. sixty-three samples were collected from four elevations (3200,3400,3600 and 3800 m) along a Tibetan alpine meadow; Three replicates in each treatment
Project description:Cruciferous vegetables and their derived compounds, such as glucosinolates, have demonstrated anti-inflammatory properties in animal models. In this study, broccoli-supplemented diet induced changes in the gut microbiome and its role in host and bacterial gene expression were examined in mice following consumption of the Total Western Diet (TWD), which is based on NHANES data and represents the composition of a typical American diet. C57BL/6 male mice were fed a TWD for six weeks followed by a supplementation of 0, 0.5, 1 or 2.5% broccoli powder for three weeks. Microbial communities from cecal contents were taxonomically profiled using 16S and metagenomics sequencing, and metatranscriptomics was used to assess functionality of bacterial species. Cecum tissues were also analyzed for host transcriptomics.
Project description:Tibet is one of the most threatened regions by climate warming, thus understanding how its microbial communities function may be of high importance for predicting microbial responses to climate changes. Here, we report a study to profile soil microbial structural genes, which infers functional roles of microbial communities, along four sites/elevations of a Tibetan mountainous grassland, aiming to explore potential microbial responses to climate changes via a strategy of space-for-time substitution. Using a microarray-based metagenomics tool named GeoChip 4.0, we showed that microbial communities were distinct for most but not all of the sites. Substantial variations were apparent in stress, N and C cycling genes, but they were in line with the functional roles of these genes. Cold shock genes were more abundant at higher elevations. Also, gdh converting ammonium into urea was more abundant at higher elevations while ureC converting urea into ammonium was less abundant, which was consistent with soil ammonium contents. Significant correlations were observed between N-cycling genes (ureC, gdh and amoA) and nitrous oxide flux, suggesting that they contributed to community metabolism. Lastly, we found by CCA, Mantel tests and the similarity tests that soil pH, temperature, NH4+M-bM-^@M-^SN and vegetation diversity accounted for the majority (81.4%) of microbial community variations, suggesting that these four attributes were major factors affecting soil microbial communities. Based on these observations, we predict that climate changes in the Tibetan grasslands are very likely to change soil microbial community functional structure, with particular impacts on microbial N cycling genes and consequently microbe-mediated soil N dynamics. Twelve samples were collected from four elevations (3200, 3400, 3600 and 3800 m) along a Tibetan grassland; Three replicates in every elevation
Project description:Cruciferous vegetables and their derived compounds, such as glucosinolates, have demonstrated anti-inflammatory properties in animal models. In this study, broccoli-supplemented diet induced changes in the gut microbiome and its role in host and bacterial gene expression were examined in mice following consumption of the Total Western Diet (TWD), which is based on NHANES data and represents the composition of a typical American diet. C57BL/6 male mice were fed a TWD for six weeks followed by a supplementation of 0, 0.5, 1 or 2.5% broccoli powder for three weeks. Microbial communities from cecal contents were taxonomically profiled using 16S and metagenomics sequencing, and metatranscriptomics was used to assess functionality of bacterial species. Cecum tissues were also analyzed for host transcriptomics.
Project description:Functional redundancy in bacterial communities is expected to allow microbial assemblages to survive perturbation by allowing continuity in function despite compositional changes in communities. Recent evidence suggests, however, that microbial communities change both composition and function as a result of disturbance. We present evidence for a third response: resistance. We examined microbial community response to perturbation caused by nutrient enrichment in salt marsh sediments using deep pyrosequencing of 16S rRNA and functional gene microarrays targeting the nirS gene. Composition of the microbial community, as demonstrated by both genes, was unaffected by significant variations in external nutrient supply, despite demonstrable and diverse nutrient–induced changes in many aspects of marsh ecology. The lack of response to external forcing demonstrates a remarkable uncoupling between microbial composition and ecosystem-level biogeochemical processes and suggests that sediment microbial communities are able to resist some forms of perturbation.
Project description:Disrupted interactions between host and intestinal bacteria are implicated in the development of colorectal cancer (CRC). However, the functional impacts of these inter-kingdom interactions remain poorly defined. To examine this interplay, we performed mouse and microbiota RNA-sequencing on colon tissue from germ-free (GF) and gnotobiotic ApcMin/+;Il10-/- mice associated with microbes from biofilm-positive human CRC tumor (BT) and biofilm-negative healthy (BX) tissues. The bacteria in BT mice differentially expressed >2,900 genes related to bacterial secretion, virulence and biofilms, but only affected 62 host genes. Importantly, the bacterial communities from BT mice were transmissible and carcinogenic when administered to a new GF ApcMin/+;Il10-/- cohort, maintaining a set of 13 bacterial genera. Our findings suggest complex interactions within bacterial communities affecting bacterial composition and CRC development.
Project description:The increased urban pressures are often associated with specialization of microbial communities. Microbial communities being a critical player in the geochemical processes, makes it important to identify key environmental parameters that influence the community structure and its function.In this proect we study the influence of land use type and environmental parameters on the structure and function of microbial communities. The present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. The overall goal of this study is to understand the role of engineered physicochemical environment on the structure and function of microbial communities in urban storm-water canals.