Project description:Understanding how the human gut microbiota and host are impacted by probiotic bacterial strains requires carefully controlled studies in humans, and in mouse models of the gut ecosystem where potentially confounding variables that are difficult to control in humans can be constrained. Therefore, we characterized the fecal microbiomes and metatranscriptomes of adult female monozygotic twin pairs through repeated sampling 4 weeks prior to, 7 weeks during, and 4 weeks following consumption of a commercially-available fermented milk product (FMP) containing a consortium of Bifidobacterium animalis subsp. lactis, two strains of Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. cremoris, and Streptococcus thermophilus. In addition, gnotobiotic mice harboring a 15-species model human gut microbiota whose genomes contain 58,399 known or predicted protein-coding genes were studied prior to and after gavage with all five sequenced FMP strains. 140 samples total. Evaluation of changes in a model community's structure over time after exposure to a consortium of 5 fermented milk product (FMP) strains.
Project description:Understanding how the human gut microbiota and host are impacted by probiotic bacterial strains requires carefully controlled studies in humans, and in mouse models of the gut ecosystem where potentially confounding variables that are difficult to control in humans can be constrained. Therefore, we characterized the fecal microbiomes and metatranscriptomes of adult female monozygotic twin pairs through repeated sampling 4 weeks prior to, 7 weeks during, and 4 weeks following consumption of a commercially-available fermented milk product (FMP) containing a consortium of Bifidobacterium animalis subsp. lactis, two strains of Lactobacillus delbrueckii subsp. bulgaricus, Lactococcus lactis subsp. cremoris, and Streptococcus thermophilus. In addition, gnotobiotic mice harboring a 15-species model human gut microbiota whose genomes contain 58,399 known or predicted protein-coding genes were studied prior to and after gavage with all five sequenced FMP strains. 73 samples total. Evaluation of changes in a model community's metatranscriptome over time after exposure to a consortium of 5 fermented milk product (FMP) strains (40 samples); evaluation of the gene expression of the FMP strains in other in vitro conditions, including MRS medium (B. animalis subsp. lactis only, 4 samples) and a commercial FMP fermentation (all 5 strains, 6 samples); evaluation of the gene expression of native human microbiomes before and after the consumption of a commercial FMP (23 samples).
Project description:The survival of probiotics could be strongly enhanced by delivery vehicles, but the mechanism was unknown. In this study, whole genome microarray technology was used to detect the gene expression profiles of probiotic Lactobacillus casei Zhang in the absence and presence of fermented milk in simulated gastrointestinal tract. The results showed the gene expression profiles were significantly different under these two different conditions. The change of the gene expression profile may be helpful to comprehend the role of delivery vehicles in enhancing the survival of probiotics. Twelve samples of bacterial cells in the absence and presence of fermented milk were collected at 3 h in simulated gastric juice, 4 h and 8 h in intestinal juice, 2 biological replicates were obtained in each time point. The average of the normalized expression values of the 2 biological replicates for each probe was regarded as the expression value of a predicted gene. To identify the expression pattern of each gene across different treatments, n-fold change ratios were calculated for every gene in pure L. casei Zhang versus L. casei Zhang in fermented milk.
Project description:The fate of the carbon stocked in permafrost soils following global warming and permafrost thaw is of major concern in view of the potential for increased CH4 and CO2 emissions from these soils. Complex carbon compound degradation and greenhouse gas emissions are due to soil microbial communities, but their composition and functional potential in permafrost soils are largely unknown. Here, a 2 m deep permafrost and its overlying active layer soil were subjected to metagenome sequencing, quantitative PCR, and microarray analyses. The active layer soil and 2 m permafrost soil microbial community structures were very similar, with Actinobacteria being the dominant phylum. The two soils also possessed a highly similar spectrum of functional genes, especially when compared to other already published metagenomes. Key genes related to methane generation, methane oxidation and organic matter degradation were highly diverse for both soils in the metagenomic libraries and some (e.g. pmoA) showed relatively high abundance in qPCR assays. Genes related to nitrogen fixation and ammonia oxidation, which could have important roles following climatic change in these nitrogen-limited environments, showed low diversity but high abundance. The 2 m permafrost soil showed lower abundance and diversity for all the assessed genes and taxa. Experimental biases were also evaluated and showed that the whole community genome amplification technique used caused large representational biases in the metagenomic libraries. This study described for the first time the detailed functional potential of permafrost-affected soils and detected several genes and microorganisms that could have crucial importance following permafrost thaw. A 2m deep permafrost sample and it overlying active layer were sampled and their metagenome analysed. For microarray analyses, 8 other soil samples from the same region were used for comparison purposes.
Project description:Human breast milk contains a diverse community of bacteria but factors that produce variation in the breast milk microbiome are largely unknown. We evaluated if 1) maternal factors including breastfeeding practices modified the diversity and abundance of bacterial communities in breast milk and 2) if subclinical mastitis (SCM), an asymptomatic inflammatory condition occurring during lactation, induced a distinctive microbiota signature.