Project description:N retention in soils can be stimulated by microorganisms carrying out dissimilatory reduction of nitrate to ammonia (DNRA), a respiratory activity that converts nitrate and/or nitrite to ammonia. Geobacter lovleyi has recently being recognized as a key driver of DNRA, providing a model to investigate the environmental signals that promote nitrate ammonification. Here we show that low nitrate concentrations (5mM) induce DNRA in G. lovleyi independently of the concentration of the electron donor, thus challenging the prevailing view that high carbon-to-nitrogen (C/N) ratio triggers this process. The nitrate transcriptome revealed a complex metabolic network of periplasmic (Nap) and cytoplasmic (Nar) nitrate reductase systems for the reduction of nitrate to nitrite. The transcriptome also included a canonical (NrfA-1), two Geobacter-specific nitrite reductases (NrfA-2 and NrfA-3) and a membrane-bound NrfH cytochrome, which electronically connects NrfA to the menaquinone pool. Flagellar motility and chemotaxis proteins were also among the most upregulated genes in the nitrate cultures, consistent with an adaptive response that allows Geobacter cells to sense and access the limited supply of nitrate in anaerobic zones of the soils and sediments. This is the first demonstration of the ability of the bacteria to use DNRA pathway under nitrate limiting conditions independently of the C/N ratio. G. lovleyi provides a model for study DNRA process and it is a good candidate that could contribute in the retention of nitrogen in soils leading to efficient use of nitrogen containing fertilizers and preventing nitrate leaching.
Project description:One of the most striking observations in the S. oneidensis genome regarding nitrate respiration is that napC is missing and nrfBCD is degenerated. To gain insights into candidate genes encoding the protein(s) in place of NapC and NrfBCD function, i.e., delivering electrons to NapA and NrfA, transcriptional profiling was carried out using the S. oneidensis whole-genome cDNA microarray. Cells of MR-1 grown on nitrate or fumarate under anaerobic conditions were sampled at the exponential phase for the analysis. The quality of the array data was statistically assessed using the method reported previously. Keywords: Compararive microarray study Compare transcriptional profiles of MR-1 grown on nitrate and Fumarate aiming at finding the electron transfer proteins to NapA and NrfA.
Project description:The advent of culture independent approaches has greatly facilitated insights into the vast diversity of bacteria and the ecological importance they hold in nature and human health. Recently, metagenomic surveys and other culture-independent methods have begun to describe the distribution and diversity of microbial metabolism across environmental conditions, often using 16S rRNA gene as a marker to group bacteria into taxonomic units. However, the extent to which similarity at the conserved ribosomal 16S gene correlates with different measures of phylogeny, metabolic diversity, and ecologically relevant gene content remains contentious. Here, we examine the relationship between 16S identity, core genome divergence, and metabolic gene content across the ancient and ecologically important genus Streptomyces. We assessed and quantified the high variability of average nucleotide identity (ANI) and ortholog presence/absence within Streptomyces, even in strains identical by 16S. Furthermore, we identified key differences in shared ecologically important characters, such as antibiotic resistance, carbohydrate metabolism, biosynthetic gene clusters (BGCs), and other metabolic hallmarks, within 16S identities commonly treated as the same operational taxonomic units (OTUs). Differences between common phylogenetic measures and metabolite-gene annotations confirmed this incongruence. Our results highlight the metabolic diversity and variability within OTUs and add to the growing body of work suggesting 16S-based studies of Streptomyces fail to resolve important ecological and metabolic characteristics. See publication: https://doi.org/10.3389/fmicb.2019.02170.
The work (proposal:https://doi.org/10.46936/10.25585/60001100) conducted by the U.S. Department of Energy Joint Genome Institute (https://ror.org/04xm1d337), a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy operated under Contract No. DE-AC02-05CH11231.
Project description:Gut microbiota were assessed in 540 colonoscopy-screened adults by 16S rRNA gene sequencing of stool samples. Investigators compared gut microbiota diversity, overall composition, and normalized taxon abundance among these groups.
Project description:IL22 induces antimicrobial peptides which influnce microbiota. We used 16s rRNA gene sequencing (16s DNA-seq) to analyze the microbiota with Fc or IL-22Fc treatment.
2024-08-01 | GSE242929 | GEO
Project description:sediment DNRA bacterial nrfA gene responding to seasonal hypoxia
Project description:The impact of mono-chronic S. stercoralis infection on the gut microbiome and microbial activities in infected participants was explored. The 16S rRNA gene sequencing of a longitudinal study with 2 sets of human fecal was investigated. Set A, 42 samples were matched, and divided equally into positive (Pos) and negative (Neg) for S. stercoralis diagnoses. Set B, 20 samples of the same participant in before (Ss+PreT) and after (Ss+PostT) treatment was subjected for 16S rRNA sequences and LC-MS/MS to explore the effect of anti-helminthic treatment on microbiome proteomes.