Project description:In this study, we analyzed the microbial communities from a methane-based bio-reactor with selenate as an electron accepter. Four biological replicates were analyzed by metagenomics, of which data can be found in the SRA database (Accession number: SRP136677, SRP136696, SRP136790 and SRP136859). Based on the metagenomic data, we detected the expressed proteins using metaproteomics. This data is also included in this submission.
Project description:Nitrite-oxidizing bacteria are vital players in the global nitrogen cycle that convert nitrite to nitrate during the 2nd step of nitrification. Within this functional guild, the genus Nitrospira is among the most widespread and phylogenetically and physiologically diverse nitrite oxidizers and its members drive nitrite oxidation in many natural and biotechnological ecosystems. Despite their ecological and biotechnological importance, our understanding of Nitrospira’s energy metabolism is still limited. The main bottleneck for a detailed biochemical characterization of Nitrospira is biomass production, since they are slow-growing organisms and fastidious to culture. In this study, we cultured Nitrospira moscoviensis in a continuous stirred tank reactor system (CSTR) allowing constant biomass harvesting. Additionally, this cultivation setup enabled accurate control of physicochemical parameters and thus avoided fluctuating levels of nitrite and accumulation of nitrate. We performed transcriptome analysis and confirmed constant gene expression profiles in the chemostat culture over a period of two weeks. The transcriptomic data supports the predicted core metabolism of N. moscoviensis, including the reductive TCA cycle as a CO2 fixation pathway, the novel bd-like oxidase as terminal oxidase and the octaheme nitrite reductase involved in nitrogen assimilation. Additionally, the expression of multiple copies of respiratory complexes suggests functional differentiation of these copies within the respiratory chain. Transcriptome analysis also suggests a soluble and a membrane-bound gamma subunit as part of the nitrite oxidoreductase (NXR), the enzyme catalyzing nitrite oxidation. Overall, the transcriptome data provided novel insights into the metabolism of Nitrospira supporting the genome-based prediction of key pathways. Moreover, the application of a CSTR to cultivate Nitrospira is an important foundation for future proteomic and biochemical characterizations, which are crucial for a better understanding of canonical and complete nitrifying microorganisms.
Project description:A functional gene microarray was developed and used to investigate phytoplankton community composition and gene expression in the English Channel. Genes encoding the CO2 fixation enzyme RuBisCO (rbcL) and the nitrate assimilation enzyme nitrate reductase (NR) representing several major groups of phytoplankton were included as oligonucleotide probes on the 'phytoarray'. Five major groups of eukaryotic phytoplankton that possess the Type 1D rbcL gene were detected, both in terms of presence (DNA) and activity (rbcL gene expression). Changes in relative signal intensity among the Type 1D rbcL probes indicated a shift from diatom dominance in the spring bloom to dominance by haptophytes and flagellates later in the summer. Because of the limitations of a smaller database, NR probes detected fewer groups, but due to the greater diversity among known NR sequences, NR probes provided higher phylogenetic resolution than did rbcL probes, and identified two uncultivated diatom phylotypes as the most abundant (DNA) and active (NR gene expression) in field samples. Unidentified chlorophytes and the diatom Phaeodactylum tricornutum were detected at both the DNA and cDNA (gene expression) levels. The reproducibility of the array was evaluated in several ways and future directions for further improvement of probe development and sensitivity are outlined. The phytoarray provides a relatively high resolution, high throughput approach to assessing phytoplankton community composition in marine environments. Keywords: seawater natural assemblages, functional gene expression Two functional genes, nitrate reductase and RuBisCO, 4 - 8 replicate features per array
Project description:A functional gene microarray was developed and used to investigate phytoplankton community composition and gene expression in the English Channel. Genes encoding the CO2 fixation enzyme RuBisCO (rbcL) and the nitrate assimilation enzyme nitrate reductase (NR) representing several major groups of phytoplankton were included as oligonucleotide probes on the 'phytoarray'. Five major groups of eukaryotic phytoplankton that possess the Type 1D rbcL gene were detected, both in terms of presence (DNA) and activity (rbcL gene expression). Changes in relative signal intensity among the Type 1D rbcL probes indicated a shift from diatom dominance in the spring bloom to dominance by haptophytes and flagellates later in the summer. Because of the limitations of a smaller database, NR probes detected fewer groups, but due to the greater diversity among known NR sequences, NR probes provided higher phylogenetic resolution than did rbcL probes, and identified two uncultivated diatom phylotypes as the most abundant (DNA) and active (NR gene expression) in field samples. Unidentified chlorophytes and the diatom Phaeodactylum tricornutum were detected at both the DNA and cDNA (gene expression) levels. The reproducibility of the array was evaluated in several ways and future directions for further improvement of probe development and sensitivity are outlined. The phytoarray provides a relatively high resolution, high throughput approach to assessing phytoplankton community composition in marine environments. Keywords: seawater natural assemblages, functional gene expression
Project description:Background: Biological conversion of the surplus of renewable electricity to CH4 could support energy storage and strengthen the power grid. Biological methanation (BM) is closely linked to the activity of biogas-producing bacterial community and methanogenic Archaea in particular. During reactor operations, the microbiome is often subject to various changes whereby the microorganisms are challenged to adapt to the new conditions. In this study, a hydrogenotrophic-adapted microbial community in a laboratory-scale BM fermenter was monitored for its pH, gas production, conversion yields and composition. To investigate the robustness of BM regarding power oscillations, the biogas microbiome was exposed to five H2 starvations patterns for several hours.
Project description:The dataset provides the whole proteome of the anammox bacterium "Candidatus Kuenenia Stuttgartiensis" strain CSTR1 growing planctonically in semi-CSTR reactor. The bacteria were growing at high growth rate (0.33 d-1) (reactor HRT 3d).