Project description:The goal of this work was to elucidate the mechanism by which pyruvate is utilized as a substrate in a mutant strain of Methanosarcina barkeri Fusaro. In this study, using RNAseq we gained insight into how the mutant strain modulate its transcriptional profile in order to use pyruvate as a substrate. In addition, we obtained information on how methanogens respond to pyruvate at the transcriptional level. The mRNA from of Methanosarcina barkeri Fusaro DSMZ804 and Pyr+ strains grown on a variety of substrates (methanol, acetate, methanol-acetate, methanol-pyruvate, methanol-pyruvate-acetate) were harvested sequenced and mapped to M. barkeri genome. Pairwise comparisons between two cell lines of the Pyr+ strain and the DSMZ 804 strain were performed in all substrates tested.
Project description:The generation of an electrical membrane potential (Δψ), the major constituent of the proton motive force (pmf) is crucial for the ATP synthesis, bacterial growth and motility. The pmf drives the rotation of flagella and is vital for the microaerophilic human pathogen Campylobacter jejuni to colonize the mucus layer of the gut of warm-blooded animals. C. jejuni harbors a branched electron transport chain, enabling respiration with different electron donors and acceptors to generate a Δψ. Here, we demonstrate which electron donor/acceptor couples generate a Δψ and show the impact of the Δψ on the growth performance and motility of this bacterium. In the absence of both oxygen and formate or hydrogen, no Δψ is generated, which strongly reduced the growth rate and the number of motile bacteria. ATP generation is driven either by the pmf, or by substrate level phosphorylation if pyruvate is present. In response to low oxygen tension, C. jejuni upregulates the transcription of the alternative respiratory acceptor complexes and increases the transcription and activity of the donor complexes formate dehydrogenase (FdhABC) and hydrogenase (HydABCD). In conclusion, C. jejuni is dependent on oxygen as electron acceptor or formate/hydrogen as electron donor to generate a pmf that sustains efficient growth and motility performance. Overall design: Comparison of growth conditions, C. jejuni strain 81116 grown under microaerophilic (5% Oxygen) condition compared to C. jejuni strain 81116 grown under oxygen limited (0.3% oxygen) conditions with or without 10mM nitrate.
Project description:The potential of the earthworm Eisenia andrei to reduce soil methanogens, and thus methane emissions to the atmosphere, were assayed in a microcosm experiment. Soils were incubated for 2, 4 and 6 months. We measured microarray parameters (methanogenic diversity) at the start of incubation, as well as after 2, 4 and 6 months of incubation in microcosms with or without earthworms. Methanosarcina barkeri was the most abundant genus that was revealed by AnaeroChip in our experiment.