Project description:Hydrogenases are a critical component of H2-dependent energy-conservation pathways in Methanosarcina barkeri. To allow phenotypic analysis of the hydrogenases, we constructed mutants lacking the frhADGB, freAEGB, vhtGACD, vhxGAC and echABCDEF operons, individually and in all possible combinations. In addition to measuring the effect of each deletion on growth, methane production, and hydrogenase activity, the effect on gene expression was measured by RNA sequencing to detect potential transcriptional regulation by the hydrogenases.
Project description:Anaerobic methanogens are an important part of the global carbon cycle and energy supply. With industrialization, Fluoranthene (Flu) accumulated in soils, sediments, and sewage plants etc., giving an uncertain impact on methane production of methanogens. Here, the effect of Flu on Methanosarcina barkeri (M. barkeri) were investigated in this paper. The methane yield of strain with 0.01 and 0.1 mg/L Flu was 1.43 and 1.65 times higher than the control. The growth of M. barkeri was also maximized at Flu of 0.1 mg/L with 1.37-fold than control. The physiological features of M. barkeri were enhanced by 0.1 mg/L Flu, such as, cell viability (154%), total-EPS (1.82-fold), and SOD enzyme activity (1.28 times). Notably, TMT proteomics provided a novel insight to reveal that Flu activated the methanogenic metabolic pathway and ABC transporters of M. barkeri, particularly promoted it to synthesize MtrA/C/D/E/G/H (8.2 times total), FrhA/B/G, iron (III)/zinc/molybdenum/vitamin B12 ABC transporter proteins, and the groups of methyltransferase and coenzyme F420 hydrogenase. The upregulated expression of methanogenesis-related enzyme proteins resulted in increased generation and transfer of methane. Overall, this study shed light on the impact of organic pollutants on global carbon cycle of M. barkeri from the molecular biology perspective.
