Project description:We measured steady-state transcript levels in 1) wild-type E. litoralis DSM 8509, 2) a nepR-ecfG deletion strain (ΔnepR-ecfG), 3) a phyR deletion strain (ΔphyR), 4) a lovK-lovR deletion strain (ΔlovKR), and 5) a gsrK-gsrP deletion strain (ΔgsrKΔgsrP) cultivated in constant white light or in constant dark conditions.
Project description:Chemoautotrophic bacteria from the SUP05 clade often dominate anoxic waters in marine oxygen minimum zones (OMZs) where reduced sulfur can fuel carbon fixation and denitrification. Some members of the SUP05 clade are facultative aerobes that thrive at the boundaries of OMZs where they experience fluctuations in dissolved oxygen (DO). The degree to which SUP05 contribute to nitrate reduction in these regions depends on their sensitivity to oxygen. We evaluated growth and quantified differences in gene expression in Ca. T. autotrophicus strain EF1 from the SUP05 clade under high DO (22 μM), anoxic, and low DO (3.8 μM) concentrations. We show that strain EF1 cells respire oxygen and nitrate and that cells have higher growth rates, express more genes, and fix more carbon when oxygen becomes available for aerobic respiration. Evidence that facultatively aerobic SUP05 are more active and respire nitrate when oxygen becomes available at low concentrations suggests that they are an important source of nitrite across marine OMZ boundary layers.
