Transcriptomic study of hydrogen sulfide toxicity in Methylococcus capsulatus

Stress response of Methylococcus capsulatus str.Bath toward hydrogen sulfide (H2S) was investigated via physiological study and transcriptomic profiling. M. capsulatus (Bath) can grow and tolerate up to 0.75%vol H2S in headspace. Vast change in pH suggests biological relevant sulfide oxidation. Dozens of H2S-sensitive genes were identified from comparison of cell transcriptome in different H2S concentrations. Mc sulfide quinone reductase (SQR) and persulfide dioxygenase were found to be active during sulfide detoxification. Moreover, xoxF, a novel lanthanide(Ln)-dependent methanol dehydrogenase (MDH) was overexpressed in H2S while mxaF, a calcium-dependent MDH, was down-regulated, and such MDH switch phenomenon is also well known to be induced by addition of lanthanide via an as-yet-unknown mechanism. Activities in quorum sensing and RND efflux pump also suggest their role in sulfide detoxification, and might provide insight on the xoxF/mxaF switch mechanism. RNA profile of M. capsulatus at mid-log phase as wild type, and in 0.1%, 0.5% and 0.75%H2S, and a H2S shock treatment.