Analysis of the molecular species of hydrogenase in the cells of an obligately chemolithoautotrophic, marine hydrogen-oxidizing bacterium, Hydrogenovibrio marinus

Hydrogenovibrio marinus was suggested to have only membrane-bound hydrogenase (MBH). The change of cultivation pO(2) did not affect the molecular species of hydrogenase expressed. We propose the MBH is grouped in class I [NiFe] MBH according to the subunit composition, size (Mw 38,000 and Mw 74,000 subunits) and N-terminal sequences of the subunits, and arrangement of the structural genes. Ni-requirement for the autotrophic growth on H-2 also suggested the MBH is the Ni-containing type. Southern hybridization analysis using a part of the MBH gene showed a possibility of the presence of two highly homologous MBHs which were not separated by SDS-PAGE.