Hydrogenase of deep-sea hydrothermal chemoautotrophic Caminibacter profundus and its response to H2

Abstract:

Hydrogenases of chemolithoautotrophic bacteria play important roles in material and energy transfer in deep-sea hydrothermal ecosystem. By designing PCR primers, a hynL gene encoding large subunit of membrane-bound group I NiFe hydrogenase from Caminibacter profundus was cloned and bioinformatively analyzed. The relative expressions of hynL, methyl viologen (MV)-reducing hydrogenase activities and bacterial growth in response to different H2 concentration were also studied. The results showed that a 864 bp hynL gene segment was obtained, predicted amino acid sequence had a 99% similarity with that of Lebetimonas acidiphila, and it belongs to the same phylogenetic branch with group I NiFe hydrogenase large subunit of hydrothermal chemolithoautotrophic Epsilonproteobacteria D group. Both hynL relative expression and MV-reducing hydrogenase activity reached the highest level at 12 h and 24 h respectively, when the strain was in the exponential growth phase. Sixty per cent of H2 concentration was optimal for hynL expression, MV-reducing hydrogenase activity and bacterial growth. All these results suggested that C. profundus regulates hynL expression in response to H2 changes in hydrothermal environment, thereby affecting the catalytic energy process, as well as the growth and propagation.