Biohydrogen Production of Obligate Anaerobic Archaeon Thermococcus onnurineus NA1 under Oxic Conditions via Overexpression of frhAGB-encoding Hydrogenase Genes

Abstract

In order to understand the physiological role of a soluble hydrogenase gene cluster, frhAGB, in a hyperthermophilic archaeon T. onnurineus NA1, we tried to understand the changes in the mutant by employing transcriptome analysis. The overexpression of frhAGB genes caused changing expression of several genes involved in stress response and transcriptional regulation. We revealed that no significant growth defect was observed when the frhAGB-overexpressing mutant (FO) was exposed to 40% air and enable grow on 20% O2 in the headspace of sealed bottle. Furthermore, FO mutant can grow and produce H2 in a bioreactor by omitting O2 removal methods. On the other hand, no growth was occurred in wild-type strain under oxic condition. This study gives an insight into the function of the frhAGB hydrogenase in T. onnurineus NA1 and we could demonstrate H2 production without oxygen removal of obligate anaerobic hyperthermophilic archaeon by overexpression of frhAGB hydrogenase.