Development of hyperthermophilic archaeon Thermococcus onnurineus NA1 to improve biohydrogen production via CO gas fermentation

Abstract

A hyperthermophilic archaeon Thermococcus onnurineus NA1 isolated from a deep-sea hydrothermal vent area has been reported to be capable of lithotrophic growth on 100 % CO coupled with equimolar production of H2 by an enzymatic system composed of carbon monoxide dehydrogenase (CODH), a hydrogenase, and a Na+/H+ antiporter. The hydrogenogenic CO-converting reaction has a potential application in the production of H2 gas as a clean renewable fuel from waste gases or synthesis gas containing CO. To enhance biological H2 production via CO gas fermentation, mutant strains derived from T. onnurineus NA1 were constructed to overexpress codh gene cluster by employing genetic engineering, such as promoter engineering and overexpression of CO-sensing regulator, and adaptive engineering. Among those studies, adaptive engineering led to highly enhanced H2 productivity using 100 % CO or synthesis gas produced from coal gasification and multi-omics analysis were conducted to uncover CO metabolism in this strain. In addition, we attempted to demonstrate that the T. onnurineus NA1 could serve as a useful platform for CO fermentation to produce both thermophilic enzymes and H2 at the same time and also investigated the potential of whole-cell lysates and purified enzymes obtained from the constructed cell factory for biotechnological application.