Formulation of a Low-cost Medium for Improved Cost-effectiveness of Hydrogen Production by Thermococcus onnurineus NA1

Hydrogen has been receiving considerable attention as a clean energy carrier. Thermococcus onnurineus NA1, a hyperthermophilic archaeon, is capable of producing hydrogen using carbon monoxide (CO) in a growth-associated manner, providing a promising platform to upcycle industrial waste gases. In order to improve cost-effectiveness of the biological hydrogen production from carbon monoxide (CO), we developed formulation of a low-cost medium for T. onnurineus 156T by substituting fishmeal and sea salt for yeast extract (YE) and reagent-grade salts, respectively. In serum bottle cultures, hydrogen production by the 156T strain was less than 30% in fishmeal-containing media when compared to that of the YE-containing MM1 medium. However, hydrogen production was increased substantially by adaptive evolution in the fishmeal-sea salt (FMSS) medium. In bioreactor experiments, the resulting strain 156T-FA showed shorter lag phase and 70% higher maximum hydrogen production rate in FMSS medium than the parent strain 156T. Our results showed that the H-2 production cost was reduced by ca. 95%, when YE and chemical salts were replaced by fishmeal and sea salt, respectively.