Electrochemical control of redox potential affects methanogenesis of the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus

To investigate the precise effect of the redox potential on the methanogenesis of the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus by using an electrochemical redox controlling system without adding oxidizing or reducing agents. A bioelectrochemical system was applied to control the redox conditions in culture and to measure the methane-producing activity of M.thermautotrophicus at a constant potential from +0 center dot 2 to 0 center dot 8V (vs Ag/AgCl). Methane production and growth of M.thermautotrophicus were 1 center dot 6 and 3 center dot 5 times increased at 0 center dot 8V, compared with control experiments without electrolysis, respectively, while methanogenesis was suppressed between +0 center dot 2 and 0 center dot 2V. A clear relationship between an electrochemically regulated redox potential and methanogenesis was revealed.