INFLUENCE OF REDOX POTENTIAL ON BIOMETHANATION OF H2 AND CO2 BY METHANOBACTERIUM THERMOAUTOTROPHICUM IN Eh-STAT BATCH CULTURES

Abstract

The influence of redox potential (Eh) on biomethanation from H2 and CO2 by Methanobacterium thermoautotrophicum ΔH was studied in pH- controlled anaerobic batch cultures at 65°C in which the Eh of the culture medium was regulated by the addition of titanium(III)-citrate or potassium ferricyanide at values ranging from -315 to -500mV. The specific growth rate μ and the specific methane production rate QCH4 were optimum under the Eh range from -370 to -500mV, while it sharply decreased at the higher Eh range of -315 to -350mV. The maximum values of QCH4 and μ under the optimum environments were 5 (l CH4) (g cell)-1 hr-1 and 0.36hr-1, respectively.