Enhanced cytochrome formation and stimulate methanogenesis rate by the increased ferrous concentrations in<i>Methanosarcina barkeri</i>culture

Abstract

The concentration of Fe2+ in the methanol minimum medium was found to be a stimulating factor on the formation of cytochromes, the excretion of hemes and the rate of methane formation by Methanosarcino barkeri cells. Overproduced hemes due to the high Fe2+ concentration were released into the medium as free forms. When Fe2+ concentration was employed more than 30 μM for the medium, the contents of cytochrome b and c in the cells seemed to be saturated at 40 nmol/g cell. Under the same condition, not only membrane-bound but also soluble cytochromes were detected in the ultracentrifuged fractions from the cells grown on 35 μM of Fe2+