Utilization of Methanol plus Hydrogen by Methanosarcina barkeri for Methanogenesis and Growth

摘要

Methanosarcina barkeri grew on methanol plus H2. Both substrates were consumed in equimolar amounts. Growth was strictly dependent on the presence of acetate, which was required for the biosynthesis of cellular constituents. Only about 0.4% of the methane produced originated from acetate. By using deuterated methanol, it was demonstrated that methanogenesis from this compound under H2 did not occur via oxidation of methanol to CO2 and subsequent reduction but by direct reduction with H2. Growth yields with methanol plus H2 and with methanol alone were not significantly different: 2.8 g of cells per mol of methanol in mineral medium and 4.6 g of cells per mol of methanol in complex medium, respectively. Growth of M. barkeri on methanol plus H2 depended strictly on the presence of sodium ions in the medium. In the presence of 50 mM K⁺ the Ks for Na⁺ was 5 mM.