Methanol and Carbon Monoxide Metabolism of Butyri-Bacterium Methylotrophicum the Marburg Strain

Abstract

Growth of B. methylotrophiewn on methanol (100mM)/acetate (50mM) required CO2 and exhibited: a chemical transformation stoichiometry of 10 methanol + 2CO2 → 3 butyrate: a cell yield of 7.8 g/mol methanol; and, a growth rate of 0.067 h-1. Cultures adapted to grow on methanol with a CO atmosphere (100%) displayed: a 3-fold increase in growth yield; increased growth rate; no requirement for CO2; and, production of acetate in lieu of butyrate. The maximum rate of CO oxidation displayed by cultures during mixotrophic growth on methanol/CO and 140 mmol/min/mg dry wt. B. methlotrophicum was adapted to grow in batch culture with a 100% CO atmosphere as the sole energy source. Fermentation parameters for growth on CO were: a chemical transformation stoichiometry of 4CO → 2.2 CO2 + 0.6 acetate; a growth yield of 2.9 g/mol CO; a final P.D.666 of 0.8; and, a maximal CO-oxidation rate of 260 nmol/min/mg dry wt. B-methylotrophicum grew on a variety of substrates in the presence of one atmosphere CO. Under these conditions, >.9 atmospheres of CO were consumed during growth on H2/CO2 or methanol, while <0.4 and <0.2 atmospheres were consumed during growth H2/CO2/CO increased greater than two-fold over that observed in the absence of CO.