METHYL-CHLORIDE METABOLISM OF THE STRICTLY ANAEROBIC, METHYL CHLORIDE-UTILIZING HOMOACETOGEN STRAIN MC

The methyl chloride metabolism of the homoacetogenic, methyl chloride- utilizing strain MC was investigated with cell extracts and cell suspe nsions of the organism. Cell extracts were found to contain all enzyme activities required for the conversion of methyl chloride or of H-2 p lus CO2 to acetate. They catalyzed the dechlorination of methyl chlori de with tetrahydrofolate as the methyl acceptor at a rate of approxima tely 20 nmol/min x mg of cell protein. Also, the O-demethylation of va nillate with tetrahydrofolate could be measured at a rate of 40 nmol/m in x mg. Different enzyme systems appeared to be responsible for the d ehalogenation of CH3Cl and for the O-demethylation of methoxylated aro matic compounds, since cells grown with methoxylated aromatic compound s exhibited a significantly lower activity of CH3Cl conversion than me thyl chloride grown cells and vice versa. In addition, ammonium thiocy anate (5 mM) completely inhibited CH3Cl dechlorination, whereas the co nsumption of vanillate was not affected significantly. The data were t aken to indicate, that the methyl chloride dehalogenation is catalyzed by a specific, inducible enzyme present in strain MC, and that tetrah ydrofolate rather than the corrinoid-protein involved in acetate forma tion is the primary acceptor of the methyl group in the dechlorination reaction.