Enzyme Regulation in Methylobacterium organophilum

Abstract

Several enzymes were assayed in M. organophilum grown on different substrates. The enzymes which are involved in growth on C1 compounds were induced by methanol and not repressed by succinate. When succinate-grown bacteria were resuspended in medium containing methanol, 4 enzymes unique to growth on C1 compounds (hydroxypyruvate reductase, serine-glyoxylate aminotransferase, methanol dehydrogenase and glycerate kinase) were fully induced by the time growth began. When methanol-grown bacteria were resuspended in medium containing succinate, all 4 enzyme activities decreased. Several mutants unable to grow on C1 compounds were examined for deficiencies in the enzymes specific for growth on these compounds. Seven of the mutants were pleiotropic, and 6 were not revertible by chemical mutagens, suggesting the possibility of genetic linkage or the presence of a regulon for the genes involved in C1 metabolism.