Abstract

Mycobacterium sp. strain JC1 DSM 3803 grown in methanol showed no methanol dehydrogenase or oxidase activities found in most methylotrophic bacteria and yeasts, respectively. Even though the methanol-grown cells exhibited a little methanol-dependent oxidation by cytochrome c-dependent methanol dehydrogenase and alcohol dehydrogenase, they were not the key enzymes responsible for the methanol oxidation of the cells, in that the cells contained no c-type cytochrome and the methanol oxidizing activity from the partially purified alcohol dehydrogenase was too low, respectively. In substrate switching experiments, we found that only a catalase-peroxidase among the three types of catalase found in glucose-grown cells was highly expressed in the methanol-grown cells and that its activity was relatively high during the exponential growth phase in Mycobacterium sp. JC1. Therefore, we propose that catalase-peroxidase is an essential enzyme responsible for the methanol metabolism directly or indirectly in Mycobacterium sp. JC1.

• Keywords: Mycobacterium sp. JC1; methanol oxidation; catalase-peroxidase