Microbiology and Biochemistry of Methylotrophic Yeasts

Abstract

This chapter describes microbiological and metabolic features of the methanol-utilizing yeasts. Methanol-utilizing yeasts reported so far are restricted to seven genera and are all facultative methylotrophs. With respect to their mode of methanol metabolism, these yeasts form a homogeneous group in contrast to methylotrophic bacteria. Many yeasts have been isolated for further selection of strains with higher growth rate. About 50 strains of yeasts are reported as methanol-utilizer. These species are involved in seven genera which include both ascomycetous and asporogenous yeasts. The yeasts can assimilate methanol and glucose simultaneously in carbon-limited chemostat culture. A mutant of methanol-utilizing yeasts was first derived with Candida boidinii by ordinary process using N-methyl-N'-nitro-N-nitrosoguanidine as mutagen. In methanol-utilizing yeasts, catalase must play an active role in the metabolism of methanol because the oxidation of methanol by alcohol oxidase is accompanied by the formation of a toxic compound, H2O2.