ABSTRACT
Microbial utilization of noncarbohydrate compounds as energy and carbon sources is an abundant phenomenon in nature. The methylotrophic yeasts belong to the genera Candida, Torulopsis, Pichia, and Hansenula. After techniques had been developed to introduce foreign DNA into suitable methylotrophic hosts, attractive systems for the production of recombinant proteins became available. The methanol metabolism in yeasts is highly compartmentalized; one part is located in specialized microbodies, peroxisomes, the other in the cytoplasm. For both, methylotrophic yeast expression vectors have been developed that harbor such a promoter sequence within the expression cassette for expression of heterologous proteins. One-third of the produced glyceraldehyde-3-phosphate molecules become available for the central metabolism of the cell to form biomass. The chapter summarizes characteristics of the methylotrophic yeasts confirm that they are useful expression systems and, in many instances, the systems of choice for the production of a recombinant protein.
