The molecular biology of Schwanniomyces occidentalis klocker.

This review describes the molecular studies of Schwanniomyces occidentalis (Debaryomyces occidentalis) concerning transformation, genome, gene cloning, gene structure, gene expression and its characteristics to application. Schw. occidentalis appears to have at least five or seven chromosomes and no native plasmid from the yeast has been reported. Four transformation systems based on complement of Schw. occidentalis auxotrophic mutants were established. Vectors with the replicon of 2-micron plasmid and autonomous replication sequences (ARS) of Saccharomyces cerevisiae and Schw. occidentalis ARS replicated extrachromosomally in Schw. occidentalis transformants, without modification of the transformed vector DNA. So far, at least 21 Schw. occidentalis genes encoding 14 different proteins have been cloned. Most of the Schw. occidentalis genes have shown homologies (45 to 91%) with the corresponding genes of other organisms, especially of S. cerevisiae. However, some Schw. occidentalis genes possess other unique structures for their operators, promoters, transcription initiation sites, and terminators. Some foreign genes were expressed in Schw. occidentalis, while Schw. occidentalis genes functioned in other yeasts and bacteria, Escherichia coli, and Streptomyces lividans. Due to a strong ability of secretion and low level of glycosylation, Schw. occidentalis might be a promising host to produce heterologous proteins.