Production of a heterologous proteinase A by Saccharomyces kluyveri

In order to evaluate the potential of Saccharomyces kluyveri for heterologo us protein production, S. kluyveri Y159 was transformed with a S. cerevisia e-based multi-copy plasmid containing the S. cerevisiae PEP4 gene, which en codes proteinase A, under the control of its native promoter. As a referenc e. S. cerevisiae CEN.PK 113-5D was transformed with the same plasmid and th e two strains were characterised in batch cultivations on glucose. The gluc ose metabolism was found to be less fermentative in S. kluyveri than in S. cerevisiae. The yield of ethanol on glucose was 0.11 g/g in S. kluyveri, co mpared to a yield of 0.40 g/g in S. cerevisiae. Overexpression of PEP4 led to the secretion of active proteinase A in both S. kluyveri and S. cerevisi ae. The yield of active proteinase A during growth on glucose was found to be 3.6-fold higher in S. kluyveri than in the S. cerevisiae reference strai n.