Effects of medium composition on hirudin production in recombinant Saccharomyces cerevisiae

The enriched medium based on Yeast nitrogen base(YNB)increased hirudin synthesis and secretion in recombinant Saccharomyces cerevisiae in batch and fed-batch cultures. Fed-batch fermentation with the defined medium ridded 342mg hirudin/l but supplementation of yeast extract increased the final hirudin concentration to 461mg hirudin/l. The defined medium, however, produced the product protein with higher purity of 21% and hence will allow easy separation of secreted hirudin from other contaminated polypeptides present in the growth medium. In a continuous culuture, the defined medium yielded higher concentrations of cell mass and hirudin than the complex medium.