Recombinant Saccharomyces cerevisiae was employed to continuously produce hirudin in a membrane cell recycle fermentor. The gene cooing for the anticoagulant protein was combined with the GAL10 promoter for controlled expression and the MF α 1 signal sequence for secretion to the fermentation broth. A dilution rate of 0.1h−1 yielded a maximum hirudin concentration of 59mg / l with a specific hirudin concentration of 2.4 mg /g cell mass among dilution rates studied ranging from 0.05h−1 to 0.3h−1. Cell bleeding gave the same fermentation results as cell recycle fermentation without cell bleeding. The productivity of the cell recycle fermentation process was 6.0mg hirudin/l · hr, corresponding to a 1.7-fold increase compared with a conventional continuous culture.
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