Modeling the growth and proteinase A production in continuous cultures of recombinant Saccharomyces cerevisiae

✍ Scribed by Morten Carlsen; Kirsten Væver Jochumsen; Claus Emborg; Jens Nielsen

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 215 KB
• Volume: 55
• Category: Article
• ISSN: 0006-3592
• DOI: 10.1002/(sici)1097-0290(19970720)55:2<447::aid-bit22>3.0.co;2-c

✦ Synopsis

Overexpression of the homologous protein proteinase A (PrA) in Saccharomyces cerevisiae has been achieved by inserting the PrA gene (PEP4) with its own promoter on a 2µ multicopy plasmid. With this system the specific PrA production rate was found to be described well by a linear function of the oxidative glucose metabolism, the reductive glucose metabolism, and the oxidative ethanol metabolism, with a significant lower yield resulting from the reductive glucose metabolism compared with the oxidative glucose metabolism. To describe the experimental data, a simple mathematical model has been set up. The model is based on an assumption of a limited respiratory capacity as suggested by Sonnleitner and Ka ¨ppeli but extended to describe production of an extracellular protein. The model predicts correctly the critical dilution rate to be between 0.15 and 0.16 h -1 , the decrease in the biomass yield above the critical dilution rate, and the production of proteinase A at different dilution rates. Both the experimental data and model simulations suggest that the optimum operating conditions for protein production is just at the critical dilution rate.