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Optimization of feeding strategy for overproduction of human lipocortin-I in Saccharomyces cerevisiae controlled by the GAL10 promoter

1997; Elsevier BV; Volume: 84; Issue: 5 Linguagem: Inglês

10.1016/s0922-338x(97)82009-0

1872-8073

Bong Hyun Chung, Dong Jin Seo, Soo Wan Nam, Jeong‐Geol Na, Yong Keun Chang,

Viral Infectious Diseases and Gene Expression in Insects

Fed-batch fermentation was conducted to overproduce human lipocortin-I (LC1) in recombinant Saccharomyces cerevisiae controlled by the GAL10 promoter. To optimize the feeding strategy, various fed-batch culture modes were performed with concentrated feed media containing carbon mixtures of galactose (Gal) and glucose (Glu) at three different concentration ratios (Gal : Glu ratios): 9 : 1, 1 : 1, 1 : 9. The cell growth, expression level of LC1, and the plasmid stability were investigated under these fed-batch culture modes. While both glucose and galactose were being fed to the fermentor, the glucose concentration in the culture broth was kept below 1 g/l for efficient gene expression. High cell concentrations of greater than 100 g dry cell weight/l were achieved with these fed-batch culture modes. A significant amount of intact LC1 was found to be secreted into the culture medium, but proteolytically cleaved products (des1-26-LC1) were also observed in the culture medium. The fed-batch fermentation with the feed medium at a Gal : Glu ratio of 1 : 1 resulted in the highest LC1 total (intact LC1 + des1-26-LC1) concentration of 500 mg/l, which corresponded to 1.73- and 1.83-fold increases over that produced with the media at Gal : Glu ratios of 1 : 9 and 9 : 1, respectively.