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Abstract
The effects of different culture conditions on the expression level of human interferon-α2a (IFN-α2a) by using recombinant yeast were investigated in a 2.6-Ljar fermentor. Appropriate supplement of glucose and the maintenance of residual glucose at a low level resulted in the reduction of ethanol formation and enhancement of the bioactivity of IFN-α2a to 4.9×10^sup 6^ from 3.1×10^sup 6^ IU/mL. When adenine was added evenlly for 10-20 h of fermentation into the basal culture medium at a speed of 2 μg/mL of medium/h, OD^sub 600^ was greatly increased to 24, and the protein increased to 276 mg/L. The content of ethanol generated was also reduced tremendously during the process and as a result, 1.3×10^sup 7^ IU/mL of biologic activity was achieved. In the expression phase, pH had an important impact on expression level, which should be controlled at 5.5[PUBLICATION ABSTRACT]