Scale-up fermentation of recombinant Candida rugosa lipase expressed in Pichia pastoris using the GAP promoter

The high-cell-density fermentation of Candida rugosa lipase in the constitutive Pichia pastoris expression system was scaled up from 5 to 800 1 in series by optimizing the fermentation conditions at both lab scale and pilot scale. The exponential feeding combined with pH-stat strategy succeeded in small scale studies, while a two-stage fermentation strategy, which shifted at 48 h by fine tuning the culture temperature and pH, was assessed effective in pilot-scale fermentation. The two-stage strategy made an excellent balance between the expression of heterogeneous protein and the growth of host cells, controlling the fermentation at a relatively low cell growth rate for the constitutive yeast expression system to accumulate high-level product. A stable lipase activity of approximately 14,000 IU ml(-1) and a cell wet weight of ca. 500 g l(-1) at the 800-1 scale were obtained. The efficient and convenient techniques suggested in this study might facilitate further scale-up for industrial lipase production.