[Studies on the expression condition of human trefoil factor 3 in Pichia pastoris]

In order to enhance the expression level of human trefoil factor 3 (hTFF3) in Pichia pastoris, we optimized the transformant growth conditions in shake flasks including carbon sources in growth medium, inoculation ratio, methanol concentration, pH rotation speed and inducing time. The transformant could grow on the glucose to OD600 5.0 after 14 hours inoculation. The best inoculation ration of 100 mL growth medium to the induction medium was 1:1. The expression level of dimeric human trefoil factor 3 induction with 1% methanol for 48 hours at pH 6.0, agitation speed 240 r/min could reach 20 mg/L with OD600 15. The protein was expressed in 5-liter fermentor with 2% methanol induction for 32 hours, finally the cell density reached OD600 120. 100 mg/L of recombinant hTFF3 was obtained in the supernatant.