Improving Performance and Operational Stability of Porcine Interferon-α Production by Pichia pastoris with Combinational Induction Strategy of Low Temperature and Methanol/Sorbitol Co-feeding

Various induction strategies were investigated for effective porcine interferon-alpha (pIFN-alpha) production by Pichia pastoris in a 10 L fermenter. We found that pIFN-alpha concentration could be significantly improved with the strategies of lowtemperature induction or methanol/sorbitol co-feeding. On this basis, a combinational strategy of induction at lower temperature (20 degrees C) with methanol/sorbitol co-feeding has been proposed for improvement of pIFN-alpha production. The results reveal that maximal pIFN-alpha concentration and antiviral activity reach the highest level of 2.7 g/L and 1.8x10(7) IU/mg with the proposed induction strategy, about 1.3-2.1 folds higher than those obtained with other sub-optimal induction strategies. Metabolic analysis and online multi-variable measurement results indicate that energy metabolic enrichment is responsible for the performance enhancement of pIFN-alpha production, as a large amount of ATP could be simultaneously produced from both formaldehyde oxidation pathway in methanol metabolism and tricarboxylic acid (TCA) cycle in sorbitol metabolism. In addition, the proposed combinational induction strategy enables P. pastoris to be resistant to high methanol concentration (42 g/L), whichconceivably occur associating with the error-prone methanol over-feeding. As a result, the proposed combinational induction strategy simultaneously increased the targeted protein concentration and operational stability leading to significant improvement of pIFN-alpha production.