A simple fermentation strategy for high-level production of recombinant phytase by Pichia pastoris using glucose as the growth substrate

The methylotrophic yeast Pichia pastoris has become a popular host for the production of recombinant protein under the tight control of methanol-induced alcohol oxidase promoter (PAOX1), which is, however, strongly repressed by glucose at the transcription level. A real-time parameter-based controlled glucose feed strategy (rpcGFS) is developed here to realize Pichia high-cell density culture. It allows for the high-level production of recombinant phytase by P. pastoris YY113 using glucose as the growth substrate instead of glycerol. As a result, high phytase production (2200 FTU phytase ml−1) and yield (0.25 FTU ml−1[phytase] g−1[methanol]) are achieved successfully, respectively, after 100 h methanol induction by this novel simple fermentation strategy.