eng Science and Education Publishing Journal of Food and Nutrition Research 2333-1240 2014-11-21 2 12 980 984 10.12691/jfnr-2-12-19 JFNR201421219 article Housheng Hong hhs@njtech.edu.cn 1 Zhaosheng Min 2 Huiming Guo 2 College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China College of Sciences, Nanjing Tech University, Nanjing, China Phytase production by Pichiapastoris was used as a case to study the mechanism and strategy for optimization of heterologous protein production. It was found that the ratio of inducer-methanol to cell concentration had a significant influence on phytase production. In this case, we found that the optimum initial cell concentration and methanol concentration were 85 g/L and 10 g/L, respectively. During induction period, an easy-to-control methanol feeding method was proposed according to the optimal ratio of methanol to cell concentration at a range of 0.063 -0.132 g/g, and phytase activity and productivity reached 53984 U/mL and 529.25 U/(mL·h), respectively. The method for optimization of phytase production through controlling the optimal ratio maybe provide an alternative idea to enhance other heterologous protein production with P. pastoris. http://pubs.sciepub.com/jfnr/2/12/19/jfnr-2-12-19.pdf Pichiapastoris feeding strategy methanol concentration cell concentration heterologous proteins