Statistical optimization of seed and induction conditions to enhance phytase production by recombinant Escherichia coli

An efficient fermentation process for the production of phytase was develop ed by statistical optimization from recombinant Escherichia coli BL21. The seed age and inoculum level highly influenced the expression of phytase gen e by lactose induction. The optimum of 3.15-h seed culture age instead of a n overnight culture and 4.8% (v/v) seed culture yielded high concentrations of cells at short intervals of time for efficient induction. Induction at a lactose concentration of 7.28 mM and at a cell optical density of 0.55 at 550 nm (equivalent to 0.23 g/l dry cell weight) was found to be most suita ble in this system. The time of induction and lactose concentration signifi cantly influenced phytase production. The optimized conditions were used to achieve 100% increase in phytase production (174 U/l.h) compared to produc tion before optimizing the conditions. (C) 2000 Elsevier Science S.A. All r ights reserved.