Phytase from Citrobacter koseri PM-7: Enhanced production using statistical method and application in ameliorating...

The present study was aimed at enhancing phytase (Phy-Ck) production from Citrobacter koseri PM-7 using response surface methodology (RSM) and improving the bioaccessibility of minerals (Fe and Zn) and protein digestibility in high-phytate food using Phy-Ck. A five-variable and three-level central composite design of RSM using wheat bran (6.681%, w/v), inoculum level (2.5%, v/v), and triton X-100 (0.2%, v/v) resulted in up to 5.57-fold (1.047 U/ml) improvement in Phy-Ck yield from C. koseri PM-7 when compared with fermentation media I and II. The model was successfully validated in the design space by taking a random set of variable combinations. Treatment of high-phytate food with partially purified Phy-Ck showed improvement in mineral bioaccessibility maximally for defatted sesame flour (DSF) (Fe 45.5%; Zn 50.7%) followed by wheat flour (WF) (Fe 13.5%; Zn 14.4%), green gram flour (GGF) (Fe 0.7%; Zn 3.8%) and defatted groundnut flour (DGF) (Zn 5.6%). The in vitro protein digestibility (IVPD) of WF increased from 48.83 to 65.04%, GGF from 45.04 to 57.12%, and DSF from 47.34 to 55.7% after Phy-Ck treatment.