Production of Phytase by Penicillium oxalicum in Solid State Fermentation Exhibiting Hydrolysis of Phytates and Haloperoxidase Activity.

Abstract

Penicillium oxalicum PBG30 produced an extracellular phytase in solid-state fermentation and maximum production was obtained (200 ± 6.01 U/g DMR) at 30 °C after 5 days. The optimal temperature and pH for enzyme were 70 °C and 3.0, respectively. The phytase is thermostable with T_1/2 of 1 h at 70 °C and showed broad-substrate specificity with K_m and V_max values of 4.42 mM and 909.1 U/ml, respectively with calcium phytate. Phytase activity was enhanced in the existence of metal ions and surfactants and retarded by SDS, EDTA, sodium molybdate, DTT, and ß-ME. Phytase exhibited resistance against trypsin and pepsin with better storage stability at 4 °C and -20 °C. Insoluble phytates (metal and protein) were efficiently hydrolyzed by fungal phytase showing liberation of inorganic phosphate in a time-dependent manner. Also, the phytic acid reduction was observed in phytase-treated fish feed with the lowest phytic acid occurring in a diet supplemented with 1500 FTU/kg dose of phytase. Furthermore, phytase was converted into vanadium-dependent peroxidase. Fungal phytase, due to its thermostability, protease resistance, broad substrate specificity, and ability to hydrolyze phytate forms, has the potential to serve as an additive for improving nutrient digestibility in the food and feed industry.