A bioprocess for the production of phytase from Schizophyllum commune: studies of its optimization, profile of fermentation parameters, characterization and stability

Schizophyllum commune produces phytase through solid-state fermentation using different agroindustrial residues. After optimization of phytase production, a maximal level of phytase (113.7 Units/gram of dry substrate) was obtained in wheat bran based medium containing 5% sucrose, 50% humidity, 7.5% of biomass at 33 °C pH 7.0 during 72 h and a 285% improvement in enzyme titre was achieved. Analysis of fermentation parameters profile for phytase production showed the highest productivity (1.466 Units/gram of dry substrate/hour) in 66 h of fermentation. Phytase has an optimal pH of 5.0, an optimal temperature of 50 °C and K (m) and V (max) values of 0.16 mM and 1.85 μmol mL(-1) min(-1), respectively. Phytase activity was stimulated essentially in the presence of K(+), Ca(2+), Mg(2+), Mn(2+), Zn(2+), Cu(2+), Fe(2+), Fe(3+), Co(2+), Ni(2+), acetate and citrate at concentrations of 1 mM. Phytase had the best shelf life when stored at a cooling temperature, maintaining 38% of its initial activity after 112 days of storage, and still presenting enzymatic activity after 125 days of storage. Stability studies of phytase performed in aqueous enzyme extracts showed satisfactory results using polyethyleneglycol 3350, carboxymethylcellulose, methylparaben, mannitol and benzoic acid in concentrations of 0.25, 0.025, 0.025, 0.25, and 0.0025%, respectively. PEG 3350 was shown to be the best stabilizing agent, resulting in 109% of phytase activity from the initial crude extract remaining activity in after 90 days.