Enhanced Cost-Effective Phytase Production by Aspergillus niger and Its Applicability in Dephytinization of Food Ingredients

摘要

Aspergillus niger grew well and secreted high phytase titres in solid state (SSF) and submerged (SmF) fermentations using sugarcane bagasse and cane molasses medium, respectively. Optimization of culture conditions increased the phytase production in both SSF and SmF. High enzymes production,was recorded at 320C and pH 4.0 after 48 h of incubation in SmF using 8% (v/v) cane molasses supplemented with ammonium nitrate (0.4% w/v). The mould secreted high enzyme titres using sugarcane bagasse in SSF at 320C with a substrate to moisture ratio of 1: 2.5 after an incubation of 48 h. Supplementation of sugarcane bagasse with starch and ammonium nitrate further increased phytase production. An overall 23- and 10-fold enhancement in phytase production was attained under SmF and SSF conditions, respectively. The crude enzyme was optimally active at pH 3.0 and 50°C that resulted in the hydrolysis of phytic acid in a time dependent manner. The enzyme resulted in dephytinization of wheat and gram flours with concomitant release of inorganic phosphate, soluble protein and reducing sugars. The enzyme being acid stable and thermostable could find application in dephytinization of food and feed ingredients of monogastric animals.