Statistical media optimization for enhanced production of α-galactosidase by a novel Rhizopus oryzae strain SUK

A novel fungus producing extracellular α-galactosidase was isolated from soybean cultivated soil of Solapur, India. It was identified as Rhizopus oryzae strain SUK using 28S rDNA sequencing. Response surface methodology was used for the optimization of medium components to achieve enhanced production of α-galactosidase by newly isolated Rhizopus oryzae strain SUK in solid state fermentation (SSF). Plackett Burman (PB) design was employed for selection of critical media constituents which were identified as wheat bran, soybean meal and molasses. Further optimization was carried out using Central composite rotatable design (CCRD) which gave optimized media components for production of α-galactosidase with wheat bran; 4 g, soybean meal; 0.5 g, molasses; 0.5 g. α-galactosidase production obtained experimentally has close agreement with the model prediction value and the model was proven to be adequate. Initial enzyme activity was 20.17 U/g which was increased up to 218.54 U/g by CCRD with 17.74fold enhancement proving the efficacy of experimental design for process optimization. TLC analysis confirmed the ability of produced α-galactosidase to hydrolyze the non-digestible oligosaccharides in soymilk, which finally increments nutritional value of soymilk. Stereochemistry of hydrolysis of glycosidic linkage was determined by NMR spectroscopy.