α-amylase from Rhizoctonia solani AG4 ZB-34 production by solid state fermentation, purification, immobilization and analysis of the usability for various industrial applications

In this study, α-amylase from Rhizoctonia solani AG4 ZB-34 fungus was produced cheaply and abundantly by solid substrate fermentation (SSF) technique using an agricultural waste corn bran. SSF conditions for the best enzyme production were determined as pH 7.00, 100% humidity level, 6 days incubation at 28 °C and 1% starch addition.The enzyme was purified by starch affinity technique with 11.17 fold and 5.32% recovery. Purified α-amylase was immobilized on chitosan and calcium alginate with the efficiency of 67.9% and 59.6%, respectively. It was found that free and immobilized enzymes showed the highest activity in the presence of starch. Optimum values for free, chitosan immobilized and calcium alginate immobilized enzymes were pH 5.50 and 50 °C; pH 4.50 and 40 °C; pH 5.50 and 60 °C, respectively. The enzymes did not follow the Michaelis-Menten kinetics and had sigmoidal substrate saturation curves. It was found that immobilized enzymes were more stable than free enzyme in terms of thermal and pH stabilities. The hydrolysis products of the free enzyme released after 1 minute incubation were identified as glucose and maltose by thin layer chromatography. In the washing performance analysis study, it was found that free and chitosan immobilized enzymes cleaned better the pieces of fabric containing jam and chocolate when used with detergents. It was seen that the desizing activity of free enzyme was better than that of chitosan immobilized enzyme. As a result of calcium alginate immobilization, the enzyme clarified both apple and orange juices more than the free enzyme.