Optimization of α‐amylase and Glucoamylase Production Using Cull Potatoes as Substrate

Abstract

Amylases are required for the conversion of starchy substrate into sugars. Commercially available enzymes are quite costly which makes the process uneconomical. This study is conducted to standardize physico-chemical parameters such as substrate concentration (1.0-5.0%), temperature (25-40°C), pH (4.0-7.0), incubation time (18-24) h for -amylase and 3-6 days for glucoamylase production) for optimum production of -amylase from bacterial isolate (AM1) and glucoamylase from Aspergillus niger by using cull potatoes as a substrate. Various organic and inorganic nitrogen sources (urea, yeast extract and soybean meal, and ammonium sulphate) are tried for maximum enzyme production. Among the four nitrogen sources, yeast extract supported maximum -amylase and glucoamylase production. Among the different amylolytic isolates from fermented jalebi dough and AM1culture, maximum -amylase activity is shown by AM1 (90.46 U mL −1 ) as compared to J1 (71.02 U mL −1 ). After optimization, -amylase activity of AM1 increases by 41.73% from 198.20 to 280.92 U mL −1 at 5.0% substrate concentration, 30°C temperature, 24 h of incubation and pH 5.0. Glucoamylase activity of A. niger increases by 38.78% from 228.72 to 317.44 U mL −1 after optimization at 5% substrate concentration, pH 5, incubation period of 4 days and temperature 30°C.