Vol. 8, Issue 8 (2019)

Author(s):
Rana Kumbha Singh, Ajay Kumar Singh, Yashab Kumar, Harison Masih and Kunal Singh

Abstract:
Filamentous fungi have been widely used to produce hydrolytic enzymes for industrial applications. Fungal enzyme glucoamylase was produced using a specific culture Aspergillus niger under solid state fermentation and the enzyme obtained was partially purified. The use of agro by-products present a great potential as substrate and support the low production costs for glucoamylase production. Screening of five agricultural residues viz. tea waste, mango peel, jack fruits, groundnut peel, pulse bran was done to produce glucoamylase. From these, tea was selected as substrate for further study as it yielded maximum glucoamylase (33.84 IU/ml) activity. Various cultural conditions such as temperature, pH, spore suspension and incubation period, carbon and nitrogen sources were optimized. Temperature of 30 °C, pH 6.0, spore suspension (4 ml) and incubation period of 10 days were found optimum for maximum production of glucoamylase enzyme. Glucoamylase from a tea waste culture of Aspergillus niger was partially purified by Ammonium Sulphate precipitation, dialysis and ion exchange chromatography. The partially purified enzyme had an activity of 64.44 IU/ml which was 2.05 folds of the activity of the crude culture filtrate. Hydrogen ion concentration as well as temperature had profound influence on enzyme activity of the partially purified enzyme while glucoamylase activity increased progressively as pH was increased from 5 to 6 reaching a maximum of 68.40 IU/ml at pH 6.0. A rapid decrease in glucoamylase activity was observed as pH was increased from 7 to 9. The glucoamylase activity increased with increase in temperature from 20 °C to 30 °C and reached a maximum of 50.04 IU/ml at 30 °C. Subsequent increase in temperature resulted into decrease in activity of the glucoamylase enzyme. The enzyme activity of glucoamylase was enhanced by Ca²⁺, Mn²⁺.