Optimization of gluco-amylase production from Aspergillus spp. for its use in saccharification of liquefied corn starch

摘要

Fungal gluco-amylase is required for the production of sugars from starchy substrates. Commercially available fungal gluco-amylase is quite costly which makes the process uneconomical. This study was undertaken to standardize physico-chemical parameters for optimum production of gluco-amylases from Aspergillus spp. Two fungal cultures, i.e., Aspergillus niger and Aspergillus terreus, were compared for gluco-amylase activity both under stationary and shake flask conditions. Among two fungal cultures, maximum gluco-amylase activity was shown by A. niger (243.09 U/ml) under stationary conditions as compared to A. terreus (126.34 U/ml). Gluco-amylase activity of A. niger increases by 42.48% from 243.09 to 346.35 U/ml after optimization using response surface methodology, whereby a substrate concentration of 7%, yeast extract 0.25%, temperature 32.5 °C and pH 5.5 were found to be optimum for gluco-amylase production. Crude enzyme was compared with commercial enzyme and it was found that when 500 U of Glucoamylase ex. Rhizopus were inoculated into starch-supplemented minimal media (SSMM) liquefied using 2 g of fungal diastase, it increases the reducing sugar concentration from 2.19 to 21.15 mg/ml and a saccharification efficiency of 77.7% was achieved, whereas 1.5 ml of crude enzyme (extracted from A. niger) was able to produce 14.46 mg/ml of reducing sugars with a saccharification efficiency of 53.2%.