Characterization an optimization of crude amylase produced by Aspergillus niger responsible for cassava (Manihot esculentum) tuber rot

Abstract

The production of amylase by Aspergillus niger , isolated from mould deteriorating cassava ( Manihot esculentum ) was studied and characterized using different conditions of substrate (starch) concentrations, pH, temperature and heating duration. Enzyme activity generally increased from 29.7 units/ml on the fourth day to 37.3 units/ml on the sixth day. The optimal enzyme activity for starch concentration, pH and temperature were 50mg/ml, 5.0 (140 units/ml), and 35 0 C (43 units/ml) respectively. Enzyme activity was inhibited at 70 0 C as the enzyme was subjected to periodic heating over time. Approximately, about 68.8%, 15.9%, 13% and 6.7% of activity was lost within one, five, ten and fifteen minutes of heating at 70 0 C. The synthesis of amylase is of special importance in the phyto-pathogenicity of Aspergillus niger during infection of hosts rich in starchy products.