Characterization and 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 350C (43 units/ml) respectively. Enzyme activity was inhibited at 700C 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 700C. The synthesis of amylase is of special importance in the phyto-pathogenicity of Aspergillus niger during infection of hosts rich in starchy products.