Biochemical properties of α-amylase isolated from Aspergillus tamarii from cassava starch using solid state fermentation

Abstract

Cassava starch can be completely hydrolyzed to produce a sweetener that can be used as a substitute for refined sugars and artificial sweeteners in the food and pharmaceutical industries. This work was designed to isolate and identify a good amylase producing fungus from cassava flour and to extract, purify, and partially characterize α-amylase produced. The enzyme was produced through solid-state fermentation followed by 70% ammonium sulphate precipitation and ion-exchange chromatography on Carboxyl-Methyl (CM) Sephadex C25. The physicochemical properties of the purified enzyme were determined. The peak with the highest activity was pooled from the latter chromatographic step and characterized afterward. The enzyme’s specific activity rose from 0.11 to 2.1 U/mg having a yield of 15.8% and a purification fold of 19.1. The optimal pH and temperature of the enzyme were 6.0 and 50°C respectively. The enzyme was observed to be thermo-stable at 50°C for 15 to 30 minutes. The kinetics revealed that the Vmax was 1.25 U/min while Km was 0.2 mg/ml. The enzyme’s native and sub-unit molecular weights were found to be 22 and 18.5KDa respectively. The results revealed conclusively that the isolated enzyme from Aspergillus tamarii exhibited the properties of glucoamylase.