Asian Journal of Biochemistry, Genetics and Molecular Biology

Amylase, a crucial enzyme within biological systems, reveals its catalytic effectiveness in facilitating the breakdown of complex carbohydrates through hydrolysis. This study sought to isolate, partially purify, and investigate the inherent physicochemical properties of amylase derived from Aspergillus niger, isolated from Long-horned beetles. Aspergillus niger, previously isolated from the gut of long-horned beetles (Cerambycidae latreille), was obtained from the Department of Biochemistry, Federal University of Technology, Akure, Ondo State Nigeria. Amylase production was accomplished through submerged fermentation, utilizing soluble starch as the primary substrate. The crude enzyme was purified by ammonium sulfate precipitation and ion-exchange chromatography. The physicochemical properties, such as effects of pH and temperature on the partially purified enzyme were thereafter evaluated. Investigation on the effects of metal ions at varying concentrations on amylase activity was also carried out. The results of partial purification yielded approximately 13.5% recovery rate and 6-fold purification increase. The partially purified amylase displayed its optimal activity at pH 6.0 and 80°C respectively, confirming its inherent thermo-stability. It maintained over 80 % activity up to 60^oC activity for 60 minutes. The amylase demonstrated maximal residual activity of about 62 % at pH 7.0 for 5 hours incubation, exhibiting broad pH stability across the range of 4.0 - 9.0. Metal ions, such as Ca²⁺, Mg²⁺, and Al³⁺, activated the enzyme, while inhibition by K²⁺ and Cu²⁺ underscored its dependence on metal cofactors. Kinetic analysis revealed a high substrate affinity, with a K_m of 0.055 mM and V_max of 0.274 mg/ml/min. However, the amylase proved effective as detergent additive, enhancing cloth stain removal. Metal-ion activation, wide pH stability, and high substrate affinity, positioning this amylase derived from Long-horned beetles as a promising candidate for starch hydrolysis in bioprocesses.