Characterization of Crude Alkaline β-mannosidase produced by Bacillus sp. 3A Isolated from Degraded Palm Kernel Cake

Abstract

A recently isolated Bacillus sp. 3A from degraded palm kernel cake was employed for β-mannosidase production in a 1.5% (w/v) Locust bean gum at pH 9.0. This isolate produced up to 22.62±2.3 nkat/ml of alkaline β-mannosidase. pH and temperature studies on the activity of the enzyme revealed that the alkaline β-mannosidase had optimum activity at pH 7.5 and 50°C, respectively. The enzyme retained about 80% of its activity at pH 5.5-9.0 after 30 minutes of incubation at 50°C. Investigation into the ability of the enzyme to resist thermal unfolding in the absence of substrate showed that the enzyme remained stable for 30 minutes between 30 and 70°C with a great decrease in activity noticed at temperature above 70°C. The Km and Vmax values for pnitrophenyl-β-D-mannopyranoside were 0.845 mM and 42.92 nkat/mg. Partial purification by ammonium sulphate precipitation and dialysis resulted in an increased specific activity from 441.99 nkat/mg to 1,645 nkat/mg. These distinctive properties of the crude alkaline β-mannosidase from Bacillus sp. 3A make this enzyme attractive for industrial application.