Improving enzyme activity, thermostability and storage stability of β-1,3-1,4-glucanase with poly-γ-glutamic acid produced by Bacillus sp. SJ-10

Abstract

β-1,3-1,4-glucanase (BG) is an industrially important enzyme owing to its stringent specificity for β-glucan cleavage. In this study, poly-γ-glutamic acid (γ-PGA) was added to BG to investigate its effect on improving the activity and stability of the enzyme. The effect of γ-PGA was investigated by analyzing kinetic and thermodynamic parameters. Compared to control, significant differences (P < .05) in enzyme activity were observed when 1.0 %, 1.5 %, and 2.0 % γ-PGA was added, and the activities were increased 1.23±0.05, 1.23±0.07, and 1.31±0.07-fold, respectively. Regarding thermostability, residual BG activity after a 1 h incubation at 60°C was 12.53±0.06 % without γ-PGA and 79.02±5.76 % with 1% γ-PGA. The storage stability at 25°C and 50°C also increased when γ-PGA was present. The kinetics and thermodynamic investigations indicated that the increased activity and stability of BG when γ-PGA was added were due to increased values of the Vmax, Kcat, and activation energy for denaturation. The findings of this study suggest that adding γ-PGA to BG increases the application value of this enzyme in the food and feed industries.