Biological Journal of Microorganism (Jun 2016)
Determination and modeling the optimum conditions of beta glucanase Bacillus subtilis B5d activity with potential used as feed additive
Abstract
Introduction: Microbial β - 1, 4 glucanase is one of the key enzymes in glucan hydrolysis. Among bacteria, Bacillus species is a main source for industrial glucanse production. According to interaction between environmental factors on the enzymatic catalytic properties, in this study the potential of β-glucanase production by native strain B. subtilis B5d isolated from apple phyllosphere orchards and determination and modeling the optimum conditions of enzyme activity was surveyed. Materials and methods: In this study, the potential of β-glucanase production by B. subtilis B5d was confirmed using qualitative method. The B. subtilis B5d isolate was identified through biochemical and molecular methods. Determination of optimum condition for beta glucanase activity was evaluated by response surface method and Central Composite Design. Investigated variables included temperature (20- 80 °C), pH (3.5- 8) and concentration of substrate (0.1- 1%). Results: According to the molecular and biochemical analysis, the strain B. subtilis B5d belonges to B.subtilis species. Based on the Central Composite Design results, the quadratic model was the most suitable model for predicting β-glucanase activity in experimental temperature, pH and substrate concentration range. Furthermore, the optimization of enzyme activity showed that the β-glucanase produced by strain B5d has highest catalytic activity at pH (5.5- 7) and temperature (50- 65°C) and the high concentration of lechinan. However, the enzyme activity is reduced in 80 and 20 °C as well as low concentration of substrate. Validation test of the prediction model of optimization obtained by response surface methodology showed a good agreement between experimental and predicted data. Discussion and conclusion: According to the optimum catalytic characteristics, the β-glucanase produced by B. subtilis B5d has a potential to be used as a feed additive.
