Purification and characterization of thermostable β-1,3-1,4 glucanase from<Emphasis Type="Italic">Bacillus</Emphasis> sp. A8-8

In this study, the extracellular enzyme activity ofBacillus sp. A8-8 was detected on LB agar plates containing 0.5% of the following substrates: carboxymethylcellulose (CMC), xylan, cellulose, and casein, respectively. The β-1,3-1,4 glucanase produced fromBacillus sp. A8-8 was purified by ammonium sulfate and hydrophobic chromatography. The molecular size of the protein was estimated by SDS-PAGE as approximately 33 kDa. The optimum pH and temperature for the enzyme activity were 6.0 and 60°C, respectiveley. However, enzyme activity was shown over a broad range of pH values and temperatures. The purified β-1,3-1,4 glucanase retained over 70% of its original activity after incubation at 80°C for 2 h, and showed over 40% of its original activity within the pH range of 9 to 12. This suggests that β-1,3-1,4 glucanase fromBacillus sp. A8-8 is thermostable and alkalistable. In addition, β-1,3-1,4 glucanase had higher substrate specificity to lichenan than to CMC. Finally the activity of the endoglucanase was inhibited by Fe³⁺, Mg²⁺, and Mn²⁺ ions. However Co²⁺ and Ca²⁺ ions were increased its activity. These authors contributed equally to this work.