Expression of Bacillus subtilis JA18 endo-β-1,4-glucanase gene in Escherichia coli and characterization of the recombinant enzyme

Abstract

Endo-β-1,4-glucanase encoded by Bacillus subtilis JA18 was expressed in Escherichia coli. The recombinant enzyme was purified and characterized. The purified enzyme showed a single band of 50 kDa by SDS-PAGE. The optimum pH and temperature for this endo-β-1,4-glucanase was pH 5.8 and 60 °C. The endo-β-1,4-glucanase was highly stable in a wide pH range, from 4.0 to 12.0. Furthermore, it remained stable up to 60 °C. The endo-β-1,4- glucanase was completely inhibited by 2 mM Zn2+, Cu2+, Fe3+, Ag+, whereas it is activated in the presence of Co2+. In addition, the enzyme activity was inhibited by 1 mM Mn 2+ but stimulated by 10 mM Mn2+. At 1% concentration, SDS completely inhibited the enzyme. The enzyme hydrolysed carboxymethylcellulose, lichenan but no activity was detected with regard to avicel, xylan, chitosan and laminarin. For carboxymethylcellulose, the enzyme had a Km of 14.7 mg/ml.