The endoglucanase from <Emphasis Type="Italic">Bacillus</Emphasis><Emphasis Type="Italic">subtilis</Emphasis> BEC-1 bears halo-tolerant,acidophilic and dithiothreitol-stimulated enzyme activity

A Bacillus subtilis strain BEC-1 demonstrating high carboxymethylcellulose-degrading activity was isolated from the forest soil sample. In order to characterize the biochemical specialty of its cellulase, the endoglucanase gene egl173 was cloned from this strain and was expressed in Escherichia coli. The gene encoded a protein of 499 amino acids with a molecular weight of 64 kDa. The purified Egl173 could hydrolyze both soluble and insoluble celluloses with distinct activities. This enzyme showed the highest enzyme activity at pH 4, maintained at least 85% activity in the pH range of 3–7, displayed maximum activity at 60°C and was highly stable between 30 and 60°C. It was found that this endoglucanase was increasedly active and retained its high stability after incubation with 5 M NaCl or 3 M KCl for 24 h. Furthermore, after incubation with 10 mM of dithiothreitol, the enzyme activity was significantly enhanced (125% of the control level). In the presence of diverse metal ions (except mercury and manganese cations), organic solvents, surfactants (except SDS) and chelating agent, this enzyme kept more than 85% active. This halo-tolerant, acidophilic and highly stable endoglucanase is prospectively to be exploited as the advanced enzymatic product for diverse industrial applications.