Characterization of production and enzyme properties of an endo-β-1,4-glucanase from Bacillus subtilis CK-2 isolated from compost soil

Bacillus subtilis CK-2, isolated from garden organic waste compost, was found to have high hydrolytic activity against carboxymethylcellulose (CMC) due to the secretion of an endo-beta-1,4- glucanase. Enzyme production was related to the sporulation process, and was regulated by the concentration of readily metabolizable carbohydrate in growth medium. Enzyme production did not require CMC or other cellulose containing materials. The endo-beta-1,4-glucanase activity was optimal at pH 5.6-5.8 and at 65 degrees C, and achieved thermal stability up to 55 degrees C. The activity was inhibited by Hg2+. The purified enzyme gave a single band corresponding to a MW of 35.5 kDa on SDS-PAGE, while the Sephadex G-75 chromatography revealed a molecular weight of the active enzyme around 70 kDa, indicating a dimeric form of the active enzyme. The enzyme activity was irreversibly inhibited by SDS. Native PAGE and IEF revealed three different isoelectric forms of the enzyme, all with an identical N-terminal amino-acid sequence.