A bifunctional endoglucanase with activity towards carboxymethylcellulose and chitosan from Lysobacter enzymogenes 521

The tropical strain Lysobacter enzymogenes 521, obtained from grass covered soil in Thailand, was found to produce a bifunctional endoglucanase activity towards carboxymethylcellulose (CMC) and chitosan. Phenotypic variations of L. enzymogenes 521 with respect to the counterpart temperate strain, L. enzymogenes C3, were observed. The CMCase and chitosanase activities, and growth rate of L. enzymogenes 521 were significantly higher than those of L. enzymogenes C3. A bifunctional CMCase-chitosanase activity in the purified enzyme from L. enzymogenes 521 was revealed by zymogram analysis. The purified enzyme had a molecular mass of 41 kDa, as estimated by SDS-PAGE. The optimal pH and temperature for CMCase activity were 5.0 and 40°C, respectively. The enzyme was stable within a range of 0-40°C and from pH 4 to 11. Among the substrates for specificity testing, CMC yielded the highest activity while colloidal chitosan (80% deacetylation) yielded about 45% of the activity measured with CMC. Phylogenetic analysis of CMCase gene and multiple alignment of the deduced amino acid sequence illustrated that the CMCase (Cel8A) from L. enzymogenes 521 displayed homology to the Family 8 glycoside hydrolases (GHF-8),with high similarity (98.3%) to the bifunctional endoglucanase (Cel8A) from Lysobacter sp. IB-9374.