Cloning and characterization of a bifunctional cellulase-chitosanase gene from Bacillus licheniformis NBL420

초록

A 1.3 kb cellulase gene encoding novel bifunctional cellulase-chitosanase activity was cloned from biopolymer-producing alkali-tolerant B. licheniformis NBL420 in E. coli. A recombinant cellulase-chitosanase, named CelA, was expressed and purified to homogeneity. The activity staining and the enzymatic characterization of the purified CelA revealed bifunctional activities on carboxymethyl cellulose (CMC) and glycol-chitosan. The similar characteristics of the enzymatic activities at the optimum pH, optimum temperature, and thermostability indicated that CelA used a common catalytic domain with relaxed substrate specificity. A comparison of the deduced amino acids in the N-terminal region revealed that the mature CelA had a high homology with the previously identified bifunctional cellulase-chitosanase of Myxobacter sp. AL-1.

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