A chitinase encoding gene from Bacillus sp. DAU101 was cloned in Escherichia coli. The nucleotide sequencing revealed a single open reading frame containing 1781 bp and encoding 597 amino acids with 66 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram. The chitinase was composed of three domains: a catalytic domain, a fibronectin III domain, and a chitin binding domain. The chitinase was purified by GST-fusion purification system. The pH and temperature optima of the enzyme were 7.5 and 60 degrees C, respectively. The metal ions, Zn2+, CU2+, and Hg2+, were strongly inhibited chitinase activity. However, chitinase activity was increased 1.4-fold by Co2+. Chisb could hydrolyze GlcNAc(2) to N-acetylglucosamine and was produced GlcNAC(2), when chitin derivatives were used as the substrate. This indicated that Chisb was a bifunctional enzyme, N-acetylglucosaminase and chitobiosidase. The enzyme could not hydrolyze glycol chitin, glycol chitosan, or CMC but hydrolyzed colloidal chitin and soluble chitosan. (c) 2006 Elsevier Ltd. All rights reserved.