Purification of a constitutive chitosanase produced by Bacillus sp. MET 1299 with cloning and expression of the gene

A chitosanase produced constitutively by Bacillus sp. MET 1299 was purified by SP-Sephadex column chromatography. The molecular weight was estimated to be 52 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Optimal enzyme activity was observed at a pH of 5.5 and temperature of 60 degrees C. The purified chitosanase showed high activity on 90% deacetylated colloidal chitosan and beta-glucan, but not on hydrolyzed colloidal chitin, CMC, or their derivatives. The N-terminal amino acid sequence of the enzyme was determined. The cloned full length gene, 1362 bp in size, encoded a single peptide of 453 amino acids and had a conserved amino acid sequence of glycosyl hydrolase family 8. A search of the cDNA sequence with NCBI BLAST showed homology with chitosanase of Bacillus sp. KTCC 0377BP and Bacillus sp. No. 7-M. The recombinant protein was expressed in Escherichia coli, purified using affinity chromatography and characterized.