Characterization of a novel glycoside hydrolase family 46 chitosanase, Csn-BAC, from Bacillus sp. MD-5.

Chitosanases play an important role in chitosan degradation, and the enzymatic degradation products of chitosan show various biological activities. Here, a novel glycoside hydrolase family 46 chitosanase (named Csn-BAC) from Bacillus sp. MD-5 was heterologously expressed in Escherichia coli BL21 (DE3). The recombinant enzyme was purified by Ni-NTA affinity chromatography, and its molecular weight was estimated to be 35 kDa by SDS-PAGE. Csn-BAC showed maximal activity toward colloidal chitosan at pH 7 and 40 °C. The enzymatic activity of Csn-BAC was enhanced by Mn2+, Cu2+ and Co2+ at 1 mM, and by Mn2+ at 5 mM. Thin-layer chromatography and electrospray ionization-mass spectrometry results demonstrated that Csn-BAC exhibited an endo-type cleavage pattern and hydrolyzed chitosan to yield, mainly, (GlcN) 2 and (GlcN) 3. The enzymatic properties of this chitosanase may make it a good candidate for use in oligosaccharide production-based industries. • A novel chitosanase Csn-BAC from Bacillus sp. MD-5 was cloned and purified. • Csn-BAC is a novel member of GH46 family. • Csn-BAC is quite stable over a 30–50 °C range. • Csn-BAC exhibits an endo-type cleavage pattern, which yields (GlcN) 2 and (GlcN) 3. [ABSTRACT FROM AUTHOR]