Expression and characterization of a novel chitinase with antifungal activity from a rare actinomycete, Saccharothrix yanglingensis Hhs.015.

Saccharothrix yanglingensis Hhs.015, a new type of rare actinomycete, was isolated from the roots of cucumber. A novel chitinase gene was cloned from S. yanglingensis Hhs.015 and overexpressed as a soluble protein Chi6769 (77.9 kDa) in Escherichia coli. Chi6769 was purified by HisTrap HP affinity chromatography with optimal pH of 7.0. The enzymatic hydrolysis assay revealed that Chi6769 was capable of hydrolyzing chitin to (GlcNAc)3, (GlcNAc)2 and GlcNAc. (GlcNAc)2 was the main hydrolyzate. The antifungal activity result showed that Chi6769 exhibited strong antifungal activity toward Valsa mali 03-8. Overall, Chi6769 was potential to be a novel biofunctional chitinase that could be used as a biological agent in the control of plant diseases.