Characterization of a yam class IV chitinase produced by recombinant Pichia pastoris X-33

A yam (Dioscorea opposita Thunb) class IV chitinase, whose genomic DNA was cloned by Mitsunaga et al. (2004), was produced by the recombinant Pichia pastoris X-33 in high yields such as 66 mg/L of culture medium. The chitinase was purified by column chromatography after Endoglycosidase H treatment and then characterized. It showed properties similar to the original chitinase E purified from the yam tuber reported by Arakane et al. (2000). This Pichia-produced chitinase also showed strong lytic activity against Fusarium oxysporum and Phytophthora nicotianae, wide pH and thermal stability, optimum activity at higher temperature such as 70 °C, and high substrate affinity, indicating that one can use this Pichia-produced yam chitinase as a bio-control agent.