Heterologous expression and characterization of an antifungal chitinase (Chit46) from Trichoderma harzianum GIM 3.442 and its application in colloidal chitin conversion

Abstract

In this study, a chitinase gene, Chit46 from a mycoparasitic fungus Trichoderma harzianum was successfully expressed in Pichia pastoris with a high heterologous chitinase production of 31.4 U/mL, much higher than the previous reports. The active center and substrate binding pocket of the recombinant Chit46 (rChit46) were analyzed and the effects of pH, temperature, metal ions and glycosylation on its activity were tested. rChit46 effectively hydrolyzed colloidal chitin with a high conversion rate of 80.5% in 3 h and the chitin hydrolysates were mainly composed of (GlcNAc)₂ (94.8%), which make it a good candidate for the green recycling of chitinous waste. rChit46 could also significantly inhibit growth of the phytopathogenic fungus Botrytis cinerea, which endowed it with the potential as a biocontrol agent.

Keywords: Antifungal; Chitin conversion; Recombinant chitinase.