Antifungal Activity of <i>Bacillus thuringiensis</i> Chitinase and Its Potential for the Biocontrol of Phytopathogenic Fungi in Soybean Seeds

Abstract

ABSTRACT: Bacillus thuringiensis var israelensis was used to produce chitinase on shrimp wastes by fermentation at 30°C and 250 rpm for 120 h. The enzyme was concentrated by ultrafiltration and was adjusted to pH 5.8. Antifungal chitinase activity on phytopathogenic fungi was investigated in growing cultures and on soybean seeds infested with Sclerotium rolfsii . Fungal inhibition was found to be 100% for S. rolfsii ; 55% to 82% for A. terreus , A. flavus, Nigrospora sp, Rhizopus sp, A. niger , Fusarium sp, A. candidus, Absidia sp, and Helminthosporium sp; 45% for Curvularia sp; and 10% for A. fumigatus (P &lt; 0.05). When soybean seeds were infected with S. rolfsii , germination was reduced from 93% to 25%; the addition of chitinase (0.8 U/mg protein) increased germination to 90%. B. thuringiensis chitinase may contribute to the biocontrol of S. rolfsii and other phytopathogenic fungi in soybean seeds in Integrated Pest Management programs.