IDENTIFICATION AND CHARACTERIZATION OF ANTIFUNGAL CHITINASE FROM BACILLUS SUBTILIS JD-09 AND THEIR ROLE IN INHIBITION OF VIABLE FUNGAL GROWTH

摘要

Objective: Chitinase plays an important role against fungal pathogen and is a hopeful solution against fungal diseases. The main of this research is to screen a chitin degrading strain which can significantly used as biocontrol agent against Fusarium oxysporum . Methods: In the present study, chitinase producing bacteria were isolated from soil sample of crop field and identified based on biochemical observation and 16S rRNA analysis. The molecular weight of the enzyme was determined by zymogram. The purified enzyme from identified strain JD-09 was tested for antagonistic activity against Fusarium oxysporum . Results: Strain JD-09 was screened and identified as Bacillus subtilis . The strain exhibited a maximum chitinase production of 1.33 U/mL in colloidal chitin broth after 3 days of cultivation at 28 °C. The molecular weight of the chitinase was estimated to be 57 kDa, 39 kDa and 30.7 kDa. Hydrolysis products of the fungal cell wall by the purified enzymes of B. subtilis JD-09 were analyzed by high-pressure liquid chromatography (HPLC) and identified as oligosaccharides. Conclusion: It can be interfered that Bacillus subtilis JD-09 may be an optimal candidate for use as an antifungal agent of Fusarium wilt in crops. The purified chitinase can be directly applied for suppressing growth of living fungal hyphae.