Antifungal activity, Hydrolysis, R. solani, 16S rRNA, Zymogram.
Chitinolytic bacterial strain KB3 was isolated from coastal soils of Buan area, Korea and tested for antagonistic activity against Rhizoctonia solani. Strain KB3 was identified as Enterobacter sp. based on morphological observation and 16S rRNA analysis. The strain exhibited a maximum chitinase production of 1.6 U/mL in colloidal chitin broth after 4 days of cultivation at 30°C. The molecular weight of the purified chitinase was estimated to be 46 kDa by 12% SDS-PAGE and zymogram. In vitro assays revealed that the purified chitinase inhibited activity of R. solani as identified by dual plate assay and microscopic methods. Hydrolysis products of the fungal cell wall by the purified enzymes of Enterobacter sp. KB3 were analyzed by high-pressure liquid chromatography (HPLC) and identified as oligosaccharides, which included monomers (GlcNAc), dimers (GlcNAc)2, and trimers (GlcNAc)3 using chitin oligomer standards. The purified chitinase obtained from Enterobacter sp. KB3 can be directly applied for suppressing growth of living fungal hyphae.
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