Nematicidal Activity of Supernatant from Bacillus thuringiensis Fermentation

Nematocidal activities of fermentation products of Bacillus thuringiensis 00-50-5 culture using a liquid or solid medium in the lab was investigated. The results showed that the supernatant collected from the 72-h-fermentation on abeef-extract broth showed a 99.0% lethality on Meloidogyne incongnita; while that from the 8-h-fermentation on a bran-based medium, 89.0%.The supernatant collected from the liquid fermentation was subsequently subjected to a Sephadex G-75 column chromatography separation. Four peaks with the absorbance of 0.601, 1.475, 1.641 and 0.392 at 280nm were present. The bioassay on them indicated that the proteins found at Peak Ⅱ, Ⅲ, and Ⅳ were toxic to M. incognita, and among them, the one from Peak Ⅳ with the smallest molecular weight exerted the greatest nematocidal effect onthe parasite. The native-PAGE profile on the supernatant showed 6 visible protein bands including a 37 kDa protein, which was the highest in amount.