[Studies on insecticidal ingredients from culture supernatant of Bacillus thuringiensis]

Studies on the insecticidal activity of culture supernatant of Bacillus thuringiensis var. kurstaki HD-1, by centrifugation, column chromatography, protein sequence determination, bioassay and other methods. Found that insecticidal activity of culture supernatant appeared on synchronism with cells lysis. Main insecticidal ingredients of culture supernatant is toxin protein of 60 kilodaltons (kDa). Analyse hat purified the toxin protein, we find that its amino acid composition was similar with 135-kDa P1 protein, and its sequence of N-terminal 18 amino acid was same with that of part of the P1 protein. The results presented here provided that the toxin protein was the same source with the P1 protein. Further found that supernatant have synergizing action on the sediment of culture.