Abstract
The supernatant of Bacillus thuringiensis culture has been shown to substantially enhance the larvicidal activity of the δ-endotoxin against Spodoptera litura, indicating the existence of synergistic activity in the supernatant (ASANO et al. (1994) Appl. Entomol. Zool. 29: 39-45; ASANO and HORI (1995) Appl. Entomol. Zool. 30: 369-374). The factor responsible for this synergistic activity was fractionated from culture supernatant using cation exchange and gel filtration chromatography. The molecular weight was estimated to be about 400 by gel filtration. The factor was adsorbed on carboxymethy (CM) Sepharose equilibrated with 50 mN Tris HCl buffer, pH 8.0 and eluted by the same buffer containing 0.2 M NaCl. Thus, the factor was apparently positively charged. Neigher α-, β-glucosidase nor pronase treatments caused a reduction in the synergistic activity. The fractionated synergistic factor significantly enhanced the activity of ICP against S. litura and S. exigua but not that against Plutella xylostella, Bombyx mori or Adoxophyes sp.
