Adsorption and binding of the insecticidal proteins from Bacillus thuringiensis subsp. kurstaki and subsp. tenebrionis on clay minerals
Authors: Tapp, H., Calamai, L., Stotzky, G.
Journal, Volume, Year: Soil Biology and Biochemistry, volume 26(6):663-679, 1994
Adsorption and binding of Btk (CryI and CryII toxins) and Btt to kaolinite (K) and montmorillonite (M), homoionic to various cations or coated with two types of polymeric oxyhydroxides of Fe (III) were evaluated. Maximum adsorption of Btk toxins occurred in <30 minutes, whereas maximal adsorption of Btt occurred in 3-4 hours with >70% of Btt adsorbed in <30 minutes. Adsorption of Btk and Btt toxins on clays was affected by the type of cation to which the clays were homoionic. Adsorption of Btk and Btt toxins was significantly lower on K than M. Smaller amounts of Btk and Btt toxins were adsorbed on coated clays compared to homoionic clays. The binding of the Btk and Btt toxins to clay did not significantly alter the structure of the toxins.
The Btk toxins (CryI and CryII) used in this study were derived from Dipel and a culture of Btk, and Btt toxins were derived from M-One (Mycogen Corp.). Experiments using natural soil or Bt toxins derived from transgenic crops were not addressed.