Microbial utilization of free and clay-bound insecticidal toxins from Bacillus thuringiensis and their retention of insecticidal activity after incubation with microbes
Authors: Koskella, J., Stotzky, G.
Journal, Volume, Year: Applied and Environmental Microbiology, volume 63(9):3561-3568, 1997
Btk and Btt toxins supported microbial growth when free, but not when bound to clays, and insecticidal activity of both toxins was retained after exposure to microbes or pronase. Insecticidal activity remained for 40 days (longest time tested) for Btk and Btt toxins bound on montmorillonite and kaolinite homoionic to Na incubated in nonsterile soil.
Additional research using natural soil and Btk and Btt from transgenic plant material also needs to be done to more accurately determine ecological relevance. The Btk and Btt toxins used in this study were derived from Dipel technical powder and M-One, respectively. Insecticidal activity was determined by adding dilutions of bound and free Btk toxin onto tobacco hornworm medium. Although this shows the insecticidal activity, the ecological relevance has not been established.