USE OF A SIMPLE METHOD FOR DETECTION OF B ETA-EXOTOXIN IN STRAINS OF BACILLUS-THURINGIENSIS

A simple chemical analysis method was used for beta-exotoxin detection in subspecies of Bacillus thuringiensis. Native strains and Internati onal Collection strains belonging to the thuringiensis variety (HD-41 and HD-59), reported as producers of beta-exotoxin, were tested. Both strains showed typical absortion UV spectra for the toxin used as refe rence stock in this work. HD-41 produced 6.8 mg/l of culture medium, w hile HD-59 produced 27.2 mg/l. These results were confirmed with bioas says with third instar Musca domestica larvae; LD50's of 240 and 98.28 mul/g were obtained for HD-59 and the reference stock, respectively. None of the native strains showed positive results for the toxin with this method, which was confirmed by mortalities lower than 10% obtaine d in bioassays.