Serotyping of Bacillus thuringiensis isolates, their distribution in different Jordanian habitats and pathogenicity in Drosophila melanogaster

The investigation of Bacillus thuringiensis in 40 different samples collected from 12 different Jordanian habitats involved the isolation of 80 Bacillus thuringiensis isolates. Out of these isolates, 47 were pathogenic to the third instar larvae of Drosophila melanogaster. The highest viable count of Bacillus thuringiensis was estimated among soil samples contaminated with decomposed animal bodies (similar to14.25 x 10(7) c.f.u. g), and the lowest viable count was obtained from soils contaminated with engine oil (similar to0.17 x 10(7) c.f.u./g). Serotyping of the 80 isolates against 55 antisera indicated the presence of 13 serotypes, 12 were identical or cross-reacted with aizawai, higo, israelensis, kenyae, kumamotoensis, kurstaki, malaysiensis, morrisoni, pakistani, sooncheon, tohokuensis, and thuringiensis, whereas the remaining one reacted negatively with the 55 tested antisera indicating the presence of an unknown serotype. Israelensis was the dominant serotype among all the samples except those from decomposed animal and olive-cultivated soils. The pathogenic isolates were found to be in 11 of the 13 serotypes. Spherical parasporal crystals were the most common and toxic crystal types.