The new Bacillus thuringiensis isolate with toxicity against snails was characterized in comparison with three B. thuringiensis standard strains representing three different serovars using Polymerase Chain Reaction (PCR), hybridization and protein analysis. The novel B. thuringiensis strain was preliminary bioassayed for its toxicity against infected, non-infected Chinese Oncomelania snails and the emitted cercariae. The new isolate reacted positively to the universal primers of cry1 and cry4 family genes. Each standard strain reacted positively to the primers of its characteristic family genes.Neither the three standard strains nor the new isolate responded to primers specific for the entire coding regions of 7 cry genes including cry1, cry3 and cry4. Moreover, the results of hybridization illustrated the presence of genes with homology to cry1, cry3 and cry4 familygenesin the new isolate strain as well as the three reference strains. The results of SDS-PAGE displayed common protein bands at about 66, 43 and 35 kDa in the protein patterns of strains from different serovars as well as the new isolate in addition to distinct protein bands for each strain. However, characterization of the new isolate by different molecular methods indicated that this isolate is closely related to the reference strains. The spore-crystal suspensions of B. thuringiensis isolate has a molluscicidal activity on non-infected snails only.
Halima, H. Salem, Bahy, A. Ali , Tian, H. Huang and Qing, D. Xie , 2006. Molecular Characterization of Novel Bacillus thuringiensis Isolate with Molluscicidal Activity Against the Intermediate Host of Schistosomes. Biotechnology, 5: 413-420.