Biodiversity of Bacillus thuringiensis Strains and Their Cry Genes in Ecosystems of Kyrgyzstan

The present study aims to isolate the unknown and known serotypes of Bacilllus thuringiensis (Bt) from natural objects in Kyrgyzstan. A total of 83 Bt strains were isolated from natural substrates, of which 30% were taken from the soil and litter samples, 69.7% from dead insects and about 0.3% from slugs. Serological examination revealed that such subspecies as var. thuringiensis (H-1), var. alesti (H-3), var. sotto (H-4a4b) and var. entomocidus (H-6) predominated in the upper horizon of soils in all climatic zones. In the dead insects such species as subsp. thuringiensis, subsp. galleria, subsp. sotto, subsp. kurstaki, subsp. Aizawai and subsp. Entomocidus dominated. A set of Bt strains isolated from insects and soil samples, selected from different ecosystems in Kyrgyzstan was molecular taxonomically characterized using the pycA gene as marker for phylogenetic reconstruction. Within the Bacillus cereus sensu lato species complex, all Kyrgyz isolates were shown to belong to the B. cereus subspecies thuringiensis. Most isolates were assigned to the lineage Bt tolworthi, with two isolates each belonging to the lineages Bt kurstaki and Bt sotto. A high degree of cry gene diversity was demonstrated in the set of Bt isolates, with several gene copies simultaneously present in a single strain; a particularly conspicuous trait was the frequent combination of Lepidopteran-specific cryI with Dipteran-specific cryIV genes in the same Bt isolate.