Frequency of cry-like genes in Bacillus thuringiensis strains of the Crimean microorganism collection

The entomopathogenic strains of Bacillus thuringiensis are used in the development of new-generation biopreparations against leaf-eating insects. The present study was aimed at analyzing the frequency of cry-like genes in the strains and at identifying a promising strain for the development of an entomopathogenic biopreparation on its basis. The study materials included the entomopathogenic strains of Bacillus thuringiensis obtained from the Crimean microorganism collection of the Crimean Agricultural Research Institute. The entomopathogenic effect of promising strains was studied in laboratory experiments on Coleoptera and Lepidoptera larvae. The following strains of Bacillus thuringiensis were identified as the most promising, i.e., containing at least four toxin genes: 708 (cry1, thuE, cry7-8, cry11), 942 (cry1, thuE, cry11, vip), 949 (cry1, thuE, cry4, cry7-8), 989 (cry1, thuE, cry11, vip), 0162 (cry1, thuE, cry11, vip), 0307 (cry1, thuE, cry4, cry7-8), 0308 (cry1, thuE, cry4, cry7-8), 0363 (cry1, thuE, cry5, cry11) & icy; 0371(cry1, thuE, cry9, cry11). The isolated strains of Bacillus thuringiensis 0162, 0307, 0363, and 0371 were found to have a high entomopathogenic effect on the larvae of the Colorado potato beetle and elm-leaf beetle (88.3-100%), as well as the caterpillars of ermine moth, cabbage moth, brown-tail moth, and fall webworm (92.3-100%). It is shown that Bacillus thuringiensis strain 0371 goes through all traditional stages of development and exhibits complete release of crystals and spores from the sporangium within 45-48 h. Thus, strain 0371 can be used to develop specifications for manufacturing a plant protection biopreparation.