Isolation and Characterization of Bacillus thuringiensis Isolated from Soil and their Possible Impact on Culex pipiens Larvae

Use of microbial agents is an important tool for insect control because of their virtual specificity and lower environmental impacts. A total of four soil samples were collected from different localities across the black sea region in Turkey to isolate native Bacillus thuringiensis (Bt) strains. Sodium acetate-(0.25 M)-selection heat-pasteurization, and 50% ethanol treatment methods were used for Bt isolation. Characterization of Bt isolates based on their morphological, physiological and biochemical parameters. PCR analysis was performed, using novel general and specific primers for cry genes (cry4A and cry10 genes) that encoding proteins active against mosquitoes. Based on results, the isolate Bt22.19 showed the highest larvicidal effect against 3 rd instar C. pipiens larvae. Bt 22.19 was isolated from soil samples in hazelnut orchards. The isolated strains had cry4A and cry10 genes. Bt isolates displayed highest similarities with the Bacillus thuringiensis subsp. israelensis regarding to the presence of cry genes. Obtained results are a promising introduction for further studies on evaluation of the potential usefulness of isolate Bt22.19 crystals for mosquito’s control.

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