Molecular Screening and Bioactivity of Native Bacillus thuringiensis Isolates

Abstract

Bacillus thuringiensis strains were isolated from various soil samples co llected from different regions of Kahramanmara ş in Turkey and were characterized by their colony morphology, PCR method with cryIAb/Ac, cryID, cry2 and cyt2 primers, and SDS-PAGE of crystal proteins with 130-140 and 60-70 kDa mole cular weights. Plasmid profiles of selected isolates were also analyzed. Among the cry genes studied, cry1Ab/Ac was found to be the most common one (60% ) in local isolates. Bioactivity tests were carried out under laboratory conditions to assess the efficacy of iso lates against the third instar larvae of the stored product insects; Anagasta kuehniella and Plodia interpunctella. Toxicity values of the isolates varied between 20.00-53.33% for A. kuehniella and 20.00-55.56% for P. interpunctella at 1,000 μg g -1 concentration. Out of 55 isolates, ST13.1 was foun d to be the most effective against A. kuehniella. Also, ST7.2, ST7.3, and ST8.2 isolates yielded remarkable control against P. interpunctella . Further research is recommended to investigate the efficacy of these promising Bt isolates against other pest insect species. Keywords: Bacillus thuringiensis , Bioactivity, Cry gene, Stored product insects, Toxicity.