Characterization of new Bacillus thuringiensis strains from Iran, based on cytocidal and insecticidal activity, proteomic analysis and gene content

Characterization of new Bacillus thuringiensis strains is a valuable tool to discover novel insecticidal toxins and to manage resistance problems. In this study, seven Iranian Bt strains were selected according to their toxicity against Plodia interpunctella, to be thoroughly characterized based on their toxicity, protein profiling, proteomic analysis, gene content and β-exotoxin production. The toxicity was assessed by insect bioassays and cell viability assays (a less cost, time and material consuming technique), using four lepidopteran pests and four lepidopteran cell lines from Trichoplusia ni (Hi5), Helicoverpa zea (HzGUT), Spodoptera exigua (UCR-SE) and Spodoptera frugiperda (Sf21). The selected Bt strains showed similar protein electrophoretic profiles, but differed in toxicity. LC–MS/MS analysis of solubilized crystal proteins and gene content analyses (PCR screening) were compared and correlated with the toxicity results. Based on our data, three Bt strains could be considered as candidates for development of future bioinsecticides.