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H.M.Mahadeva Swamy, R.Asokan, Riaz Mahmood, Geetha G. Thimmegowda, D.K.Arora and Nagesha S.N
Posters: J Proteomics Bioinform
Biocontrol of pests via Bacillus thuringiensis (Bt) δ-endotoxins represents the most successful use of a biological control agent to date. The most notable characteristic of Bacillus thuringiensis is its ability to produce insecticidal proteins. More than 300 different proteins have been described with specific activity against insect species. The six isolates of Bacillus thuringiensis from Andaman and Nicobar Islands which were previously characterized by PCR analysis for the presence of Coleopteran active cry genes were used for Cry1I full length gene amplification. A 2.16-kb DNA fragment of Cry1I gene was PCR amplified, cloned in expression vector pQE 80 L, and then used for transformation of E. coli M15 cells. The optimum expression was obtained with 1 mM IPTG at 370C for 3 h. The sequence of the cloned crystal protein gene showed almost complete homology with a Cry1I toxin gene from Bacillus thuringiensis var. kurstaki, with scattered mutations in the toxic region. The deduced sequence of the protein has homologies of 91.0% with Cry1I and Cry1Ia, and 98.0% with Cry1Ib.Cloning of this gene may help to overcome the increasing resistance of pests to currently used insecticides. Based on the results obtained, the PCR method may be a valuable and reliable tool for specific detection and identification of cry1I genes. The toxicity of Bt recombinant protein was determined against first instar larvae of Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae) and Adults; Helicoverpa armigera H�bner (Noctuidae: Lepidoptera) at 310μg/mL and 15.5μg/mL respectively. The novel cry1I gene will be an important resource in constructing genetically engineered bacteria and transgenic plants for biocontrol of insect pests and Bt based biopesticidal formulations, aiming to reduce the use of chemical insecticides.