BACILLUS THURINGIENSIS PROTEINS WITH INCREASED INSECTICIDE TOXICITY AND METHODS FOR OBTAINING THE SAME.

摘要

The present disclosure is related to compositions comprising Bacillus thuringiensis proteins with increased insecticidal toxic activity, as well as methods for obtaining the same. From the LBIT-1200 strain of Bacillus thuringiensis isolated from the soil that shows an increase in toxicity of between 6.4 and 9.5 times more against Manduca sexta and Trichoplusia ni respectively, compared to the HD-73 reference strain. It was determined that the sequence of its cry gene is of the cry1Ac-type with 4 amino acid differences, including 2 amino acid replacements in domain III, compared with the Cry1Ac1 protein of HD-73, which explains its high toxicity. In order to increase the toxicity of known Cry proteins of Bacillus thuringiensis, amino acid substitutions in the corresponding domain II were introduced into the Cry1Ac1 protein of HD-73. Three mutants were obtained for bioassays (mutant N547Y, mutant R602G and double mutant N547Y and R602G), where the mutant N547Y and the double mutant expressing the mutations N547Y and R602G, showed high toxicity. Noting that the amino acid at position N547Y is related to the high toxicity shown by LBIT-1200 for Manduca sexta and Trichoplusia ni.