Isolation and curing of plasmid DNA from bacillus thuringiensis israelensis strains showing variable insecticidal activities

ABSTRACT

Bacillus thuringiensis israelensis 4Q1-WT [B. t. i.] have 9 plasmids. 14 mutates of this wild type were prepared with cured plasmids. The wild bacterial strain, the mutants and 14 industrial strains were compared according to the number, size of plasmids and their potential to induce mortality to Aedes caspius larvae. The 108 Kb plasmid is essential for B. t. israelensis to induce insect killing