Contribution of the individual components of the δ-endotoxin crystal to the mosquitocidal activity of Bacillus thuringiensis subsp. israelensis

Abstract

The δ-endotoxin crystal of the mosquitocidal bacterium Bacillus thuringiensis subsp. israelensis contains four major 0-endotoxins. Expression systems were devised to synthesize each of the four toxins at concentrations at which they formed inclusion bodies in an acrystalliferous mutant of Bacillus thuringiensis . The relative activities of these inclusions were then determined against Aedes aegypti larvae. Bioassays of mixtures of the individual toxins revealed a number of synergistic interactions which explained in part why the native crystal is considerably more toxic than any of the individual toxins.