Cloning and expression of Bacillus thuringiensis israelensis delta-endotoxin DNA in B. sphaericus

Bacillus thuringiensis israelensis delta-endotoxin genes were cloned into Bacillus sphaericus 2362, producing stable transformants reacting with antibody to the 28- and 65-kDa B. thuringiensis israelensis crystal proteins and approximately 10 times more toxic to Aedes mosquito larvae than the original host strain. The LC50 after 48 hr of exposure of Aedes larvae to the most active transformed clone was 0.19 microgram/ml, compared with an LC50 of 1.9 microgram/ml for B. sphaericus 2362 and less than 0.1 microgram/ml for B. thuringiensis israelensis. The cloning vector, plasmid pPL603E, was also effective in transforming B. subtilis 1E20 with B. thuringiensis israelensis DNA, producing highly toxic clones with less stable gene expression than the clones of B. sphaericus.