Increased production of Coleoptera-specifi c delta-endotoxin by homologous expression of cry3Aa11 in Bacillus thuringiensis Mm2

Th e cry3Aa11 gene of Bacillus thuringiensis strain Mm2 (B. thuringiensis Mm2) was PCR-amplifi ed and cloned into E. coli/B. thuringiensis shuttle vector pHT315. Th e recombinant plasmid carrying the cry3Aa11 gene was introduced into the parental B. thuringiensis Mm2. Th e toxin production capacities of parental and recombinant strains grown in DSM, containing either 50 mM or 200 mM inorganic phosphate (Pi), were compared by SDS-PAGE and western blot analyses. In comparison to the parental strain, recombinant B. thuringiensis Mm2 produced 4-fold more Cry3Aa11 toxin aft er 12 h of growth in the presence of 50 mM Pi. However, the 200 mM Pi concentration did not cause a drastic increase in toxin production by the recombinant strain. Th is study shows that higher toxin production could be obtained from the cultures during the early hours of growth by introducing the multicopy cry3Aa11 gene into the source organism.