Insecticidal activity of the CryIIA protein from the NRD-12 isolate of Bacillus thuringiensis subsp. kurstaki expressed in Escherichia coli and Bacillus thuringiensis and in a leaf-colonizing strain of Bacillus cereus.

Abstract

A 4.0-kb BamHI-HindIII fragment encoding the cryIIA operon from the NRD-12 isolate of Bacillus thuringiensis subsp. kurstaki was cloned into Escherichia coli. The nucleotide sequence of the 2.2-kb AccI-HindIII fragment containing the NRD-12 cryIIA gene was identical to the HD-1 and HD-263 cryIIA gene sequences. Expression of cryIIA and subsequent purification of CryIIA inclusion bodies resulted in a protein with insecticidal activity against Heliothis virescens, Trichoplusia ni, and Culex quinquefasciatus but not Spodoptera exigua. The 4.0-kb BamII-HindIII fragment encoding the cryIIA operon was inserted into the B. thuringiensis-E. coli shuttle vector pHT3101 (pMAU1). pMAU1 was used to transform an acrystalliferous HD-1 strain of B. thuringiensis subsp. kurstaki and a leaf-colonizing strain of B. cereus (BT-8) by using electroporation. Spore-crystal mixtures from both transformed strains were toxic to H. virescens and T. ni but not Helicoverpa zea or S. exigua.