IMPROVED INSECTICIDAL BACTERIA, AND METHODS FOR MAKING AND USING THEM.

摘要

The invention relates to nucleic acid sequences comprising a BtI or BtII promoter, or a combination of a BtI and a BtII promoter, at least 6 contiguous nucleotides of a bacterial STAB-SD sequence, and a sequence encoding a polypeptide with at least 80% sequence identity to a 41.9 kD protein of the B. sphaericus (Bs) binary toxin, which polypeptide has at least 50% of the toxicity of the native 41.9 kD protein. Optionally, the sequence further encodes a second polypeptide with at least 80% sequence identity to the 51.4 kD protein of the Bs binary toxin and which can function as a binding domain for the Bs 41.9 kD toxin protein. When the nucleic acid sequences are expressed in B. thuringiensis (Bt) or Bs cells, they result in at least 10 times the production of Bs binary toxin compared to untransformed Bs cells. The invention provides nucleic acid sequences, expression vectors, host cells, and methods of increasing the toxicity of an insecticidal bacterium by transforming the bacterium with nucleic acid sequences of the invention. Further, the invention relates to the discovery that the Cyt1Aa1 protein of Bt subspecies israelensis (Bti) reverses resistance to Bs binary toxin in larvae of Bs-resistant mosquitoes. The invention provides Bs cells expressing Bti Cyt1Aa1 protein, and methods of reducing resistance to Bs binary toxin by co-administering the Cyt1Aa1 protein with Bs binary toxin.