38th Annual Meeting of the Society for Invertebrate Pathology

Bioassay screening demonstrated that culture supernatants of Bacillus thuringiensis strains EG2158 and EG5438 were toxic to Colorado potato beetle (CPB) larvae and diamondback moth (DBM) larvae, respectively. Ion exchange fractionation revealed that EG2158 produced a secreted protein of approximately 38 kDa that exhibited insecticidal activity to CPB. EG5438 produced a secreted protein of approximately 70 kDa that exhibited insecticidal activity to DBM. Gene specific oligonucleotides, whose designs were based on partial sequences of the purified ~38 kDa and ~70 kDa proteins, were used to clone the corresponding genes. The gene for the ~38 kDa protein encoded a protein of 367 residues (41,492 Da) whose sequence had no significant homology to any proteins in GenBank. The gene for the ~70 kDa protein encoded a protein of 601 residues (68,869 Da) whose sequence was distantly related (49% identity) to the toxin portion of the B. thuringiensis Cry1Ca protein.