Identification and molecular characterization of novel cry1-type toxin genes from Bacillus thuringiensis K1 isolated in Korea.

To clone novel c/y7-type genes from the Bacillus thuringiensis Kl isolate, about 2.4-kb-long PCR fragments were amplified with two primer sets of ATGI-F/N400-R and 1BeATG1-F/N400-R. Using PCR-RFLP, three novel cry1-type genes, cryl-1, cry1-7, and cry1-44, were obtained from B. thuringiensis Kl and the complete coding sequences of these novel genes were analyzed. The Cry1-1, Cryl-7, and Cryl-44 proteins showed maximum similarities of about 78.0%, 99.7%, and 91.0% with the Cry1Ha1, Cry1Be1, and Cry1Ac2 proteins, respectively. These novel cryJ-type genes were expressed using a baculovirus expression vector system and their insecticidal activities were investigated. Whereas all three novel genes were toxic to Plutella xylostella larvae, only Cryl-1 showed insecticidal activity against Spodoptera exigua larvae.