Study on the isolation and identification of Bacillus thuringiensis in soil samples from Yakushima island [Japan], 2: Insecticidal activity and the identification of cry genes
1999
Kikuta, H. (College of Dairying, Ebetsu, Hokkaido (Japan)) | Kuroiwa, M. | Takagi, R. | Iizuka, T.
We previously reported that 53 B. thuringiensis Isolates in soils from Yakushima Island were serologically investigated. In the present study, the insecticidal activity of these strains against the silkworm Bombyx mori and the mosquito larvae Aedes japonicus was investigated and the identification of cry genes in these strains was conducted using the PCR method. Oligonucleotide primers used for making DNA probes were cry1Aa, cry1Ab, cry1Ac, cry1Ba, cry1Ca, cry1Da, cry1Ea, cry2Aa, cry4Aa, cry1Ba, cry10Aa and cry11Aa genes, depending on their specific nucleotide domains. Cry gene profiles of 24 serovar kurstaki strains were the same for cry1A;, cry1Ab and crylAc with a type strain of HD-1, except for cry1Aa the Jano9-2-2 strain composed of cry1Aa and cry1Ab. All of the strains included the cry2Aa gene. In the 14 strains of serovar galleriae, all of the strains included the same cry1Ab and cry2Aa genes as the type Strain. In the other serovar from Yakushima Island, thuringiensis, kenyae and israelensis strains displayed different profiles from the type strains used in this experiment. Serovar kurstaki Jano9-2-2 revealed high insecticidal activity against silkworm larvae compared with the control strain HD-1. Serovar israelensis Aiko2-1-1 also revealed high activity against the Aedes japonicus larvae compared with the type strain. These two strains seem to include novel cry genes
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