Abstract:

By the temperature-antibiotic method, the author isolated 74 strains Bacillus thuringiensis from totally 764 soil samples which were collected from different altitude Damaoshan mountains of Hebei province. The results showed the optimal collecting area at an altitude of 900 to1200 m. Light microscope observation showed that the crystals of these Bt strains were in shape of spherical, bipyramidal, square, irregular and so on; 7 kinds of cry gene were found by PCR-RFLP system, and 11 Bt strains harbour unknown cry genes; The results of SDS-PAGE analysis showed that these Bt strains mainly expressed 130 kDa, 97 kDa, 66 kDa and 45 kDa proteins. 17 strains were shown to be highly toxic to scarabaeoidae larvae, 16 of them contained the gene of cry8Ca, one of them could not be found any known cry gene. All of these showed the great diversity of Bt strains in Damaoshan mountains of Hebei province.