球形芽孢杆菌C3—41二元毒素基因在苏云金芽孢杆菌以色列亚种中的？…

球形芽孢杆菌Ｃ３－４１是我国分离的一株对蚊幼虫有毒杀作用的高毒力菌株，对库蚊、按蚊幼虫的毒性高于２３６２菌株，Ｓｏｕｔｈｅｒｎ杂交证明Ｃ３－４１总ＤＮＡ中３．５ＫｂＨｉｎｄＩＩＩ片段上带有４１．９和５１．４ｋＤ二元毒素基因。

Cloning and expression of the binary toxin genes of Bacillus sphaericus C3-41 in a crystal minus B. thuringiensis subsp. israelensis]

Bacillus sphearicus C3-41, belonging to serotype H5a5b, is ahighly toxic strain isolated from a mosquito-breeding site in China. It has been shown that it had a higher toxicity against Culex spp. than the reference strain 2362 at the laboratory and field conditions. Using synthetic oligonucleotides designed on the basis of the binary toxin gene sequence of 2362, a 1.1 kb DNA fragment was produced and the genetic library was prepared from a HindIII digest of total DNA from C3-41. One colony containing the 3.5 kb HindIII fragment was selected for further studies. Sequence analysis revealed that this 3.5 kb Hind DNA fragment was composed of 3479 nucleic acids and the sequence of the binary toxin gene of C3-41 is completely identical to that of strain 2362. The toxin genes have been transferred into a nontoxic crystal-minus strain of Bacillus thuringiensis subsp. israelensis. The recombinant strains could express the binary toxin of B. sphaericus as crystaline structures during their sporulation. The expression products of the recombinants have a highly toxicity to susceptible Culex pipiens subsp. quinquefasciatus and no toxicity to resistant larvae(Culex pipiens subsp. pipiens) from France.