几株球形芽孢杆菌二元毒素基因的检测及对敏感和抗性尖音库蚊的毒性

DETECTION OF THE BINARY TOXIN GENES OF SEVERAL BACILLUS SPHAERICUS STRAINS AND THEIR TOXICITIES AGAINST SUSCEPTIBLE AND RESISTANT CULEX PIPIENS

根据Bacillussphaericus2362二元毒素基因核着酸序列合成的一组寡聚核苷酸为引物，通过PCR扩增出1．1kb的DNA片段作探针检测了C3-41、IAB881、IAB872、BS－197和LP1－G菌株中二元毒素基因。Southern杂交表明C3-41、IAB881、IAB872和BS－197菌株中3·5kbHindⅢ及LP1-G中4.7kbHindⅢ的酶切片段分别带有与探针有高度同源性的二元毒素基因。SDS－PAGE和Western印迹杂交表明所有菌株都能产生41．9kD和51．4kD的毒素蛋白。C3－41、IAB881、BS－197和2362的全发酵液和碱抽提液对敏感尖音库蚊Culexpipienssubsp．pipiens幼虫毒性高，但对抗性幼虫几乎无毒；LP1－G对敏感和抗性蚊幼虫具有相同的中度毒杀作用；IAB872对敏感幼虫毒性高，对抗性幼虫的毒力同LP1－G相似。这两株菌对抗性蚊幼虫的毒性可能是由Mtx毒素蛋白所导致的。

Using synthetic oligonucleotides designed on the basis of the binary toxin gene sequence of 2362, a 1. 1 kilodalton DNA fragment has been prepared as a probe to study the toxin genes of several Bacillus sphaericus strains. The 3. 5kb Hind III DNA fragments of C3-41, IAB881, IAB872 and BS-197 as well as the 4. 7kb Hind III DNA fragment of LP1-G are homologous to the probe. The 51. 4 and 41. 9 kilodalton binary toxin can be detected by SDS-PAGE and Western Blotting. The results of the bioassay showed that C3-41, IAB881, BS-197 and the reference strain 2362 have a high potency against susceptible Culex pipiens subsp. pipiens and no potency against the resistant mosquito larvae from France (SPHRAE). IAB872 and LPI-G have medium toxicity against the resistant larvae.