Midgut bacteria required for Bacillus thuringiensis insecticidal activity
Midgut bacteria required for Bacillus thuringiensis insecticidal activity
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DOI：
10.1073/pnas.0604865103
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发表时间：
2006-10-10
影响因子：
11.1
通讯作者：
Handelsman, Jo
中科院分区：
文献类型：
--
作者：
Broderick, Nichole A.;Raffa, Kenneth F.;Handelsman, Jo
苏云金芽孢杆菌是应用最广泛的生物杀虫剂，用于管理影响林业和农业并传播人类和动物病原体的昆虫。这种无处不在的孢子形成细菌主要通过杀虫晶体蛋白的作用杀死昆虫幼虫，通常作为直接细菌喷雾剂使用。此外，用编码B.苏云金杆菌晶体蛋白是最广泛栽培的转基因作物。几十年来，昆虫的死亡机制一直被认为是毒素介导的肠上皮细胞溶解，这导致饥饿，或B。苏云金杆菌败血症在这里，我们报告说，B。苏云金杆菌在没有固有中肠细菌的情况下不能杀死舞毒蛾的幼虫。通过口服抗生素消除肠道微生物群落消除了B。苏云金杆菌杀虫活性，并重建肠杆菌属，通常居住在中肠微生物群落恢复B。苏云金杆菌介导的杀伤。大肠杆菌工程生产的B。苏云金杆菌杀虫毒素杀死舞毒蛾幼虫，而不管中肠中是否存在其他细菌。然而，当工程E.大肠杆菌被热杀死，然后喂给幼虫，幼虫没有死亡的情况下，土著中肠细菌。E.与B相比，大肠杆菌和肠杆菌在血淋巴中获得了较高的群体。苏云金杆菌，似乎死在血淋巴中。结果表明，B.苏云金杆菌引起的死亡率取决于肠道细菌。
Bacillus thuringiensis is the most widely applied biological insecticide and is used to manage insects that affect forestry and agriculture and transmit human and animal pathogens. This ubiquitous spore-forming bacterium kills insect larvae largely through the action of insecticidal crystal proteins and is commonly deployed as a direct bacterial spray. Moreover, plants engineered with the cry genes encoding the B. thuringiensis crystal proteins are the most widely cultivated transgenic crops. For decades, the mechanism of insect killing has been assumed to be toxin-mediated lysis of the gut epithelial cells, which leads to starvation, or B. thuringiensis septicemia. Here, we report that B. thuringiensis does not kill larvae of the gypsy moth in the absence of indigenous midgut bacteria. Elimination of the gut microbial community by oral administration of antibiotics abolished B. thuringiensis insecticidal activity, and reestablishment of an Enterobacter sp. that normally resides in the midgut microbial community restored B. thuringiensis-mediated killing. Escherichia coli engineered to produce the B. thuringiensis insecticidal toxin killed gypsy moth larvae irrespective of the presence of other bacteria in the midgut. However, when the engineered E. coli was heat-killed and then fed to the larvae, the larvae did not die in the absence of the indigenous midgut bacteria. E. coli and the Enterobacter sp. achieved high populations in hemolymph, in contrast to B. thuringiensis, which appeared to die in hemolymph. Our results demonstrate that B. thuringiensis-induced mortality depends on enteric bacteria.