Midgut bacteria required for Bacillus thuringiensis insecticidal activity
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TLDR
The results demonstrate that B. thuringiensis-induced mortality depends on enteric bacteria, and that engineered E. coli and the Enterobacter sp.Abstract:
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.read more
Citations
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References
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Journal ArticleDOI
Bacillus thuringiensis and Its Pesticidal Crystal Proteins
E. Schnepf,Neil Crickmore,J. Van Rie,Didier Lereclus,J. Baum,Jerald S. Feitelson,Daniel R. Zeigler,Donald H. Dean +7 more
TL;DR: Researchers are reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.
Journal ArticleDOI
Insecticidal crystal proteins of Bacillus thuringiensis.
Herman Höfte,H R Whiteley +1 more
TL;DR: In this article, a classification for crystal protein genes of Bacillus thuringiensis is presented, based on the insecticidal spectra and the amino acid sequences of the encoded proteins.
Insecticidal crystal proteins of Bacilllus thuringiensis
H. Höfte,H.R. Whiteley +1 more
TL;DR: Studies on the biochemical mechanisms of toxicity suggest that B. thuringiensis crystal proteins induce the formation of pores in membranes of susceptible cells, and these approaches are potentially powerful strategies for the protection of agriculturally important crops against insect damage.
Journal ArticleDOI
The mode of action of Bacillus thuringiensis endotoxins.
TL;DR: The use of synthetic organic insecticides developed during the last half of this century may pose risks to human health and can cause environmental damage, Consequently, interest has developed in using alternative strategies for insect pest management, including Bacillus thuringiensis toxins as insecticides.
Journal ArticleDOI
Bacillus thuringiensis CryIA(a) insecticidal toxin: crystal structure and channel formation.
Pawel Grochulski,Luke Masson,Svetlana Borisova,Marianne Pusztai-Carey,Jean-Louis Schwartz,Roland Brousseau,Miroslaw Cygler +6 more
TL;DR: Comparison with the structure of CryIIIA, a coleopteran-specific toxin, shows that although the fold of these two proteins is similar, there are significant structural differences within domain II, which supports the conclusions from genetic studies that domain II is involved in recognition and binding to cell surface receptors.