Bacillus thuringiensis

Several toxins can be found in one strain. For example, 5-endotoxin from B. thuringiensis var. kurstaki contains a mixture of Cry 1 and Cry 2. 

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Bacillus thuringiensis ai wa diamond back larvae, wax moth... 

Bacillus thuringiensis israelensis mosquito and black fly larvae... 

Miscellaneous compounds such as biopesticides (for example. Bacillus thuringiensis and pherhormones), heterocycles (for example, atrazine), pyrethroids (for example, cypermethrin), and urea derivatives (for example, diuron). 

Interestingly, certain other pore-forming toxins possess helix-bundle motifs that may participate in channel formation, in a manner similar to that proposed for colicin la. For example, the S-endotoxui produced by Bacillus thuringiensis is toxic to Coleoptera insects (beetles) and is composed of three domains, including a seven-helix bundle, a three-sheet domain, and a /3-sandwich. In the seven-helix bundle, helix 5 is highly hydrophobic, and the other six helices are amphipathic. In solution (Figure 10.32), the six amphipathic... 

FIGURE 10.32 The structures of (a) S-eudotoxiu (two views) from Bacillus thuringiensis and (b) diphtheria toxin from Cmynehacterium diphtheriae. Each of these toxins possesses a bundle of a-hehces which is presumed to form the trausmembraue channel when the toxin Is Inserted across the host membrane. In S-endotoxln, helix 5 (white) Is surrounded by 6 helices (red) In a 7-hellx bundle. In diphtheria toxin, three hydrophobic helices (white) lie at the center of the transmembrane domain (red). 

Li, J., Carroll, J., and Ellar, D., 1991. Cry.stal. structure of in.secticidal 5-endo-toxin from Bacillus thuringiensis at 2.5 A resolution. Nature 353 815-821. 

Prince, R. C., 1990. At least one Bacillus thuringiensis toxin forms ion-selecdve pores in membranes. Trends in Biochemical Sciences 15 2-3. 

A possible example of this thesis is the crystalline insect toxin found in Bacillus thuringiensis spores and discussed here by Dr. Anderson. Although neither the bacillus nor its spores exhibit useful antibiotic activity against other microorganisms, the very specific toxicity to insects has become of major commercial interest. The enormous number and variety of fungal species available for further examination must lead inevitably to one or more which produces pesticidal metabolites. 

Bacillus thuringiensis produces a variety of organic compounds which are toxic to the larvae of certain susceptible insect hosts. Among the toxic entities are proteinaceous crystals, probably three soluble toxins, and certain enzymes. The protein material is the major toxin active in killing lepidopterous larvae. The protein is formed by the cells apparently in close synchrony with sporulation, and its nature is a constant function of bacterial strain. The mode of action of the protein is under study. The sequence of events in the pathology observed is probably solubilization of the crystal (enzymatic or physical)—>liberation of toxic unit—>alteration of permeability of larval gut wall— change in hemolymph pH—>invasion of hemolymph by spores or vegetative cells of the bacterium. 

Preparations of the bacterium Bacillus thuringiensis (BT) are applied as sprays to control insect pests on agricultural crops. The bacterium produces endotoxins that are highly toxic to insects. 

Mackowiack P.A. (1979) Clinical uses of microorganisms and their products, JMed, 67,293-306. Priest EG. (1992) Biological control of mosquitoes and other biting flies hy Bacillus sphaericus and Bacillus thuringiensis. J Appl Bacterial, 72, 357-369. 

The biotransformation of gylcerol trinitrate by strains of Bacillus thuringiensis/cereus or Enterobacter agglomerans (Meng et al. 1995), by strains of Pseudomonas sp., and some Entero-bacteriaceae (Blehert et al. 1997) involves the expected successive loss of nitrite with the formation of glycerol. The biotransformation of pentaerythritol tetranitrate by Enterobacter cloacae proceeds comparably with metabolism of two hydroxymethyl groups produced by loss of nitrite to the aldehyde (Binks et al. 1996). 

Meng M, W-Q Sun, LA Geelhaar, G Kumar, AR Patel, GF Payne, MK Speedie, JR Stacy (1995) Denitration of glycerol trinitrate by resting cells and cell extracts of Bacillus thuringiensis/cereus and Enterobacter agglomerans. Appl Environ Microbiol 61 2548-2553. 

Bacillus thuringiensis, Streptomyces viridochromogenes Agrobacterium sp. strain CP4... 

Bacillus thuringiensis subsp. tenebrionis (Btt), potato vims Y (PVY)... 

Bacillus thuringiensis subsp. tolworthi (Bt), Streptomyces hygroscopicus... 

Corn Ciba-Geigy/1995 CrylAb protein Bacillus thuringiensis subsp. kurstaki (Btk) Resistance to European corn borer... 

As is the case with identifications based on protein molecular masses, it appears that the use of tryptic or other peptide masses as the basis for identification is extended with difficulty to mixtures of microorganisms. This reflects unpredictable suppression. Another limitation is redundancy of peptide masses across several microorganisms. For example, the most abundant proteins (SASPs), and thus the most abundant peptides, in spores of Bacillus anthracis and the closely related pesticide Bacillus thuringiensis have extensive sequence homology.25,82... 

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