B. thuringiensis

Bacillus sp. These bacteria are gram-positive soil microbes. Members of the Bacillus species supply 58% of iadustrial enzymes sold (19). Eor example, proteases from B. amjloliquefaciens and amylases from B. licheniformis glucose isomerase from B. coagulans are used ia a variety of iadustrial processes (see Enzyme applications-industrial). The proteiaaceous iaclusioas produced by B. thuringiensis are useful as iasect toxias. Thus exteasive fermentation technology has been developed for Bacillus species and low cost media are available (19). 

Thuringiensin (184), produced by B. thuringiensis (1,4) is a P-exotoxia that exerts its toxic action on insects and mammals through the inhibition of RNA polymerases. 

The exotoxin reported by Smirnoff (31) is definitively different from other soluble toxins, as indicated by its reported heat lability. This soluble toxin was obtained from the supernatant of a sporulated B. thuringiensis culture. In testing, it was found to be very toxic by ingestion to 18 species of larch sawfly larvae. No further studies on this toxin have been reported at this time. 

The second B. thuringiensis toxin, the /3-exotoxin has a much broader spectrum encompassing the Lepidoptera, Coleoptera and Diptera. It is an adenine nucleotide, probably an ATP analogue which acts by competitively inhibiting enzymes which catalyse the hydrolysis of ATP and pyrophosphate. This compound, however, is toxic when administered to mammals so that commercial preparations of the B. thuringiensis 5-endotoxin are obtained from strains which do not produce the j8-exotoxin. 

B. thuringiensis is an aerobic, gram-positive, spore-forming, rod-shaped bacterium. Vegetative cells are motile and approximately 1 /am wide and 5 /am long. It is very common in soil and on plants. 

Fig. 10.14. MALDI spectra of protein extracts from Bacillus species (matrix a-CHCA). (a) B. anthracis (Sterne), (b) B. thuringiensis (4A1), (c) B. cereus (6E1), (d) B. sub-...

The basis of phenotypic discrimination of closely related species via Raman spectroscopy lies in its sensitivity to the intracellular molecular components including extrachromosomally encoded phenotypes, such as the Bacillus anthracis or B. thuringiensis toxins or polyglutamic acid capsules. Other prominent examples are cell storage materials like the polyhydroxy butyric acid (PHB), carotenoid-based pigments like sarcinaxanthin, hemoproteins like cytochrome or calcium dipicolinate (CaDPA). Raman spectra of single bacteria, in which the latter four intracellular substances occur, are shown in... 

The bacterium Bacillus thuringiensis forms an internal crystal that contains a number of insecticidal protein toxins. When eaten by the insect, the crystal dissolves in the midgut, the toxin mixture is released, and the proteins are cleaved into active forms. The toxins bind specifically to midgut cells and assemble a pore that leads to disintegration of the cells, gut paralysis, and death. B. thuringiensis strains have toxins specific for caterpillars, beetles, or flies. They have little or no effect on mammals. 

When B. thuringiensis is grown on an iron- and molybdenum-deficient medium (42) at pH 6.8 with added Z-arginine, it produces compounds which form charge transfer complexes with molybdate. Pre-... 

Approximately 50% of the molybdenum-reactive compounds were extracted from acidified culture filtrates of B. thuringiensis with ethyl acetate. The ethyl acetate was washed with NaHC03 and then reextracted with ethyl acetate according to the method of Tait (43). High voltage electrophoresis of the ethyl-acetate extractable compounds at pH 3.6 for 45 min at 5 kV and 60 ma separates out three blue-green fluorescent bands which react with molybdate to form yellow complexes. They... 

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. 

In the bacterial PI-PLC structures, the top of the barrel rim has several hydrophobic residues that are fully exposed to solvent and poorly defined in the crystal structures (implying significant mobility). The active site of PI-PLC is accessible and well-hydrated, and these mobile elements at the top of the barrel offer a different motif for interactions of the protein with phospholipid interfaces. The PI-PLC from B. thuringiensis (nearly identical in sequence to the enzyme from B. cereus whose crystal structure was determined) exhibits the property of interfacial activation, where enhanced activity is observed when the substrate PI is present in an interface compared to monomeric substrate (Lewis et al., 1993). However, other non-substrate lipids such as phosphatidylcholine (PC), phosphatidic acid (PA), and other anionic lipids have an effect on the activity of PI-PLC toward both substrates PI and water-soluble cIP (Zhou et al., 1997). In particular, the presence of PC enhances the catalytic activity of... 

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