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Bacillus thuringiensis
Bacillus thuringiensis is a bacterium that lives in the soil, in the caterpillars of some moths and butterflies and also on the surface of plants. It was discovered 1901 in Japan and 1911 in Germany by Ernst Berliner (he discovered a disease called "Schlaffsucht" in caterpillars of the flour moth). It seems that it is the same organism as B. cereus, a soil bacterium, and B. anthracis, the cause of anthrax; the three organisms only differ in their plasmids. Like other members of the genus, all three are aerobes capable of producing endospores.
B. thuringiensis produces crystals of toxin that are lethal to larval stages (caterpillars) of the insects which belong to orders Coleoptera, Lepidoptera and Diptera, but are considered harmless to most other organisms, including humans. Therefore, the spores of the bacterium and the toxic crystals (that are produced in the plasmids of the bacterium) are used in crop protection, especially in organic farming, where the use of chemical pesticides is not considered an option. This is done by spraying plants with the bacterium itself, or with an insecticide that contains the bacterial spores. The agent has been available since 1938 in France, 1950 in the USA, and was improved in the 1960s. Today different subspecies are used against the different insects, For instance, Bacillus thuringiensis israelensis is effective against mosquito larvae and some midges. Other variants used are B. thuringiensis kurstaki, B. thuringiensis aizawa, B. thuringiensis san diego, and B. thuringiensis tenebrionis.
Another way to protect plants is to create transgenic plants that express the gene for the bacterial toxin, as is currently done in the USA, India, China and Australia for cotton (Bt-cotton), and for corn (Bt-corn) in USA and Canada. This has generated some controversy, especially regarding the ill effects Bt corn was purported to have on monarch butterflys. The emergence of resistance in affected insects is another significant issue [1].
Category: Bacillaceae
Other related archivesAustralia, B. anthracis, B. cereus, Bacillaceae, Bacillus thuringiensis israelensis, Canada, China, India, USA, aerobes, anthrax, bacterium, butterflies, caterpillars, corn, cotton, endospores, express, gene, insecticide, monarch butterflys, mosquito, moths, plasmids, toxin, transgenic plants
 Adapted from the Wikipedia article "Bacillus thuringiensis", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki |
