Chapter 19 : Bacteria as Environmental Tools

Abstract:

Bacillus thuringiensis was discovered in Japan in silkworms in 1902 and was later isolated from flour moths in Thüringen, Germany, in 1911. B. thuringiensis is an entomopathogenic bacterium that was rapidly adopted worldwide as a biopesticide thanks to its toxicity to the larvae of insects, including butterflies, beetles, flies, hymenoptera, homoptera, and lice, as well as certain invertebrates. The B. thuringiensis toxin, often referred to as Bt toxin, is made up of the proteins Cry and Cyt, two delta-endotoxins that are generated during sporulation. More than 600 cry genes have so far been identified. Beyond its unique ability to produce Cry toxins, B. thuringiensis is very similar to Bacillus anthracis, the bacterial agent of anthrax, and to Bacillus cereus, an environmental bacterium that can cause foodborne disease. B. thuringiensis produces other factors that contribute to its usefulness as an insecticide, including chitinases, proteases, and other toxins. The specificity of Bt's action is related to the specificity of its toxins.