Which bacterium produces insecticidal crystal proteins used in biological pest control?

Bacillus thuringiensis produces insecticidal crystal proteins used in biological pest control.

Bacillus thuringiensis, commonly abbreviated Bt, is a soil-dwelling, spore-forming bacterium. During sporulation, many Bt strains produce crystalline proteins known as Cry proteins. When susceptible insect larvae eat them, the crystals are dissolved and activated in the alkaline insect gut, where they damage the gut lining.

Bt was first described in 1901 by the Japanese biologist Shigetane Ishiwata, who associated it with a disease of silkworms. The German scientist Ernst Berliner later named the species in 1911 after the province of Thuringia. Bt preparations became important microbial insecticides, and genes encoding some Bt proteins have also been introduced into certain crops.

Bt is not simply a general poison for every animal. Toxicity depends on the protein, the insect species, and exposure route. Bacillus cereus is a close relative associated with food poisoning, but it is not the standard answer for Bt pest-control proteins.