Bacillus thuringiensis (Bt) is a Gram-positive, soil-dwelling bacterium, which produces the Cry toxin. The Cry toxin has insecticidal action which has led to its use as a pesticide, and in more recent years its introduction into genetically modified crops using Bt genes. Description: Isolated from Bt spores. Alternative Names: BtCry1Ac protein, Bacillus thuringiensis protein, Bacillus thuringiensis Cry1Ac toxin, BtCry1 protein