Which genus produces BT toxin?
Bacillus thuringiensis, a Gram-positive aerobic spore-forming rod within Firmicutes, synthesizes parasporal crystalline inclusions composed of delta-endotoxins Cry and Cyt proteins encoded by plasmid-borne cry genes during sporulation. Crystals accumulate and upon ingestion by susceptible lepidopteran, dipteran, or coleopteran larvae, alkaline midgut solubilizes crystal, proteases activate toxin, binding cadherin receptors forming lytic pores leading to epithelial breakdown and larval death. Widely deployed as biopesticide, it represents environmentally safe alternative to chemical insecticides, distinct from related Clostridium or filamentous Streptomyces producing different bioactive metabolites.
Ref: Madigan Microbiology Chapter 15 Bacillus thuringiensis Cry toxins; NCERT Class 12 Biology Chapter 12 Bt toxin biopesticide parasporal