Dl. Prietosamsonov et al., BACILLUS-THURINGIENSIS - FROM BIODIVERSITY TO BIOTECHNOLOGY, Journal of industrial microbiology & biotechnology, 19(3), 1997, pp. 202-219
Bacillus thuringiensis is a Gram-positive bacterium, widely used in ag
riculture as a biological pesticide, The biocidal activity mainly resi
des in a parasporal protein inclusion body, or crystal, The inclusion
is composed of one or more types of delta-endotoxins (Cry and Cyt prot
eins). Cry proteins are selectively toxic to different species from se
veral invertebrate phyla: arthropods (mainly insects), nematodes, flat
worms and protozoa, The mode of action of. the insecticidal proteins i
s still a matter of investigation; generally, the active toxin is supp
osed to bind specific membrane receptors on the insect midgut brush-bo
rder epithelium, leading to intestinal cell lysis and subsequent insec
t death by starvation or septicemia. The toxin-encoding cry genes have
been extensively studied and expressed in a large number of prokaryot
ic and eukaryotic organisms, The expression of such genes in transgeni
c plants has provided a powerful alternative for crop protection.