This is all I found today: Abstract: The aim of this study was to evaluate the toxicology safety of a genetically modified (GM) Bacillus thuringiensis with vegetative insecticidal protein (VIP) gene. Acute and subacute toxicity studies by using its powder preparation were conducted in Wistar rats. The result of the acute study showed the no-observable-adverse-effect level (NOAEL) of this GM B. thuringiensis powder preparation was greater than 5000mg/kg body weight (BW). In the subacute study, the data analysis of body weight gain, food and water consumptions, clinical observations, haematology, serum biochemistry, organ weight ratios and histopathological findings did not show significant differences between control and treated groups. These results proved the NOAEL of this GM B. thuringiensis powder preparation in subacute test was greater than 5000mg/kg BW. Since both the acute and subacute oral toxicity were not detected at the highest dose recommended by OECD guidelines, this GM B. thuringiensis could be generally regarded as safe for use in bio-pesticide industry.
I found this interesting:
Bacillus thuringiensis is a Gram-positive bacterium, widely used in agriculture as a biological pesticide. The biocidal activity mainly resides in a parasporal protein inclusion body, or crystal. The inclusion is composed of one or more types of σ-endotoxins (Cry and Cyt proteins). Cry proteins are selectively toxic to different species from several invertebrate phyla: arthropods (mainly insects), nematodes, flatworms and protozoa. The mode of action of the insecticidal proteins is still a matter of investigation; generally, the active toxin is supposed to bind specific membrane receptors on the insect midgut brush-border epithelium, leading to intestinal cell lysis and subsequent insect death by starvation or septicemia. The toxin-encoding cry genes have been extensively studied and expressed in a large number of prokaryotic and eukaryotic organisms. The expression of such genes in transgenic plants has provided a powerful alternative for crop protection.
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Abstract: The occurrence of Bacillus thuringiensis bacteremia in a neutropenic [ no raw food diet] patient suffering from severe pulmonary disease addressed the question of whether the aggressive behavior of B. thuringiensis depended on the host status and/or on the membrane-damaging toxins the isolate produced. After intratracheal injection, BALB/c mice developed pneumonia followed by fatal dissemination into deep organs, with mice rendered neutropenic by cyclophosphamide injection being extremely more susceptible to infection than normal animals. In animals infected with isogenic strains of B. thuringiensis progressively more defective in membrane-damaging toxins (407 Cry->IP2>MP02), an increase in the 50% lethal dose was registered (3.9×105, 1.1×106, 1.2×107 CFU). Consistently, after non-lethal dose application, only 407 Cry- replicated intrapulmonary, reaching a bacterial burden 4.7-fold and 40.9-fold higher than IP2 (P =0.018) and MP02 (P =0.008) at 48h post-inoculation. Notably, the time-course of infection was similar in animals infected with viable bacilli or spores, with neutropenic mice always being more susceptible to infection. The overall results indicate that B. thuringiensis may be responsible for opportunistic infections and strongly suggest that membrane-damaging toxins contribute to intrapulmonary bacterial persistence favoring dissemination.