Bt toxins kill worms too

Crystal proteins from the Gram-positive soil bacterium, Bacillus thuringiensis (Bt), are pore-forming toxins used extensively to control insect pests, but their effect on the invertebrate phylum Nematoda — which includes many soil dwelling species — has been under-investigated. In the February 18 Early Edition of Proceedings of the National Academy of Sciences, Jun-zhi Wei and colleagues at the University of California, San Diego, US, show that Bt crystal proteins are also toxic to nematodes (PNAS, DOI:10.1073/pnas.0538072100, February 18, 2003).

Wei et al. expressed seven different crystal toxin proteins from two largely unstudied Bt protein subfamilies and measured their toxicity on diverse free-living nematode species. They observed that four of these crystal proteins are active against multiple nematode species, including a rat intestinal nematode. Toxicity in nematodes correlated with damage to the intestine — consistent with the mechanism of crystal toxin action in insects. In addition, they...