title: Persistence of Bacillus thuringiensis bioinsecticides in the gut of human-flora-associated rats.
abstract: The capability of two bioinsecticide strains of Bacillus thuringiensis (ssp. israelensis and ssp. kurstaki) to germinate and persist in vivo in the gastrointestinal tract of human-flora-associated rats was studied. Rats were dosed either with vegetative cells or spores of the bacteria for 4 consecutive days. In animals fed spores, B. thuringiensis cells were detected in faecal and intestinal samples of all animals, whereas vegetative cells only poorly survived the gastric passage. Heat-treatment of intestinal samples, which kills vegetative cells, revealed that B. thuringiensis spores were capable of germination in the gastrointestinal tract. In one animal fed spores of B. thuringiensis ssp. kurstaki, these bacteria were detected at high density (10(3)-10(4) CFU g(-1) faecal and intestinal samples) even 2 weeks after the last dosage. In the same animal, passage of B. thuringiensis ssp. kurstaki to the spleen was observed; however, no other adverse effects were observed. Denaturing gradient gel electrophoresis of PCR-amplified bacterial 16S rRNA genes in faecal samples revealed no major effect of B. thuringiensis on the composition of the indigenous gut bacteria. Additionally, no cytotoxic effect was detectable in gut samples by Vero cell assay.
authors.affiliation: Department of Microbiology and Risk Assessment, Danish Institute for Food and Veterinary Research, Søborg, Denmark. anw@dfvf.dk
authors.forename: Andrea
authors.initials: A
authors.lastname: Wilcks
authors.forename: Bjarne Munk
authors.initials: BM
authors.lastname: Hansen
authors.forename: Niels Bohse
authors.initials: NB
authors.lastname: Hendriksen
authors.forename: Tine Rask
authors.initials: TR
authors.lastname: Licht
mesh_terms: D000821:Animal Feed / Q000382:microbiology*; D000818:Animals; D001413:Bacillus thuringiensis / Q000254:growth & development*; D004587:Electrophoresis, Agar Gel; D005243:Feces / Q000382:microbiology; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006801:Humans; D010572:Pest Control, Biological; D051381:Rats; D017207:Rats, Sprague-Dawley; D013171:Spores, Bacterial / Q000254:growth & development