title: Persistence of detectable insecticidal proteins from Bacillus thuringiensis (Cry) and toxicity after adsorption on contrasting soils.
abstract: Insecticidal Cry, or Bt, proteins are produced by the soil-endemic bacterium, Bacillus thuringiensis and some genetically modified crops. Their environmental fate depends on interactions with soil. Little is known about the toxicity of adsorbed proteins and the change in toxicity over time. We incubated Cry1Ac and Cry2A in contrasting soils subjected to different treatments to inhibit microbial activity. The toxin was chemically extracted and immunoassayed. Manduca sexta was the target insect for biotests. Extractable toxin decreased during incubation for up to four weeks. Toxicity of Cry1Ac was maintained in the adsorbed state, but lost after 2 weeks incubation at 25 °C. The decline in extractable protein and toxicity were much slower at 4 °C with no significant effect of soil sterilization. The major driving force for decline may be time-dependent fixation of adsorbed protein, leading to a decrease in the extraction yield in vitro, paralleled by decreasing solubilisation in the larval gut.
authors.affiliation: INRA, UMR Eco&Sols, INRA-IRD-Cirad-SupAgro, 2 Place Viala, 34060 Montpellier, France; Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi, Viet Nam.
authors.forename: T P
authors.initials: TP
authors.lastname: Hung
authors.affiliation: INRA, UMR Eco&Sols, INRA-IRD-Cirad-SupAgro, 2 Place Viala, 34060 Montpellier, France; Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi, Viet Nam.
authors.forename: L V
authors.initials: LV
authors.lastname: Truong
authors.affiliation: Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi, Viet Nam.
authors.forename: N D
authors.initials: ND
authors.lastname: Binh
authors.affiliation: Cirad, UMR17, Intertryp, Cirad-IRD, TA-A17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France; Université de Montpellier, UMR 5236-CPBS, CNRS-Université de Montpellier, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: R
authors.initials: R
authors.lastname: Frutos
authors.affiliation: INRA, UMR Eco&Sols, INRA-IRD-Cirad-SupAgro, 2 Place Viala, 34060 Montpellier, France.
authors.forename: H
authors.initials: H
authors.lastname: Quiquampoix
authors.affiliation: INRA, UMR Eco&Sols, INRA-IRD-Cirad-SupAgro, 2 Place Viala, 34060 Montpellier, France. Electronic address: staunton@montpellier.inra.fr.
authors.forename: S
authors.initials: S
authors.lastname: Staunton
mesh_terms: D000327:Adsorption; D000818:Animals; D001413:Bacillus thuringiensis; D001426:Bacterial Proteins / Q000032:analysis / Q000633:toxicity; D018556:Crops, Agricultural / Q000378:metabolism; D004731:Endotoxins / Q000378:metabolism; D004784:Environmental Monitoring; D006460:Hemolysin Proteins / Q000378:metabolism; D007313:Insecta / Q000378:metabolism; D007306:Insecticides / Q000032:analysis* / Q000633:toxicity; D007814:Larva / Q000378:metabolism; D018402:Manduca; D010573:Pesticide Residues / Q000032:analysis* / Q000633:toxicity; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; D010573:Pesticide Residues; D012987:Soil
keywords: Adsorption; Bacillus thuringiensis; Persistence; Soil; Toxicity