MP5 Agrochemicals and Pesticides
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(PRI-1117-838891) Examination of the fate of Bt Cry3Bb1 protein in aerobic and anaerobic aquatic systems.

Prihoda, K¹, Coats, J¹, ¹ Iowa State Universtiy Pesticide Toxicology Laboratory, Ames, IA, USA

ABSTRACT- Transgenic crops containing Bacillus thuringiensis (Bt) insecticidal proteins were introduced to the agricultural market in 1996. Despite increasing worldwide usage, relatively little is known regarding Bt protein fate in the environment. Persistence and movement of Bt proteins are important parameters governing exposure to non-target organisms, however, there have been few studies thus far examining the fate of Bt proteins from transgenic crops in the aquatic environment. There is potential for transport of Bt proteins into aquatic environments via runoff/wind erosion of crop residue and protein bound to soil particles. In two laboratory experiments, microcosms were used to investigate the fate of the beetle-active Cry3Bb1 protein in an aerobic or anaerobic aquatic system. Sediment and water samples were collected from Iowa State University Horticulture Research Field Station Pond (Gilbert, IA). In each experiment (aerobic or anaerobic), either purified Cry3Bb1 protein, ground corn material containing Cry3Bb1 protein, or ground corn material of the nearest isoline was added to the sediment/water system. The aerobic experiment had seven time-points (0, 1, 3, 7, 14, 21, and 30 days). The anaerobic experiment had six time-points (0, 30, 60, 90, 180, and 360 days); methylene blue was used to confirm the anaerobicity of the system. At each time point, six microcosms were removed from each experiment and dissolved oxygen, pH, hardness, and alkalinity of the water were measured. Bt concentration in the water was measured using enzyme-linked immunosorbent assay (ELISA). The sediment was sieved to remove any remaining corn material. The sediment and remaining corn material were extracted using a high-salt buffer and analyzed using ELISA. The half-life of the Bt protein and the measured dissipation curve observed in these studies will be presented.

Key words: Bacillus thuringiensis, aquatic, fate