Adsorption of CrylAb Protein Isolated from Bt Transgenic Rice on Bentone, Kaolin, Humic Acids, and Soils

摘要

Adsorption on a soil matrix of the insecticidal protein from Bacillus thuringiensis (Bt) transgenic plants affects their accumulation and release and, hence, bioavailability in soil. CrylAb protein isolated from Bt transgenic rice was used to evaluate the adsorption and desorption on bentone, kaolin, and humic acids (HAs). The adsorption equilibrium of CrylAb protein was reached within 1 -2 h for bentone and kaolin and within 4-8 h for HAs. The adsorption isotherms were better described by linear expressions (R~2 ≥ 0.973) rather than by the Freundlich model. No saturation was observed, even at the maximum concentration used (3.71 μg mL~(-1)). The adsorbed protein was not easily desorbed at the used protein concentrations (0.18-3.71 μg mL~(-1)); more than 50-70%, 70-80%, and 90% of the adsorbed protein remained on HAs, kaolin, and bentone, respectively, after washing with water. Adsorption and desorption of the CrylAb protein were further studied using five soils, and the isotherms were also well-described by linear equations (p < 0.05). Adsorption of the CrylAb protein on soils was positively related to the soil organic matter content.