Adsorption of Insecticidal Cry1Ab Protein to Humic Substances. 2. Influence of Humic and Fulvic Acid Charge and Polarity Characteristics

作者：Tomaszewski Jeanne E; Madliger Michael; Pedersen Joel A; Schwarzenbach Rene P; Sander Michael^*

来源：Environmental Science & Technology, 2012, 46(18): 9932-9940.

DOI：10.1021/es302248u

Assessing the fate and potential risks of transgenic Cry proteins in soils requires understanding of Cry protein adsorption to soil particles. The companion paper provided evidence that patch-controlled electrostatic attraction (PCEA) and the hydrophobic effect contributed to CrylAb protein adsorption to an apolar humic acid (HA). Here, we further assess the relative importance of these contributions by comparing CrylAb adsorption to seven humic substances varying in polarity and charge, at different solution pH and ionic strength, I. CrylAb adsorption to relatively apolar HAs at I = 50 mM exhibited rapid initial rates, was extensive, and was only partially reversible at pH 5-8, whereas adsorption to more polar fulvic acids was weak and reversible or absent at pH >6. The decrease in adsorption with increasing HS polarity at all tested pH strongly supports a large contribution from the hydrophobic effect to adsorption, particularly at I = 50 mM when PCEA was effectively screened. Using insect bioassays, we further show that CrylAb adsorbed to a selected HA retained full insecticidal activity. Our results highlight the need to consider adsorption to soil organic matter in models that assess the fate of Cry proteins in soils.

• 出版日期2012-9-18