Degradation of Cry1Ab Protein Within Transgenic Bt Maize Tissue by Composite Microbial System of MC1

Abstract

Environmental safety issues involved in transgenic plants have become the concern of researchers, practitioners and policy makers in recent years. Potential differences between Bt maize (ND1324 and ND2353 expressing the insecticidal Cry1Ab protein) and near-isogenic non-Bt varieties (ND1392 and ND223) in their influence on the composite microbial system of MC1 during the fermentation process were studied during 2011-2012. Cry1Ab protein in Bt maize residues didn't affect characteristics of lignocellulose degradation by MC1, pH of fermentation broth decreasing at initial stage and increasing at later stage of degradation. The quality of various volatile products in fermentation broth showed that no significant difference of residues fermentation existed between Bt maize and non-Bt maize. During the fermentation MC1 efficiently degraded maize residues by 83%–88%, and cellulose, hemicelluloses and lignin content decreased by 70%–72%, 72%–75% and 30%–37%, respectively. Besides that, no consistent difference was found between Bt and non–Bt maize residues lignocellulose degradation by MC1 during the fermentation process. MC1 degraded 88%–89% Cry1Ab protein in Bt maize residues, and in the fermentation broth of MC1 and bacteria of MC1 Cry1Ab protein was not detected. DGGE profile analyses revealed that the microbial community drastically changed during 1–3 days and became stable until the 9th day. Though the dominant strains at different fermentation stages had significantly changed, no difference on the dominant strains was observed between Bt and non–Bt maize at different stages. Our study indicated that Cry1Ab protein did not influence the growth characteristic of MC1.