Transport and instream removal of the Cry1Ab protein from genetically engineered maize is mediated by biofilms in experimental streams

• Published in: PloS one 2019-05, Vol.14 (5), p.e0216481-e0216481
• Main Authors: Shogren, Arial J, Tank, Jennifer L, Rosi, Emma J, Dee, Martha M, Speir, Shannon L, Bolster, Diogo, Egan, Scott P
• Format: Article
• Language: English
• Subjects: Algae; Animals; Aquatic habitats; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biofilms; Biology and Life Sciences; Carbon; Chlorophyll; Corn; Creeks & streams; Crop residues; Crops; Decomposition; Detritus; Disease Resistance - genetics; Dissolved organic carbon; Earth Sciences; Ecology and Environmental Sciences; Ecosystems; Endotoxins - genetics; Endotoxins - metabolism; European corn borer; Experiments; Genetic aspects; Genetic engineering; Genetically engineered foods; Genetically modified crops; Genetically modified organisms; Harvesting; Hemolysin Proteins - genetics; Hemolysin Proteins - metabolism; Internet; Moths; Organic carbon; Physical Sciences; Plants, Genetically Modified - genetics; Plants, Genetically Modified - growth & development; Plants, Genetically Modified - parasitology; Proteins; Receiving waters; Research and Analysis Methods; Streams; Substrates; Transport; Water; Water circulation; Water column; Water transportation; Water treatment; Waterways; Zea mays - genetics; Zea mays - growth & development; Zea mays - parasitology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0216481

The majority of maize planted in the US is genetically-engineered to express insecticidal properties, including Cry1Ab protein, which is designed to resist the European maize borer (Ostrinia nubilalis). After crop harvest, these proteins can be leached into adjacent streams from crop detritus left on fields. The environmental fate of Cry1Ab proteins in aquatic habitats is not well known. From June-November, we performed monthly short-term additions of leached Cry1Ab into four experimental streams with varying benthic substrate to estimate Cry1Ab transport and removal. At the start of the experiments, when rocks were bare, we found no evidence of Cry1Ab removal from the water column, but uptake steadily increased as biofilm colonized the stream substrate. Overall, Cry1Ab uptake was strongly predicted by measures of biofilm accumulation, including algal chlorophyll a and percent cover of filamentous algae. Average Cry1Ab uptake velocity (vf = 0.059 ± 0.009 mm s-1) was comparable to previously reported uptake of labile dissolved organic carbon (DOC; mean vf = 0.04 ± 0.008 mm s-1). Although Cry1Ab has been shown to rapidly degrade in stream water, benthic biofilms may decrease the distance proteins are transported in lotic systems. These results emphasize that once the Cry1Ab protein is leached, subsequent detection and transport through agricultural waterways is dependent on the structure and biology of receiving stream ecosystems.