Mercury is a highly toxic heavy metal and the ability of the neurotoxin methylmercury to biomagnify in the food chain is a serious concern for both public and environmental health globally. Because thousands of tons of mercury are released into the environment each year, remediation strategies are urgently needed and prompted this study. To facilitate remediation of both organic and inorganic forms of mercury, Escherichia coli was engineered to harbor a subset of genes (merRTPAB) from the mercury resistance operon. Protein products of the mer operon enable transport of mercury into the cell, cleavage of organic C-Hg bonds, and subsequent reduction of ionic mercury to the less toxic elemental form, Hg(0). E. coli containing merRTPAB was then encapsulated in silica beads resulting in a biological-based filtration material. Performing encapsulation in aerated mineral oil yielded silica beads that were smooth, spherical, and similar in diameter. Following encapsulation, E. coli containing merRTPAB retained the ability to degrade methylmercury and performed similarly to nonencapsulated cells. Due to the versatility of both the engineered mercury resistant strain and silica bead technology, this study provides a strong foundation for use of the resulting biological-based filtration material for methylmercury remediation.
Bibliographical noteFunding Information:
This project was conducted by the 2014 iGEM team at the University of Minnesota and was supported by the Office of Naval Research (Award N000141210309 to JAG) and the University of Minnesota MnDRIVE initiative: Advancing industry, conserving our environment. We would like to thank Dr. Anne Summers (University of Georgia) for providing pDU1358, safety protocols, and project guidance. We would also like to thank Professor Alptekin Aksan and Dr. Baris Mutlu (University of Minnesota) for initial discussions concerning encapsulation protocols, and Gail Celio (University of Minnesota Imaging Center) for assistance with microscopy.
© 2016 Kane et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.