Toward Bioremediation of Methylmercury Using Silica Encapsulated Escherichia coli Harboring the mer Operon

PLoS One. 2016 Jan 13;11(1):e0147036. doi: 10.1371/journal.pone.0147036. eCollection 2016.

Abstract

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 non-encapsulated 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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biodegradation, Environmental*
  • Disk Diffusion Antimicrobial Tests
  • Drug Resistance, Neoplasm
  • Escherichia coli / drug effects
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism*
  • Methylmercury Compounds / metabolism*
  • Methylmercury Compounds / pharmacology
  • Microspheres
  • Operon*
  • Silicon Dioxide*

Substances

  • Methylmercury Compounds
  • Silicon Dioxide

Grants and funding

This project was supported by the Office of Naval Research (Award N000141210309 to JAG) and the University of Minnesota MnDRIVE initiative: Advancing industry, conserving our environment (https://mndrive.umn.edu/environment). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.