Hg-binding peptide decreases mercury ion accumulation in fish through a cell surface display system.

Mercury is a potentially toxic trace metal that poses threats to aquatic life and to humans. In this study, a mercury-binding peptide was displayed on the surface of Escherichia coli cells using an N-terminal region ice nucleation protein anchor. The surface-engineered E. coli facilitated selective adsorption of mercury ions (Hg) from a solution containing various metal ions. The Hg adsorption capacity of the surface-engineered cell was four-fold higher than that of the original E. coli cells. Approximately 95% of Hg was removed from solution by these whole-cell sorbents. The transformed strains were fed to Carassius auratus, so that the bacteria could colonize fish intestine. Engineered bacteria-fed C. auratus showed significantly less (51.1%) accumulation of total mercury when compared with the group that had not been fed engineered bacteria. The surface-engineered E. coli effectively protected fish against the toxicity of Hg in aquatic environments by adsorbing more Hg. Furthermore, the surface-engineered E. coli mitigated microbial diversity changes in the intestine caused by Hg exposure, thereby protecting the intestinal microbial community. This strategy is a novel approach for controlling Hg contamination in fish.