Cell Surface Display of MerR on Saccharomyces cerevisiae for Biosorption of Mercury.

The metalloregulatory protein MerR which plays important roles in mer operon system exhibits high affinity and selectivity toward mercury (II) (Hg2+). In order to improve the adsorption ability of Saccharomyces cerevisiae for Hg2+, MerR was displayed on the surface of S. cerevisiae for the first time with an α-agglutinin-based display system in this study. The merR gene was synthesized after being optimized and added restriction endonuclease sites EcoR I and Mlu I. The display of MerR was indirectly confirmed by the enhanced adsorption ability of S. cerevisiae for Hg2+ and colony PCR. The hydride generation atomic absorption spectrometry was applied to measure the Hg2+ content in water. The engineered yeast strain not only showed higher tolerance to Hg, but also their adsorption ability was much higher than that of origin and control strains. The engineered yeast could adsorb Hg2+ under a wide range of pH levels, and it could also adsorb Hg2+ effectively with Cd2+ and Cu2+ coexistence. Furthermore, the engineered yeast strain could adsorb ultra-trace Hg2+ effectively. The results above showed that the surface-engineered yeast strain could adsorb Hg2+ under complex environmental conditions and could be used for the biosorption and bioremediation of environmental Hg contaminants.