We believe our project Rare-Earth Enrichment By Optimized Tools(REEBOT) will achieve its goal for the following reasons:

The whole circuit we build is based on the paper showed in JACS: Engineering Bacterial Two-Component System PmrA/PmrB to Sense Lanthanide Ions. In this paper we found that PmrA/PmrB two component systems could be used as triggers to start gene expression.

Moreover, we find it is possible to build up the whole circuit due to our experimental results.

1.SDS-PAGE shows that the OprF-3* LBT(in this experiment we use OprF-3* LBT 4 as example), OprF-Sitag can be expressed on the surface of the e.coli.

2. Then we did immunofluorescence detection to figure out whether the cell surface display system works or not. According to Figure 3, the cell surface display of our LBTs is successful.

3. Then we used Precipitation titration detection for further verification by adding different concentration of terbium ions.

The amount of precipitation in WT group(with distilled water being added) is much less than that in the test group. This huge difference in precipitation means capture part can recollect rare earth ions.

To be more convincing, we also did a precipitation-dissolving titration with hydrochloric acid.

Compared with control group, test group has significantly reduced the concentration of Tb3+ in the water. Our capture part really works.