We’ve built the endosymbiotic system to clean up cadmium contamination. The engineered organism can collect cadmium ion in the soil and can be easily gather together; moreover, the device won’t become another pollution source to our environment.
Cadmium contamination is a serious problem in many countries; cadmium can cause respiratory system damage, renal failure, bones softening, and, maybe the most infamous case in Asia, Itai-itai disease. The rice absorbed the cadmium in the soil and the cadmium accumulated in the people eating contaminated rice. The aim of our project is to build up a system that can collect Cadmium ion in the soil and can be easily gather together; besides, we don’t want our device become another pollution source to our environment. We found that the endosymbiotic system between the soil-living amoeba Dictyostelium discoideum and E.coli would be our favorite solution.

Cadmium ions were absorbed by amoeba then accumulated inside of E.coli

Why Dictyostelium discoideum

Dictyostelium discoideum is a soil-living amoeba, so it is a good choice to collect cadmium ion in soil. In addition, the amoeba naturally has endosymbiont inside the cell. The E.coli living in amoeba accumulates cadmium ions, just like an organelle, the E.coli acts as a compartment preventing its host from cadmium poisoning. Furthermore, keeping the E.coli inside the amoeba avoid unexpectedly gene exchange between engineered E.coli and other wild types bacteria. Moreover, Dictyostelium discoideum chemotaxis is well-studied and can be easily gather by adding cAMP.

Single cell amoeba Dictyostelium discoideum gathered when cAMP was added.