Both cadmium and sulfate can be found in wastewater and, if not removed have a detrimental impact upon the environment, ecosystems and humans. Both cadmium and sulfates can be found in high concentrations in industrial output. This year, our project at iGEM York is focusing on increasing the uptake of cadmium and sulfate in our chosen chassis E. coli. The project has two main, interlinked approaches:

• Firstly, the increased uptake of sulfur using an exogenous sulfate transporter from Bacillus.

• Secondly the increased uptake and chelation of cadmium ions through the use of metal-binding proteins, to produce a potentially recoverable metal product.

The link between these two processes is the cysteine-rich phytochelatins. The phytochelatins we are over-expressing in our chassis are rich in cysteine and as a result, rich in sulfate. Thus our phytochelatins act as a sink for sulfate whilst chelating the cadmium that builds up inside the cell.