Missouri University of Science and Technology iGEM Team 2017
Plant-based biosensors have immense benefits over analytical chemistry or potentiometric techniques for a variety of reasons. Plants have an inherent biological property of taking up chemicals over time and have access to a large sample of groundwater, which allows them to be more accurate than many market available testers - which often do not test for particulates or at very low concentrations. A biosensor has the added benefit of not compromising ease of use when increasing accuracy. When an appropriate indicator is selected, the average person should be able to look at a plant and immediately notice that a contaminant is present.
Our team selected Arabidopsis as the system for our biosensor and trichloroethylene, or TCE, as our first contaminant of interest. Trichloroethylene is the most common groundwater contaminant in the United States, contaminating between 9 and 34% of drinking water in the US. TCE has been classified as a carcinogen; many of its biological metabolites are highly reactive and have cancerous effects to specific organs. A plant that could be placed outside of factories possibly releasing TCE, or even a house plant to be watered by from the tap drinking water, could prove to be a powerful agent in reducing the amount of TCE consumed by humans.
Though we focused first on TCE, ideally our system could spread to a variety of groundwater or drinking water contaminants. The system is based on important developments in biosensors, namely the creation of synthetic signal transduction systems in plants and the redesign of natural periplasmic binding proteins for the detection of new ligands. So simply, a plant is exposed to contaminated water, a designed periplasmic binding protein binds that protein, a signal transduction pathway causes a reporter piece of DNA to be triggered, which in our case will lastly de-green the plant, meaning that the plant will turn almost clear when exposed to the contaminant. This will become obvious to any observer, and they can then begin to take the next necessary precautions.