Missouri University of Science and Technology iGEM Team 2017

We aim to harness the passive accumulation of soil and groundwater contaminants in plants for the detection of pollutants. Plant-based biosensors have immense benefits over analytical chemistry or potentiometric techniques because they continuously sample a large volume of the environment, provide warning to laypeople, and achieve the amazing specificity and sensitivity of biomolecules. We are developing two approaches to biosensing contaminants with plants. Trees' uptake of pollutants through extensive root systems is currently utilized for groundwater monitoring by analyzing cores taken out of trees in a laboratory. Our engineered Escherichia coli would live off tree sap in a filtered insert to these holes and change color through a chromo- or fluorescent protein when the pollutant is detected in the tree tissue. Meanwhile, our standalone Arabidopsis thaliana plants would signal the presence of a pollutant by degrading its green chlorophyll and expressing a chromo- or fluorescent protein. Both systems are based on important developments in biosensors, namely the creation of synthetic signal transduction systems in bacteria and plants and the redesign of natural periplasmic binding proteins for the detection of new ligands. Taken together, these advances could allow a computationally-designed periplasmic binding protein which binds a contaminant of interest extracellularly to transfer the signal through a phosphorylation cascade and produce a transcriptional response. We will create circuits to implement these synthetic signal transduction systems, attempt to computationally design periplasmic binding proteins for new ligands, and test the efficacy of our two biosensing approaches. We hope our final systems will strongly transcribe our reporter in an orthogonal detection which is obvious to the eye.