Developing an Optimized Cadmium Biosensor for Pseudomonas putida

Presenter: Tiffany Tan

Faculty Sponsor: Lauren Andrews

School: UMass Amherst

Research Area: Chemical and Biomolecular Engineering

Session: Poster Session 6, 4:15 PM - 5:00 PM, Auditorium, A19

ABSTRACT

Heavy metal contamination is a major source of soil and environmental pollution. Common heavy metal pollutants include mercury, cadmium, and lead. Cadmium is the most widespread toxic metal in topsoil worldwide. Cadmium exhibits higher mobility in soil environments which makes it easier for it to be absorbed by and accumulate in plants, where it can enter the food chain.  Current physical or chemical approaches to remediation face several drawbacks such as high cost, creation of secondary pollutants, and being limited to small-scale use. An alternative is bioremediation, which uses living cells and biological processes and can be more economical, less energy-intensive, and scalable. Here, we investigated using synthetic biology approaches to engineer the resilient bacterium  Pseudomonas putida KT2440 to sense and sequester cadmium. To create a cadmium biosensor, we utilized the allosteric transcription factors CadC (P. putida KT2440) and CadR (from P. putida 06909) with designed synthetic promoters for the sensor output. We performed sensor characterization in KT2440 and E. coli with varying the regulator expression. For the biosorption of cadmium, we further designed P. putida KT2440 to express a fusion protein consisting of a membrane surface anchor protein with a fused cadmium-binding domain that is displayed on the cell surface to capture environmental cadmium. Optimization of this biosensor construct will involve the design of synthetic promoter and ribosome binding site libraries to investigate the maximum output of the sensor without being overly toxic to bacteria and further fine tune this sensor. Overall,  this work explores a new strategy to create an optimized soil bacterium for cadmium detection and sequestration.

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