Date created: | Last Updated:

Category: Project

Description: Lakes and coastal regions are increasingly threatened by harmful algal blooms driven by high concentrations of phosphorus, often from domestic and agricultural fertilizers. Algal blooms decrease water quality, interrupt the function of critical infrastructure, and harm businesses reliant on affected bodies of water, disturbing both the environment and the economy. Still, despite the damage that excess phosphorus can cause, phosphorus is a limited resource and a vital nutrient required for agriculture. To improve phosphate management, we developed a strain of modified Escherichia coli that can accumulate and store large amounts of phosphorus, while also being able to release stored phosphorus in a controlled manner. As E. coli is both robust and easy to engineer, a phosphorus management system utilizing E. coli can be used in a wide range of environmental conditions and can be adapted to meet the specific needs of each application scenario and environment. To create our system, we identified genes putatively responsible for phosphate uptake, storage, and preparation for exportation in the polyphosphate-accumulating organism Microlunatus phosphovorus. We then transformed these genes into E. coli to characterize functions of these previously uncharacterized proteins. Concurrently, we built a bioreactor and designed a suite of cost-effective phosphorus reclamation modules around xerogel-immobilized cells for contained, multipoint phosphate bioremediation. Xerogel beads are a porous glass matrix which entrap cells but allow water, phosphates, and other nutrients to flow through. Characterization of the exopolyphosphatase (PPX2) homolog revealed that PPX2 leads to increased phosphorus release, and preliminary characterization of the polyphosphate kinase 2 (PPK2) homolog C suggests that PPK2 homolog C is potentially responsible for polyphosphate hydrolysis. Through applied genetic, chemical, and mechanical engineering principles we expect to provide a means for preventing harmful algal blooms in both developed and developing countries while also recovering phosphorus for later agricultural use.