Team:UMaryland/Description
What is PhosphoREUSE?
UMaryland iGEM’s 2021 project, PhosphoREUSE, uses synthetic biology to solve the problem of phosphorus pollution in water. The project uses engineered Escherichia coli with genes from the phosphorus accumulating organism Microlunatus Phosphovorus.
The phosphorus recycling system created in E.coli has three main objectives
- Uptake phosphorus from water
- Store phosphorus as a polyphosphate chain
- Cleave terminal phosphorus from chain for subsequent export from the cell
The project also focuses on the implementation of the E.coli as it would be applied to agricultural workers. The engineered E.coli would be encapsulated in silica gel beads in order to prevent interaction with the water. The silica gel beads would be housed in a bioreactor system that would allow the agricultural worker to obtain the phosphorus and reuse it as a fertilizer.
How did PhosphoREUSE come about?
The UMaryland iGEM team decided that one of its project goals was to solve a problem close to home this year. One of the greatest natural resources in the state of Maryland is the Chesapeake Bay. For this reason, the team decided that our project should tackle an environmental project that would help restore the Bay.
One of the greatest problems that plagues the Chesapeake Bay is excess phosphorus from agricultural runoff. The phosphorus allows for dangerous amounts of algae to grow, known as algal blooms. These blooms block sunlight from reaching the bottom of the Bay and deplete the amount of nutrients that reach the floor of the Bay. For this reason, many species such as crabs and oysters are experiencing population instability. This phenomenon is known as eutrophication1.
So now UMaryland had a problem to solve, but what came next?
When looking through existing synthetic biology solutions to eutrophication problems, the team was drawn to iGEM Purdue’s 2016 project.The project accomplished the characterization of many of the Microlunatus Phosphorus genes that would be useful in a phosphorus recycling system. Those genes included:
- PPK1, PPK2 (homologs A, B, C): polyphosphate kinases
- PitA, PitB, PitC: inorganic phosphorus transporters
- PPX2: responsible for hydrolysis of terminal phosphate of polyphosphate chain
Although the team achieved some characterization, there was still more work to be done to develop a novel phosphorus recycling system. For this reason, UMaryland decided to test the same genes, but in a combinatorial approach. This may create a better system that would enhance mechanisms of phosphorus uptake, storage, and release from the cell.
The following plasmids were tested and constructed:
UMaryland also wanted the synthetic biology phosphorus recycling solution to focus on the controlled release of phosphorus from the cell. For this reason, the Pit functional gene group were regulated by the pLac promoter and the PPX2 functional gene group was regulated by the pBAD promoter.