Description & Inspiration
Without phosphorus, life is not possible. Being one of the main components of DNA, RNA and cell membrane, phosphorus supports all living things.
Phosphorus fertilizer is essential for modern food production, however, when excessed phosphorus enters the environment, algae proliferate and consume oxygen in the water, consequently aquatic ecosystems are disrupted. Another problem about phosphorus is that it is estimated to be depleted in the near future, so now is the time to think about its recycling.
Our university is surrounded by nature and agriculture, we are familiar with environmental issues. As we consisted of members from various majors, we wanted to work on something related to the environment, and came up with this project.
This year we are solving the environmental and resource problems of phosphorus at the same time by removing the element from wastewater and recycling it. The goal of this project is to engineer E.coli bacteria to have an increased capacity of phosphorus accumulation. We looked into phosphorus metabolism of bacteria and hope to enhance the capacity by increasing the expression of polyphosphate kinase (ppk) and triggering stringent response using relA to decrease exopolyphosphatase (ppx). The advantage of our solution is that by removing extra phosphorus in wastewater more efficiently we can contribute to environmental problems, as well as resource problems by regenerating high-quality phosphorus without containing radioactive elements and other harmful substances.
In the future, the world is expected to experience significant population growth and it will lead to higher demand of phosphorus. Our project plays an important role in making a sustainable society.
When excessed phosphorus enters aquatic environments, it allows algae to grow faster. This is called eutrophication. Increase in algae eliminates oxygen in the water and leads to the death of aquatic lives, resulting in ecological imbalance. Some algae species produce toxins harmful to humans, and also place a burden on drinking water production.
Phosphorus is a finite resource, and its rocks are not evenly distributed around the world. In 2015, world’s total phosphate rock reserves were reported as 223 million t, of which 70% in China, Morocco and America. High quality phosphate rocks with relatively low concentration of heavy metals and radionuclides are estimated to be exhausted in about 125 years. Japan relies on imports for all the phosphorus needs, so securing the sustainable supply is a rising issue.
The main technology for removing phosphorus from wastewater that exists today is the anaerobic method. This is a modification of the standard water treatment method, the activated sludge method, to remove more phosphorus. In the aerobic method, wastewater is mixed with activated sludge, and the microorganisms in the activated sludge take up the phosphorus from the wastewater. It takes advantage of the habits that after the microorganisms release phosphorus from them in an anaerobic state, they take up more phosphorus than the original amount when they are in an aerobic state. This activated sludge is dewatered to reduce its volume, water with a high concentration of phosphorus is discharged, and the MAP method is used for removing phosphorus from the water. The phosphorus removed here turns to a fertilizer.
 Matsubae, K., and Nagasaka, T., (2017). “Use of Unused Resources in Society for Responsible Resource Use” [Translated from Japanese.], Chemistry & Education. 65(1). 4-7.
 Gilbert, N.,(2009). Environment: The disappearing nutrient. Nature. 461(8).716-718.  Matsubae, K. et al.,(2008). Recovery of Artificial Phosphorus Resource from Wastes. Sociotechnology Research. 5, 106-113.
COVID-19 has had a huge impact on our project. Launched in March 2020, we needed to spend almost all of our time online. This is our first time participating in iGEM and had to recruit members, but it was difficult because only a few students have heard about the competition. We couldn’t meet team PIs to ask for advice in person. There was a cluster of the disease at our university, our lab has been closed this season.