Addressing freshwater environmental issues is the core direction of our project, especially the eutrophication of Dongting Lake.

Eutrophication is a kind of water pollution caused by excessive nitrogen, phosphorus and other plant nutrients. Under natural conditions, with the continuous sedimentation and deposition of alluvial materials and aquatic biological debris in the bottom of the lake, the lake will transition from a poor trophic lake to a rich trophic lake, and then evolve into a swamp and land, which is a very slow process. However, due to human activities, a large amount of industrial wastewater, domestic sewage and plant nutrients from farm runoff are discharged into slow-flow water bodies such as lakes, reservoirs, estuaries and bays, and aquatic organisms, especially algae, will multiply, which will change the species and quantity of biomass population and destroy the ecological balance of water bodies.Water eutrophication will affect water quality, reduce the transparency of water and make it difficult for sunlight to penetrate the water layer, thus affecting the photosynthesis of plants in water, and may also cause the supersaturation of dissolved oxygen, which is harmful to aquatic animals and causes a large number of fish deaths. At the same time, a large number of algae with cyanobacteria and green algae as the dominant species will grow on the surface of eutrophication water body, forming a layer of "green scum", which will cause harmful gases and biotoxins produced by some plankton generated by the decomposition of organic materials at the bottom under anaerobic conditions, and also harm fish. Again, because eutrophication water contains nitrates and nitrites, people and livestock long-term drinking these substances content over a certain standard of water, will also be poisoned.

Dongting Lake, the second largest freshwater lake in China, is located in the middle and lower reaches of the Yangtze River. It has important ecological status such as regulating the flood of the Yangtze River, providing drinking water and protecting biodiversity, and is also one of the key areas of ecological environment protection in the Yangtze River basin. However, with the increase of population in the region, the rapid development of social economy and the construction of water conservancy projects, the excessive input of exogenous nutrients leads to the enrichment of phosphorus in the water body of Dongting Lake and the increasing of phosphorus pollution, which leads to the eutrophication.

Phosphorus is an important chemical element as well as an important chemical raw material, which is widely applied through industrial workmanship. Industrial phosphorus is mainly extracted from phosphate rock, which is a non-renewable resource. In order to meet the needs of production and life, a large amount of phosphorus is put into Dongting Lake, but the excess phosphorus causes a series of environmental problems. Is there a way to solve the contradiction between industrial demand for phosphorus and the eutrophication of Dongting Lake?

To solve the above problems, our team HNU_China designed P Pack, which realize the recycling of phosphate by modified Escherichia coli strain.By regulating the genetic circuit related to phosphate metabolism, P Pack is modified to be a biological phosphorus battery which could release or supply phosphate under our regulation.