Team:Linkoping Sweden
Project background
Although approximately 70% of our planet is covered in water, only 2.5% of that amount is freshwater. Of that, only 1% is available for use with the rest being contained in glaciers and snowfields. That leaves 7.9 billion people with access to only 0.025% of the earth's water resources where agriculture accounts for 70% of the current freshwater withdrawals. The freshwater shortage is already apparent in all parts of the world and given that the world population will keep increasing leading to an expansion in integrated agriculture, the freshwater crisis will get even more severe. The world is in urgent need for an energy efficient and economical solution to the freshwater crisis.
Current desalination solutions
Currently, there are several methods for desalinating seawater and brackish water that have been developed as a solution to the freshwater crisis. The most commonly used methods are multi-effect distillation, multistage flash, vapour compression, and reverse osmosis. Although these methods are effective, some of the methods either require large amounts of non-renewable energy or are significantly more expensive. This means that none of the available methods can offer an environmentally and economically sustainable solution. The aim with CyaSalt is to provide a desalination method that is both environmentally and economically sustainable, giving people access to freshwater regardless of social status.
Desalination
CyaSalt is a desalination method that utilizes halophilic and phototrophic organisms to create freshwater for agricultural use. By expressing the inward-directed chloride pump halorhodopsin and the cation channel channelrhodopsin, the phototrophs will import sodium and chloride ions from the surrounding seawater. Halorhodopsin and channelrhodopsin are both activated by light, and when activated by light halorhodopsin allows chloride ions to move into the cell against the concentration gradient. The chloride ion influx caused by halorhodopsin creates a negatively charged membrane potential, which will cause the sodium ions to migrate into the cell through channelrhodopsin.
Separation
After the phototrophs have imported the sodium and chloride ions into the cell, the phototrophs are going to be separated from the desalinated water. To achieve that, the phototrophic organisms will express a cellulose binding domain (CBD) on the surface of the cell. CBD has a strong affinity for cellulose, which enables separation of the cells from the water by filtering the water and phototroph mixture through a cellulose based filter. This results in desalinated water ready to be used in agriculture.
Implementation
The ultimate goal is to be able to implement our desalination method on an industrial scale, where the ultimate users are within the agricultural industry. The desalination construct would consist of a simple setup where the seawater would be accessed directly from the sea through a pump. The water would be collected in a separate container where the modified phototrophic organisms are added to initiate the desalination process. The phototrophs would be cultivated by the natural sunlight and the nutrients in the seawater. Once the water has been desalinated, the water would flow through a filter to isolate the phototrophic organisms from the water, and finally enter a second tank where the desalinated water would be stored and used within agriculture.
Did you know?
Cyanobacteria are thought to be the first organisms to evolve and develop photosynthesis.
Did you know?
Cyanobacteria are found all over the world, even in extreme environments like deserts and hot springs.
Did you know?
Spirulina tablets are a dietary supplement made from two species of cyanobacteria.
In the Lab
Read more about how we worked with our project CyaSalt in the lab. And visit our lab pages to read about the results we obtained.
Human Practices
Public opinion is highly valued within our group. Therefore we have a human practices team that aims to reach out to various parts of the community and people within the field to raise awareness and gain knowledge.
The Team
We are a group of students from the University of Linköping in Sweden who have joined together to compete in an international competition in synthetic biology, iGEM.
Modeling
To complement our wet-lab work, we created a model that impacted the direction of our project.