Problem
Climate change presents humanity with many challenges, including extreme weather events, disrupted agriculture, and species extinction [1]. There is an urgent need to combat climate change and identify solutions to mitigate its adverse effects. One of the largest contributors to global greenhouse gas emissions is the agricultural sector.
Current solutions
Algae farming has been applied to a wide variety of uses — including biofuel, animal feed, fertilizer, and bioremediation — and has recently gained interest as a greener alternative to conventional agricultural practices. One of the biggest limitations for large-scale microalgae farming is the cost associated with harvesting [2].
Flocculation, the process by which algae clump together, has been shown to be an efficient method for harvesting microalgae [3]; however, it often requires the use of chemicals such as FeCl2 and Al2(SO4)3 to induce flocculation. These chemicals increase cost and present environmental risks.
Our solution
The main goal of iGEM Team Uppsala 2025 is to create a strain of Chlamydomonas reinhardtii, a microalga, capable of auto-flocculation without the use of harsh chemicals. We plan to genetically modify the algae to produce and display specialized flocculation proteins on their surface, promoting aggregation.
To control the timing of aggregation, we will use a salt inducible promoter — a DNA sequence that activates the engineered genes when the salt concentration in the culture medium is changed. This enables deliberate triggering of flocculation when desired.
End product
When these genetically engineered, salt-activated algae encounter each other, they will aggregate and sink to the bottom for subsequent harvesting and processing. This approach avoids the use of harsh chemicals commonly used in the industry today, making microalgae cultivation more affordable and environmentally friendly.