UCL iGEM Team 2022






Biocrafter: The future of sustainable construction

Climate change is the most pressing problem of our generation, causing ecosystem collapse.

One of the main contributors that has escaped significant public scrutiny is the construction industry, which accounts for 40% of global CO2 emissions, with 8% due to production of cement. To produce cement, fossil fuelled furnaces heat limestone to 1400 ºC to produce various calcium oxides, releasing 600 kg of CO2 for every tonne of cement produced [Wieser et al., 2021].

To tackle this challenge, we engineered Bacillus subtilis to overexpress carbonic anhydrase and urease enzymes. These enzymes produce carbonate ions from atmospheric or waste stream CO2, which when exposed to free calcium form stratified formation of calcite crystals at the bacterial cell outer surface. The precipitated crystalline calcium carbonate acts as the binding agent within our material, giving it properties comparable to concrete.
Using engineered B. subtilis we produced a drop-in replacement of traditional cement and decarbonise this critical industry.









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Concrete is the most used material in the world. It has incredibly high compression strenght and continues to strengthen over the course of decades as it absorbs carbon dioxide from the athmosphere and converts calcium hydroxide into calcium carbonate.
Examples of famous structures made out of concrete include the Hoover Dam, the Panama Canal and, even the tallest building in the world, the Burj Khalifa. The malleablity. durability and ease of maintenance of these constructions highlight why concrete is so attractive to commercial builders.
Currently, potential solutions for the environmental impacts of concrete are introduction of alternative products, changes in use or simply targeting the consequences.
One of the most well studied alternatives 'Lunarcrete' involves using a waterless concrete with sulfur as a binding agent, thereby replacing the need for both the cement mix and water. However, this project has received lots of development for space exploration but fails for terrestrial uses due to sulfur's sensitivity to temperature.
In the meantime, legislation for a carbon control was introduced for instance the EU has committed to a 2026 carbon levy to prevent imports of cement from non-carbon neutral sources. Whilst extremely important, these measures do not solve the issue at hand.
Finally, targeting the consequences of climate change has not been successful as the 2011-2020 period has been labeled the warmest decade on record for the globe.





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