Bacteria designed like corals to achieve carbon-neutral cement production

By mimicking the way corals capture CO2 in the ocean, researchers have designed bacteria that can help the construction industry reduce CO2 emissions.

Bacteria designed by researchers can help solving one of the big CO2 challenges in the construction industry. Photo: Thomas Steen Sørensen
Bacteria designed by researchers can help solving one of the big CO2 challenges in the construction industry. Photo: Thomas Steen Sørensen

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Corals as a source of inspiration

The ambition to find a circular solution to capture CO2 from a polluting industry is far from unique. But the technology the researchers are working on is very unique and not yet patented.

“Other biologists typically try to design bacteria that mimic photosynthesis, in which plants capture CO2 from the air and convert it into sugar. The problem is that this is very difficult to do. That’s why we chose to say: Forget about plants! We want to mimic corals,” says Professor Ivan Mijakovic, who is head of the group and came up with the original idea for the project.

Just as plants on land capture CO2 from the air, the ocean’s corals also capture CO2 when they are building the elaborate structures we know as coral reefs. The CO2 is captured in maritime construction, so to speak, which is made of calcium carbonate, just like cement.

“We have genetically engineered the bacteria to behave like ocean corals. Our bacteria also grow under water, and when the solution is to be scaled up, the cell factory inside the bioreactor will also have to be liquid,” says Ivan Mijakovic.

The researchers can already say now that this sets special requirements for the bioreactor. Because while the cell factory is liquid, the calcium carbonate formed in the reactor is a solid material. In the design phase, it is therefore important to take into account the fact that the solid limestone will need to be transported easily and efficiently out of the reactor.


Huge potential

So far, the solution has only been proven effective in the laboratory, which means that lots of testing is still required to create more results before the researchers can proceed to an actual scale-up.

The main challenge is making the bacteria tough enough to withstand the harsh environment and high temperatures they will be subjected to in the industry. If the researchers succeed with the project, the potential is huge.

“We’ve created a product that can initially be extremely valuable for the construction industry. But since we can create calcium carbonate with our bacteria, we can also create other carbonates that can be used in, for example, the pharmaceutical industry or the papermaking industry. The potential really is huge,” says Colleen Manyumwa.

Although there is still a long way to go from the microorganisms in the laboratory to the final goal, she finds motivation in the big picture of her research.

“Innovation is always challenging, and some days are definitely easier than others. But I believe that within a few years, this solution will exist as one of several solutions to remove CO2 from the atmosphere and help slow down climate change,” she says.

CO2 emission in the construction industry

• Every year, 36 billion tonnes of CO2 are released into the atmosphere globally.

• In 2021, 2.9 billion tonnes of CO2 were emitted through the construction industry’s cement production, corresponding to more than seven percent of the total global CO2 emissions.

• Figures from CICERO (Center for International Climate Research and the Global Carbon Project) show that global CO2 emissions from the construction industry’s cement production have doubled over the past 20 years.