A new paint harnesses living bacteria to capture carbon dioxide and produce oxygen. The robust “living paint” can withstand harsh conditions, which means it could be used anywhere on Earth to trap carbon.
It produces high levels of oxygen and carbon capture for at least one month despite being completely dried and then rehydrated, researchers from the University of Surrey report in the journal Microbiology Spectrum. Such biocoatings could be further developed for a variety of applications, they say, “including carbon capture, wastewater treatment and biofuel production.”
Bacteria are tiny but powerful workhorses, able to perform complex chemical reactions. By tweaking the genetics of various natural bacteria, researchers have engineered the microbes to produce ammonia, synthesize drugs and fuels, break down plastics, convert waste to fuel, and even produce power.
Research interest in coatings and materials that trap bacteria for various applications has also grown recently. One example is a concrete-like building material containing bacteria that can absorb carbon dioxide and repair tiny cracks in the material. Given the climate crisis, scientists are also trying to harness cyanobacteria, or blue-green algae, which like plants are photosynthetic, able to breathe in carbon dioxide and convert it into different compounds.
Bacteriology professor Suzanne Hingley-Wilson and her colleagues wanted to make a mechanically robust coating that can soak up carbon dioxide and release oxygen. So they turned to a type of cyanobacteria called extremophiles, because they can live in challenging conditions.
Their work is “the revolutionary, first-ever use” of an extremophile cyanobacteria in biocoatings, the team writes. They made a water-based paint with three different cyanobacteria. The challenge was to make the coating porous enough for the cells to be able to breathe, while also being hard and tough.
So the researchers mixed cyanobacteria cells in a solution of tiny latex and clay particles in water. They dried it fully before hydrating it slightly for the bacteria to kick off photosynthesis.
Only one strain, Chroococcidiopsis cubana, remained viable. This bacterium is known to survive in arid conditions, and under high temperatures, salt concentrations, and radiation levels. Biocoatings made with C. cubana captured carbon dioxide and produced up to 0.4 grams of oxygen per gram of biomass per day. The researchers measured oxygen production for over a month and saw no signs of reduced activity.
Source: Simone Krings et al. Oxygen evolution from extremophilic cyanobacteria confined in hard biocoatings. Microbiology Spectrum, 2023.