Researchers at the University of California Berkeley may have introduced a new era in artificial photosynthesis by devising a way to cover bacteria with cadmium sulfide semiconductor nanocrystals to breakdown carbon dioxide (CO2) into acetic acid, a precursor to a host of other products.
In research that is being presented at the 254th National Meeting & Exposition of the American Chemical Society (ACS), Kelsey K. Sakimoto, a researcher at the lab of Peidong Yang at Berkeley, has demonstrated that the non-photosynthetic bacterium known a moorella thermoacetica can self-assemble itself into nanocrystal-clad cyborgs that essentially supercharges the bacteria into CO2 reduction powerhouses.
One of the natural properties of the bacterium is that it takes CO2 molecules and breaks them down to produce acetic acid. However, another feature of the bacteria is that it is naturally inclined to become a cyborg, so to speak.
“It’s actually a natural, overlooked feature of their biology,” explains Sakimoto in an e-mail interview with IEEE Spectrum. “This bacterium has a detoxification pathway, meaning if it encounters a toxic metal, like cadmium, it will try to precipitate it out, thereby detoxifying it. So when we introduce cadmium ions into the growth medium that M. thermoacetica is hanging out in, it will convert the amino acid cysteine into sulfide, which precipitates out cadmium as cadmium sulfide. The crystals then assemble and stick onto the bacterium through normal electrostatic interactions.”