Scientists have developed so-called ‘cyborg’ bacteria that mimic the natural photosynthesis of leaves to renewably generate food, fuels and plastics using only sunlight.
The bacteria, which are covered in minute semiconductors that serve as tiny solar panels, function in much the same way as natural leaves, but in a far more efficient manner.
“Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” explained Dr Kelsey K Sakimoto, who undertook the research in Dr Peidong Yang’s lab at the University of California, Berkeley. “These nanocrystals are much more efficient than chlorophyll and can be grown at a fraction of the cost of manufactured solar panels.”
The research, which is being presented today at the 254th National Meeting & Exposition of the American Chemical Society has the potential to be developed into a valuable alternative to fossil fuels.
“Once covered with these tiny solar panels, the bacteria can synthesize food, fuels and plastics, all using solar energy,” said Sakimoto. “These bacteria outperform natural photosynthesis.”
The research involved taking a natural bacterium, Moorella thermoacetica, which is not conventionally capable of photosynthesis, and feeding it chemicals that it synthesised to augment its capabilities.
As the bacterium naturally produces acetic acid from CO₂, introducing other genetically engineered bacteria can enable it to produce fuels, polymers and even pharmaceuticals. In this case, Sakimoto fed it both cadmium and cysteine, an animo acid that contains sulphur, causing the bacteria to synthesis cadmium sulphide nanoparticles on its surface: the tiny solar panels that allow it to beat leaves in photosynthesising.
“The thrust of research in my lab is to essentially ‘supercharge’ nonphotosynthetic bacteria by providing them energy in the form of electrons from inorganic semiconductors, like cadmium sulfide, that are efficient light absorbers,” explained Dr Peidong Yang. “We are now looking for more benign light absorbers than cadmium sulfide to provide bacteria with energy from light.”
While the bacteria has only been developed in a lab setting, with an 80% efficiency, if it can be developed into a commercial product, it has the potential to be a hugely impactful technology in the transition away from fossil fuels.
“Synthetic biology and the ability to expand the product scope of CO₂ reduction will be crucial to poising this technology as a replacement, or one of many replacements, for the petrochemical industry,” said Sakimoto.
Other research has been previously undertaken to produce artificial leaves, which many hope could be used to form future decentralised power plants, however this research offers a significant improvement that could give it a much higher chance of being commercialised.
“Many current systems in artificial photosynthesis require solid electrodes, which is a huge cost,” explained Sakimoto. “Our algal biofuels are much more attractive, as the whole CO₂-to-chemical apparatus is self-contained and only requires a big vat out in the sun.”