Scientists have created a bacterium that makes a potential fuel source from sunlight, carbon dioxide and water. The so-called "cyborgs" generate acetic acid, a chemical that can be converted into fuel and plastic.
In laboratory experiments, bacteria were found to be much more efficient at absorbing sunlight than plants. The work was presented at a meeting of the American Chemical Society in Washington.
Researchers have tried to artificially replicate photosynthesis for many years. In nature, the green pigment chlorophyll is the main element of this process. Thanks to sunlight, it helps plants convert carbon dioxide and water into oxygen and glucose. While it works, scientists say the process is relatively ineffective. This is the same problem with most of the artificial systems developed so far.
The new approach aims to improve performance by essentially equipping bacteria with solar panels. After reviewing the old microbiological literature, the researchers realized that some bacteria have a natural defense against cadmium, mercury, or lead, which allows them to convert heavy metals into inorganic sulfides. The transformation results in tiny crystalline semiconductors on the surface of the microorganism.
“It's embarrassingly simple, we have adapted the natural ability of these bacteria, which have never been looked at from this angle,” says Kelsey Sakimoto of Harvard University (USA). “We grow bacteria and inject small amounts of cadmium, and they produce cadmium sulfide crystals that then accumulate outside their bodies. Grow them in a liquid broth and just add small aliquots of cadmium solution, wait a couple of days, and these photosynthetic organisms will appear."
These newly popular bacteria produce acetic acid, essentially vinegar, from CO2, water and light. Their productivity is about 80%, which is 4 times higher than commercial solar panels and 6 times higher than chlorophyll.
Sakimoto believes that these bacteria have advantages over other methods of producing green energy from biological sources. Other technologies for artificial photosynthesis require expensive solid electrodes. Cyborgs, on the other hand, only need huge reservoirs of liquid, which must be in the sun - bacteria reproduce and self-repair themselves, which makes the technology low-waste. It is suitable for rural areas or developing countries.
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The research work was carried out at the University of California, Berkeley. Next, scientists will look for more harmless light absorbers than cadmium sulfide.