Nano-creatures that consume light and carbon dioxide and produce plastic and fuel

Researchers have succeeded in transforming bacteria into nano-bio-hybrid organisms capable of consuming carbon dioxide and nitrogen in the air and producing a variety of plastics and fuel from them - a promising first step towards cheap carbon capture and environmentally friendly production of chemicals

The researchers used quantum dots (A particle of nanometer size, made of a semiconductor, in which there is a quantum demarcation) are exposed to light in order to activate specific enzymes inside bacterial cells and have succeeded in creating "living factories" capable of consuming harmful carbon dioxide and converting it into useful products such as biodegradable plastic, gasoline, ammonia and even biodiesel.

"The invention is a testament to the power of biochemical processes," said Prashant Nagpal, lead author of the paper describing the study, a professor in the Department of Chemical and Biological Engineering at the University of Colorado. "We are testing a method that can improve the degree of capture of carbon dioxide, with the aim of fighting climate change, and perhaps, one day, a method that can replace existing production methods of plastic and fuel that are high in carbon."

The project began back in 2013, when the team of researchers began testing the extended capability of nanoscopic quantum dots, which are tiny semiconductors similar to those used in television screens. Quantum dots can be tolerably injected into cells and programmed to self-assemble and bind to defined enzymes and then be activated on command using defined wavelengths of light radiation. The researchers wanted to know if quantum dots could be used as a kind of spark that could activate specific enzymes found inside bacterial cells, enzymes that are able to convert carbon dioxide and nitrogen carried in the open air into other useful substances, but do not normally do this due to their inability to assimilate light (photosynthesis ). By injecting engineered dots into the cells of common strains of bacteria found in the soil, the researchers were able to bridge this gap (the inability to assimilate light). Now, exposure to even small amounts of sunlight will activate the bacteria's "appetite" for carbon dioxide, without the need for an additional source of energy or food in order to carry out the high-energy biochemical conversions. "Each cell produces millions of these chemicals and we were able to demonstrate that they can do this at twice the rates that exist in nature," said the lead researcher.

The bacteria, which are in a dormant state in the water, release the product they produce to the surface of the water, where it can be collected and used for the various production processes. Different combinations of points and wavelengths give rise to different products: wavelengths in the green color range cause bacteria to consume nitrogen and create the substance ammonia; Whereas wavelengths in the red color range cause bacteria to consume carbon dioxide and create plastic. The process also shows promising signs that it could be scaled up to an industrial process on a larger scale. The study found that even when the bacterial factories were activated continuously for several hours at a time, they showed little signs of decay or depletion, a fact indicating that the cells could be reactivated, and therefore the need to renew them in an additional quantity would be reduced. "We were very surprised to find that the method worked as effectively as it did," says the lead researcher. "We are just beginning to discover the synthetic applications of our new method."

The best future scenario, the lead researcher explains, is one in which homes and businesses would flow their carbon dioxide emissions directly into a nearby catchment pond, where bacteria would convert those emissions into useful bioplastics. These products will be able to be sold at a low cost while reducing their carbon footprint. "Although the profit margins are low and the prices are not competitive in terms of basic cost, the social benefit of this method is still growing," said the researcher. "Even if we convert even a small part of the quantities in local landfills, this will have a significant impact on the cities' carbon emissions. This will not be a harsh decision on the residents. Many of the residents are already making beer at home, for example, and this operation is no longer complicated."

The goal now, says the lead researcher, is to improve the conversion process and make this research a required course in the undergraduate studies of chemical engineers and chemists. The research findings were published in the scientific journal Journal of the American Chemical Society.
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