Cyborg Bacteria Turn Carbon Dioxide Into Chemicals and Fuels With Zero Waste

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Promo image. Kelsey K. Sakimoto

The word cyborg was invented when we started to imagine giving people super-human capabilities by integrating mechanical or electrical equipment into biological systems. Think of Darth Vader, Iron Man, or the 6 Million Dollar Man as concept studies.

Implants and exoskeletons already show great promise in delivering on the dream of cyborg super powers. But take a step back from the action-film excitement and think about it: the real dream consists of harnessing the miracle of biological capabilities to the power and efficiency we can develop with technology.

And with all the ethical dilemmas involved in turning humans into quasi-robots, it should be no surprise that some of the exciting advances inspired by the idea of cyborgs don't upgrade humans. Instead, scientists have turned to Moorella thermoacetica, a bacteria that resides at the bottom of very still swamps, silently breathing in carbon dioxide and excreting acetic acid (the acid in vinegar), which is a remarkably useful chemical that could be reacted into other valuable resources like fuels, drugs, or plastics.

Scientists have helped the M. thermoacetica turn itself into a bionic hybrid, by feeding the bacteria cadmium and the amino acid cysteine, from which a sulfur atom can be harvested. The bacteria make these feedstuffs into cadmium sulfide nanoparticles, which soon cover the surface of the bacteria.

The M. thermoacetica usually eat sugars as a power source for their production of acetic acid, and they do not perform any photosynthesis. But the new bacteria cyborgs, which they are calling M. thermoacetica-CdS, can use the light-absorbing Cd-S particles like little solar cells. Thus powered, the bacteria can produce acetic acid from CO2 and water, at "quantum efficiencies above 80%."

The beauty of biological systems really comes to light in this discovery: because the bacteria are living organisms, the system is self-replicating and self-regenerating, which make this a zero-waste system. The process also seems to offer advantages in a world that will be looking for good solutions for using up carbon dioxide and getting away from fossil fuels.

Little wonder then, that when a bunch of scientists gather for the 254th National Meeting & Exposition of the American Chemical Society (ACS), these miniature cyborgs (and their inventors) will be headliners. There is still more work to do to make the bacteria cyborgs a viable commercial proposition, but the idea will certainly inspire new ways we can turn sunlight into the fulfilling the needs of future humans, whether we become cyborgs or not.