On Mars or Earth, biohybrid can turn carbon dioxide into new products

If humans ever hope to colonize Mars, the settlers will need to manufacture on-planet a huge range of organic compounds, from fuels to drugs, that are too expensive to ship from Earth.

University of California, Berkeley, and Lawrence Berkeley National Laboratory (Berkeley Lab) chemists have a plan for that.

On Mars or Earth, biohybrid can turn carbon dioxide into new products Onmarsoreart

On Mars or Earth, biohybrid can turn carbon dioxide into new products Onmarsoreart

For the past eight years, the researchers have been working on a hybrid system combining bacteria and nanowires that can capture the energy of sunlight to convert carbon dioxide and water into building blocks for organic molecules. Nanowires are thin silicon wires about one-hundredth the width of a human hair, used as electronic components, and also as sensors and solar cells.

"On Mars, about 96% of the atmosphere is CO2. Basically, all you need is these silicon semiconductor nanowires to take in the solar energy and pass it on to these bugs to do the chemistry for you," said project leader Peidong Yang, professor of chemistry and the S. K. and Angela Chan Distinguished Chair in Energy at UC Berkeley. "For a deep space mission, you care about the payload weight, and biological systems have the advantage that they self-reproduce: You don't need to send a lot. That's why our biohybrid version is highly attractive."

The only other requirement, besides sunlight, is water, which on Mars is relatively abundant in the polar ice caps and likely lies frozen underground over most of the planet, said Yang, who is a senior faculty scientist at Berkeley Lab and director of the Kavli Energy Nanoscience Institute.

The biohybrid can also pull carbon dioxide from the air on Earth to make organic compounds and simultaneously address climate change, which is caused by an excess of human-produced CO2 in the atmosphere.

In a new paper to be published March 31 in the journal Joule, the researchers report a milestone in packing these bacteria (Sporomusa ovata) into a "forest of nanowires" to achieve a record efficiency: 3.6% of the incoming solar energy is converted and stored in carbon bonds, in the form of a two-carbon molecule called acetate: essentially acetic acid, or vinegar.

Acetate molecules can serve as building blocks for a range of organic molecules, from fuels and plastics to drugs. Many other organic products could be made from acetate inside genetically engineered organisms, such as bacteria or yeast.

The system works like photosynthesis, which plants naturally employ to convert carbon dioxide and water to carbon compounds, mostly sugar and carbohydrates. Plants, however, have a fairly low efficiency, typically converting less than one-half percent of solar energy to carbon compounds. Yang's system is comparable to the plant that best converts CO2 to sugar: sugar cane, which is 4-5% efficient.

Yang is also working on systems to efficiently produce sugars and carbohydrates from sunlight and CO2, potentially providing food for Mars colonists.

https://phys.org/news/2020-03-mars-earth-biohybrid-carbon-dioxide.html

On Mars or Earth, biohybrid can turn carbon dioxide into new products

On Mars or Earth, biohybrid can turn carbon dioxide into new products

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