We’re getting closer to being able to grow food in the dark

Its first results are encouraging. In the dark, the researchers grew lettuce tissue in a liquid suspension containing acetate, confirming that it can absorb and metabolize an externally supplied carbon source.

And when they grew whole lettuce plants in the light (along with rice, canola, tomatoes, and other crop species), feeding them extra acetate, they found that the plants incorporated acetate in their tissues. Acetate labeled with a heavy carbon isotope, called carbon-13, could be traced back to both amino acids and sugars, suggesting that plants can use it to support a variety of metabolic processes.

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However, the study did not show that whole plants can be grown on acetate without access to sunlight; in fact, the researchers’ experiments with lettuce indicated that too much acetate inhibits plant growth. Jinkerson says his lab is currently working on genetic engineering and breeding plants to be more acetate tolerant. This will be necessary for the team’s artificial photosynthesis method to contribute significantly to plant growth and food production.

Emma Kovakagriculture and food analyst Revolutionary Institute, says the authors’ findings represent a “first step toward the potential use of acetate to help feed plants for indoor production.” This could reduce the energy needed to run indoor farms if it allows growers to reduce indoor light levels. But “massive progress would be needed,” says Kovak, to allow plants to grow robustly using acetate, even in low light conditions.

Evan Groover, a synthetic biology doctoral student at the University of California, Berkeley, whose research focuses on genetically modifying plants to enhance photosynthesis, agrees. The study “shows that plants can take up acetate, but it doesn’t show that they are able to thrive or synthesize food, fuel or medicine in any meaningful way,” Groover said. Achieving the latter, he says, would require “complete plant reprogramming”.

At the same time, Groover says he finds the authors’ article “inspiring.”

“It shows us how we could capture light and carbon in extraterrestrial, non-terrestrial environments, or environments where you can’t do traditional agriculture,” he says.

(Related: Here’s how nutrient imbalance affects life on Earth)

deep space food

The researchers’ technology could be applied for the first time in an extraterrestrial environment. The researchers presented their concept of artificial photosynthesis to the NASA Deep Space Food Challenge, which awards cash prizes and recognition to groups with innovative ideas for fueling astronauts on long-duration space missions. Last fall, the team concept was named one of 18 winning U.S. Phase 1 projects. In phase 2, these teams deberan build a prototype that actually produces food. Winners will be announced next year.

Winning the competition does not guarantee that a new food production technology will fly on a future space mission. Many technical details would have to be ironed out first, he says Lynn Rothschild, a researcher at NASA Ames Research Center who was not involved in the new study. Weight is a key factor, and artificial photosynthesis will likely require transporting new equipment to space, such as additional solar panels and electrolyzers.

But Rothschild says it’s worth keeping an open mind about how any effort to revamp a fundamental biological process like photosynthesis might be applied, in space or on Earth: “The payoff can be anything that we haven’t imagined yet.”

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