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Lettuce grown on the International Space Station is popular with astronauts, but researchers believe it is unhealthy
Space lettuce has been popular on the International Space Station (ISS), with astronauts enjoying leafy greens in a space garden called Veggie and even munching on a piece of red leaf lettuce they grew themselves.
However, scientists have found that lettuce grown in a simulated microgravity environment on Earth is more susceptible to infections like E. coli or Salmonella than lettuce grown in space and may not be as safe for astronauts.
An article recently published in Scientific Reports revealed that a group of researchers grew plants in a device called a clinostat, which rotated them like a roast chicken so that they lost their sense of direction. Gizmodo reported.
“In effect, the plant would not know which direction is up or down,” Noah Totsline, lead author of the new paper, said in a statement. “We were confusing their response to gravity a little bit.”
Plants have gravity-sensitive cells that cause their roots to grow downward, while the plant grows upward. However, in microgravity environments, the plant’s natural defense against stressors is less effective.
Stomata, small pores in leaves and stems, help with breathing and close when they detect stressors such as bacteria. According to the research, during their carnival ride in the clinostat, the plants became disoriented and opened their pores in the presence of bacteria.
“The fact that they remained open when we presented them with what seemed to be a stress was really unexpected,” Totsline said.
From the experiment, the researchers concluded that bacteria such as Salmonella can invade leaf tissue more easily under simulated microgravity conditions, such as those on the ISS.
A 2020 study of the first lettuce crop grown on the ISS between 2014 and 2016 revealed that while the lettuce had the same nutrient content as the Earth variety, it exhibited higher levels of bacteria.
Despite efforts to mitigate microgravity, the closed environment of the ISS with astronauts living in its headquarters can expose plants to pathogens, potentially affecting the Veggie system, which is a source of nutritious food for future missions to the Moon or Mars. .
Researchers propose modifying the genetics of space lettuce to prevent the stomata from opening further in space, thus reducing the risk of bacterial infections for astronauts who consume the vegetables.
They are currently testing several varieties of lettuce in a simulated microgravity environment.