The International Space Station (ISS)’s weightlessness may not be optimal for growing healthy greens or salads for astronauts. Fascinating research from the University of Delaware sheds light on what could be wrong and why space-grown salads are prone to bacterial contamination.
NASA has been serving space-grown salads on the ISS buffet for more than three years. This is carefully nurtured in control rooms that simulate the conditions required for plant growth.
However, a recent study published in Scientific Reports and npj Microgravity found a potential health risk connected with these leafy greens. The International Space Station contains harmful germs and fungus, which could endanger astronauts’ health.
The fear is not only for the well-being of the spacefarers, but also for the prospect of a foodborne illness outbreak derailing a space mission, given NASA and SpaceX’s significant investment in space exploration.
University of Delaware explores space farming
The University of Delaware researchers conducted a study in which lettuce was grown under conditions similar to the weightless environment of the International Space Station.
Surprisingly, plants treated to simulated microgravity were shown to be more susceptible to Salmonella infections, as the plant’s stomata, which allow it to breathe, remain open in space.
According to the paper’s primary author, Noah Totsline, “The fact that they were remaining open when we were presenting them with what would appear to be stress was really unexpected.”
To simulate microgravity, the researchers employed a clinostat, which rotates plants, confounding their response to gravity. The findings demonstrated that Salmonella could enter leaf tissue more easily in space than on Earth, therefore after rotating, which confused the plant, the stomata were found to be closed.
The researchers also introduced a helper bacteria called B. subtilis UD1022, which is known to promote plant development. However, in space-like conditions, UD1022 was ineffective in protecting plants. “The failure of UD1022 to close stomata under simulated microgravity is both surprising and interesting, and it opens another can of worms,” said Harsh Bais, a plant biology professor who participated in the study.