Lettuce and Other Plants More Susceptible to Bacterial Infections in Space, Study Finds
In a groundbreaking study conducted by researchers at the University of Delaware, it has been discovered that plants grown in space are more susceptible to bacterial infections compared to plants grown on Earth. This finding has significant implications for the future of space exploration and the safety of astronauts aboard the International Space Station (ISS).
For over three years, NASA has been experimenting with growing lettuce in space, providing astronauts with a fresh and healthy addition to their diet. However, this new research reveals a potential threat to the success of these missions. The ISS is known to harbor pathogenic bacteria and fungi, some of which can easily colonize lettuce and other plants. If astronauts were to consume lettuce contaminated with E. coli or Salmonella, they could fall ill, jeopardizing the entire mission.
To better understand this issue, the University of Delaware researchers conducted experiments to simulate the weightless environment of the ISS. They grew lettuce under conditions that imitated microgravity and found that these plants were more prone to infections from Salmonella, a human pathogen. Normally, plants close their stomata, tiny pores in leaves and stems, when they sense the presence of bacteria. However, under the simulated microgravity conditions, the lettuce kept their stomata wide open instead of closing them.
Noah Totsline, the lead author of the study, explained that this unexpected response from the lettuce was surprising. The researchers used a device called a clinostat to rotate the plants, confusing their sense of gravity. While it wasn’t true microgravity, it served its purpose in helping the plants lose their sense of directionality. Ultimately, the researchers discovered that Salmonella could invade leaf tissue more easily under simulated microgravity conditions than under normal Earth conditions.
In an attempt to mitigate this risk, the researchers introduced a helper bacteria called B. subtilis UD1022, which is known to promote plant growth and fitness against pathogens. However, they found that the bacterium failed to protect the plants in space-like conditions. It seems that the bacterium’s inability to trigger a biochemical response that would force the plants to close their stomata may have contributed to Salmonella’s ability to invade the plants.
This research highlights the importance of food safety in space and the need for further understanding of how bacterial pathogens react to microgravity. Kali Kniel, a microbial food safety professor, emphasized the potential risks associated with bacterial pathogens in space and the need for appropriate mitigation strategies. She and Harsh Bais, a plant biology professor, have been collaborating on studying human pathogens on plants to develop ways to reduce risks associated with the contamination of leafy greens.
The implications of this research extend beyond space exploration. With the Earth’s population projected to reach 9.7 billion by 2050, and agricultural land diminishing over time, alternate habitation spaces are becoming a serious consideration. Leafy greens, such as lettuce, are a popular choice for indoor cultivation, making it crucial to ensure their safety for consumption. Bais emphasized that a food safety outbreak could have catastrophic consequences for a mission, underscoring the need for solutions to prevent bacterial infections in space-grown plants.
One potential solution proposed by Kniel is starting with sterilized seeds to reduce the risk of microbial contamination. However, microbes can still find their way onto plants through the space environment. Bais suggested that tweaking plants’ genetics may be necessary to prevent them from opening their stomata wider in space. His lab is currently evaluating different lettuce varieties under simulated microgravity to identify those that close their stomata compared to those that keep them open.
The findings of this study shed light on the challenges and risks associated with growing plants in space. As humans venture further into space exploration, it is crucial to prioritize food safety and develop strategies to mitigate the threat of bacterial infections. By understanding how plants and pathogens interact in microgravity, scientists can work towards ensuring the safety of astronauts and the success of future missions.
