The researchers found that lettuce and other plants are more susceptible to bacterial infections in space than on Earth.
Lettuce and other leafy green vegetables are part of a healthy, balanced diet for astronauts on missions.
National Aeronautics and Space Administration (NASA) Added lettuce grown in space to astronaut menus. international space station. In addition to flour tortillas and powdered coffee, which are staples of the space diet, astronauts also eat salads grown in the ISS’s control room with the ideal temperature, amount of water, and light necessary for plants to mature. You can munch on it.
The challenge of pathogens in space
But there’s a problem. The International Space Station is home to many pathogenic bacteria and fungi. Many of these pathogenic microorganisms present in the ISS are highly aggressive and can easily colonize lettuce and other plant tissues. Eating lettuce that is infested with E. coli or salmonella can make you sick.
Billions of dollars are poured into space exploration each year by NASA and private companies such as: space xSome researchers are concerned that food poisoning could occur aboard the International Space Station and derail the mission.
In a new study published in scientific report And then npj microgravity, researchers at the University of Delaware grew lettuce under conditions that mimic the zero-gravity environment aboard the International Space Station. Plants are masters at sensing gravity and use their roots to find it. Plants grown in UD were exposed to simulated microgravity by rotation. Researchers found that these plants, placed in artificial microgravity, were actually more susceptible to infection by the human pathogen Salmonella enterica.
Stomata, the tiny holes in leaves and stems that plants use to breathe, normally close to protect themselves when plants sense that stressors, such as bacteria, are nearby, said researchers in UD’s Department of Plant and Soil Sciences. said alumnus and graduate Noah Totzlein. December program. When researchers added bacteria to lettuce under microgravity simulations, they found that the leafy vegetable’s stomata opened wide instead of closing them.
“The fact that they remained open while we were putting them through what we thought was stress was really unexpected,” Totzlein said.
Totzlein, lead author on both papers, collaborated with plant biology professor Harsh Bice, microbial food safety professor Kari Kneel, and Chandran Savanayagam of the Delaware Institute of Biotechnology. The research team used a device called a clinostat to spin the plants at the speed of a rotisserie chicken on a spinner.
“Effectively, the plant won’t know which way is up or down,” Totzlein said. “We were confusing their response to gravity.”
It wasn’t true microgravity, Totzlein said, but it did help the plants become disoriented. Ultimately, the researchers found that Salmonella seemed to be able to invade leaf tissue more easily under simulated microgravity conditions than under typical conditions on Earth.
moreover, Beis and other UD researchers: usage of A helper bacterium called B. subtilis UD1022 Promotes plant growth and adaptability to pathogens and other stressors such as drought.
They added UD1022 to microgravity simulations that could protect plants from Salmonella on Earth, and wondered if it might help plants protect against Salmonella in microgravity.
Instead, it turns out that the bacterium can’t actually protect plants in space-like conditions. This may be due to the inability of bacteria to trigger a biochemical reaction that forces plants to close their stomata.
“The failure of UD1022 to close its stomata under simulated microgravity is surprising and interesting, and opens up a new can of worms,” Vice said. “We believe that UD1022’s ability to override stomatal closure under microgravity simulations may overwhelm the plant, rendering the plant and UD1022 unable to communicate with each other, and potentially facilitating Salmonella entry into the plant. Masu.”
Food poisoning pathogens on the International Space Station
Microorganisms are everywhere. These bacteria are present in us, animals, the food we eat, and the environment.
So it’s no surprise, said Kari Cunir, a professor of microbial food safety at UD, that bacterial pathogens can coexist anywhere there are humans.
According to NASA, about seven people live and work in space at any one time. international space station.
It’s not quite as cramped as a six-bedroom house, but it’s still a place where germs can wreak havoc.
“We need to prepare for and reduce risks in space for the people currently living on the International Space Station and for those who may live there in the future,” Knier said. “To develop appropriate mitigation strategies, it is important to better understand how bacterial pathogens respond to microgravity.”
Kniel and Bais have a long history of studying human pathogens on plants, integrating the subject areas of microbial food safety and plant biology.
“We need a better understanding of the interactions between human pathogens in space-grown plants to develop the best ways to reduce the risks associated with contamination of leafy vegetables and other agricultural products.” he said. “And the best way to do this is with a multidisciplinary approach.”
As the population on Earth increases, the need for safe food in space will increase.
It may still be some time before humans can live on the moon. Marshowever, UD research could have a major potential impact on coexistence in outer space.
according to united nations reportEarth could be home to 9.7 billion people in 2050 and 10.4 billion in 2100.
Beyond that, Bice, the UD plant biology professor, said food safety and security measures are already at their peak around the world. As agricultural land used to grow food is lost over time, “people will soon start thinking seriously about alternative living spaces,” he says. “These are no longer fictions.”
And more often, the Centers for Disease Control and Prevention or the U.S. Food and Drug Administration issue recalls for certain lettuces around the globe, often telling people not to eat them due to the risk of E. coli or salmonella. It seems that.
Leafy greens are a favorite food for many astronauts, and they can be easily grown in indoor environments, such as the International Space Station’s hydroponic environment, ensuring that these greens are always safe to eat. That’s important, Bice said.
“We don’t want the entire mission to fail just because of a food safety outbreak,” Vice said.
The solution: sterile seeds and improved genetics
So what can we do if plants expand their stomata in microgravity, making it easier for bacteria to invade?
As it turns out, the answer isn’t that simple.
“Starting with sterilized seeds is a way to reduce the risk of getting microorganisms on your plants,” Knier says. “However, microorganisms exist in space environments and can attach to plants that way.”
Bice said scientists may need to tweak plant genetics to prevent plants from opening their stomata wider in space. His lab has already harvested different lettuce varieties with different genetics and evaluated them in simulated microgravity.
“For example, if we find a variety that closes its stomata compared to a variety that has open stomata that we have already tested, we can try to make a genetic comparison of these two different varieties,” Vice said. “That would raise a lot of questions in terms of what would change.”
The answers they found could help prevent future problems with rocket salad.
References:
“Pseudo-microgravity promotes stomatal intrusion such as: Salmonella in lettuce and suppresses biocontrol agents,” by Noah Totzlein, Kalmia E. Kneel, Chandran Sabagyanam, and Harsh P. Bice, January 9, 2024. scientific report.
DOI: 10.1038/s41598-024-51573-y
“Microgravity and the Evasion of Plant Innate Immunity by Human Bacterial Pathogens” by Noah Totzlein, Kalmia E. Kneer, and Hirsch P. Bice, September 7, 2023. npj microgravity.
DOI: 10.1038/s41526-023-00323-x
This research was funded by NASA-EPSCoR.