Study raises concerns about astronauts’ health | Top Vip News

A research team discovers that lettuce and other plants are more susceptible to bacterial infections in space than on Earth.

Lettuce and other leafy greens are part of a healthy, balanced diet, even for astronauts on a mission.

It has been more than three years since the National Aeronautics and Space Administration (POT) made space-grown lettuce a menu item for astronauts aboard the International Space Station. In addition to the staples of their space diet, which consist of flour tortillas and coffee powder, astronauts can eat a salad, grown in control chambers aboard the ISS that take into account temperature, the amount of water and the ideal light that plants need to mature.

The challenge of pathogens in space

But there is a problem. The International Space Station has many pathogenic bacteria and fungi. Many of these disease-causing microbes on the ISS are very aggressive and can easily colonize the tissue of lettuce and other plants. Once people eat lettuce that has been invaded by E. coli or Salmonella, they can get sick.

With billions of dollars invested each year in space exploration by NASA and private companies such as SpaceXSome researchers worry that an outbreak of foodborne illness aboard the International Space Station could derail a mission.

In new research published in Scientific Reports and in npj microgravity, researchers at the University of Delaware grew lettuce in conditions that mimicked the weightless environment aboard the International Space Station. Plants are masters at detecting gravity and use their roots to find it. Plants grown in UD were exposed to simulated microgravity by rotation. The researchers found that those plants under the manufactured microgravity were actually more prone to infections by a human pathogen, Salmonella.

Stomata, the small pores in leaves and stems that plants use to breathe, are typically nearby to defend a plant when it detects a stressor, such as bacteria, nearby, said Noah Totsline, a Department of Plant Sciences alumnus. and Soils from UD who finished his postgraduate degree. program in December. When the researchers added bacteria to lettuce under their microgravity simulation, they found that the leafy greens opened their stomata widely instead of closing them.

“The fact that they remained open when we presented them with what seemed to be a stress was really unexpected,” Totsline said.

Totsline, senior author of both papers, worked with plant biology professor Harsh Bais, as well as microbial food safety professor Kali Kniel and Chandran Sabanayagam of the Delaware Institute of Biotechnology. The research team used a device called a clinostat to rotate the plants at the speed of a roast chicken on a spinner.

“In effect, the plant would not know which direction is up or down,” Totsline said. “We were confusing their response to gravity a little bit.”

It wasn’t true microgravity, Totsline said, but it helped plants lose their sense of direction. Ultimately, the researchers found that it appears that Salmonella can invade leaf tissue more easily under simulated microgravity conditions than under typical conditions on Earth.

Besides, Bais and other UD researchers have shown the use of a helper bacteria called B. subtilis UD1022 to promote plant growth and fitness against pathogens or other stressors such as drought.

They added UD1022 to the microgravity simulation that on Earth can protect plants against Salmonella, thinking it could help plants defend against Salmonella in microgravity.

Instead, they found that the bacteria actually failed to protect plants in space-like conditions, which could be due to the bacteria’s inability to trigger a biochemical response that would force a plant to close its stomata.

“The failure of UD1022 to close stomata under simulated microgravity is surprising and interesting and opens another can of worms,” ​​Bais said. “I suspect that UD1022’s ability to deny stomatal closure under microgravity simulation may overwhelm the plant and render the plant and UD1022 unable to communicate with each other, helping Salmonella to invade a plant.”

Foodborne Pathogens Aboard the International Space Station

Microbes are everywhere. These germs are on us, on animals, in the food we eat, and in the environment.

So naturally, Kali Kniel, a professor of microbial food safety at UD, said that wherever humans are, there is the potential for bacterial pathogens to coexist.

According to NASA, around seven people live and work at the same time in the International Space Station.

It’s not the tightest environment (as big as a six-bedroom house), but it’s still the kind of place where germs can wreak havoc.

“We need to be prepared and reduce risks in space for those who live on the International Space Station now and for those who might live there in the future,” Kniel said. “It is important to better understand how pathogenic bacteria react to microgravity so that appropriate mitigation strategies can be developed.”

Kniel and Bais have a long history of bringing together their topic areas of microbial food safety and plant biology to study human pathogens in plants.

“To develop better ways to reduce the risks associated with contamination of leafy greens and other agricultural products, we need to better understand the interactions between human pathogens on plants grown in space,” Kniel said. “And the best way to do that is with a multidisciplinary approach.”

A growing population on Earth, a greater need for safe food in space

It may be some time before humans can live on the Moon or Marsbut UD research has great potential impacts for coexistence in outer space.

According to a United Nations reportThe Earth could be home to 9.7 billion people in 2050 and 10.4 billion people in 2100.

On top of that, Bais, a UD plant biology professor, said food safety measures are already at their peak around the world. With the loss of agricultural land to grow food, “people will soon be thinking seriously about alternative living spaces,” he said. “These are no longer fiction.”

And apparently more often, the Centers for Disease Control and Prevention or the U.S. Food and Drug Administration will issue a recall on certain lettuces on Earth, telling people not to eat them because of the risk of E. coli or Salmonella.

Since leafy greens are the food of choice for many astronauts and are easy to grow in indoor environments like a hydroponic environment on the International Space Station, Bais said it’s important to make sure those greens are always safe to eat.

“We don’t want the entire mission to fail just because of a food safety outbreak,” Bais said.

Solutions: sterilized seeds and improved genetics

So if plants open their stomata more in a microgravity environment and allow bacteria to enter easily, what can be done?

It turns out that the answer is not so simple.

“Starting sterilized seeds is one way to reduce the risks of having microbes on plants,” Kniel said. “But then microbes can be in the space environment and reach plants that way.”

Bais said scientists may need to modify the plants’ genetics to prevent them from opening their stomata more in space. His lab is already taking different varieties of lettuce that have different genetics and evaluating them under simulated microgravity.

“If, for example, we find one that closes its stomata compared to another one we’ve already tested that opens its stomata, then we can try to compare the genetics of these two different cultivars,” Bais said. “That’s going to raise a lot of questions for us in terms of what’s changing.”

Any answers they find could help prevent future problems with arugula salad.

References:

“Simulated microgravity facilitates stomatal entry through Salmonella in lettuce and suppresses a biocontrol agent” by Noah Totsline, Kalmia E. Kniel, Chandran Sabagyanam and Harsh P. Bais, January 9, 2024, Scientific Reports.
DOI: 10.1038/s41598-024-51573-y

“Microgravity and evasion of plant innate immunity by human bacterial pathogens” by Noah Totsline, Kalmia E. Kniel and Harsh P. Bais, September 7, 2023, npj microgravity.
DOI: 10.1038/s41526-023-00323-x

The research was funded by NASA-EPSCoR.