The science of space mold: Can fungi harm humans in space?

Fungi are everywhere. Even in our bodies. Most don’t harm us — but scientists at NASA's Jet Propulsion Lab want to find out if in space, things might change.

A new JPL report shows that certain types of fungi that grow on surfaces are shown to cause infections in humans and can change and multiply in simulated environments like the International Space Station or the habitats proposed for lunar or Mars missions. 

Fungi are a normal part of human life, said JPL senior researcher Kasthuri Venkateswaran.

"We're all walking fermentors," he said. "We are carrying at least 10 times more microbial cells compared to our own human cells."

And they can do a lot of good. Last year, JPL partnered with USC researcher Clay Wang to send fungi to the space station to "stress" the fungi enough to hopefully produce substances that could pave the way for the development of new medicines.

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"With that experiment, we knew exactly what we were sending," Wang said.

But this time, JPL focused on looking at what kind of fungi would grow — and how they interacted — in a simulated environment here on earth. 

The study was conducted in the Inflatable Lunar/Mars Analog Habitat at the University of North Dakota. It mimics the environment astronauts live in on the space station. 

Three groups of students were housed inside the enclosure for 30 days at different times. Researchers collected samples four different times from eight locations inside the space: just before the students entered and at days 13, 20 and 30.

Scientists examined the samples to see what kinds of fungal species were co-existing with humans and also to determine both the total and viable — aka able to reproduce — fungal populations.

To get an idea of what the Inflatable Lunar/Mars Analog Habitat looks like, here's a video of three University of North Dakota students who spent 10 days inside it last year. 

Researchers found that some fungi increased in numbers while humans were living in the space. That, Venkateswaran said, could be a problem for astronauts spending months or years in space.

"Not on day one, but at day 500, humans are not the same," he said.

In other words, living in a simulated environment for a long period of time stresses out the human immune system. It could make astronauts more susceptible to fungi-related illness.

JPL also found that the types of fungal populations changed throughout the length of the experiment.

"Characterizing and understanding possible changes and succession of fungal species is of high importance since fungi are not only hazardous to inhabitants but also deteriorate the habitats," the study says. 

Venkateswaran says further study will help scientists develop "appropriate countermeasures" to combat "opportunistic pathogens" — or fungi that take advantage of a weakened immune system and cause disease. 

Students spent 30 days inside this Inflatable Lunar/Mars Analog Habitat (ILMAH).

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The study concluded that keeping a "properly maintained" closed habitat is essential for keeping astronauts healthy. 

"They cannot simply call in a maid service," Venkateswaran said. "They have to do it themselves."

Astronauts are conducting similar fungi research right now on the space station, he said. JPL scientists are comparing it with the data from the Inflatable Lunar/Mars Analog Habitat to delve deeper into the issue. 

It's inevitable that fungi will grow and change alongside humans, said Wang. Scientists still have a lot to learn about what they might do — and what they might produce — while side-by-side with humans in space over a long time. 

"Even if you try to clean something, it's impossible to have no microorganisms," he said. "So we need to study what will happen over time with these interactions."