Episode Summary

Jessica Lee, Ph.D., scientist for the Space Biosciences Research Branch at NASA’s Ames Research Center in Silicon Valley uses both wet-lab experimentation and computational modeling to understand what microbes really experience when they come to space with humans. She discusses space microbiology, food safety and microbial food production in space and the impacts of microgravity and extreme radiation when sending Saccharomyces cerevisiae to the moon.

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Ashley's Biggest Takeaways

  • Lee applied for her job at NASA in 2020.
  • Prior to her current position, she completed 2 postdocs and spent time researching how microbes respond to stress at a population level and understanding diversity in microbial populations.
  • She has a background in microbial ecology, evolution and bioinformatics.
  • Model organisms are favored for space research because they reduce risk, maximize the science return and organisms that are well understood are more easily funded.
  • Unsurprisingly, most space research does not actually take place in space, because it is difficult to experiment in space.
  • Which means space conditions must be replicated on Earth.
  • This may be accomplished using creative experimental designs in the wet-lab, as well as using computational modeling.

Featured Quotes:

I am first and foremost a microbiologist. And all of my training has been in in microbiology, through evolution and ecology and a little bit of physiology and metabolism. And really, it wasn't until I applied for the job at NASA in 2020, that I even considered doing Microbiology in space. But I'm pleased that it worked out because I think it's a really exciting place to do microbiology.

If you’re a microbe and you go to space, the kinds of stresses that you are going to feel depend on how you get to space. If you're hitchhiking on the outside of a lunar lander, you're going to feel some of the raw effects of complete lack of atmosphere, temperature extremes, desiccation stress and unshielded radiation. I do some planetary protection research, but most of what I do is relevant to the microbes that come with humans to space and into our habitats. And in those situations—if you're a microbe who's coming to space in a bioreactor because you're going to do some work for the astronauts like produce something for them—in that case, you will be shielded by the environment that the astronauts have built for you. And the 2 main stress factors, in that case, are the ones that are hard to shield. So, one is microgravity and then also space radiation.

I have a small early career research grant to study the effects of microgravity on microbial communities. So, where you have 2 species that are dependent on being able to exchange metabolites through the medium. I’m looking at how they will react when they're put into microgravity, where the fluid environment is very different, because there isn't convective mixing.

Then on the radiation side, I do some computational modeling to simulate radiation effects on microbes. I'm very fortunate to have a project scientist position on a mission called LEIA, which is going to send yeast to the moon in 2026 to measure the effects of deep space radiation on microbes as a model organism.

One of one of the important things is that an organism in microgravity doesn't feel the gravity vector pulling downward. So, we have these rotational culture systems that make sure that the gravity vector that's pointing downwards is actually, over time, averaged.

For bacteria—we don't actually have any evidence that bacteria can sense gravity directly—the more important thing is the fluid environment. There's been decade's worth of work creating this model of our understanding of how the fluid environment affects microbes in microgravity. In short, if there's no gravity to pull down the denser pockets of fluid, and thereby create convective mixing, then force of mixing in microgravity will be driven primarily by diffusion. So, it'll be slower, and we call that the quiescent environment of microgravity.

In the lab, we try to reproduce that by, in our rotational vessels, ensuring that the fluid rotates as a solid body. The things fold at no bubbles, no headspace—it's filled up to the top with fluid. And the rate of rotation is such that the cells inside that rotational medium pretty much stay within a very small radius, relative to the medium at all times.

My hope, in the long run, is that is that we can have enough of a fundamental understanding of what's going on in the fluid systems and the immediate environment of the cells that we can use computational modeling to make predictions for people who are designing bioreactors for space.

There are lots of things that microbes do for us on Earth that they really could be doing for us in space. And they aren't right now. Right now, our life support systems, like on the International Space System, are 100% chemically mediated. We're not using microbes to produce oxygen or to recycle our waste. And we would like to do that in the long run.

We'd also like to be able to use microbes to produce fresh foods. There is, for instance, out of AIMS Research Center, a mission called Bio Nutrients, which is testing the use of engineered yeast to produce beta carotene and Zeaxanthin as potential dietary supplements for astronauts.

Project LEIA will be our first opportunity to grow and monitor the growth of microbes on the surface of the moon. We haven't done this before. And the goal is to understand the radiation environment on the moon, and specifically in in the area that the lunar South Pole, where we're going to be sending astronauts for the first time in decades.
LEIA will include a couple of radiation sensors, 1 for charged particles and 1 for neutral particles, to help us understand what that environment is. And then it includes a device called the biosensor, which is essentially a culturing instrument, that has 16 culture and microfluidic cards, and each card has 16 wells. So, we can do 256 replicates or controls or whatever it is that we want to put in those wells.

We're using yeast, essentially, as a model organism. It's a eukaryotic microbe, and so it has a lot in common with humans, in terms of DNA repair mechanisms. And we anticipate that the main effects of radiation are going to be in DNA damage. So, we're sending a few strains that have different alterations in their DNA repair pathways. We're also sending some of the strains from that bio nutrients project that I mentioned earlier to look at the effects of the environment on their ability to produce carotenoid compounds.

It's really exciting to think about how we can use microbes to support life in space. And we're going to need this understanding of how microbes are experiencing space environment in order to build those systems that finally allow us to use microbes to make food that astronauts can eat, or to use microbes to recycle our waste. There are so many more spaceflight opportunities coming up soon, like commercial space stations coming online soon. There's this real push to go to the moon with much greater frequency. And so, it is a really exciting time to be tackling those questions.

I'm really looking forward to this year's ASM microbe, because there are going to be, it seems, a couple of space-related keynote speakers. And, I'm going to be chairing a session on, the math of microbes. My interest in doing computational modeling to understand the effects of the space environment on microbes has really pushed me in that direction. So, I'm hoping to meet some more folk who are, are into computational modeling.

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Dr. Jessica Lee