The A.I.M. Interview: NASA Ames’ Dr. Leslie Prufert-Bebout

by David Schwartz

Algae in space. Imagine the possibilities—growing algae on long term space flights to recycle the CO2 in the capsule air back into oxygen…turning waste generated on the mission back into fuel, food, and nutritionals. All the wonders of photosynthesis—just add water. Maybe.

These are some of the questions that NASA Ames research scientists ask themselves, experiment with in their earthly labs, and, when budgets permit, test in outer space. And most of their development work does happen on earth, sometimes in a rooftop greenhouse, where they extrapolate and mimic the conditions of a very different environment.

Dr. Leslie Bebout (who goes by “Lee”) heads the team of microbial ecologists at NASA’s Moffett Field, CA-based research facility, though much of their work is done in far away places like salt marshes, or high in the Andes mountains, out on barrier reefs, or in the open ocean.

With an educational background in biology and a masters in geology, Lee worked at the University of North Carolina Institute of Marine Sciences for about seven years as a lab manager and researcher on a number of different ecosystems, including natural estuaries, open ocean, barrier islands sediment, hypersaline environments in the Bahamas—in all cases looking at microbial community dynamics. “We were trying to understand why we saw certain cyanobacteria or algae species thriving in certain situations,” she says. “Sometimes the research went to understanding what methods we might need or want to control to change these communities.”

But that was back in the early eighties, and the Big Picture algae bug had not yet bitten. “It was interesting at that time when we had several hundred organisms in culture, I remember speaking with some of the pharmaceutical companies about doing screening for natural products. At that point folks weren’t that interested in mass culture. They were interested in finding out what properties these organisms had that could be useful, and then slicing those genes into E. coli or yeast, or something that was easy to grow. I was very frustrated by that because, at that point, no one was interested in cultivating algae just for the sake of algae, even though they could do positive things like use CO2 and help remediate waste. But times have changed a lot since the eighties,” she points out.

Lee later got a degree in microbial ecology through the Max Planck Institute for Marine Microbiology, in Bremen, Germany, and then returned to Maryland for a stint “working in the marshes” before coming to NASA Ames when her husband, Brad, landed his job there.

Based in the NASA Ames Exobiology Branch...

Based in the NASA Ames Exobiology Branch, the Algae for Exploration (ALEX) working group consists of the core full-time members (left to right) Angela Detweiler, Erich Fleming, Brad Bebout and Leslie Prufert-Bebout. ALEX projects leverage long term Astrobiology basic research to understand current terrestrial ecosystem health issues, as well as develop Space and Energy initiatives towards NASA mission goals. The lab has a dual emphasis on biological community response to ecosystem change and co-development of the technologies used to monitor and modulate those responses. Photo: Dominic Hart

We spoke with Lee about NASA’s plans for algae, and why NASA is interested in the algae industry at large…

What were you working on at the time you came to NASA Ames?

I was doing more geobiology at that point, working on stromatelites, and microbial systems. My dissertation work was on light sharing – how different algae species growing together share the light partition—which could be a function of wavelength, and understanding which species used which wavelength.

What about NASA Ames work in biology appealed to you?

They were interested in understanding why you found one particular species dominating in an environment and not the other one. And that is interesting in helping you interpret early Earth ecosystems. If you find fossil remnants, those remnants could be lipid biomarkers, but they could also be structural clues, or they could be trapped gases. So it was a good interface for geobiology at that point for me.

What is the core of your job description at NASA?

The past two or three years we’ve been expanding from basic research in exobiology/astrobiology to start to look at possible applications. We have a grant with Lawrence Livermore National Labs and the Department of Energy to study vented microbial ecosystems and understand the hydrogen dynamics of those better. That’s a long way from applications, but it’s trying to understand the gene regulation and in a complex community how you can predict what kind of processes are going to occur, and see if there might be ways to manipulate that. A lot of what we do is manipulating complex communities to see how we can change the end product.

So it sounds like individual strains aren’t that much of concern, it’s more how they all work together in a community?

It’s both. Some people say that only 1% of the microbes out there can be isolated, and that may be true. But in many cases, with organisms that people say can’t be cultivated, with more research and paying more attention we can start to understand how to cultivate some of those. It may be that that organism always needs a partner, and in understanding what they really need, then we can start to understand how to provide that, how to optimize for growth, and/or manipulate it more toward a product that we want.

Light microscope view of organisms in a micobial mat

Light microscope view of organisms in a micobial mat from Area 4 in the Exportadora de Sal saltern system in Guerrero Negro, Baja California Sur, Mexico. An empty sheath (presumably from the cyanobacterium Microcoleus chthonoplastes) appears to have been colonized by the corkscrew-shaped trichomes of the cyanobacterium Spirulina sp.

Which strains are of interest to you…which are the ones you isolate?

Mostly cyanobacteria—planktonic or benthic from a wide variety of environments. But recently we’ve done a little bit of work with local sewage treatment control plants in looking at the population dynamics of mostly green algal species in sewage environments, as well as collaborating in looking at natural biofilm assemblages in the San Francisco Baylands that are mostly diatoms. We also work in a lot of hypersaline extreme environments in the Andes, and in Mexico. We look at those species, try to understand their adaptations to those extreme environments and, of course, are now always keeping an eye out to see if any of those might have a potential for biofuels. Other members of our group have an additional focus on the heterotrophic populations, particularly those which cycle methane and hydrogen, which are commonly associated with phototrophic populations.

What are microbial mats, and why might they be important in understanding algae cultivation in space?

Microbial mats are basically a biofilm—a mix of microbial, algal, and bacterial species that are growing as a biofilm. If that biofilm were not consumed and it built up over time, you would get a more complex community with really efficient recycling of nitrogen, phosphorus and carbon, as well as hydrogen.

These are the kind of ecosystems that are the earliest evidence of life on Earth, and are basically driving a lot of the carbon-nitrogen flow in the biosphere. Now you don’t see them very often because they are pretty much consumed as fast as they grow. Whether you go out to a beach, a salt marsh or any stream or rock, there’s always some kind of algae or biofilm growing there, but it’s the base of the food chain so it’s consumed very quickly.

So we go to extreme places like hot springs or super salty places where there’s less of the grazing population, and less competition from higher plants, so the situation is more like early Earth. Then you get these very efficient microbial ecosystems that have hundreds to thousands of different microbes all working in tandem—that’s where the recycling processes really happen.

So then, if you go to a more complex system, you have to understand how the interaction between the different microbes will occur. An impetus for looking at a mixed system is that it could be recycling and self-supporting, because there are very few monocultures that occur on Earth, if any. Everything is kind of in collaboration. So studying monocultures in space is really useful, because it simplifies things and you can really target what you are looking at. But, it’s also useful to study communities that are more complex, because that is how life is on Earth.

A snapshot of an evolving field

A snapshot of an evolving field, compiled by the ALEX (Algae for Exploration) working group, illustrating multiple areas where they can envision NASA interests and/or technologies having synergies with the biofuels industry. Some of these avenues are being explored, others are just projections for some of the areas that could develop in the future.

How do you extend this into NASA applications?

In the past it’s been of interest for understanding what we might look for on other places in the universe for life. But there’s also a lot to be figured out about how we can take biology into space to support us as a species. These microbes are supporting us here on Earth and we take it for granted, so a lot of work needs to be done to see how the microbes will behave in space. Photosynthesis is of course an essential process to support us as humans, so that needs to be assessed as to how radiation and micro gravity will affect performance.

In a paper you authored called “Utility of Microbes in Space,” you say that “…for long-term, extended space habitation life support, utilization of the (Microbial) ecosystem-scale recycling methods that support human life on Earth will provide cheap, clean, and virtually waste-free primary support systems.” What specific role, if there is one, does NASA see algae playing in space, and how and when do you think there will be significant progress in this area?

That’s kind of a tricky question because it really goes to cost. It costs so much money to launch materials into space and that’s why there’s been a move toward cheaper, smaller, nanosatellite platforms, so that you can do more experiments with higher replication at lower costs.

On the other hand you need real dependability in space, and you need to have very quantitative knowledge and predictability of biological systems. Right now we don’t use biology in space in that way, even though we all have a concept of it.

We see projections of life in space in science fiction and we have this assumption that we will take biology with us to support us the same way it does on Earth. There was a lot of research done on this twenty or so years ago, but people kind of eventually threw up their hands. It’s complex.

Anybody who’s running a biofuel operation right now is really appreciating how many things can go wrong, how many tweaks to the system are needed, and the effects environmental changes can have on predicted consequences. So that’s a challenge, and it’s one of the reasons why we are so tuned in to what’s going on in the biofuels industry as they are figuring out this agriculture model. That’s going to be where we start to make improvements that can help us think about putting life in space for life support.

Right now there is not a lot of funding in that area, because there are higher priorities. But it is something that I think people envision for the future, and it’s just a question of how and when.

Erich Fleming

Teaming with Lee Bebout on many of her NASA projects, Erich D. Fleming is a microbial ecologist specializing in cyanobacterial ecology and diversity.

“A lot of these tests are about trying to identify what new kinds of stresses will be present in various space environments and then how they will affect organisms evolved for life on Earth,” says Fleming. “Anything that is moved to a new location, even if the environment is only slightly different, can have a large effect over time. And this has a greater impact on microbes, which have a very short lifespan. There will be many generations over the course of a year, so you can imagine that these organisms will be evolving when you put them into space—but to what end? We don’t really know, so it is interesting to study that.

“We’re looking at experimenting both with direct sunlight and artificial light in our tests. Right now the Gravisat Mission has an artificial light system, so we can have complete control over that. There is another satellite mission we’ve been trying to get funded called Algaesat, where we would actually put a window in the satellite. That mission is more designed to see how cosmic radiation and solar light affects algae in space.

“Just based on what we know of algae down here, they’re not going to like full sunlight up there. They’ll do quite poorly, so we know we’ll have to use a system that cuts down the amount of visible light they get up there, or convert it to electricity and use LEDs to then convert it back into very specific wavelengths of light that we know algae are able to efficiently convert into biomass.

“I think this a great time for algae to take the spotlight, in general. I think that there are an immense amount of uses for algae, like the way soybeans are now being used for everything. Algae can be used like that as well, even more so.”

What tests of the microbial environment performed in space would you like to see, or do you think would be beneficial to happen sooner rather than later?

In a nutshell, basic effects on physiology, and the longer-term effects. If we look at something on a short-term space flight, for a few days or a week, that gives us some information, but we need to know what happens over time.

Do you anticipate testing photosynthesis on microbial mats to see if they might recycle the CO2 in the capsule and produce oxygen to support human breathing?

That would be great and those are areas where we are hoping to do more research. One of the major costs of algal production at commercial scale is getting CO2 into solution, into the water so that the cell can take it up. That becomes a big cost factor, and one of the advantages of an attached biofilm system is that you can minimize the water layer over the top, so you pull more directly from the atmosphere. Microbial mats are largely diffusion driven. In space, with low gravity, circulation doesn’t happen the same way that it does on Earth, so that’s an area that we’re really going to be looking at: capillary and diffusion-based systems for nutrient and gas exchange.

What is our most important opportunity in this area?

I think there is a growing recognition of how important photosynthesis is. We’ve talked about it a lot for food crops in space, but algae, since they use the same photosynthesis, can allow us to get a lot of useful research done, maybe more inexpensively.

We’re really interested in lowering our infrastructure costs. We run green houses on our roofs to do our experiments. We know those offer a lot of benefits in terms of climate control, but they also come at a cost, so we’re working with engineers to look at whether or not there are ways to lower those costs.

That would be important in a space environment, but it might also be useful to the algae industry. We hope so, and if something useful comes of that, we’ll want to make that available. That could be, as well, in smart systems, which remotely take the pulse of the algae and automatically adjusts their conditions.

NASA has a goal for its technology to be beneficial for the mission of the space program, but if it can be useful to other industries, that’s also in our mandate. That’s another reason why we’ve kept in touch with so many people in the algae industry, because we are keeping ourselves in the conversation if the opportunity for NASA technologies can be of use.

What would you like to accomplish in this field before you retire?

Twenty-five years ago I had this hope that large-scale algal biomass would be really useful at some point in time, and the last ten years have been really exciting to see it start to come together. I would be thrilled to see it all happen, and if there’s a role that I can bring to bear with understanding feedback from the environment, be it temperature, salinity, pH, light conditions, or help with understanding how we can modify the engineering to fit the microbes to get what we want in ways that are cost effective…that would be really rewarding.

If not, I can just be a cheerleader for algae, which is also wonderful.