When the Space Shuttle Atlantis launched on Friday, the astronauts were accompanied by thousands of bacteria.
Dr. Cynthia Collins, assistant professor of chemical and biological engineering at Rensselaer Polytechnic Institute, is leading a series of experiments that were set up aboard the shuttle. The research seeks to understand how microgravity changes the way potentially dangerous bacteria grow, especially how they form difficult-to-kill colonies called biofilms.
The bacteria that Collins is studying are Pseudomonas aeruginosa and Staphylococcus aureus. The experiments are funded by the NASA Ames Research Center. I talked to Dr. Collins as she prepared her experiments for the mission.
How did these shuttle experiments come about?
We thought it would be interesting to look at bacteria in microgravity. One of the holes has been looking at biofilm formation. Biofilm is the stuff on your teeth in the morning, or in your shower. Some previous work had been done by other groups that show they do respond to zero gravity. Because biofilms are so important to infections and a lot of biofilms exist in nature, this could have important implications for spaceflight.
How does one secure an experiment on the Space Shuttle?
We sent a proposal to NASA using modeled microgravity. We used a set-up in our lab where we suspend cells in free fall using a specific reaction. NASA contacted us and said we have an opportunity for you to send some samples up on the shuttle, and we worked with BioServe Space Technologies out of University of Colorado. Essentially they had developed this hardware where you’re able to mix different components in space. That allows us to have cells in media that mix at certain times during the flight.
The astronaut has to pull our bacteria out of an incubator and turn a crank. BioServe takes care of [preparing the astronaut]. Essentially, there’s not a whole lot of training. They just pull a crank on the top of something and look at a level on the outside and crank it down. It’s really important that they do it and do it correctly, but it’s pretty simple compared to their spacewalks. To get them to do this for us is pretty awesome.
How many samples will there be?
We’ll be sending up 126 samples--a variety of conditions and the two different organisms. We’re following up on some experiments that were performed last year on the shuttle mission that launched May 14, 2010.
What did you learn from that one?
Different microbes respond differently to microgravity. For one we found less biofilm; for the other we found more.
How does the experiment need to be set up differently in space than in your lab?
In a laboratory we can set up a new experiment once a week. But in the shuttle you have a once-in-a-lifetime opportunity. Or twice in a lifetime. So we sent up a whole lot of samples. I brought down a team of six people including myself so we can load all these chambers in the next few days.
How are you set up at Kennedy Space Center, and how do the experiments get on the shuttle?
We load them in something that looks like a test tube and hand them over to BioServe, and they integrate them into their contraptions.
And will you watch the samples launch into space?
We will. We get to see the shuttle launch. We’re excited, especially because it’s the last one.
What happens after the shuttle returns on the 20th?
We get the samples six or so hours after the shuttle lands. We will start processing them at Kennedy. The first thing we do is count the number of cells that have grown in the biofilms. Then some samples we’ll do microscopy on, some we’ll do gene expression on.
When the astronauts are doing their thing up there, I’ll be doing the same thing in the laboratory. We do a duplicate set on the ground to get a baseline. They tell us when the astronaut does the experiment, and then I do it here with an hour delay. I don’t start anything here until we’ve gotten word that the astronaut has done it.
What would you like to learn from these experiments?
We’d like to get a better idea of how bacteria are responding to gravity. If we think about long-term space flight, if we knew more about the response of these organisms, we could be more confident that we could fight infections if they happened. Also, being able to understand the good bacteria that are in our bodies and required for digestion could hopefully give astronauts a better idea of long-term health and survival in space; we want to be able to understand the bacteria. You will always have the bacteria in your environment. It’s not a sterile environment there.
We tend to think the shuttle is sterile.
Humans have evolved to require bacteria—for digestion and proper immunization. As much as we’d like to think about eradicating bacteria from things like the Space Shuttle, it’s just not possible ; so we need to think about what to do if there’s an infection and how to use the good bacteria.
People have observed that astronauts have been immunosuppressed on spaceflights, so it can be a potential serious combination if there were a bacteria that grew faster [in microgravity] it could be potentially a not great situation.
One of the additional things we’re doing is trying to understand whether a new antimicrobial surface developed by one of my colleagues can help slow the growth of staph during spaceflight. [Actual MRSA, the bacteria responsible for antibiotic-resistant infections, will not be used for the safety of the astronauts; a safer strain of bacteria with similar properties will serve as a proxy.]