Germs....in......SPACE!

by Tara Smith     Department: Health & Life Sciences

In the early days of space travel, there was much concern about the astronauts bringing back to earth some kind of terrible space pathogen back to earth with them. Even today, many parts of the shuttle are wiped down to disinfect it after its return to earth, in order to eliminate any potential hitchhikers. This seems the stuff of fiction--an Andromeda strain scenario--but if bacteria are out there somewhere in space where we can contact them, we need to proceed with caution.

However, what if the space bacteria we have to worry about aren't extraterrestrial in origin at all? What if they're ordinary species of bacteria that many of us carry in our gut, or on our skin, or in our mouths--but the low gravity environment does all kinds of crazy things to them, including making them cause more severe disease in the host? This phenomenon was investigated in a recent article published in PNAS earlier this month. As one experiment on last year's space shuttle Atlantis flight, astronauts took samples of Salmonella bacteria, a common cause of food poisoning, along for the ride. They grew them in zero gravity aboard the shuttle, while colleagues back at home on earth did the exact same experiment under normal conditions (so that a comparison could be made between the space-grown and earth-grown bacteria).

When the astronauts returned home, the bacteria were quickly analyzed to examine their RNA and protein expression, and samples were also fed to groups of mice in order to determine if they had differences in their capability to cause disease--and found that indeed, they did. The space-grown bacteria were nastier in the mouse model than their earth-raised counterparts. (Many more scientific details can be found in a post on my home blog, Aetiology).

This was a very limited study that needs to be repeated (and other researchers are already working on doing just that), but it has major implications as the "space tourism" industry grows. Right now, astronauts are thoroughly trained and screened, their health is monitored, and many precautions are taken to avoid bringing something nasty back to earth (and spreading it out through the population). Will similar precautions be taken with space tourists? It's quite possible that any virulent bacteria they bring back may not flourish on earth and be quickly outcompeted by their less deadly brethren, but right now we just don't know enough about the effects of space on different species, or how long those effects last. More research needs to be done, but obviously it's technically quite difficult, and shuttle missions are few and far between. Things are always so much more clear cut in science fiction!

Tags: Salmonella, space travel