The absence of gravity appears to make bacteria more virulent, researchers say.
The findings, recently published in the Proceedings of the National Academy of Sciences, involve salmonella strains carried last September aboard the Space Shuttle STS-115.
Earthbound mice infected with salmonella from the shuttle were four times more likely to die than those exposed to terrestrial bugs, and a smaller dose was required to kill them.
The bacteria apparently flourished because the pressure of fluid passing over them is so low in a zero-gravity environment. That pressure, known as fluid shear, is also low in the human gastrointestinal tract -- another place where salmonella does very well.
As for why low fluid shear is so beneficial, scientists aren't sure.
But some 167 genes were activated in the spacefaring salmonella;
something's going on. But even without this understanding, the lesson is clear for long-distance spaceflight planners: sterilize everything, and be prepared to get sick. But on the positive side: if we learn what makes the bacteria stronger, maybe that'll help scientists figure out how to make them weaker.
Bacteria turn nastier in space experiment: study [Reuters]
Germs Taken to Space Come Back Deadlier [Associated Press]
