westlake writes "Sounds like the plot for a B-movie, doesn't it? Germs go into space and come back stronger and deadlier than ever. Except, it really happened. In a medical experiment, salmonella carried about the space shuttle in the fall of 2006 proved far more lethal to lab mice than their earth-bound source. 90% dead vs. 60% dead in twenty-six days, with half the mice dying at 1/3 the oral dose. Apparently 167 genes in the space-evolved strain had changed. The likely cause: In microgravity the force of fluids passing over the cells is low, similar to conditions in the gastrointestinal tract, and the cells adapted quickly to the new environment."