The researchers placed identical strains of salmonella in containers and sent one into space aboard the shuttle, while the second was kept on Earth, under similar temperature conditions to the one in space.
After the shuttle returned, mice were given varying oral doses of the salmonella and then were watched.
After 25 days, 40 percent of the mice given the Earth-bound salmonella were still alive, compared with just 10 percent of those dosed with the germs from space. And the researchers found it took about one-third as much of the space germs to kill half the mice, compared with the germs that had been on Earth.
The researchers found 167 genes had changed in the salmonella that went to space.
There's talk about fluid shear, but, so far, the researchers really don't know why this is.