Bacteria that was sent into space on the shuttle came back to Earth genetically altered and significantly deadlier.
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Salmonella, the bacterium that causes food poisoning, was sent in special test tubes as a payload on the space shuttle Atlantis in September 2006. When it returned, scientists found the bugs were three times more deadly to laboratory mice than the same germs grown in identical containers and at the same temperature and humidity as on the spacecraft.

Researcher James Wilson, lead author of a report on the phenomenon in Tuesday’s edition of the Proceedings of the National Academy of Sciences, said the bacteria grown in space showed altered protein production arising from 167 of their estimated 4,000 genes, which made them far more virulent than their Earth-bound counterparts.

After the shuttle touched down on terra firma 12 days later, the researchers gave lab mice varying doses of the salmonella. After 25 days, 40 per cent of the animals given bacteria that had stayed home were still alive, compared with only 10 per cent of rodents given the space-travelling germs.

Furthermore, Wilson said, it took about one-third as much of the bacteria from the orbiting shuttle to kill half the mice, compared with the salmonella on Earth.

So what is it about space that so alters bacteria and what does that mean for astronauts or future space travellers?

“The answer is we don’t know, ” Wilson, a research assistant professor at the Biodesign Institute at Arizona State University, said Monday from Tempe, Ariz.

But he believes the bacteria reacted to what’s called “low fluid shear,” caused by microgravity’s effect on the liquid inside the test tubes aboard the space vehicle.

When new salmonella cells grow in microgravity, the force of the liquid passing over the cells is reduced, likely causing them to change, said Wilson.

That fluid shear effect also occurs in humans, in certain areas of the gastrointestinal tract, where salmonella can take up residence and cause illness, he noted.

“A major goal of the study was to see how space flight affects a bacteria and particularly a pathogen, because those pathogens (disease-causing germs) will be up there with astronauts. With all the quality control we do and efforts to prevent that, it will happen.”

“We do want to apply the results we have here to crew safety,” he said. “And seeing how these changes affect their (bacteria’s) ability to cause disease, we can also use that information to fight infections here on Earth.”

“So this is not just space-type stuff. It does also help humankind on Earth as well.”

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