Zero-G Germs Return to Earth

Astronautsweren't the only living things aboard the space shuttle Endeavour that landedsafely this week – a precious payload of germs, grown and frozen inzero-gravity, also returned to Earth.

Researcherssent up sealed containers of Streptococcus pneumoniae bacteria,the germs responsible for many diseases in patients with weakened immunesystems. David Niesel, a microbiologist at the University of Texas Medical Branch at Galveston, said the experiment will help scientists explore the risksof getting sick in space.

"There'sa decline in people's immune function the longer they're in the spaceenvironment, and it's been shown that other bacteria also alter theirproperties in microgravity," Niesel said."They grow faster, they tend to be more virulent and resistant tomicrobial treatment."

The S.pneumoniae bacteria are normally harmless, but Nieselsaid they never turn down opportunities to exploit weak immune systemsand turn into full-blown disease. For astronauts on long spaceflights, he said,the germs could prove tobe dangerous.

"Streppneumoniae is a very potent pathogen in people who are immunosuppressed,"he said. "It's the No. 1 cause of community-acquired pneumonia and aleading mediator of bacteremia [bacterial blood infections] and meningitis."

Having nowell-equipped hospital in a small cabin millions of miles from Earth, Nieseland his colleagues wanted to know how S. pneumoniae behaved in space, asothershuttle missions have explored with different germs.

To do so,the researchers rocketed six refrigerated vials of bacteria into orbit, thenhad the spaceshuttle crew warm them up so that they could grow. After 15 hours and 30minutes, the bacteria were chilled to -139 degrees Fahrenheit (-95 Celsius).

"Thatlocked the bacteria at whatever stage they were at ? so we get a picture ofwhat they were like in space at that time, which is the cool part," Niesel said. While the bacteria grew in space, Niesel and his team performed the same experiment onthe ground for comparison.

"Weshould be able to see the differences that result when the bacteria see thisunique space environment," Niesel said of the two perfectly syncedexperiments. ?"We think it will provide important information forunderstanding the adaptation of bacteria to unique environments and begin toanswer the question of whether this species is a cause for concern forlong-duration space travelers."

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