Space flight turns bugs bad
28 September 2007
Scientists have tested the effect of space flight on bacteria - and it's not good news. After 12 days orbiting Earth, the bugs became 3 times more deadly than bacteria back home. Antenna finds out if space-faring germs could be more than just a headache for astronauts...
Around 450 people have travelled into space since Russian cosmonaut Yuri Gagarin first blasted into orbit in 1961. Over the years scientists have been studying what space flight does to the human body, but so far no-one has worked out what effect it has on bacteria's ability to cause disease.
Now, in a bid to find out, a team of US scientists have sent some food-poisoning bugs into space. The salmonella bacteria hitched a ride on board the Space Shuttle Atlantis as it visited the International Space Station. When experts got the bugs back to Earth, they made some startling discoveries.
The bacteria took off on board Shuttle mission STS-115, shown here blasting off from the Kennedy Space Center in Florida on 9 September 2006.
Image: NASA-MSFC
Salmonella expert Cheryl Nickerson and her team found 167 genetic changes in response to the bacteria's journey into space. But that wasn't the only surprise...
Cheryl's team also infected mice with the salmonella to compare the space-faring bugs with a sample that had stayed on Earth. The results, published this week in the journal Proceedings of the National Academy of Sciences, showed that the space bacteria were almost 3 times more lethal.
The bacteria Salmonella typhimurium is the leading cause of gut infections in humans.
Image: Rocky Mountain Laboratories/NIAID/NIH
When Cheryl and her team looked at the salmonella under a microscope, they saw the bugs' behaviour had changed too. They were clumping together more and producing sticky proteins, a telltale sign that a harmful 'biofilm' was starting to form.
'Biofilms make the bacteria better able to bind to surfaces and persist in an infection,' says Cheryl. 'They can also make bacteria more resistant to antibiotics. It might be one reason why the space-flight-grown salmonella were better able to cause infection in the mice.'
Cheryl Nickerson, Arizona State University, Tempe, Arizona.
Image: Biodesign Institute at Arizona State University
What caused the changes?
The inside of an orbiting spaceship is very different from the Earth's surface - everything's floating around in free fall, for starters. The most likely cause of the bacteria's changes is something linked to this weightlessness - there's less force applied to the outside of the bacterial cells, so they behave differently.
Astronaut Heide Stefanyshyn-Piper activates the growth of the bacteria in a specially sealed chamber on board the Space Shuttle.
Image: NASA
How will this research affect astronauts?
Cheryl is upbeat about the findings: 'This information can help us work out how to reduce the risk of infectious diseases to the crew in future missions, and make sure astronaut health and safety is at the highest possible level.'
Other experts agree it's useful research. 'Space flight is tough on the body and its effects will be particularly important if we are to send people on the long journey to Mars,' says Alison Boyle, space curator at the Science Museum.
'A better understanding of how bacteria behave in space will help to reduce astronauts' risk of catching diseases during missions, and in the long term might lead to new treatments that work for us here on Earth.'
Alison Boyle, Science Museum.
Image: Terry McCormick/Science Museum