Salmonella in Space Get Even Nastier

Salmonella sent to space have revealed secrets about the disease-causing bacteria that could help treat humans with food poisoning.

Scientists sent Salmonella bacteria to the International Space Station aboard two space shuttle missions in September 2006 and March 2008. The researchers found that when the bacteria were cultured in the microgravity environment of orbit, they became more virulent than those on Earth. The findings showed that the conditions in which the bacteria grows affect how dangerous it will become.

"This research opens up new areas for investigations that may improve food treatment, develop new therapies and vaccines to combat food poisoning in humans here on Earth, and protect astronauts on orbit from infectious disease," said Julie Robinson, program scientist for the International Space Station at NASA's Johnson Space Center in Houston.

Salmonella is a leading cause of food poisoning and related illnesses. About 40,000 Salmonella infections occur in the United States each year, according to the Centers for Disease Control and Prevention.

It turns out that the zero-G environment of space actually bears a resemblance to the conditions inside our intestines, as both have a similar level of a mechanical force called fluid shear, which is related to the motion of fluids passing over cells. Since both space and human intestines have lower fluid shear conditions than most experimental conditions in labs on Earth, studying the bacteria on the space station could give researchers a better idea of how it behaves in the human body.

"To our knowledge, no one had previously looked at a mechanical force like fluid shear on the disease-causing properties of a microorganism during the infection process," said Cheryl Nickerson of the Biodesign Institute at Arizona State University in Tempe, a principal investigator of the experiments sent up to the space station. "We can use the innovative research platform of the space station to contribute to new translational advances for the development of new strategies to globally advance human health."

Nickerson found that tweaking the amount of ions in the bacteria's environment can stop the increase in virulence seen in space. The researchers hope this technique could also lead to treatments for Salmonella infections in humans, both on the ground and in orbit.

Learning how to combat dangerous microbial infections in space is especially important as NASA looks toward sending people on longer-duration missions to the moon and Mars. Astronauts on these future missions will have to fight illnesses far from ground-based medical help. Additionally, studies suggest that the human immune system is weakened by the microgravity environment, so astronauts may tend to get sick more often, and have a more difficult time fending off infections.

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