Bacteria that flew in a space shuttle overtook their earthbound counterparts in toxicity. The finding could have implications not only for protecting astronauts from sickness as spaceflights become longer and more frequent but also for understanding bacteria on Earth.
Previous experiments using a spaceflight stimulator had hinted that bacteria might grow more virulent in the absence of gravity. To see whether real space flight would produce a similar result, a team led by Cheryl Nickerson of Arizona State University in Tempe sent samples of Salmonella typhimurium, a leading cause of food poisoning, into orbit on the Space Shuttle Atlantis in September 2006. The bacteria grew in closed tubes, and shuttle crew members tended to them—controlling their temperature, for example, or adding nutrients. Meanwhile, scientists on the ground mirrored the astronauts' procedures on cultures kept in a room designed to reproduce conditions on the shuttle. The only difference: