Scientists from the University of Houston in Texas discovered that not only do some bacterial strains grow in low or zero-gravity, but they also mutate.
This raises some serious concerns for extended voyages into space and could put space travelers' health at risk and either gum up delicate machinery on a spacecraft or short circuit the electrical systems. Bacterial biofilms have already become a problem in the International Space Station, which already has a thick layer of bacteria coating some of the equipment.
Madhan Tirumalai and his colleagues at the University of Houston wanted to know how microorganism who hitch rides with us into space would fare with the loss of gravity. We already know the immune systems of astronauts change in space, possibly making them more at risk for infection.