The international space station: An extreme environment for key host-microbe discoveries: Microgravity encountered during spaceflight helps to determine how various forces influence microbes as they interact with hosts and environments

Since the early period of the 1960s, when the focus was on how spaceflight might affect the health of crew members, NASA experiments involving microbiology expanded considerably. Experiments over the past 50 years indicate that microorganisms respond to the spaceflight environment in unusual ways, including alterations in virulence and resistance to antibiotics. Experiments conducted in spaceflight and NASA rotating-wall vessels are enabling investigators to determine how fluid shear regulates virulence, stress responses, and gene expression in a manner that profoundly differs from what happens in traditional shake flasks and static cultures. The conserved RNA-binding protein Hfq appears to control the response of Salmonella and other types of bacteria to spaceflight and other low-fluid-shear environments. The microgravity environment of spaceflight affords a tool to investigate how various forces, which gravity obscures, are manifest in structural and functional processes in microbial and human cells that are important for disease progression.