The SIGNAL experiment in BIORACK: Escherichia coli in microgravity.

Microgravity affects certain physical properties of fluids, such as convection movement and surface tension. As a consequence, cells and living organisms may exhibit different behaviour in space, which may result from differences in the immediate environment of the cell or changes in the structure of the membrane in microgravity. Two experiments to examine the effects of microgravity on cell microenvironment and signal transduction through membranes were performed using a well-characterized system with different strains of the non-pathogenic Gram-negative bacterium Escherichia coli. Our results indicate that (i) microgravity appears to reduce the lag period of a non-motile culture of E. coli, and (ii) the ompC gene, regulated by the two-component system EnvZ-OmpR, is induced as well or better in microgravity than in ground controls.