A major concern for long-duration space flight is how the microorganisms who hitch a ride with us will adapt to the loss of gravity. Astronauts’ immune systems change in space, potentially making them more susceptible to infection, so if these bacteria become more virulent or antibiotic-resistant, they could pose a risk.
To assess that risk, Madhan Tirumalai at the University of Houston in Texas and his colleagues placed E. coli in a rotating vessel designed to simulate microgravity. They kept them there for 1,000 bacterial generations, much longer than in previous studies.
After giving the cells time to adapt to microgravity, the researchers combined them with another strain of E. coli that hadn’t been subjected to microgravity and allowed them to grow together. The adapted cells grew about three times as many colonies as the others.
Even after the cells were taken out of microgravity for up to 30 generations before being combined with the control strain, they maintained 72 per cent of their adaptive advantage, pointing to permanent mutations in the genes rather than merely a temporary adjustment.