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.
The researchers posed the question – Would bacteria adapt over generations, and more importantly, would they become more virulent or antibiotic resistant? To access the risk, the research team placed colonies of E. coli in a rotating vessel designed to simulate microgravity.
And in a first of its kind study, they kept the bacteria in the vessel for 1,000 generations. After first doing genetic sequencing, the team gave the bacteria time to adjust to the microgravity conditions, then they introduced another strain of E. coli that had not been subjected to microgravity.
Now, here’s the interesting part of the study – After 1,000 generations, repeat genomic sequencing revealed the colonies of bacteria that had adapted grew three times as many colonies as the new strain. The researchers also found 16 genetic mutations in the adaptive strain that were not erased after 30 generations of growth under normal gravity conditions.
“We are, in fact, seeing true genomic changes – permanent changes,” says team member George Fox at the University of Houston. We can see which genes are mutating, “but we don’t know what they’re doing exactly”.
Of particular concern was that some of the cell mutations occur in genes related to the ability to form biofilms, colonies of cells embedded in protective slime. This hardier bacteria could cause a real problem if the biofilm got into a spacecraft’s life-support system.
“We need more of this kind of experiment, especially with human space flight gaining more traction in recent years,” says Tirumalai. “E. coli is relatively innocuous, but the infection risk for astronauts on long missions could skyrocket if microgravity also makes more dangerous bacteria, such as salmonella, permanently hardier.”
The researchers were lucky that the mutated cells were just as susceptible to antibiotics as the original cells before they were exposed to zero-gravity. Let’s just hope any other bacteria that goes into space with us is also susceptible to antibiotics.
