International Space Station
Complete genome sequencing of viruses and bacteria taken to the International Space Station revealed both mutations specific to the microgravity environment.
Bacteria and the viruses that infect them have been fighting an evolutionary battle for billions of years. Bacteria develop defenses against viral infections, while viruses develop new ways to break down these defenses. This process shapes microbial ecosystems across the Earth, from the ocean depths to soil communities. But what happens when this battle is taken to space?
Phil Huss and his colleagues at the University of Wisconsin-Madison decided to find out by sending samples of *E. coli* infected with the T7 virus to the International Space Station. They compared how the virus-bacteria interaction unfolded in microgravity with identical samples held on Earth, observing evolution in real time under fundamentally different physical conditions.
Although the T7 viruses eventually managed to infect their bacterial hosts aboard the station, everything it happened differently than on Earth. Complete genome sequencing revealed that both viruses and bacteria accumulated specific distinct mutations for the microgravity environment, changes that simply do not appear in terrestrial populations.
Space-dwelling viruses have gradually developed mutations that could increase your infectivity and improve their ability to bind to receptors on the surface of bacterial cells. However, orbital populations of *E. coli* have accumulated their own set of protective mutations, helping them survive both the viral attack and the challenges of near weightlessness.
Microgravity fundamentally changes the physics of how viruses encounter bacteria. On Earth, gravity influences fluid dynamics and sedimentation behaviors that affect collision rates between viruses and their targets. In orbit, these familiar rules no longer apply. The researchers discovered that the infection proceeded more slowly in Space, suggesting that these physical changes really matter for viral success.
The team then used a technique called deep mutational scanning to examine changes in the T7 receptor-binding protein, the molecular key that unlocks bacterial cells. This revealed even more significant differences between microgravity and terrestrial conditions. Most notably, some of these Space-induced adaptations proved useful back on Earth.
When researchers introduced the microgravity-associated mutations into T7 and tested them against *E. coli*, the mutations associated with microgravity proved to be more effective. In E. coli* strains that cause urinary tract infections in humans, strains normally resistant to T7, the modified viruses showed drastically improved activity. Evolution in orbit has revealed solutions to problems here on Earth.
The findings highlight an unexpected benefit of orbital research. By subjecting familiar biological systems to radically different environments, scientists can discover evolutionary pathways and genetic solutions that would not arise naturally on Earth. The ISS becomes not only a platform for studying space biology, but a laboratory for discovering new approaches to terrestrial challenges, from antibiotic resistance to the management of microbial ecosystems.
