Researchers have recently discovered that bacteria aboard the International Space Station (ISS) show a “shape-shifting” behavior.
In a recent study, published in the journal Frontiers in Microbiology, researchers took cultured E. coli bacteria and exposed them to different concentrations of a common antibiotic, gentamicin sulfate, that is deadly to E. coli on Earth.
What they observed is that the cell volume of the drugged bacteria decreased by 73 percent, while the number of cells multiplied 13-fold compared to those in a similar experiment on Earth.
The bacteria’s cell walls and outer membrane—called the envelope—became thicker, likely protecting the bacteria from the antibiotic.
Small capsules were also found forming outside some of the bacterial cell walls. These capsules, know as membrane vesicles, act as messengers between bacterial cells in a colony and can allow them to communicate and synchronize the start of the infection process.
Scientists have long observed that bacteria in space show a greater resistance to antibiotics compared to their earthly, gravity-bound counterparts, but they never directly linked the increased drug resistance to physical changes in the bacteria.
“We knew bacteria behave differently in space and that it takes higher concentrations of antibiotics to kill them,” Luis Zea, University of Colorado microbiologist and lead scientist for the study told CU Boulder Today. “What’s new is that we conducted a systematic analysis of the changing physical appearance of the bacteria during the experiments.”
Researchers believe that this “shape-shifting,” possible in the low-gravity conditions on the ISS, could be the reason the space bacteria had a greater resistance to the antibiotics.
“Both the increase in cell envelope thickness and in the outer membrane vesicles may be indicative of drug resistance mechanisms being activated in the spaceflight samples,” Zea said, according to CU Boulder Today.
Such research could help to protect astronaut health in the strange living conditions that teams experience on the ISS, a tiny life-sustaining capsule whizzing around the Earth at around 17,500 miles per hour.
Unlike single-celled bacteria, which seem to do fairly well on the ISS, microgravity conditions weaken astronauts’ immune systems, increasing their risk of infection. Astronauts also suffer from loss of bone density, radiation poisoning, and eyesight degradation, among other symptoms.
With NASA’s plans to send humans on a three-year mission to Mars (ISS astronauts usually go up for only six months at a time) in the 2030s, the research will be key for the wellbeing of future astronauts.
In addition to its space applications, this experiment helps to understand how bacteria can become resistant to antibiotics on Earth, BioServe Director Louis Stodieck told CU Boulder Today.
“In space, for example, scientists can learn more about biochemical changes in various cells and organisms that the force of gravity on Earth may be masking.”