In space, bacteria “shapeshifts” to defend itself against antibiotics, experiments on board the International Space Station (ISS) have revealed. The discovery potentially poses a big problem for future space travel—as long duration missions happen more frequently, we will need antibiotics to treat sick astronauts. But if space bacteria is able to quickly and effectively develop resistance, common infections could become deadly.
Scientists have known for some time that bacteria behaves differently in space compared to how it does on Earth. It takes higher concentrations of antibiotics to kill it, for example. Exactly how and why this is, however, is unknown.
To find out how bacteria behaves in the microgravity conditions of space, a team of researchers led by Luis Zea from the University of Colorado Boulder sent E. coli samples up to the ISS. From here, they were able to directly compare how the bacteria grew and responded to the antibiotic gentamicin sulfate, which kills it on Earth. “We conducted a systematic analysis of the changing physical appearance of the bacteria during the experiments,” Zea explained in a statement.
The scientists treated the bacteria with different concentrations of the antibiotics to see what effect the drugs had. Their findings, published in the journal Frontiers in Microbiology, showed there was a 13-fold increase in the E. coli cell numbers and a 73 percent decrease in cell size, compared to control bacteria on Earth. The space samples also developed a thicker cell wall and membrane, which the team believes helped the bacteria protect itself from the antibiotic.
Researchers also found that some cells produced membrane vesicles, which allow cells to communicate with one another—potentially to initiate the infection process. “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.
Another finding was that the space E. coli formed in clumps more, which they suggest is a defensive maneuver to sacrifice the outer cells to protect the inner ones. This may be related to the formation of biofilms, where multicellular communities build up over time—the scum you find on vinyl shower curtains is an example of this. Because biofilms can form on various surfaces, they pose a risk when it comes to space travel.
“By default, bacteria will accompany humans in our exploration of space,” the researchers write. “The average healthy individual carries trillions of microorganisms in and on their body, outnumbering human cells. This human microbiome includes opportunistic pathogens, microbes that do not normally cause disease in a healthy person but can provoke an infection when the person’s immune system is suppressed, a concern known to occur during spaceflight.
“The increased cell aggregation of bacteria and fungi observed in space, and its association with biofilm formation and potentially with enhanced conjugation, may therefore present deleterious effects for long-term human spaceflight and warrant further studying of these phenomena.”