Astronauts on long-term missions might have to face off many dangers and some of those might be coming from Earth. A new study on the adaptability of bacteria in space has shown that they can fight off antibiotics better because they change shape.
An international team of researchers sent cultures of E. Coli to the International Space Station to be treated with different concentrations of gentamicin sulfate, an antibiotic that easily kills the bacteria on Earth. The team discovered at the end of the experiment there were 13 times more E. Coli in the space cultures compared to the Earth-bound control sample and the cell size was 63 percent smaller. The results are published in Frontiers in Microbiology.
“We knew bacteria behave differently in space and that it takes higher concentrations of antibiotics to kill them,” lead author Luis Zea, from the University of Colorado Boulder, said in a statement. “What’s new is that we conducted a systematic analysis of the changing physical appearance of the bacteria during the experiments.”
Without gravity, there’s no longer buoyancy and sedimentation, which helps bacteria reach nutrients. Bacteria are at the “mercy” of natural diffusion so with a smaller surface area they are less likely to allow drugs to get in. Their cell envelopes also increase in thickness and develop vesicles, which are used for sending molecular signals to other cells. If all of this wasn’t already enough, they also clump together in groups, which protects the inner cells from the antibiotics even more.
“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,” continued Zea. “And this experiment and others like it give us the opportunity to better understand how bacteria become resistant to antibiotics here on Earth.”
The clumping of the E. Coli has been linked to biofilm formation in certain bacteria here on Earth. Biofilms are groups of microorganisms that stick together thanks to a slimy extracellular matrix. Dental plaques and the scum on shower curtains are two good (and somewhat manageable) examples. More worrying cases are tuberculosis biofilms, which are extremely difficult to kill.
This research could hopefully benefit astronauts and civilians alike. Novel techniques need to be used to fight off bacteria in space and they might have applications also here on Earth.