Tuesday, 12 February 2019

ISS is not causing bacteria to mutate into dangerous, antibiotic-resistant superbugs


A new study has found that -- despite its seemingly harsh conditions -- the ISS is not causing bacteria to mutate into dangerous, antibiotic-resistant superbugs. The bacteria are instead simply responding, and perhaps evolving, to survive in a stressful environment.
A new Northwestern University study has found that -- despite its seemingly harsh conditions -- the ISS is not causing bacteria to mutate into dangerous, antibiotic-resistant superbugs.

While the team found that the bacteria isolated from the ISS did contain different genes than their Earthling counterparts, those genes did not make the bacteria more detrimental to human health. The bacteria are instead simply responding, and perhaps evolving, to survive in a stressful environment.
"There has been a lot of speculation about radiation, microgravity and the lack of ventilation and how that might affect living organisms, including bacteria," said Northwestern's Erica Hartmann, who led the study. "These are stressful, harsh conditions. Does the environment select for superbugs because they have an advantage? The answer appears to be 'no.'"

The ISS houses thousands of different microbes, which have traveled into space either on astronauts or in cargo. The National Center for Biotechnology Information maintains a publicly available database, containing the genomic analyses of many of bacteria isolated from the ISS. Hartmann's team used that data to compare the strains of Staphylococcus aureus and Bacillus cereus on the ISS to those on Earth.

Found on human skin, S. aureus contains the tough-to-treat MRSA strain. B. cereus lives in soil and has fewer implications for human health.

"Bacteria that live on skin are very happy there," Hartmann said. "Your skin is warm and has certain oils and organic chemicals that bacteria really like. When you shed those bacteria, they find themselves living in a very different environment. A building's surface is cold and barren, which is extremely stressful for certain bacteria."

To adapt to living on surfaces, the bacteria containing advantageous genes are selected for or they mutate. For those living on the ISS, these genes potentially helped the bacteria respond to stress, so they could eat, grow and function in a harsh environment.


See:

Ryan A. Blaustein, Alexander G. McFarland, Sarah Ben Maamar, Alberto Lopez, Sarah Castro-Wallace, Erica M. Hartmann. Pangenomic Approach To Understanding Microbial Adaptations within a Model Built Environment, the International Space Station, Relative to Human Hosts and Soil. mSystems, 2019; 4 (1) DOI: 10.1128/mSystems.00281-18

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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