Prior to Nickerson and her team's study, the genetic behavior of Salmonella typhimurium--the main culprit in cases of food poisoning and typhoid fever--was unknown. The microbe poses a significant threat to astronauts during spaceflight, especially because it is resistant to many antibiotic treatments.
The researchers' experiment revealed that a genetic switch called "Hfq," which may control more than 160 genes in S. typhimurium, turns on in space and causes S. typhimurium to become three times more virulent than on the Earth's surface.
Based on what the space-faring bacteria did to animal models on the ground, Nickerson and her colleagues think hard-to-control biofilms are responsible for the increased danger.
"Biofilms are associated with increased pathogenicity because the immune system can't clear the bacteria effectively and antibiotics don't treat them effectively," Nickerson said. "The change that we observed [in space] is consistent with what looks like formation of a biofilm. The ground-grown samples did not show biofilm formation."
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