Scientists have identified five strains of bacterium Enterobacter that were recovered in 2015 from the exercise platform and toilet area on the International Space Station (ISS). Scientists caution that these microbes should be investigated in detail for potential health implications for future space missions.
The strains recovered from the ISS were examined by scientists at NASA's Jet Propulsion Laboratory, who found that these strains were not pathogenic to humans.
The primary aim of this study was to identify and characterise the bacterial communities that dwell on surfaces inside the ISS.
To precisely identify the microbes collected on the ISS, the research team compared the strains to genomes of 1,291 Enterobacter strains recovered on Earth. The analysis showed that the ISS strains were genetically similar to three strains found on Earth.
According to the research team, these three strains belong to a single bacterium species Enterobacter bugandensis that has been found to cause disease in newborns admitted to three different hospitals (in Washington state, Colorado and east Africa).
The investigation also enabled scientists to understand if the ISS strains had developed any antimicrobial resistance and whether they had gene profiles similar to those seen in known multi-drug resistant bacteria.
The results showed that antimicrobial resistance patterns of ISS strains were similar to that of three strains found on Earth. The ISS microbes also had 112 genes involved in disease, virulence, and defence. However, they didn't contain combinations linked with high infection rates.
The research team also predicts a 79 per cent probability of these strains potentially causing disease. Because of the unusual conditions in which these strains live, there is a degree of uncertainty about the development of the strains.
"Whether or not an opportunistic pathogen like E. bugandensis causes disease and how much of a threat it is, depends on a variety of factors, including environmental ones," said Dr. Kasthuri Venkateswaran, Senior Research Scientist at the JPL Biotechnology and Planetary Protection Group and the corresponding author of the study.
"Further in vivo studies are needed to discern the impact that conditions on the ISS, such as microgravity, other space, and spacecraft-related factors, may have on pathogenicity and virulence."
The study is published in the open access journal BMC Microbiology.
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