There should be more of them.
Of all the problems the Back Page can anticipate having with life on the International Space Station, “too clean” is not one that had occurred to us.
But the sterility of the ISS has been blamed for common astronaut health problems such as allergies, skin rashes, latent virus reactivation and fungal or bacterial infections, says a new paper in Cell.
The ISS is regularly profiled for microorganisms, given the known risks of antimicrobial resistance and increased virulence. You don’t want to go for a week and be stuck up there for eight months with an out-of-control mutated pathogen, I guess.
Or with any out-of-control life form. Completely irrelevantly, the Back Page highly recommends the 2017 film Life.
But a microbial desert is also a problem.
“Evidence increasingly links chronic inflammatory diseases in developed countries to reduced microbial exposures, a consequence of modern behaviors such as indoor living, enhanced hygiene, and dietary changes,” say the authors, from UC San Diego.
“These shifts can exacerbate inflammatory responses to otherwise innocuous agents.”
As co-author Professor Rob Knight told media: “There’s a big difference between exposure to healthy soil from gardening versus stewing in our own filth, which is kind of what happens if we’re in a strictly enclosed environment with no ongoing input of those healthy sources of microbes from the outside.”
The team used swabs of more than 800 locations, a technique called three-dimensional microbial mapping and source tracking to survey the nature and diversity of the ISS’s microbiome and where it came from.
Comparing the profile to those of other built environments, they found a “striking loss of microbial diversity, positioning the ISS at the extreme end of a gradient from open-air habitats like rainforests to controlled, enclosed environments dominated by human inputs”.
The primary source of ISS microbiota was, unsurprisingly, human skin, followed by building materials. The kitchen and bathroom modules “showed unique microbial patterns” – you can guess what those were.
Chemical profiling found that disinfectant use correlated positively with bacterial phylogenetic diversity. So either disinfectants were used more frequently where high bioburdens were expected, or more worryingly they create “a ‘clean slate’ promoting bacterial colonisation”.
Probiotic sanitation and other alternatives should be considered to mitigate the antimicrobial resistance carnival that chemical disinfection may be promoting, the authors say.
If we’re to pursue extraterrestrial living, the authors say, we need all the help we can get.
If we’re to form a colony on Mars within 20 years seeded by Elon Musk’s generously donated sperm, we just need help.
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