The ISS Is a Cesspool of Bacteria and Fungi, Study Finds

An extensive survey of bacteria and fungi on surfaces inside the International Space Station has revealed an astonishing number of microorganisms living among the astronauts -- the health impacts of which aren't entirely clear. Gizmodo reports: Since it was first established in 1998, the International Space Station has been visited by hundreds of astronauts (227 to be exact). These trips have invariably introduced an array of microbes to the orbital outpost, as have shipments of cargo. But while astronauts return to Earth, their germs stay behind. New research published today in Microbiome offers the most comprehensive catalogue to date of the bacteria and fungi living on the ISS, detailing the station's distinctive and ever-changing microbiological profile. This research will now be used by NASA and other space agencies to develop safety measures for the ISS and other long-term space missions.

NASA astronauts took swabs using sterile wipes at eight predefined locations on the ISS, on three different occasions during a 14 month period. The locations included both high and low traffic areas, including the viewing window, toilet, exercise platform, stowage rack, dining table, and sleeping quarters. NASA astronaut Terry Virts performed the first two sampling sessions on March 4, 2015 and then three months later on May 15, 2015. NASA astronaut Jeffrey Williams took the third sample a year later on May 6, 2016. The samples were returned to Earth for analysis. The ISS may seem like a cold, sterile place in space, but the analysis showed it's a veritable cornucopia for microbes. The most prolific bacteria, according to culture results, were Staphylococcus (26 percent of total samples), Pantoea (23 percent), Bacillus (11 percent), Staphylococcus aureus (10 percent) and Pantoea conspicua and Pantoea gaviniae (both at 9 percent). The fungal population was primarily comprised of Rhodotorula mucilaginosa. The authors warn that some strains of bacteria could form damaging biological sheets known as biofilms: '[B]iofilm formation on the ISS could decrease infrastructure stability by causing mechanical blockages, reducing heat transfer efficiency, and inducing microbial influenced corrosion...'

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