A comprehensive study of bacteria and fungi found on surfaces on the International Space Station could help prepare for longer space travel.
Using molecular and culture-based methods to study ISS surfaces, NASA researchers catalogued a number of organisms that are mostly found on humans, including some considered opportunistic pathogens.
Dr Kasthuri Venkateswaran, from NASA's Jet Propulsion Laboratory, said: “Our study provides the first comprehensive catalogue of the bacteria and fungi found on surfaces in closed space systems and can be used to help improve safety measures that meet NASA requirements for deep space human habitation.
“Specific microbes in indoor spaces on Earth have been shown to impact human health," he said. "This is even more important for astronauts during spaceflight, as they have altered immunity and do not have access to the sophisticated medical interventions available on Earth."
The researchers used traditional culture techniques and gene sequencing methods to analyse surface samples collected from eight locations on the ISS, including the viewing window, toilet, exercise platform, dining table and sleeping quarters, during three flights across 14 months.
Staphylococcus, Pantoea and Bacillus were the dominant genera of bacteria found, accounting for 26%, 23% and 11% of total isolates. Staphylococcus can cause blood poisoning and toxic shock in humans and some strains of the bacteria are resistant to antibiotics. Staphylococcus aureus, which is commonly found on human skin and in the nasal passage, accounted for 10% of total isolates identified.
They also found Enterobacter, which is associated with the human gastrointestinal tract, as well as Ascomycota and Basidiomycota fungi. Fungal communities were found to be stable, while microbial communities were similar across locations but changed over time.
Samples taken during the second flight mission had higher microbial diversity than samples collected during the first and third missions, which may have been due to the different astronauts on the flights.
It is unknown whether the microbes could cause disease in astronauts on the ISS, which could depend on factors such as individual health status of each ISS crewmember. Dr Checinska Sielaff, first author, has called for further studies to determine how these microbes function in space.
The team detailed their findings in the journal Microbiome.