Characterization of the microbial composition of the International Space Station (ISS) is a topic that currently interests the National Aeronautics and Space Administration (NASA). The ISS is an interesting environment because it is a built environment that experiences constant human contact, microgravity and space radiation. Understanding the ISS microbial community would help with help and safety concerns as well as proper maintenance of the ISS. Scientists across the United States combined their efforts to properly characterize the microbial community of the ISS, and compared it to cleanrooms on Earth. The results were published by Microbiome.

Samples were collected from ISS high-efficiently particulate arrestance (HEPA, vacuum cleaner bag components from the ISS, and two cleanrooms at the Jet Propulsion Laboratory (JPL) in Pasadena, CA. Cleanrooms are closed rooms with little human traffic and filtered air. Bacterial and fungal samples were cultured and sequenced using next generation sequencing techniques in order to determine identities. Sixteen fungal strains were isolated from the ISS samples compared to the three strains from JPL samples, with most strains being associated with the phylum Ascomycota. Bacterial samples from the ISS were dominated by Actinobacteria, Bacilli, and Clostridia, while samples from the JPL were dominated by Alphaproteobacteria and Gammaproteobacteria. On a genus level, the two sample environments were completely distinct as well.

This study shows that the International Space Station has a very distinct microbial community that must be monitored. As we know that the microbiome is so influential on health, it is important that the ISS bacteria are characterized in order to ensure the health and safety of those on board. This is just another important example that the microbiome has a great influence on humans, even from out in space.