The International Space Station (ISS) is a unique working environment, to say the least, and yet while it presents a multitude of challenges, a greater understanding of the microbial environment in orbit could help astronauts for longer space travel or even how microbiomes evolve here on terra firma. As such, investigators at the University of Montreal and McGill University have pioneered and tested a new genomic methodology which reveals a complex bacterial ecosystem at work on the ISS. Findings from their new study were published recently in Environmental Microbiology through an article titled “ANCHOR: a 16S rRNA gene amplicon pipeline for microbial analysis of multiple environmental samples.”

Until recently, relatively little was known about the different types of microbes found on the space station. The new approach enables researchers to identify and map different species inside the ISS, which will ultimately help safeguard astronauts’ health and be key to future long-term space travel.

“Analysis of 16S ribosomal RNA (rRNA) gene amplification data for microbial barcoding can be inaccurate across complex environmental samples,” the authors wrote. “A method, ANCHOR, is presented and designed for improved species‐level microbial identification using paired‐end sequences directly, multiple high‐complexity samples, and multiple reference databases. A standard operating procedure (SOP) is reported alongside benchmarking against artificial, single sample, and replicated mock data sets. The method is then directly tested using a real‐world data set from surface swabs of the ISS.”

Senior study investigator Nicholas Brereton, PhD, a researcher at the University of Montreal’s Plant Biology Research Institute added that this new methodology “provides us spectacular snapshots of the bacterial world in space and the possibilities of applying this method to explore new microbiome environments are really exciting.”

The challenge of maintaining cleanliness within space environments was first documented on the Russian MIR space station, where conditions eventually deteriorated so much that mold became widespread. On the ISS, space agencies have been trying to reduce the amount of microbial growth in the station since it was first launched in 1998.

Strict cleaning and decontamination protocols are now in place to maintain a healthy ISS environment; in orbit, crew members regularly clean and vacuum the space station’s living and working quarters. But as resupply missions arrive carrying a range of material including food, lab equipment, live plants and animals, new bacteria species are continually being added.

In the current study, the authors stated that “simple mock community analysis identified 100% of the expected species and 99% of expected gene copy variants (100% identical). A replicated mock community revealed similar or better numbers of expected species than MetaAmp, DADA2, Mothur, and QIIME1. Analysis of the ISS microbiome identified 714 putative unique species/strains and differential abundance analysis distinguished significant differences between the Destiny module (U.S. laboratory) and Harmony module (sleeping quarters). Harmony was remarkably dominated by human gastrointestinal tract bacteria, similar to enclosed environments on earth; however, Destiny module bacteria also derived from nonhuman microbiome carriers present on the ISS, the laboratory’s research animals.”

Although the microbial characterization method was piloted in space, its applications will be far broader, say the scientists behind the technology. Researchers can replicate this approach to address many challenges and environments, including in oceans and soils. It is already being applied to human diseases and microbiomes.

“Scientists have a well-documented understanding of broad bacterial families on the ISS, but now we’ve discovered a more diverse bacterial ecosystem that we ever expected,” concluded lead study investigator Emmanuel Gonzalez, PhD, a metagenomic specialist at McGill. “It’s an exciting step forward in understanding the biosphere that will accompany humans into extra-terrestrial habitats.”

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