Variations in Urinary Microbiota in Astronauts on a Short Duration Space Mission to the International Space Station

Space travel exposes crew to substantial stressors, which may potentially alter their microbiome and be detrimental to their health and safety. We hypothesize that urinary microbiota is altered during a short-duration space flight to the International Space Station (ISS). Urine samples were collected from four crew members. One crew member provided samples while on orbit on the ISS using a urine collection kit (UCK) designed for low-gravity environments. This crew member also provided paired mid-stream and UCK samples on Earth prelaunch and upon return for direct comparison of collection methods. Three additional crew provided mid-stream samples prelaunch and upon return. Urine was stored at -80 degrees Celsius and sent for 16s next-generation sequencing (MicroGenDX, Lubbock, TX). Bacterial load (p=0.42), species richness (p=0.63), and differences in microbiota composition (p=0.22) did not vary by collection method (mid-stream versus UCK). Significant differences in microbial composition among preflight, orbital, and return samples were detected (p=0.001, F=3.16, d.f.=2,9, R2=0.47). Orbital microbial composition notably differed from preflight (p=0.06) and significantly differed from return (p=0.03), while preflight and return samples did not differ (p=0.2). Continuous temporal effects on composition were evaluated: bacterial load (p=0.02) and the product of load and richness (p=0.03) were statistically significant, while species richness alone was not significant (p>0.05).