As humans venture into space for longer space missions, novel medical challenges arise, calling for effective mitigating measures. Background radiation exposure, circadian rhythm changes and microgravity have been shown to affect microbiome in several studies. This study looked into the variations in urinary microbiota on a short duration space flight to the International space station (ISS) among 4 male crew members.1 Prelaunch and postlaunch and orbital urine samples were collected and analyzed using the 16 s next-generation sequencing. Orbital microbial composition significantly differed with the bacterial load peaking during the orbital period. Although this study assesses this on a short orbital flight, it is important to assess this effect in long-duration space missions because chronic changes in the microbiome can lead on to nutritional deficiencies and metabolic dysregulation. Studies on the effect of space travel on the human body are scarce and generally have small sample size, reducing the statistical power. Male astronauts predominate in all these studies, with nothing much known on the effect of long duration spaceflights on the female body. Female astronauts have a 4.5 times chance of urinary retention than their male counterparts in space. All the more, this calls for future studies on this topic to recruit more female astronauts. However, the effect of long distance flights on the human microbiome will be known only when such missions happen in the future. Space travel can alter the microbiomes in the gut and urine causing new challenges to the crew. For example, Apollo-Soyuz Test Project revealed that the bacteria isolated from astronauts in space were more resistant to antibiotics than those isolated from preflight and postflight samples.2 The chemical nature of urine is altered in microgravity because of bone demineralization, and future studies should ideally assess both the chemical and microbiome changes in urine. Future studies on this topic will need to focus on the effect of long distance flights on urinary microbiome; assessing this in microgravity during astronaut simulation/training and including other commercial crews in future studies can provide valuable insights. However, the long-term effects of space travel on the human body remains to be seen.
Danny Darlington Carbin (Sun,) studied this question.