Effects of 60 days of 6 degrees head down bed rest on the composition and function of the human gut microbiota

Abstract Spaceflight is rigorous and dangerous environment which can negatively affect astronauts’ health and the entire mission. Recently studies showed that the human gut microbiota were enormously affected by spaceflight. The 60 days of 6 degrees head down bed rest(HDBR) experiment provided us with an opportunity to trace the change of gut microbiota under simulated microgravity. The gut microbiota of volunteers was analyzed and characterized by 16S rRNA gene sequencing and metagenomic sequencing. Our results showed that the composition and function of the volunteers’ gut microbiota were markedly affected by 60 days of 6 degrees HDBR. We further confirmed the species and diversity fluctuations. Resistance and virulence genes in the gut microbiota were also affected by 60 days of 6 degrees HDBR, but the species attributions remained stable. The human gut microbiota affected by 60 days of 6 degrees HDBR which was partially consistent with the effect of spaceflight, implying that HDBR can be used as the spaceflight simulation model in terms of gut microbiota.