Time series analysis of microbiome and metabolome at multiple body sites in steady long-term isolation confinement.

We read the article by Flemer et al ,1 which suggests that the combined analysis of the oral and faecal microbiota may have significant value in the detection of colorectal cancer, with great interest. The oral and intestinal microbiomes are distant anatomic populations that highly abundant, with distinct microbiota and metabolomes, but microbes from the two sites interact with each other.2 External factors, such as residence changes, bacterial infections, irregular diet and circadian rhythm alterations, can lead to a shift in the microbial ecosystem.3 Therefore, understanding the dynamic changes of the microbiome and metabolic profile of faeces and saliva in steady long-term isolation confinement can establish the change rule of human microbiome and the possible disease risk in a long time space travel. In this study, we examined the human microbiome and metabolome with a time series from multiple body sites to evaluate the stability of the microbial ecosystem and its connection with the human metabolome. The salivary and faecal microbiome and the plasmatic, urinary and faecal metabolome of four simulated astronauts were investigated at a total of 18 time points and were compared with before, during and after 180 days of a test of living in the well-controlled ecological life support system (CELSS) (figure 1 and online supplementary file).### Supplementary data [gutjnl-2020-320666supp001.pdf] Figure 1 Overview of the study design and sample collection (saliva (S), faeces (F) and plasma …