BioProject

The effects on the microbiome that prolonged human space travel could have are unclear, and could impact the successful outcome of space travel. Here, the expedition members of the Trans-Antarctic Winter Traverse, a terrestrial analogous expedition to space travel, gave stool and saliva samples for each of the eight months of travel, in addition to a preliminary baseline sample. For saliva, significant (P < 0.001) differences were seen between Baseline salivary bacterial load and all other time points, but not between participants. Bacterial diversity was significantly (P = 0.002) lower in Baseline samples than all other sampling months, though individual differences were also significant (P = 0.016). At the taxonomic level of classification, significant time point differences in the Bacteroidetes (P = 0.008) phylum, and the Desulfotomaculum (P = 0.013), Veillonella (P = 0.016), Prevotella (P = 0.022), Megasphaera (P = 0.041), Bacillus (P = 0.047), and Rothia (P = 0.047) genera were evident. Of these genera, some contain species capable of opportunistic, anaerobic infections of the respiratory tract. The stool microbiome showed no significant differences in bacterial load between participants (P = 0.131) or sampling month (P = 0.867), but bacterial diversity was significantly (P < 0.001) different between participants. Stool water content (P < 0.001), pH of raw saliva (P < 0.001), and saliva supernatant (P = 0.001) all showed significant differences between participants. Overall, the human microbiome shows a spatially different response to the stresses of extreme physiological and environmental conditions, which may have important implications for prolonged human space travel.