BACKGROUND Space environment imposes a range of challenges to mammalian physiology and the gut microbiota, and interactions between the two are thought to be important in mammalian health in space. While previous findings have demonstrated a change in the gut microbial community structure during spaceflight, specific environmental factors that alter the gut microbiome and the functional relevance of the microbiome changes during spaceflight remain elusive. METHODS We profiled the microbiome using 16S rRNA gene amplicon sequencing in fecal samples collected from mice after a 37-day spaceflight onboard the International Space Station. We developed an analytical tool, named STARMAPs (Similarity Test for Accordant and Reproducible Microbiome Abundance Patterns), to compare microbiome changes reported here to other relevant datasets. We also integrated the gut microbiome data with the publically available transcriptomic data in the liver of the same animals for a systems-level analysis. RESULTS We report an elevated microbiome alpha diversity and an altered microbial community structure that were associated with spaceflight environment. Using STARMAPs, we found the observed microbiome changes shared similarity with data reported in mice flown in a previous space shuttle mission, suggesting reproducibility of the effects of spaceflight on the gut microbiome. However, such changes were not comparable with those induced by space-type radiation in Earth-based studies. We found spaceflight led to significantly altered taxon abundance in one order, one family, five genera, and six species of microbes. This was accompanied by a change in the inferred microbial gene abundance that suggests an altered capacity in energy metabolism. Finally, we identified host genes whose expression in the liver were concordantly altered with the inferred gut microbial gene content, particularly highlighting a relationship between host genes involved in protein metabolism and microbial genes involved in putrescine degradation. CONCLUSIONS These observations shed light on the specific environmental factors that contributed to a robust effect on the gut microbiome during spaceflight with important implications for mammalian metabolism. Our findings represent a key step toward a better understanding the role of the gut microbiome in mammalian health during spaceflight and provide a basis for future efforts to develop microbiota-based countermeasures that mitigate risks to crew health during long-term human space expeditions.

中文翻译：

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肠道微生物组的可重复变化表明太空飞行期间微生物和宿主代谢发生了变化。

背景技术太空环境给哺乳动物生理学和肠道微生物群带来了一系列挑战，并且两者之间的相互作用被认为对于哺乳动物在太空中的健康很重要。虽然之前的研究结果表明太空飞行期间肠道微生物群落结构发生了变化，但改变肠道微生物组的特定环境因素以及太空飞行期间微生物组变化的功能相关性仍然难以捉摸。方法 我们使用 16S rRNA 基因扩增子测序对在国际空间站进行 37 天太空飞行后收集的小鼠粪便样本中的微生物组进行分析。我们开发了一种名为 STARMAP（一致且可重复的微生物组丰度模式的相似性测试）的分析工具，用于将此处报告的微生物组变化与其他相关数据集进行比较。我们还将肠道微生物组数据与同一动物肝脏中公开的转录组数据进行了系统级分析。结果我们报告了与航天环境相关的微生物组α多样性的升高和微生物群落结构的改变。使用STARMAP，我们发现观察到的微生物组变化与之前航天飞机任务中飞行的小鼠报告的数据具有相似性，这表明太空飞行对肠道微生物组影响的可重复性。然而，这种变化与地球研究中太空辐射引起的变化无法比较。我们发现太空飞行导致一目、一科、五属和六种微生物的分类单元丰度发生显着改变。与此同时，推断的微生物基因丰度发生了变化，表明能量代谢能力发生了变化。最后，我们确定了肝脏中表达与推断的肠道微生物基因含量一致改变的宿主基因，特别强调了参与蛋白质代谢的宿主基因与参与腐胺降解的微生物基因之间的关系。结论这些观察结果揭示了太空飞行期间对肠道微生物群产生强烈影响的特定环境因素，对哺乳动物的新陈代谢具有重要意义。我们的研究结果代表了更好地了解肠道微生物组在太空飞行期间哺乳动物健康中的作用的关键一步，并为未来开发基于微生物群的对策奠定了基础，以减轻长期载人太空探险期间船员健康的风险。