Microbes vs. chemistry in the origin of the anaerobic gut lumen
Microbes vs. chemistry in the origin of the anaerobic gut lumen
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DOI：
10.1073/pnas.1718635115
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发表时间：
2018-04-17
影响因子：
11.1
通讯作者：
Wu, Gary D.
中科院分区：
文献类型：
--
作者：
Friedman, Elliot S.;Bittinger, Kyle;Wu, Gary D.
婴儿肠道中从好氧和兼性厌氧菌到专性厌氧菌的演替沿着粘膜粘附微生物群与管腔微生物群的组成之间的差异，表明肠道微生物消耗氧气，氧气从肠组织扩散到管腔中，使管腔保持在深度厌氧状态。值得注意的是，腔氧水平的测量显示，在常规和无菌小鼠中几乎相同的pO（2）（氧分压）曲线，表明存在除微生物呼吸外的氧消耗机制。体外实验证实，无菌小鼠的管腔内容物能够化学消耗氧气（例如，通过脂质氧化反应），尽管其速率显著低于在常规饲养小鼠的情况下观察到的速率。对于常规小鼠，我们还表明粘附于肠道粘膜和整个肠道长度的管腔中的肠道微生物群的分类组成与氧水平相关。同时，肠道微生物群生物量的增加为远端与近端肠道中管腔氧的减少提供了解释。这些结果证明了肠道微生物群如何利用哺乳动物宿主的氧气，而微生物和氧化化学反应都调节管腔氧气水平，从而塑造肠道不同区域的微生物群落组成。
The succession from aerobic and facultative anaerobic bacteria to obligate anaerobes in the infant gut along with the differences between the compositions of the mucosally adherent vs. luminal microbiota suggests that the gut microbes consume oxygen, which diffuses into the lumen from the intestinal tissue, maintaining the lumen in a deeply anaerobic state. Remarkably, measurements of luminal oxygen levels show nearly identical pO(2) (partial pressure of oxygen) profiles in conventional and germ-free mice, pointing to the existence of oxygen consumption mechanisms other than microbial respiration. In vitro experiments confirmed that the luminal contents of germ-free mice are able to chemically consume oxygen (e.g., via lipid oxidation reactions), although at rates significantly lower than those observed in the case of conventionally housed mice. For conventional mice, we also show that the taxonomic composition of the gut microbiota adherent to the gut mucosa and in the lumen throughout the length of the gut correlates with oxygen levels. At the same time, an increase in the biomass of the gut microbiota provides an explanation for the reduction of luminal oxygen in the distal vs. proximal gut. These results demonstrate how oxygen from the mammalian host is used by the gut microbiota, while both the microbes and the oxidative chemical reactions regulate luminal oxygen levels, shaping the composition of the microbial community throughout different regions of the gut.