Université Paris Saclay, INRAE, Micalis Institute, MicrobAdapt, Jouy en Josas, France.
Laboratoire Pathogenèses des Bactéries Anaérobies, Institut Pasteur, UMR CNRS 2001, Université de Paris, Paris, France.
mSphere. 2021 May 5;6(3):e00232-19. doi: 10.1128/mSphere.00232-19.
Aerobic bacteria are frequent primocolonizers of the human naive intestine. Their generally accepted role is to eliminate oxygen, which would allow colonization by anaerobes that subsequently dominate bacterial gut populations. In this hypothesis-based study, we revisited this dogma experimentally in a germfree mouse model as a mimic of the germfree newborn. We varied conditions leading to the establishment of the dominant intestinal anaerobe Two variables were introduced: inoculum size and preestablishment by bacteria capable or not of consuming oxygen. High inoculum size enabled its primocolonization. At low inocula, we show that bacterial preestablishment was decisive for subsequent colonization. However, even non-oxygen-respiring bacteria, a mutant and the intestinal obligate anaerobe , facilitated establishment. These findings, which are supported by recent reports, revise the long-held assumption that oxygen scavenging is the main role for aerobic primocolonizing bacteria. Instead, we suggest that better survival of aerobic bacteria during vectorization between hosts could be a reason for their frequent primocolonization.
需氧菌是人类原始肠道的常见初代定植菌。它们的公认作用是消除氧气，从而为随后在肠道菌群中占主导地位的厌氧菌的定植创造条件。在这项基于假设的研究中，我们在无菌小鼠模型中对这一教条进行了实验性研究，以模拟无菌新生儿。我们改变了导致主要肠道厌氧菌定植的条件，引入了两个变量：接种物大小和能够或不能够消耗氧气的细菌预先定植。大接种物大小使其能够初代定植。在低接种物的情况下，我们表明细菌预先定植对于随后的定植是决定性的。然而，即使是非需氧细菌，突变体和肠道专性厌氧菌，也促进了定植。这些发现得到了最近报告的支持，修正了长期以来认为氧气清除是需氧初代定植菌主要作用的假设。相反，我们认为，在宿主之间传播过程中需氧菌更好的存活可能是它们频繁初代定植的一个原因。
