When anaerobes encounter oxygen: mechanisms of oxygen toxicity, tolerance and defence.
When anaerobes encounter oxygen: mechanisms of oxygen toxicity, tolerance and defence.
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DOI：
10.1038/s41579-021-00583-y
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发表时间：
2021-12
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影响因子：
--
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中科院分区：
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--
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专性厌氧菌的决定性特征是氧气阻止它们的生长，但潜在的机制尚不清楚。一种流行的假说是，这些微生物未能进化出防御系统，以保护自己免受超氧化物和过氧化氢等活性氧物种(ROS)的伤害，而这种失败是阻止它们向有氧生境扩张的原因。然而，研究表明，厌氧菌实际上具有与需氧菌相同的大部分防御能力，其中许多菌具有耐受大量氧气的能力。因此，为了了解微生物群落的结构和现实世界的动态，研究人员研究了类杆菌、硫化弧菌、热球菌和梭状芽孢杆菌等厌氧菌是如何。与氧气作斗争和应对。这些生物居住的低氧环境--包括哺乳动物的肠道、硫磺喷口和深层沉积物--经历了间歇性的氧合作用。在这篇综述中，我们探讨了氧气损害厌氧菌的分子机制，以及细菌保护其代谢途径免受其影响的程度。厌氧菌的最新观点是，厌氧代谢的最佳策略依赖于自由基化学和低电势金属中心。这样的催化位置本质上很容易受到分子氧和ROS的直接中毒。观察表明，厌氧菌已经进化出了一些策略，要么将氧气干扰其新陈代谢的程度降至最低，要么在压力消散后不久恢复功能。
The defining trait of obligate anaerobes is that oxygen blocks their growth, yet the underlying mechanisms are unclear. A popular hypothesis was that these microorganisms failed to evolve defences to protect themselves from reactive oxygen species (ROS) such as superoxide and hydrogen peroxide, and that this failure is what prevents their expansion to oxic habitats. However, studies reveal that anaerobes actually wield most of the same defences that aerobes possess, and many of them have the capacity to tolerate substantial levels of oxygen. Therefore, to understand the structures and real-world dynamics of microbial communities, investigators have examined how anaerobes such as Bacteroides, Desulfovibrio, Pyrococcus and Clostridium spp. struggle and cope with oxygen. The hypoxic environments in which these organisms dwell — including the mammalian gut, sulfur vents and deep sediments — experience episodic oxygenation. In this Review, we explore the molecular mechanisms by which oxygen impairs anaerobes and the degree to which bacteria protect their metabolic pathways from it. The emergent view of anaerobiosis is that optimal strategies of anaerobic metabolism depend upon radical chemistry and low-potential metal centres. Such catalytic sites are intrinsically vulnerable to direct poisoning by molecular oxygen and ROS. Observations suggest that anaerobes have evolved tactics that either minimize the extent to which oxygen disrupts their metabolism or restore function shortly after the stress has dissipated.
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