Ancient microbes invented biochemical mechanisms and assembled core metabolic pathways on an anoxic Earth. Molecular oxygen appeared far later, forcing microbes to devise layers of defensive tactics that fend off the destructive actions of both reactive oxygen species (ROS) and oxygen itself. Recent work has pinpointed the enzymes that ROS attack, plus an array of clever protective strategies that abet the well known scavenging systems. Oxygen also directly damages the low-potential metal centers and radical-based mechanisms that optimize anaerobic metabolism; therefore, committed anaerobes have evolved customized tactics that defend these various enzymes from occasional oxygen exposure. Thus a more comprehensive, detailed, and surprising view of oxygen toxicity is coming into view.

古代微生物发明了生化机制，并在缺氧的地球上组装了核心代谢途径。分子氧的出现要晚得多，迫使微生物设计出多层防御策略来抵御活性氧（ROS）和氧本身的破坏作用。最近的工作已经查明了 ROS 攻击的酶，以及一系列巧妙的保护策略，这些策略促进了众所周知的清除系统。氧气还直接损害低电位金属中心和优化无氧代谢的自由基机制；因此，顽固的厌氧菌已经进化出定制的策略来保护这些不同的酶免受偶尔的氧气暴露。因此，关于氧毒性的更全面、更详细、更令人惊讶的观点正在浮现眼前。