Life emerged and diversified in the absence of molecular oxygen. The prevailing anoxia and unique sulfur chemistry in the Paleo-, Meso- and Neoarchean, and early Proterozoic eons may have supported microbial communities that are drastically different than those currently thriving on the earth’s surface. Zodletone spring in southwestern Oklahoma represents a unique habitat where spatial sampling could substitute for geological eons: from the anoxic, surficial light exposed sediments simulating a preoxygenated earth, to overlaid water column where air exposure simulates the relentless oxygen intrusion during the Neo Proterozoic. We document a remarkably diverse microbial community in the anoxic spring sediments, with 340/516 (65.89%) of genomes recovered in a metagenomic survey belonging to 200 bacterial and archaeal families that were either previously undescribed or that exhibit an extremely rare distribution on the current earth. Such diversity is underpinned by the widespread occurrence of sulfite-, thiosulfate, tetrathionate-, and sulfur-reduction, and paucity of sulfate-reduction machineries in these taxa; hence greatly expanding lineages mediating reductive sulfur cycling processes in the tree of life. Analysis of the overlaying water community demonstrated that oxygen intrusion lead to the development of a significantly less diverse community dominated by well-characterized lineages and a prevalence of oxidative sulfur cycling processes. Such transition from ancient novelty to modern commonality underscores the profound impact of the great oxygenation event on the earth’s surficial anoxic community. It also suggests that novel and rare lineages encountered in current anaerobic habitats could represent taxa once thriving in an anoxic earth, but have failed to adapt to earth’s progressive oxygenation.

中文翻译：

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早期地球类似物中的微生物多样性和硫循环：从古代新奇到现代共性

在没有分子氧的情况下，生命出现并多样化。古、中、新太古代以及元古代早期盛行的缺氧和独特的硫化学可能支持了与目前在地球表面蓬勃发展的微生物群落截然不同的微生物群落。俄克拉荷马州西南部的 Zodletone 泉代表了一个独特的栖息地，在那里空间采样可以替代地质时代：从模拟预氧化地球的缺氧、表面光暴露沉积物到覆盖水柱，其中空气暴露模拟新元古代期间无情的氧气侵入。我们在缺氧泉沉积物中记录了一个非常多样化的微生物群落，340/516 (65. 89%) 的基因组在宏基因组调查中恢复，这些基因组属于 200 个细菌和古菌家族，这些家族以前未被描述过，或者在当前地球上表现出极其罕见的分布。这种多样性的基础是亚硫酸盐、硫代硫酸盐、连四硫酸盐和硫还原的广泛存在，以及这些类群中硫酸盐还原机制的缺乏；因此大大扩展了介导生命之树中还原性硫循环过程的谱系。对覆盖水群落的分析表明，氧气侵入导致了一个由特征明确的谱系和氧化硫循环过程的普遍主导的多样性显着降低的群落的发展。这种从古代新奇到现代共性的转变强调了大氧化事件对地球表面缺氧群落的深远影响。它还表明，在当前厌氧生境中遇到的新奇和稀有谱系可能代表曾经在缺氧地球中繁衍生息的分类群，但未能适应地球的渐进式氧化。