Carleton College, Northfield, MN, USA.
Ocean Sciences Department, University of California Santa Cruz, Santa Cruz, CA, USA.
Sci Adv. 2023 Jul 7;9(27):eade4847. doi: 10.1126/sciadv.ade4847.
The biogeochemical sulfur cycle plays a central role in fueling microbial metabolisms, regulating the Earth's redox state, and affecting climate. However, geochemical reconstructions of the ancient sulfur cycle are confounded by ambiguous isotopic signals. We use phylogenetic reconciliation to ascertain the timing of ancient sulfur cycling gene events across the tree of life. Our results suggest that metabolisms using sulfide oxidation emerged in the Archean, but those involving thiosulfate emerged only after the Great Oxidation Event. Our data reveal that observed geochemical signatures resulted not from the expansion of a single type of organism but were instead associated with genomic innovation across the biosphere. Moreover, our results provide the first indication of organic sulfur cycling from the Mid-Proterozoic onwards, with implications for climate regulation and atmospheric biosignatures. Overall, our results provide insights into how the biological sulfur cycle evolved in tandem with the redox state of the early Earth.
生物地球化学硫循环在为微生物代谢提供动力、调节地球氧化还原状态和影响气候方面起着核心作用。然而，古硫循环的地球化学重建受到同位素信号不明确的影响。我们使用系统发育协调来确定生命之树中古代硫循环基因事件的时间。我们的结果表明，在太古代就已经出现了利用硫化物氧化的代谢途径，但涉及硫代硫酸盐的代谢途径仅在大氧化事件之后才出现。我们的数据表明，观察到的地球化学特征不是由单一类型的生物体的扩张引起的，而是与整个生物圈的基因组创新有关。此外，我们的结果首次表明从中元古代开始就存在有机硫循环，这对气候调节和大气生物特征有影响。总的来说，我们的结果提供了关于生物硫循环如何与早期地球的氧化还原状态协同进化的见解。
