Hydrothermal systems, including terrestrial hot springs, contain diverse geochemical conditions that vary over short spatial scales due to progressive interactions between reducing hydrothermal fluids, the oxygenated atmosphere, and, in some cases, seawater. At Jinata Onsen on Shikinejima Island, Japan, an intertidal, anoxic, iron-rich hot spring mixes with the oxygenated atmosphere and seawater over short spatial scales, creating diverse chemical potentials and redox pairs over a distance of ~10 m. We characterized geochemical conditions along the outflow of Jinata Onsen as well as the microbial communities present in biofilms, mats, and mineral crusts along its traverse using 16S rRNA gene amplicon and genome-resolved shotgun metagenomic sequencing. Microbial communities significantly changed downstream as temperatures and dissolved iron concentrations decreased and dissolved oxygen increased. Biomass was more limited near the spring source than downstream, and primary productivity appeared to be fueled by the oxidation of ferrous iron and molecular hydrogen by members of Zetaproteobacteria and Aquificae. The microbial community downstream was dominated by oxygenic Cyanobacteria. Cyanobacteria are abundant and active even at ferrous iron concentrations of ~150 μM, which challenges the idea that iron toxicity limited cyanobacterial expansion in Precambrian oceans. Several novel lineages of Bacteria are also present at Jinata Onsen, including previously uncharacterized members of the phyla Chloroflexi and Calditrichaeota, positioning Jinata Onsen as a valuable site for the future characterization of these clades.

中文翻译：

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Jinata Onsen 的地球化学和宏基因组特征，一个元古界模拟温泉，揭示了新的微生物多样性，包括耐铁光养生物和嗜热岩石营养生物

包括陆地温泉在内的热液系统包含多种地球化学条件，由于还原性热液流体、含氧大气以及某些情况下的海水之间的逐渐相互作用，这些条件在短空间尺度上会发生变化。在日本志根岛的真田温泉，潮间带缺氧、富含铁的温泉在短空间尺度上与含氧大气和海水混合，在约 10 m 的距离内产生不同的化学势和氧化还原对。我们使用 16S rRNA 基因扩增子和基因组解析的鸟枪宏基因组测序表征了 Jinata Onsen 流出道沿线的地球化学条件以及沿其横向存在于生物膜、垫子和矿物结壳中的微生物群落。随着温度和溶解铁浓度的降低以及溶解氧的增加，下游微生物群落发生了显着变化。泉源附近的生物质比下游更有限，初级生产力似乎是由 Zetaproteobacteria 和 Aquificae 成员氧化亚铁和分子氢来推动的。下游微生物群落以含氧蓝藻为主。即使亚铁浓度约为 150 μM，蓝藻也很丰富且活跃，这对铁毒性限制前寒武纪海洋中蓝藻扩张的观点提出了挑战。Jinata Onsen 也出现了几种新的细菌谱系，包括以前没有特征的 Chloroflexi 门和 Calditrichaeota，