Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA.
Department of Chemistry and Geochemistry, Montana Technological University, Butte, MT, USA.
Nat Commun. 2024 Aug 29;15(1):7506. doi: 10.1038/s41467-024-51841-5.
The geosphere and the microbial biosphere have co-evolved for ~3.8 Ga, with many lines of evidence suggesting a hydrothermal habitat for life's origin. However, the extent that contemporary thermophiles and their hydrothermal habitats reflect those that likely existed on early Earth remains unknown. To address this knowledge gap, 64 geochemical analytes were measured and 1022 metagenome-assembled-genomes (MAGs) were generated from 34 chemosynthetic high-temperature springs in Yellowstone National Park and analysed alongside 444 MAGs from 35 published metagenomes. We used these data to evaluate co-variation in MAG taxonomy, metabolism, and phylogeny as a function of hot spring geochemistry. We found that cohorts of MAGs and their functions are discretely distributed across pH gradients that reflect different geochemical provinces. Acidic or circumneutral/alkaline springs harbor MAGs that branched later and are enriched in sulfur- and arsenic-based O-dependent metabolic pathways that are inconsistent with early Earth conditions. In contrast, moderately acidic springs sourced by volcanic gas harbor earlier-branching MAGs that are enriched in anaerobic, gas-dependent metabolisms (e.g. H, CO, CH metabolism) that have been hypothesized to support early microbial life. Our results provide insight into the influence of redox state in the eco-evolutionary feedbacks between thermophiles and their habitats and suggest moderately acidic springs as early Earth analogs.
岩石圈和微生物生物圈共同进化了约 38 亿年，有许多证据表明生命起源于热液栖息地。然而，现代嗜热生物及其热液栖息地在多大程度上反映了早期地球上可能存在的情况仍然未知。为了填补这一知识空白，我们测量了 64 种地球化学分析物，并从黄石国家公园的 34 个化学合成高温泉中生成了 1022 个宏基因组组装基因组（MAG），并与 444 个来自 35 个已发表的宏基因组的 MAG 进行了分析。我们利用这些数据评估了 MAG 分类学、代谢和系统发育随热泉地球化学的协同变化。我们发现，MAG 及其功能的群体在反映不同地球化学区的 pH 梯度上离散分布。酸性或近中性/碱性泉水含有分支较晚的 MAG，富含基于硫和砷的 O 依赖性代谢途径，这与早期地球的条件不一致。相比之下，由火山气体供应的中等酸性泉水含有更早分支的 MAG，富含厌氧、气体依赖的代谢（例如 H、CO、CH 代谢），这些代谢被认为支持早期微生物生命。我们的研究结果提供了关于氧化还原状态对嗜热生物及其栖息地之间生态进化反馈的影响的见解，并表明中等酸性泉水是早期地球的模拟物。
