Subsurface environments are among Earth’s largest habitats for microbial life. Yet, until recently, we lacked adequate data to accurately differentiate between globally distributed marine and terrestrial surface and subsurface microbiomes. Here, we analyzed 478 archaeal and 964 bacterial metabarcoding datasets and 147 metagenomes from diverse and widely distributed environments. Microbial diversity is similar in marine and terrestrial microbiomes at local to global scales. However, community composition greatly differs between sea and land, corroborating a phylogenetic divide that mirrors patterns in plant and animal diversity. In contrast, community composition overlaps between surface to subsurface environments supporting a diversity continuum rather than a discrete subsurface biosphere. Differences in microbial life thus seem greater between land and sea than between surface and subsurface. Diversity of terrestrial microbiomes decreases with depth, while marine subsurface diversity and phylogenetic distance to cultured isolates rivals or exceeds that of surface environments. We identify distinct microbial community compositions but similar microbial diversity for Earth’s subsurface and surface environments.

中文翻译：

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地表和地下微生物组的全球比较揭示了大规模的生物多样性梯度和海洋-陆地鸿沟


地下环境是地球上最大的微生物栖息地之一。然而，直到最近，我们还缺乏足够的数据来准确区分全球分布的海洋和陆地表面和地下微生物组。在这里，我们分析了来自不同和广泛分布环境的 478 个古细菌和 964 个细菌宏条形码数据集以及 147 个宏基因组。局部和全球尺度的海洋和陆地微生物组的微生物多样性相似。然而，海洋和陆地之间的群落组成差异很大，证实了反映动植物多样性模式的系统发育鸿沟。相比之下，群落组成在地表与地下环境之间重叠，支持多样性连续体，而不是离散的地下生物圈。因此，陆地和海洋之间的微生物生命差异似乎比表面和地下之间的差异更大。陆地微生物组的多样性随着深度的增加而降低，而海洋地下多样性和与培养分离株的系统发育距离与表层环境相当或超过。我们确定了地球地下和地表环境的不同微生物群落组成，但相似的微生物多样性。