地球深处的地下,在地表以下数百米到数公里的地方,以贫营养条件为特征,黑暗和经常缺氧的环境,随着pH值的波动,盐度,和水的可用性。尽管如此,微生物种群被检测到并活跃,在地质时间内促进生物地球化学循环。因为很难进入深层生物圈,对这些社区的身份和新陈代谢知之甚少,尽管它们可能具有未知的途径,并可能干扰深层废物沉积。因此,我们分析了深层的岩石和地下水微生物群落,两个地区的孤立盐水含水层可以追溯到奥陶纪和泥盆纪,使用扩增子和全基因组测序。我们观察到两个地区之间的多样性和群落结构存在显着差异,表明站点年龄和组成的影响。深层高盐地下水不含典型嗜盐菌,和基因组提示参与蛋白质和碳氢化合物降解的途径,和碳固定。我们确定了应对渗透胁迫的主要策略:相容的溶质吸收和生物合成。最后,我们发现了许多噬菌体家族,可能表明细菌被感染。然而,我们还在病毒基因组中发现了辅助代谢基因,可能会给受感染的宿主带来好处。
The deep terrestrial subsurface, hundreds of meters to kilometers below the surface, is characterized by oligotrophic conditions, dark and often anoxic settings, with fluctuating pH, salinity, and water availability. Despite this, microbial populations are detected and active, contributing to biogeochemical cycles over geological time. Because it is extremely difficult to access the deep biosphere, little is known about the identity and metabolisms of these communities, although they likely possess unknown pathways and might interfere with deep waste deposits. Therefore, we analyzed rock and groundwater microbial communities from deep, isolated brine aquifers in two regions dating back to the Ordovician and Devonian, using amplicon and whole genome sequencing. We observed significant differences in diversity and community structure between both regions, suggesting an impact of site age and composition. The deep hypersaline groundwater did not contain typical halophilic bacteria, and genomes suggested pathways involved in protein and hydrocarbon degradation, and carbon fixation. We identified mainly one strategy to cope with osmotic stress: compatible solute uptake and biosynthesis. Finally, we detected many bacteriophage families, potentially indicating that bacteria are infected. However, we also found auxiliary metabolic genes in the viral genomes, probably conferring an advantage to the infected hosts.