School of Marine Science and Policy, University of Delaware, Lewes, DE, USA.
Department of Biological Sciences, Willamette University, Salem, OR, USA.
Sci Rep. 2020 May 15;10(1):8048. doi: 10.1038/s41598-020-64904-6.
Oil reservoirs have been shown to house numerous microbial lineages that differ based on the in-situ pH, salinity and temperature of the subsurface environment. Lineages of Firmicutes, including Clostridiales, have been frequently detected in oil reservoirs, but are typically not considered impactful or relevant due to their spore-forming nature. Here we show, using metagenomics, a high temperature oil reservoir of marine salinity contains a microbial population that is predominantly from within the Order Clostridiales. These organisms form an oil-reservoir specific clade based on the phylogenies of both 16S rRNA genes and ribosomal proteins, which we propose to name Petromonas tenebris, meaning they are single-celled organisms from dark rocks. Metagenome-assembled genomes (MAGs) of these Petromonas sp. were obtained and used to determine that these populations, while capable of spore-formation, were also likely replicating in situ in the reservoir. We compared these MAGs to closely related genomes and show that these subsurface Clostridiales differ, from the surface derived genomes, showing signatures of the ability to degrade plant-related compounds, whereas subsurface genomes only show the ability to process simple sugars. The estimation of in-situ replication from genomic data suggest that Petromonas tenebris lineages are functional in-situ and may be specifically adapted to inhabit oil reservoirs.
油藏中存在着许多微生物谱系，这些谱系根据地下环境的原位 pH 值、盐度和温度而有所不同。厚壁菌门（Firmicutes）的谱系，包括梭菌目（Clostridiales），经常在油藏中被检测到，但由于其孢子形成的性质，通常不被认为具有重要影响或相关性。在这里，我们使用宏基因组学表明，具有海洋盐度的高温油藏中存在主要来自梭菌目（Clostridiales）的微生物种群。这些生物体根据 16S rRNA 基因和核糖体蛋白的系统发育形成一个油藏特异性的分支，我们建议将其命名为 Petromonas tenebris，意思是它们是来自黑暗岩石的单细胞生物。获得了这些 Petromonas sp. 的宏基因组组装基因组（MAG），并用于确定这些种群虽然能够形成孢子，但也可能在储层中就地复制。我们将这些 MAG 与密切相关的基因组进行了比较，表明这些地下梭菌目（Clostridiales）与源自地表的基因组不同，表现出降解与植物相关化合物的能力的特征，而地下基因组仅显示出处理简单糖的能力。来自基因组数据的原位复制估计表明，Petromonas tenebris 谱系在原位具有功能，并且可能专门适应栖息在油藏中。
