Recycling and metabolic flexibility dictate life in the lower oceanic crust
Recycling and metabolic flexibility dictate life in the lower oceanic crust
复制标题
回收和代谢灵活性决定了下洋壳的生命
DOI：
10.1038/s41586-020-2075-5
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发表时间：
2020-03-01
期刊：
影响因子：
64.8
通讯作者：
Edgcomb, Virginia P.
中科院分区：
文献类型：
--
作者：
Li, Jiangtao;Mara, Paraskevi;Edgcomb, Virginia P.
石化的下洋壳是地球最后的生物边界之一，因为它很难进入。对于生活在海洋地下沉积物或火成岩基底中的微生物群来说，在资源稀缺期间获得足够的碳资源和能量以支持生长（1-3）或满足基础能量需求（4）是具有挑战性的。在这里，我们展示了有限和不可预测的碳和能源来源如何决定低生物量微生物群落的生存策略，这些微生物群落生活在印度洋亚特兰蒂斯海岸海底以下10-750米处，地球的下地壳暴露在海底。对酶活性、脂质生物标志物、标记基因和显微镜检查的分析表明，生物量分布不均，细胞密度极低（每厘米不到2,000个细胞）。参与意想不到的异养过程的基因的表达包括那些在多环芳烃的降解，使用聚羟基链烷酸酯作为碳储存分子和回收氨基酸以产生可以参与氧化还原反应和能量产生的化合物中起作用的基因。我们的研究提供了深入了解深成地壳中的微生物如何能够通过将能源与可能通过海底流体或海水循环输送的有机和无机碳资源相结合，在裂缝或多孔基质中生存。
The lithified lower oceanic crust is one of Earth's last biological frontiers as it is difficult to access. It is challenging for microbiota that live in marine subsurface sediments or igneous basement to obtain sufficient carbon resources and energy to support growth(1-3) or to meet basal power requirements(4) during periods of resource scarcity. Here we show how limited and unpredictable sources of carbon and energy dictate survival strategies used by low-biomass microbial communities that live 10-750 m below the seafloor at Atlantis Bank, Indian Ocean, where Earth's lower crust is exposed at the seafloor. Assays of enzyme activities, lipid biomarkers, marker genes and microscopy indicate heterogeneously distributed and viable biomass with ultralow cell densities (fewer than 2,000 cells per cm(3)). Expression of genes involved in unexpected heterotrophic processes includes those with a role in the degradation of polyaromatic hydrocarbons, use of polyhydroxyalkanoates as carbon-storage molecules and recycling of amino acids to produce compounds that can participate in redox reactions and energy production. Our study provides insights into how microorganisms in the plutonic crust are able to survive within fractures or porous substrates by coupling sources of energy to organic and inorganic carbon resources that are probably delivered through the circulation of subseafloor fluids or seawater.