Metabolic activity analyses demonstrate that Lokiarchaeon exhibits homoacetogenesis in sulfidic marine sediments
Metabolic activity analyses demonstrate that Lokiarchaeon exhibits homoacetogenesis in sulfidic marine sediments
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DOI：
10.1038/s41564-019-0630-3
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发表时间：
2019-12
影响因子：
28.3
通讯作者：
W. Orsi;A. Vuillemin;P. Rodríguez;Ö. Coskun;Gonzalo V. Gomez-Saez;G. Lavik;V. Mohrholz;T. Ferdelman
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文献类型：
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作者：
W. Orsi;A. Vuillemin;P. Rodríguez;Ö. Coskun;Gonzalo V. Gomez-Saez;G. Lavik;V. Mohrholz;T. Ferdelman
古细菌阿斯加特总门的基因组提供了有关在真核生物起源时获得线粒体的宿主细胞性质的线索，，-。阿斯加德候选门候选洛基古菌门 (Lokiarchaeota) 的代表具有产乙酸和发酵的能力，但人们对它们的代谢活动如何响应环境条件知之甚少。在这里，我们发现在缺氧的纳米比亚陆架沉积物中，Lokiarchaeon 基因表达水平高于细菌门，并且随着海底以下深度的增加而增加。 Lokiarchaeon基因表达在缺氧-硫化物氧化还原梯度中显着不同，其中涉及生长、发酵和H2依赖性碳固定的基因在还原性最强（硫化物）条件下具有最高表达。定量稳定同位素探测表明，Lokiarchaeon 对二氧化碳和硅藻细胞外聚合物的厌氧利用高于细菌平均水平，这与 Lokiarchaeon 基因的较高表达一致，包括那些参与糖和氨基酸运输和发酵的基因。定量稳定同位素探测和基因表达数据证明了 Candidatus Lokiarchaeota 的同型产乙酸活性，其中有机底物的发酵 H2 生产与 Wood-Ljungdahl 碳固定途径相结合。同型乙酸生成提供的高能量效率有助于解释洛基古菌在这种缺氧、能量有限的环境中代谢活动的升高。
The genomes of the Asgard superphylum of Archaea hold clues pertaining to the nature of the host cell that acquired the mitochondrion at the origin of eukaryotes, , –. Representatives of the Asgard candidate phylumCandidatusLokiarchaeota (Lokiarchaeon) have the capacity for acetogenesis and fermentation, –, but how their metabolic activity responds to environmental conditions is poorly understood. Here, we show that in anoxic Namibian shelf sediments, Lokiarchaeon gene expression levels are higher than those of bacterial phyla and increase with depth below the seafloor. Lokiarchaeon gene expression was significantly different across a hypoxic–sulfidic redox gradient, whereby genes involved in growth, fermentation and H2-dependent carbon fixation had the highest expression under the most reducing (sulfidic) conditions. Quantitative stable isotope probing revealed that anaerobic utilization of CO2and diatomaceous extracellular polymeric substances by Lokiarchaeon was higher than the bacterial average, consistent with higher expression of Lokiarchaeon genes, including those involved in transport and fermentation of sugars and amino acids. The quantitative stable isotope probing and gene expression data demonstrate homoacetogenic activity ofCandidatusLokiarchaeota, whereby fermentative H2production from organic substrates is coupled with the Wood–Ljungdahl carbon fixation pathway. The high energetic efficiency provided by homoacetogenesis helps to explain the elevated metabolic activity of Lokiarchaeon in this anoxic, energy-limited setting.