Thermoprofundales (Marine Benthic Group D archaea, MBG-D) is a newly proposed archaeal order and widely distributed in global marine sediment, and the members in the order may play a vital role in carbon cycling. However, the lack of pure cultures of these oeganisms has hampered the recognition of their catabolic roles. Here, by constructing high-quality metagenome-assembled genomes (MAGs) of two new subgroups of Thermoprofundales from hydrothermal sediment and predicting their catabolic pathways, we here provide genomic evidences that Thermoprofundales are capable of degrading aromatics via the phenylacetic acid (PAA) pathway. Then, the gene sequences of phenylacetyl-CoA ligase (PCL), a key enzyme for the PAA pathway, were searched in reference genomes. The widespread distribution of PCL genes among 14.9% of archaea and 75.9% of Thermoprofundales further supports the importance of the PAA pathway in archaea, particularly in Thermoprofundales where no ring-cleavage dioxygenases were found. Two PCLs from Thermoprofundales MAGs, PCLM8-3 and PCLM10-15 , were able to convert PAA to phenylacetyl-CoA (PA-CoA) in vitro, demonstrating the involvement of Thermoprofundales in aromatics degradation through PAA via CoA activation. Their acid tolerance (pH 5-7), high-optimum temperatures (60°C and 80°C), thermostability (stable at 60°C and 50°C for 48 h) and broad substrate spectra imply that Thermoprofundales are capable of transforming aromatics under extreme conditions. Together with the evidence of in situ transcriptional activities for most genes related to the aromatics pathway in Thermoprofundales, these genomic, and biochemical evidences highlight the essential role of this ubiquitous and abundant archaeal order in the carbon cycle of marine sediments.

中文翻译：

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海洋底栖嗜热菌中芳香族化合物主要通过苯乙酸途径降解的证据。

深潜热体（海洋底栖生物D类古细菌，MBG-D）是新近提出的古细菌类，广泛分布于全球海洋沉积物中，该类成员可能在碳循环中起着至关重要的作用。然而，这些自交植物缺乏纯净的文化，阻碍了人们对其分解代谢作用的认识。在这里，通过从热液沉积物中构建高温热原的两个新亚组的高质量的基因组组装基因组（MAG），并预测它们的分解代谢途径，我们在这里提供了基因组证据，表明高温热原能够通过苯乙酸（PAA）途径降解芳香族化合物。然后，在参考基因组中搜索苯乙酰辅酶A连接酶（PCL）（PAA途径的关键酶）的基因序列。PCL基因在14.9％的古细菌和75个古细菌中广泛分布。9％的Thermoprofundales进一步支持了PAA途径在古细菌中的重要性，尤其是在没有发现环裂解双加氧酶的Thermoprofundales中。Thermoprofundales MAG的两个PCL PCLM8-3和PCLM10-15能够在体外将PAA转化为苯乙酰-CoA（PA-CoA），证明了Thermoprofundales通过CoA活化通过PAA参与芳烃降解。它们的耐酸性（pH 5-7），最佳温度（60°C和80°C），热稳定性（在60°C和50°C稳定48小时）以及广泛的底物光谱意味着Thermoprofundales能够转化极端条件下的芳烃。这些基因组，