Abstract Microbial mineralization plays a significant role in the removal of polycyclic aromatic hydrocarbons (PAHs) from polluted environments. Bacteria affiliated to the Roseobacter clade are ubiquitous and abundant in various environments, including PAH-polluted areas. However, very little is known about the PAH degradation mechanism utilized by the Roseobacter clade. In this study, eight bacterial strains belonging to the Roseobacter clade were isolated from sediments collected from the estuary of the Pearl River. Degradation of pyrene and two other typical PAHs (phenanthrene and benzo[a]pyrene) was studied in the eight isolated strains of Roseobacter clade bacteria (RCB) and three other type strains. The results revealed that all strains had low PAH-degrading efficiency when PAHs were used as the sole source of carbon. However, upon supplementation with an alternative carbon source, the degradation was greatly stimulated. This implies that RCB degrade PAHs via a co-metabolism pathway. A putative pyrene degradation pathway in RCB was re-constructed based on genomic analysis. pahE, a functional marker gene for PAH degradation, was detected in the genomes of RCB. PAH ring-hydroxylating dioxygenase alpha subunit domain family and beta subunit domain family and PAH degradation-related Rieske [2Fe–2S] domain were also identified in the test strains. These findings provide fundamental evidence that RCB are capable of degrading PAHs through a versatile metabolic pathway.

中文翻译：

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芘生物降解及其涉及玫瑰杆菌进化枝细菌的潜在途径

摘要 微生物矿化在从污染环境中去除多环芳烃 (PAHs) 方面发挥着重要作用。隶属于玫瑰杆菌进化枝的细菌在各种环境中无处不在且丰富，包括多环芳烃污染地区。然而，人们对玫瑰杆菌进化枝所利用的 PAH 降解机制知之甚少。在这项研究中，从珠江口收集的沉积物中分离出属于玫瑰杆菌进化枝的 8 株细菌。在玫瑰杆菌进化枝细菌 (RCB) 的八种分离菌株和其他三种类型的菌株中研究了芘和其他两种典型多环芳烃（菲和苯并 [a] 芘）的降解。结果表明，当多环芳烃作为唯一碳源时，所有菌株的多环芳烃降解效率都较低。然而，补充替代碳源后，降解受到极大的刺激。这意味着 RCB 通过共代谢途径降解 PAH。基于基因组分析重建了 RCB 中假定的芘降解途径。在 RCB 的基因组中检测到 PAH 降解的功能性标记基因 pahE。PAH 环羟基化双加氧酶 α 亚基域家族和 β 亚基域家族以及 PAH 降解相关的 Rieske [2Fe-2S] 域也在测试菌株中被鉴定出来。这些发现提供了基本证据，证明 RCB 能够通过多种代谢途径降解多环芳烃。基于基因组分析重建了 RCB 中假定的芘降解途径。在 RCB 的基因组中检测到 PAH 降解的功能性标记基因 pahE。在测试菌株中还鉴定了 PAH 环羟基化双加氧酶 α 亚基域家族和 β 亚基域家族以及与 PAH 降解相关的 Rieske [2Fe-2S] 域。这些发现提供了基本证据，证明 RCB 能够通过多种代谢途径降解多环芳烃。基于基因组分析重建了 RCB 中假定的芘降解途径。在 RCB 的基因组中检测到 PAH 降解的功能性标记基因 pahE。在测试菌株中还鉴定了 PAH 环羟基化双加氧酶 α 亚基域家族和 β 亚基域家族以及与 PAH 降解相关的 Rieske [2Fe-2S] 域。这些发现提供了基本证据，证明 RCB 能够通过多种代谢途径降解多环芳烃。