The mineralization of alkane is mainly driven by microorganisms, and the detailed mechanisms of long-chain aliphatic alkane degradation are undeciphered in archaea. We used a hexadecane-degrading haloarchaeon, Halorientalis hydrocarbonoclasticus IM1011 (= CGMCC 13754), as a model system to decode this through transcriptomic and biochemical studies. During growth on hexadecane as sole carbon source, the activity of 3-hydroxyacyl-CoA dehydrogenase, a β-oxidation pathway enzyme, was measured. Biochemical and culture growth experiments confirmed the role of the β-oxidation pathway in aliphatic alkane degradation. Subsequently, transcriptomic analysis of H. hydrocarbonoclasticus cultured in acetate vs. acetate and hexadecane revealed that seven up-regulated genes were common in 5- and 24-h samples. Three were annotated as ribonucleoside-diphosphate reductase R2-like (RNRR2-like) genes, which were predicted to involve in the biodegradation of hexadecane. Based on the transcriptomic level, the putative functional genes were inferred from multiple isogenes. Among these genes, an important cluster encodes three enzymes for the β-oxidation pathway as well as long-chain fatty acid-CoA ligase for pre-step. The present research identified the function of the β-oxidation pathway in aliphatic alkane degradation and recognized the functional genes in haloarchaea. The mineralization of aliphatic alkane in extreme environments driven by archaea was further understood through this study.

中文翻译：

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洞察古细菌中长链脂族烷烃降解的代谢途径和功能基因。

烷烃的矿化作用主要由微生物驱动，长链脂肪族烷烃降解的详细机理尚不清楚。我们使用可降解十六烷的卤代古细菌，Halorientalis hydrocarbonoclasticus IM1011（= CGMCC 13754），作为模型系统通过转录组和生化研究对其进行解码。在十六烷作为唯一碳源的生长过程中，测量了β-氧化途径酶3-羟酰基-CoA脱氢酶的活性。生化和培养物生长实验证实了β-氧化途径在脂肪族烷烃降解中的作用。随后，对H进行转录组分析。烃碎屑在醋酸盐对醋酸盐和十六烷中进行培养表明，在5小时和24小时样品中共有七个上调基因。三个被注释为核糖核苷二磷酸还原酶R2样（RNRR2样）基因，据预测它们参与十六烷的生物降解。根据转录组水平，推定的功能基因是从多个同工基因推断的。在这些基因中，重要的簇编码用于β氧化途径的三种酶以及用于长链脂肪酸的CoA连接酶。本研究确定了β-氧化途径在脂肪族烷烃降解中的功能，并识别了卤古菌中的功能基因。通过这项研究进一步了解了古细菌驱动的极端环境中脂肪族烷烃的矿化作用。