Comparison of mechanisms of alkane metabolism under sulfate-reducing conditions among two bacterial isolates and a bacterial consortium
Comparison of mechanisms of alkane metabolism under sulfate-reducing conditions among two bacterial isolates and a bacterial consortium
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DOI：
10.1128/aem.02896-05
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发表时间：
2006-06-01
影响因子：
4.4
通讯作者：
Young, Lily Y.
中科院分区：
文献类型：
--
作者：
Callaghan, Amy V.;Gieg, Lisa M.;Young, Lily Y.
近年来的研究表明，富马酸加成和羧化是烷烃厌氧降解的两种可能机制。在本研究中，我们调查了在十六烷上生长过程中形成的硫酸盐还原分离物AK-01和Hxd 3和混合硫酸盐还原财团的代谢产物。将培养物与质子化或全氘代十六烷一起孵育;还将硫酸盐还原聚生体与[1，2-C-13（2）]十六烷一起孵育。提取所有培养物，甲硅烷基化，并通过气相色谱-质谱法进行分析。我们检测到一系列代谢产物，支持AK-01降解十六烷的富马酸加成机制，包括甲基十五烷基琥珀酸、4-甲基十八烷酸、4-甲基十八碳-2，3-烯酸、2-甲基十六烷酸和十四烷酸。通过使用d（34）-十六烷，质谱证据强烈支持AK-01的第一中间体甲基十五烷基琥珀酸的碳骨架重排。在AK-01浸提液中未发现十六烷羧化的证据，但在Hxd 3浸提液中观察到十六烷羧化。然而，在混合硫酸盐还原培养物中，检测到与十六烷降解的富马酸加成和羧化机制一致的代谢物，这表明在不同的厌氧群落中可以同时发生多种烷烃降解途径。总的来说，这些发现强调了富马酸加成和羧化是重要的烷烃降解机制，可能在遗传学和/或生理学上不同的微生物中广泛存在。
Recent studies have demonstrated that fumarate addition and carboxylation are two possible mechanisms of anaerobic alkane degradation. In the present study, we surveyed metabolites formed during growth on hexadecane by the sulfate-reducing isolates AK-01 and Hxd3 and by a mixed sulfate-reducing consortium. The cultures were incubated with either protonated or fully deuterated hexadecane; the sulfate-reducing consortium was also incubated with [1,2-C-13(2)] hexadecane. All cultures were extracted, silylated, and analyzed by gas chromatography-mass spectrometry. We detected a suite of metabolites that support a fumarate addition mechanism for hexadecane degradation by AK-01, including methylpentadecyllsuccinic acid, 4-methyloctadecanoic acid, 4-methyloctadec-2,3-enoic acid, 2-methylhexadecanoic acid, and tetradecanoic acid. By using d(34)-hexadecane, mass spectral evidence strongly supporting a carbon skeleton rearrangement of the first intermediate, methylpentadecylsuccinic acid, was demonstrated for AK-01. Evidence indicating hexadecane carboxylation was not found in AK-01 extracts but was observed in Hxd3 extracts. In the mixed sulfate-reducing culture, however, metabolites consistent with both fumarate addition and carboxylation mechanisms of hexadecane degradation were detected, which demonstrates that multiple alkane degradation pathways can occur simultaneously within distinct anaerobic communities. Collectively, these findings underscore that fumarate addition and carboxylation are important alkane degradation mechanisms that may be widespread among phylogenetically and/or physiologically distinct microorganisms.