School of Civil Engineering and Geosciences, Newcastle University Newcastle upon Tyne, UK.
Front Microbiol. 2014 Apr 3;5:131. doi: 10.3389/fmicb.2014.00131. eCollection 2014.
Methanogenic degradation of crude oil in subsurface sediments occurs slowly, but without the need for exogenous electron acceptors, is sustained for long periods and has enormous economic and environmental consequences. Here we show that volatile hydrocarbons are inhibitory to methanogenic oil biodegradation by comparing degradation of an artificially weathered crude oil with volatile hydrocarbons removed, with the same oil that was not weathered. Volatile hydrocarbons (nC5-nC10, methylcyclohexane, benzene, toluene, and xylenes) were quantified in the headspace of microcosms. Aliphatic (n-alkanes nC12-nC34) and aromatic hydrocarbons (4-methylbiphenyl, 3-methylbiphenyl, 2-methylnaphthalene, 1-methylnaphthalene) were quantified in the total hydrocarbon fraction extracted from the microcosms. 16S rRNA genes from key microorganisms known to play an important role in methanogenic alkane degradation (Smithella and Methanomicrobiales) were quantified by quantitative PCR. Methane production from degradation of weathered oil in microcosms was rapid (1.1 ± 0.1 μmol CH4/g sediment/day) with stoichiometric yields consistent with degradation of heavier n-alkanes (nC12-nC34). For non-weathered oil, degradation rates in microcosms were significantly lower (0.4 ± 0.3 μmol CH4/g sediment/day). This indicated that volatile hydrocarbons present in the non-weathered oil inhibit, but do not completely halt, methanogenic alkane biodegradation. These findings are significant with respect to rates of biodegradation of crude oils with abundant volatile hydrocarbons in anoxic, sulphate-depleted subsurface environments, such as contaminated marine sediments which have been entrained below the sulfate-reduction zone, as well as crude oil biodegradation in petroleum reservoirs and contaminated aquifers.
在地下沉积物中，原油的甲烷生成降解速度缓慢，但无需外部电子受体即可持续很长时间，并且具有巨大的经济和环境影响。在这里，我们通过比较去除挥发性烃的人工风化原油与未风化的相同原油的降解情况，表明挥发性烃会抑制甲烷生成的原油生物降解。挥发性烃（nC5-nC10、甲基环己烷、苯、甲苯和二甲苯）在微宇宙的顶部空间中进行了定量。从微宇宙中提取的总烃馏分中定量了直链烷烃（nC12-nC34）和芳烃（4-甲基联苯、3-甲基联苯、2-甲基萘、1-甲基萘）。通过定量 PCR 定量了已知在甲烷生成烷烃降解中起重要作用的关键微生物的 16S rRNA 基因（Smithella 和 Methanomicrobiales）。微宇宙中风化油的降解产生了快速的甲烷生成（1.1±0.1 μmol CH4/g 沉积物/天），其化学计量产率与较重的直链烷烃（nC12-nC34）的降解一致。对于未风化的油，微宇宙中的降解速率明显较低（0.4±0.3 μmol CH4/g 沉积物/天）。这表明非风化油中存在的挥发性烃会抑制，但不会完全阻止甲烷生成的烷烃生物降解。这些发现对于在缺氧、硫酸盐耗尽的地下环境（如被卷入硫酸盐还原带以下的污染海洋沉积物）中富含挥发性烃的原油生物降解率以及储层中的原油生物降解和污染含水层中的生物降解率具有重要意义。
