Mishra Sonakshi, Wefers Peggy, Schmidt Mark, Knittel Katrin, Krüger Martin, Stagars Marion H, Treude Tina
GEOMAR Helmholtz Center for Ocean Research KielKiel, Germany.
Max Planck Institute for Marine MicrobiologyBremen, Germany.
Front Microbiol. 2017 Apr 28;8:763. doi: 10.3389/fmicb.2017.00763. eCollection 2017.
The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δC signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SOm day in untreated cores to 5.7 mmol SOm day in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2-C6 -alkanes) passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier -alkanes (C10-C38) decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (<C14) and longer chain -alkanes (>C30) was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core.
利用新开发的沉积物-油-流通（SOFT）系统，对取自里海附近天然烃渗漏结构处的一个完整圆形沉积物岩芯（长16厘米）中微生物群落对石油渗漏的响应进行了研究。在长达190天的模拟石油渗漏过程中，岩芯中形成了不同的氧化还原带并垂直迁移。实验结束时，未处理岩芯中的甲烷浓度为8 μM，而SOFT岩芯中无硫酸盐的下部区域的甲烷浓度为2300 μM，表明发生了产甲烷的石油降解，同时甲烷的δC信号相应地从-33.7‰降至-49.5‰。在添加十六烷、甲基萘、甲苯和乙苯后，SOFT沉积物富集培养物中产生甲烷，进一步证实了产甲烷菌参与石油降解。与硫酸盐还原耦合的石油降解表现为实验结束时，未处理岩芯中综合硫酸盐还原率从2.8 mmol SO₄²⁻/天增加到SOFT岩芯中的5.7 mmol SO₄²⁻/天，同时硫化物相应地从30 μM积累到447 μM。挥发性烃（C₂-C₆烷烃）大多未发生变化地穿过产甲烷带，并在硫酸盐还原带内被消耗。较重的烷烃（C₁₀-C₃₈）的量朝着沉积物岩芯顶部逐步减少，并且在渗漏过程中观察到较短链（<C₁₄）和较长链烷烃（>C₃₀）的优先降解。据我们所知，本研究首次阐明了在一个完整圆形沉积物岩芯中石油通过过程中产甲烷石油降解的发展以及底栖微生物过程的演替。
