Consumption of Methane and CO2 by Methanotrophic Microbial Mats from Gas Seeps of the Anoxic Black Sea
Consumption of Methane and CO2 by Methanotrophic Microbial Mats from Gas Seeps of the Anoxic Black Sea
复制标题
DOI：
10.1128/aem.02685-06
复制
发表时间：
2007-02
影响因子：
4.4
通讯作者：
T. Treude;V. Orphan;K. Knittel;A. Gieseke;C. House;A. Boetius
中科院分区：
文献类型：
--
作者：
T. Treude;V. Orphan;K. Knittel;A. Gieseke;C. House;A. Boetius
摘要 黑海西北部的深部缺氧陆架有许多气体渗漏，这些气体渗漏处充满了海底及其上方的甲烷氧化微生物垫。在海底上方，这些垫子可以形成由多孔碳酸盐和微生物生物质组成的高大的礁状结构。在这里，我们研究了从大型珊瑚礁结构表面获得的垫样品中 CH4 和 CO2 同化与 ANME 群体及其相关细菌分布的空间模式。将不同方法（包括放射性示踪剂孵育、β显微成像、二次离子质谱和催化报告沉积荧光原位杂交）组合应用于从大型珊瑚礁结构获得的垫子切片上，以定位甲烷氧化的热点并识别负责的微生物群落。此外，研究了在存在或不存在甲烷、硫酸盐和氢气的情况下二氧化碳还原为甲烷的情况。该垫的平均δ13C碳同位素特征为-67.1‰，表明甲烷是主要碳源。 ANME-1 主导的区域的同位素特征明显重于 ANME-2 主导的中心区域（−72.9 ‰ ± 2.2 ‰；n = 7）（−66.4‰ ± 3.9 ‰ [平均值±标准差；n = 7]）。从放射性标记的 CH4 或 CO2 中掺入 14C 揭示了靠近垫子表面的甲烷氧化和 CO2 固定的一个热点以及低同化效率（1% 至 2% 的甲烷被氧化）。垫子与 14CH4 或 14CO2 的重复孵育表明存在 CH4 和 CO2 的相互转化。 CO2 还原水平约为甲烷厌氧氧化水平的 10%。然而，由于仅在甲烷和硫酸盐存在的情况下才观察到大量甲烷形成，因此该过程似乎是甲烷厌氧氧化的再反应，而不是净产甲烷作用。
ABSTRACT The deep anoxic shelf of the northwestern Black Sea has numerous gas seeps, which are populated by methanotrophic microbial mats in and above the seafloor. Above the seafloor, the mats can form tall reef-like structures composed of porous carbonate and microbial biomass. Here, we investigated the spatial patterns of CH4 and CO2 assimilation in relation to the distribution of ANME groups and their associated bacteria in mat samples obtained from the surface of a large reef structure. A combination of different methods, including radiotracer incubation, beta microimaging, secondary ion mass spectrometry, and catalyzed reporter deposition fluorescence in situ hybridization, was applied to sections of mat obtained from the large reef structure to locate hot spots of methanotrophy and to identify the responsible microbial consortia. In addition, CO2 reduction to methane was investigated in the presence or absence of methane, sulfate, and hydrogen. The mat had an average δ13C carbon isotopic signature of −67.1‰, indicating that methane was the main carbon source. Regions dominated by ANME-1 had isotope signatures that were significantly heavier (−66.4‰ ± 3.9 ‰ [mean ± standard deviation; n = 7]) than those of the more central regions dominated by ANME-2 (−72.9‰ ± 2.2 ‰; n = 7). Incorporation of 14C from radiolabeled CH4 or CO2 revealed one hot spot for methanotrophy and CO2 fixation close to the surface of the mat and a low assimilation efficiency (1 to 2% of methane oxidized). Replicate incubations of the mat with 14CH4 or 14CO2 revealed that there was interconversion of CH4 and CO2. The level of CO2 reduction was about 10% of the level of anaerobic oxidation of methane. However, since considerable methane formation was observed only in the presence of methane and sulfate, the process appeared to be a rereaction of anaerobic oxidation of methane rather than net methanogenesis.