School of Ocean Sciences, China University of Geosciences, Beijing, 100083, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, China.
School of Ocean Sciences, China University of Geosciences, Beijing, 100083, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, China.
Mar Environ Res. 2019 Feb;144:230-239. doi: 10.1016/j.marenvres.2019.01.009. Epub 2019 Jan 23.
Cold seep is a unique habitat for microorganisms in deep marine sediments, and microbial communities and biogeochemical processes are still poorly understood, especially in relation to hydrate-bearing geo-systems. In this study, two cold seep systems were sampled and microbial diversity was studied at Site GMGS2-08 in the northern part of the South China Sea (SCS) during the GMGS2 gas hydrate expedition. The current cold seep system was composed of a sulfate methane transition zone (SMTZ) and an upper gas hydrate zone (UGHZ). The buried cold seep system was composed of an authigenic carbonate zone (ACZ) and a lower gas hydrate zone (LGHZ). These drill core samples provided an excellent opportunity for analyzing the microbial abundance and diversity based on quantitative polymerase chain reaction (qPCR) and high-throughput 16S rRNA gene sequencing. Compared to previous studies, the high relative abundance of ANME-1b, a clade of anaerobic methanotrophic archaea (ANME), may perform anaerobic oxidation of methane (AOM) in collaboration with ANME-2c and Desulfobacteraceae in the SMTZ, and the high relative abundances of Hadesarchaea, ANME-1b archaea and Aerophobetes bacteria were found in the gas hydrate zone (GHZ) at Site GMGS2-08. ANME-1b, detected in the GHZ, might mainly mediate the AOM process, and the process might occur in a wide depth range within the LGHZ. Moreover, bacterial communities were significantly different between the GHZ and non-GHZ sediments. In the ACZ, archaeal communities were different between the two samples from the upper and the lower layers, while bacterial communities shared similarities. Overall, this new record of cold seep microbial diversity at Site GMGS2-08 showed the complexity of the interaction between biogeochemical reactions and environmental conditions.
冷泉是深海沉积物中微生物的独特栖息地，微生物群落和生物地球化学过程仍知之甚少，特别是在与含水地质系统有关的方面。在这项研究中，在南海北部 GMGS2 天然气水合物考察期间，在 GMGS2-08 站位对两个冷泉系统进行了采样，并研究了微生物多样性。当前的冷泉系统由硫酸盐甲烷转换带 (SMTZ) 和上覆天然气水合物带 (UGHZ) 组成。埋藏的冷泉系统由自生碳酸盐带 (ACZ) 和下覆天然气水合物带 (LGHZ) 组成。这些岩芯样本为基于定量聚合酶链反应 (qPCR) 和高通量 16S rRNA 基因测序分析微生物丰度和多样性提供了极好的机会。与以前的研究相比，厌氧甲烷氧化古菌 (ANME) 的一个分支 ANME-1b 的相对丰度较高，可能与 ANME-2c 和脱硫杆菌科一起在 SMTZ 中进行厌氧甲烷氧化 (AOM)，并且在 GMGS2-08 站位的天然气水合物带 (GHZ) 中发现了 Hadesarchaea、ANME-1b 古菌和 Aerophobetes 细菌的相对丰度较高。在 GHZ 中检测到的 ANME-1b 可能主要介导 AOM 过程，并且该过程可能在 LGHZ 内的广泛深度范围内发生。此外，GHZ 和非 GHZ 沉积物中的细菌群落存在显著差异。在 ACZ 中，来自上下层的两个样本的古菌群落不同，而细菌群落具有相似性。总的来说，GMGS2-08 站位冷泉微生物多样性的这一新记录表明了生物地球化学反应和环境条件之间相互作用的复杂性。
