The Okinawa Trough (OT) is a back-arc basin with a wide distribution of active cold seep systems. However, our understanding of the metabolic function of microbial communities in the cold seep sediments of the OT remains limited. In this study, we investigated the vertical profiles of functional genes involved in methane, nitrogen, and sulphur cycling in the cold seep sediments of the OT. Furthermore, we explored the possible coupling mechanisms between these biogeochemical cycles. The study revealed that the majority of genes associated with the nitrogen and sulphur cycles were most abundant in the surface sediment layers. However, only the key genes responsible for sulphur disproportionation (sor), nitrogen fixation (nifDKH), and methane metabolism (mcrABG) were more prevalent within sulfate-methane transition zone (SMTZ). Significant positive correlations (P < 0.05) were observed between functional genes involved in sulphur oxidation, thiosulphate disproportionation with denitrification, and dissimilatory nitrate reduction to ammonium (DNRA), as well as between AOM/methanogenesis and nitrogen fixation, and between sulphur disproportionation and AOM. A genome of Filomicrobium (class Alphaproteobacteria) has demonstrated potential in chemoautotrophic activities, particularly in coupling DNRA and denitrification with sulphur oxidation. Additionally, the characterized sulfate reducers such as Syntrophobacterales have been found to be capable of utilizing nitrate as an electron acceptor. The predominant methanogenic/methanotrophic groups in the OT sediments were identified as H2-dependent methylotrophic methanogens (Methanomassiliicoccales and Methanofastidiosales) and ANME-1a. This study offered a thorough understanding of microbial ecosystems in the OT cold seep sediments, emphasizing their contribution to nutrient cycling.IMPORTANCEThe Okinawa Trough (OT) is a back-arc basin formed by extension within the continental lithosphere behind the Ryukyu Trench arc system. Cold seeps are widespread in the OT. While some studies have explored microbial communities in OT cold seep sediments, their metabolic potential remains largely unknown. In this study, we used metagenomic analysis to enhance comprehension of the microbial community's role in nutrient cycling and proposed hypotheses on the coupling process and mechanisms involved in biogeochemical cycles. It was revealed that multiple metabolic pathways can be performed by a single organism or microbes that interact with each other to carry out various biogeochemical cycling. This data set provided a genomic road map on microbial nutrient cycling in OT sediment microbial communities.

Geochemistry of iron and trace metals in seep carbonates and its dependence on anaerobic oxidation of methane (AOM)-driven diagenesis in cold seeps are not well documented. Here we characterize geochemistry of Fe and trace metals in carbonate nodules collected at an active cold seep in the middle Okinawa Trough (OT) impacted by hydrothermal plumes. The carbonate nodules in the studied core are dominated by aragonite even at sulfatelow core bottom. Most aragonite at the core bottom may have formed much earlier close to the seafloor under high sulfate concentration. Additionally, porewater at the depth may not be developed to a condition for the formation of calcite dominating over aragonite due to constant downward replenishment of sulfate across through shallow SMTZ (40 cm below sediment surface). As indicated by delta 13C and delta 18O of the carbonates, anaerobic oxidation of thermogenic methane from gas hydrate dissociation is the dominant fluid source for carbonate precipitation. It can be inferred from the existence of vivianite that Fe reduction coupled to AOM (FeAOM) may have ever been prevalent at the hydrothermal Fe-impacted seep site. Enhanced inputs of Mo, Co, Cu, Ni, and Zn associated with hydrothermal Fe-oxyhydroxides-organic colloids is the main source for their high enrichment in the carbonate nodules, and clay minerals and AOM-related microbial organics may have played an important role in their partitioning in the nodules. Uranium enrichment in the carbonate nodules is mainly through enhanced U delivery associated with Fe-oxyhydroxides-scavenged organic colloids and additional U enrichment induced by U(VI) reduction. U(IV) incorporation into carbonate lattices dominates U partitioning in the carbonate nodules over the upper 60 cm of the seep sediments, but the incorporation is substantially dampened at depth due to an increase in concentration of dissolved inorganic carbon, which consequently may have rendered U(IV) adsorption on clay minerals as the important U sink in the nodules. Our results suggest that the exceptional enrichments of Co, Cu, Ni, Zn, Mo, and U in seep carbonates may be used as a paleo-proxy to differentiate cold-seep carbonates whose formation has been co-impacted by hydrothermal plumes.

Large-scale and multi-sample datasets have revealed that microbial diversity and geographic distribution patterns are distinct across various habitats, particularly between hydrothermal vent and cold seep ecosystems. To date, our understanding of the effects of spatial and geochemical gradients on marine microbial communities remains limited. Here, we report the microbial diversity and metabolic versatility of a remote seafloor sediment ecosystem at different sites (GC-2, -4, -5, -6, -8) in the Mid-Okinawa Trough (Mid-OT) using high-throughput metagenomic sequencing technology. Desulfobacteraceae (3.1%) were detected in a high abundance at GC-2 with intense methane concentrations (353 μL/L), which showed a clear correlation with cold seeping. Whereas Candidatus Brocadiaceae (1.7%), Rhodobacteraceae (0.9%), and Rhodospirillaceae (0.7%), which are commonly involved in denitrification and sulfur oxidation, were enriched at GC-8. Concurrently investigating the potential of deep-sea microbial metabolism, we gained insights into the adaptive capabilities and metabolic mechanisms of microorganisms within seafloor environments. Utilizing the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, the analysis of functional modules revealed a significant enrichment (71–74%) of genes associated with metabolic pathways. These results expand our knowledge of the relationship between microbial biodiversity and metabolic versatility in deep-sea extreme environments.

冷泉活动是现代深海极端环境系统之一,其在天然气水合物资源勘探、全球气候变化、极端环境生命活动等方面具有重要的科学研究意义.重建海底冷泉区氧化还原环境是研究其中生物地球化学过程、揭示甲烷渗漏活动特征的重要途径.近年来,大量矿物学及地球化学指标在冷泉系统氧化还原条件的恢复研究中获得了成功的应用.在前人研究的基础上,对自生矿物学标志、稀土元素、氧化还原敏感元素(Mo、U、Fe)和稳定同位素(钼同位素δ98Mo、铁同位素δ56Fe、硫同位素δ34S)等不同指标对氧化还原环境变化的响应机制进行了系统总结,从测试分析方法、后期成岩改造、单一指标的多解性等多个方面探讨了各指标的影响因素和当前仍存在的问题,并指出了未来该领域需进一步加强的关键研究方向.

Abstract Iron (Fe), sulfur (S), and molybdenum (Mo) geochemistry in marine sediments impacted by hydrothermal plumes and/or cold seeps is complex and has not been systematically documented. Here we characterize Fe, S, and Mo diagenesis in sediments between the Minami‐Ensei Knoll hydrothermal field and a cold‐seep site of the middle Okinawa Trough. Results show that distances away from the hydrothermal field and the steep trough slope may significantly affect the transport of hydrothermal Fe. The transformation of hydrothermal reactive Fe to poorly reactive or unreactive Fe‐bearing phyllosilicates decreased the relative fractions of highly reactive Fe (FeHR) in total Fe (FeHR/FeT). Despite this, the standing stocks of Fe oxides in the methane‐free sediments have not been dampened, indicating no net impacts of hydrothermal Fe inputs on the size of Fe oxides. In the methane‐free sediments, low ratios of total reduced inorganic sulfide (TRIS) to total organic carbon (TOC) (TRIS/TOC), highly 34S‐depleted pyrite, and low Mo contents suggest that organoclastic sulfate reduction is at low rates and plays a limited role in carbon cycle. In the cold‐seep sediments, however, intense sulfate reduction coupled to anaerobic methane oxidation significantly elevate TRIS/TOC ratios, Mo enrichment, and isotope compositions of Mo and pyrite‐S. This pathway is expected to be important in carbon cycle in the basin due to the wide occurrence of cold seeps. Our results highlight the important controls of the local extreme depositional/diagenetic conditions on sedimentary S and Mo records, with implications for the reconstruction of paleoredox states of the past earth's surface.

Shallow methane/sulfate transition zones in cold seeps are hotspots to study microbially mediated geochemical cycles due to high methane fluxes. However, our knowledge about the microbial communities in remote seafloor cold seep ecosystems with different methane seepage intensity is still sparse due to the challenge for sampling and visual observations. In this work, three remotely operated vehicle (ROV) video-guided push sediment cores were sampled from cold seep fields with different methane seepage intensity (low-intensity seepage, R5-C1; moderate-intensity seepage, R6-C2; high-intensity seepage, R6-C3) at the western slope of Mid-Okinawa Trough (Mid-OT) and subjected to high throughput sequencing of 16S rRNA genes for bacteria and archaea. Vesicomyid clams and white microbial mats are visible by video at R6-C3 with methane bubbles. The high relative abundances of anaerobic methanotrophic archaea (ANME-1, -2, and -3), δ-Proteobacteriacea and Campylobacteria in R6-C3 indicated that the processes of anaerobic methane oxidation (AOM), sulfate reduction and sulfur oxidation might occur in this active seeping site. In contrast, Bathyarchaeia, Nitrosopumilales, Sphingomonadales, and Burkholderiales were enriched in bubble-free sites, which commonly involved in the degradation of organic compounds. Principal coordinate analysis showed that both bacterial and archaeal communities were clustered according to sampling sites, also indicating the impact of methane seepage intensity on microbial communities. The co-occurrence network analysis revealed that microbes at the site with high methane fluxes mainly cooperated with each other to sustain the ecosystems, whereas competition enhanced at sites with low methane fluxes. Detection of thermophiles Thermoanaerobaculia and Hydrothermarchaeota may indicate microbial transmission from nearby hydrothermal vents, suggesting potential interactions between cold seepage and hydrothermal vent ecosystems. These results expand our knowledge about the composition and distribution of bacteria and archaea with different methane seepage intensity in cold seep field at the Mid-OT, contributing to the ongoing efforts in understanding carbon cycling in the cold seep ecosystems.

Submarine cold seeps and hydrothermal vents are the key agents of material and energy exchange between the marine lithosphere and outer geospheres. Moreover, they breed natural gas hydrates, massive metal sulfides, and precious genetic resources and are one of the main targets of modern marine scientific research and resource exploration. A series of cold seeps and hydrothermal systems are developed in the Okinawa Trough (OT), a typical back-arc basin in the western Pacific. Due to their geographical proximity, the two extreme environments have evident mutual exchange or influence on the geological structure, material transportation, and ecological community, resulting in a unique carbon cycle model in this region. This study presents a series of recent research results in a symbiotic zone between hydrothermal vents and cold seeps in the OT. First, the genesis, carbon source, fluxes, and carbon fixation of cold seeps in the western slope of the OT are systematically summarized. In addition, characteristics of the carbon source, genesis, and flux in the hydrothermal area, near the spreading center of the basin, are compared and described. Second, the latest discoveries on the interaction between the two extreme systems on the seabed of the OT are illustrated. Furthermore, the evidence and progress of metal reduction driven anaerobic oxidation of methane and the global significance of the Fe–C coupling cycle are presented. Finally, key scientific problems in future research on the submarine symbiotic zone between cold seeps and hydrothermal vents are discussed. This study aims to provide an accurate model for the global marine methane cycle with additional consideration for metal electron receptors to gain further insights into the evolutionary history of the global carbon cycle process.

出于对全球气候变化的担忧和资源探测的需要,海洋天然气水合物富集区的甲烷排放已逐步引起了全社会重视.目前,关于水合物富集区的甲烷排放的调查研究仍处于初级阶段,一方面在于对海洋天然气水合物分解释放机理仍不甚清晰;另一方面,深海甲烷排放活动的监测技术仍有待于成熟完善,导致迄今对全球海洋甲烷循环甚至碳循环过程难以把握.自2013年起,面向国家重大需求和科学研究的需要,青岛海洋地质研究所依托一系列地质调查国家专项,创新建立了海底甲烷排放、运移、消耗及相关水合物资源成藏理论模式,自主研发了一系列海洋甲烷排放监测装备,逐步掌握了海底甲烷过程的精细探测能力,实现了水合物富集区关键界面甲烷排放活动的监测,连续实施了多个航次的系统调查,在新区发现大量海底甲烷排放系统,同时建立了海洋天然气水合物资源开发环境监测技术体系,支撑了我国天然气水合物产业化,获得了显著的技术进步和社会效益.

Active cold seeps in the Okinawa Trough (OT) have been widely identified, but the sediment microbial communities associated with these sites are still poorly understood. Here, we investigated the distribution and biomass of the microbial communities, particularly those associated with the anaerobic oxidation of methane (AOM), in sediments from an active cold seep in the mid-Okinawa Trough. Methane-oxidizing archaea, including ANME-1a, ANME-1b, ANME-2a/b, ANME-2c, and ANME-3, were detected in the OT cold seep sediments. Vertical stratification of anaerobic methanotrophic archaea (ANME) communities was observed in the following order: ANME-3, ANME-1a, and ANME-1b. In addition, the abundance of methyl coenzyme M reductase A (mcrA) genes corresponded to high levels of dissolved iron, suggesting that methane-metabolizing archaea might participate in iron reduction coupled to methane oxidation (Fe-AOM) in the OT cold seep. Furthermore, the relative abundance of ANME-1a was strongly related to the concentration of dissolved iron, indicating that ANME-1a is a key microbial player for Fe-AOM in the OT cold seep sediments. Co-occurrence analysis revealed that methane-metabolizing microbial communities were mainly associated with heterotrophic microorganisms, such as JS1, Bathy-1, and Bathy-15.

N2O is among the most potent greenhouse gases. In this study, we investigated one of the important N2O production hotspots, the continental margins. We looked at N2O spatiotemporal distributions in situ as well as the potential contributions of nitrification and denitrification to N2O production in sediment cores from the Bohai and South Yellow Seas. Real-time PCR and shotgun metagenomics sequencing were used to analyze the microbial communities related to N2O production. The results showed that N2O concentrations roughly decreased with depth-a trend that was consistent throughout the year and showed no significant seasonal variations. When all the research stations along the continental margin were considered, the estuary exhibited the lowest average N2O concentration. Moreover, nitrification was identified as the main process responsible for N2O production in estuary areas. This study demonstrates that spatial, as opposed to temporal, heterogeneity is the primary factor influencing N2O concentration differences in sediments.

甲烷是一种重要的温室气体,深刻影响着全球的气候变化.同时,甲烷还是海底潜在能源—天然气水合物的主要成分.海洋沉积物是甲烷生物转化的一个重要生态区域,产甲烷菌主要利用H2、CO2及简单的有机物(甲醇、甲胺、二甲基硫等)作为底物生成甲烷,产生的甲烷在向上迁移的过程中主要被甲烷厌氧氧化(anaerobic oxidation of methane,AOM)和甲烷好氧氧化(aerobic oxidation of methane,AeOM)消耗,进而大大减少了甲烷向大气的排放量.AeOM主要发生在含氧的沉积物及沉积物-水界面中,由甲烷好氧氧化菌(aerobic methane-oxidizing bacteria,MOB)介导.然而,绝大部分甲烷在穿透缺氧沉积物层之前是被AOM反应消耗,甲烷厌氧氧化古菌(anaerobic methanotrophic archaea,ANME)是主要的参与者,这些功能微生物耦联电子受体SO42-、NO2-/NO3-或Fe3+和Mn4+将甲烷进行氧化.本文对产甲烷菌和甲烷氧化菌的种类、代谢途径及其在海洋沉积物中的分布特征进行了综述,并在前人工作基础上,对今后海洋生境中甲烷代谢过程的研究进行了展望,以期为进一步开展海洋环境中甲烷的生物转化过程及元素耦合的研究提供理论依据.

当前出于对全球气候变化的担心以及获取能源资源的需求,甲烷日渐成为人类社会关注的焦点.海洋中聚集了巨量的天然气水合物,存在与甲烷有关的多种重要生化作用,支持了海底繁盛的化能自养合成生物群落,有效调节了进入大气的甲烷通量,在全球碳循环中的地位无可替代.同时,因天然气水合物动态活动造成的甲烷泄漏是岩石圈向外部圈层进行物质和能量输送的重要途径,对海洋环境有着深远影响.系统介绍了现代海底甲烷泄漏的地质控制因素、沉积物和水体对富甲烷流体的消耗、海洋甲烷循环模拟研究以及全球典型海域甲烷观测及相关研究成果,最后指出了海洋甲烷循环研究发展趋势.综合考虑了环境、生物和技术因素对海洋甲烷循环的影响和限制,从一个地质工作者的视角对阶段成果和存在问题进行审视,并提出了自己的思考,借此引发全社会对与甲烷有关的重大科学问题及海洋观测技术的重视与支持.

全球甲烷排放主要来源于厌氧环境中产甲烷菌的代谢活动.采集渤海典型站位沉积物样品,测定了沉积物中甲烷和硫酸盐含量.通过提供不同类型产甲烷底物进行培养,分析了各样品中甲烷产量;通过高通量测序,分析了产甲烷菌群落特征.结果表明,渤海沉积物中产甲烷途径以甲基营养型为主,同时具有H2/CO2还原型途径.同一站点随着深度的增加,甲烷产生量逐渐减少,产甲烷速率相应降低.古菌群落以Crenarchaeota、Asgardaeota和Nanoarchaeota为主,产甲烷菌Ca.Methanofastidiosales占据优势地位.本研究为全面了解产甲烷菌在海洋生境中产甲烷过程提供了重要参考.

Although coastal sediments are major contributors to the production of atmospheric methane, the effects of environmental conditions on methanogenesis and the community of methanogenic archaea are not well understood. Here, we investigated the methanogenesis pathways in nearshore and offshore sediments from the South Yellow Sea (SYS). Moreover, the effects of the supply of methanogenic substrates (H-2/CO2, acetate, trimethylamine (TMA), and methanol) and temperature on methanogenesis and the community of methanogenic archaea were further determined. Methylotrophic, hydrogenotrophic and acetotrophic methanogenesis were found to be responsible for biogenic methane production in nearshore sediments. In the offshore sediments, methylotrophic methanogenesis was the predominant methanogenic pathway. The changes in methanogenic community structure under different substrate amendments were characterized. Lower diversities were detected in substrate-amended samples with methanogenic activity. Hydrogenotrophic Methanogenium, multitrophic Methanosarcina, methylotrophic Methanococcoide, Methanococcoide or methylotrophic Methanolobus were dominant in H-2/CO2-, acetate-, TMA- and methanol-amended sediment slurries, respectively. PCoA showed that the methanogen community in H-2/CO2 and acetate amendments exhibited greater differences than those in other treatments. Lower temperature (10 degrees C) limits hydrogenotrophic and acetoclastic methanogenesis, but methylotrophic methanogenesis is much less affected. The response of methanogen diversity to the incubation temperature varied among the different substrate-amended slurries. The multitrophic methanogen Methanosarcina became increasingly abundant in H-2/CO2- and acetate-amended sediment slurries when the temperature increased from 10 to 30 degrees C.

海洋生境来源的甲烷好氧氧化菌及其产生的甲烷氧化作用是否具有独特性,对氧浓度这一环境因子如何响应,目前尚不清楚.本文采用海底新鲜沉积物作为菌种来源,借助微生物培养技术,实验研究了不同氧浓度条件(0％、1％、10％和50％)下的甲烷好氧氧化过程.结果表明,完全无氧条件(0％)不能发生甲烷好氧氧化作用,实验体系的甲烷氧化速率及甲烷氧化菌总丰度随氧浓度升高而降低,当氧浓度由1％升高至50％时,甲烷氧化速率减弱了约15倍,甲烷氧化菌总丰度降低了两个数量级.甲烷氧化菌优势菌属为I型氧化菌Methylobacter属,由Methylobacter leteus和Methylobacter whittenburyi组成,氧浓度增加时Methylobacter leteus的占比随之降低,Methylobacter whittenburyi则相反.本实验中甲烷好氧氧化菌及其氧化作用的最适氧浓度条件为1％,这与采样位置的原始生存环境最为接近.在海底低氧条件叠加低温、高压等特殊生境的长期驯化下,甲烷氧化菌的最适氧浓度条件将逐渐趋于其原始生存环境.

Aerobic methane (CH4) oxidation plays a significant role in marine CH4 consumption. Temperature changes resulting from, for example, global warming, have been suggested to be able to influence methanotrophic communities and their CH4 oxidation capacity. However, exact knowledge regarding temperature controls on marine aerobic methane oxidation is still missing. In this study, CH4 consumption and the methanotrophic community structure were investigated by incubating sediments from shallow (Bohai Bay) and deep marine environments (East China Sea) at 4, 15, and 28 °C for up to 250 days. The results show that the abundance of the methanotrophic population, dominated by the family Methylococcaceae (type I methanotrophs), was significantly elevated after all incubations and that aerobic methane oxidation for both areas had a strong temperature sensitivity. A positive correlation between the CH4 oxidation rate and temperature was witnessed in the Bohai Bay incubations, whereas for the East China Sea incubations, the optimum temperature was 15 °C. The systematic variations of pmoA OTUs between the Bohai Bay and East China Sea incubations indicated that the exact behaviors of CH4 oxidation rates with temperature are related to the different methanotrophic community structures in shallow and deep seas. These results are of great significance for quantitatively evaluating the biodegradability of CH4 in different marine environments.

The biogeography of active microbial communities and the underlying mechanisms in marine sediments are important in microbial ecology but remain unclear. Here, using qPCR and high-throughput sequencing, we investigated bacterial and archaeal community abundances and activities by quantifying the abundance and expression of the 16S rRNA gene respectively, RNA-derived bacterial and archaeal community biogeography, assembly mechanisms and co-occurrence relationships in surface sediment samples from the Bohai Sea (BS), South Yellow Sea (SYS) and the north East China Sea (NECS) of the eastern Chinese marginal seas. The results revealed a higher heterogeneity of bacterial and archaeal community activities than of abundances and heterogeneous ecological functions among areas reflected by community compositions. Furthermore, clear geographic groups (i.e., the BS, SYS and NECS groups) were observed for all, abundant and rare active bacterial and archaeal communities, accompanied by significant distance-decay patterns. However, the abundant and rare taxa showed inconsistent geographic patterns. More importantly, deterministic processes played a greater role than stochastic processes in active bacterial and archaeal community assembly. The rare taxa had weaker abilities to disperse and/or adapt and more complex ecological processes than the abundant taxa. In addition, this study also showed that intertaxa competition was the dominant interaction between active bacterial and archaeal members, which could greatly contribute to dispersal limitation. Moreover, active bacterial and archaeal co-occurrence patterns showed significant distance-decay patterns, which were consistent with the community compositions.

海洋环境中微生物驱动的甲烷好氧氧化作用是甲烷迁移转化过程的关键环节之一,在降解甲烷方面的贡献不容忽视,能够有效降低甲烷大气通量、影响海洋碳循环.本文系统调研了国内外文献资料,认识到海洋环境中甲烷好氧氧化的赋存范围十分广泛,可赋存于超过3000 m水深的深海环境、热液喷口等极端环境,其中海底高压、渗漏甲烷的动态运移等是甲烷好氧氧化所面临的特殊环境,在该赋存环境下,好氧甲烷氧化菌主要以I型氧化菌为主.I型与II型氧化菌对甲烷、微量金属元素等环境条件具有一定偏向性,并且在水体和沉积物两种赋存环境下氧化菌的类型也不尽相同.同时,在该赋存环境下甲烷好氧氧化强度存在时间或空间上的差异,受温度、甲烷浓度、氧浓度、微量金属元素等环境因子影响显著,但目前对压力以及甲烷渗漏运移状态对好氧氧化过程的影响规律认识不清.随着深海科研探索不断发展,甲烷氧化菌菌群多样性研究将更加丰富.此外,还需进一步针对海底高压渗漏状态下的好氧氧化过程开展精细研究工作,进一步理解海洋环境中甲烷的好氧氧化规律,这对深刻揭示甲烷迁移转化机制、科学评估甲烷生态环境效应具有重要意义.

海洋沉积物中大部分甲烷会通过甲烷厌氧氧化作用(anaerobic oxidation of methane,AOM)而被消耗.早期研究表明,AOM可与硫酸盐、硝酸盐和亚硝酸盐的还原作用相耦合,从而有效减少甲烷向大气的排放.最近,金属依赖型AOM(metal-AOM,活性金属氧化物还原反应驱动的AOM)被证实存在于自然界沉积物和富集培养的样品中.但是,目前仍未从自然海洋环境中分离获得能够介导metal-AOM的微生物.对海洋沉积物中metal-AOM的研究大多聚焦于热液或冷泉等海洋特殊生境,一系列研究表明地质流体在这些海底化能自养生态系统的维持和演化方面起到了重要作用,并深刻影响全球地球化学循环,因此,该科学问题研究吸引了越来越多的注意力.本文讨论了可能参与海洋沉积物中metal-AOM的微生物类群及其地球化学证据,并在前人工作基础上,以冲绳海槽冷泉-热液共生区为例,提出一种新的metal-AOM作用机制.认为在全球冷泉-热液系统相互作用地区的调查有助于更好地探讨metal-AOM的发生机制及微生物在深海生境中分布的连通性问题.

This study was conducted to characterize the diversity and function of microbial communities in marine sediments of the Pearl River Mouth Basin（PRMB） in the South China Sea. The results showed that the bacterial and archaeal communities varied greatly with depth. Proteobacteria in bacterial communities and Nitrososphaeria and Woesearchaeota in archaeal communities were dominant in the shallow sediments（1-40 cm）, while Chloroflexi in bacterial communities and Bathyarchaeia in archaeal communities were dominant in the deep sediments（50-200 cm）. Regarding ecological functions based on the metatranscriptomic data, genes involved in various pathways of nitrogen metabolism and sulfur metabolism were observed in the tested sediment samples. Metagenomic analysis revealed that Proteobacteria contribute the most to nearly all genes involved in nitrogen and sulfur metabolism. Moreover, Thaumarchaeota contribute the most to certain genes involved in nitrification, denitrification and assimilatory sulfate reduction pathways. The most abundant bacterial genus, Candidatus Scalindua, is crucial for nitrification, dissimilatory nitrate reduction, denitrification and assimilatory sulfate reduction pathways.