Microbial community structure and metabolic activities have profound impacts on biogeochemical processes in marine sediments. Functional bacteria such as nitrate- and sulfate-reducing bacteria respond to redox gradients by coupling specific reactions amenable to relevant energy metabolisms. However, similar functional patterns have not been observed for sedimentary archaea (except for anaerobic methanotrophs and methanogens). We coupled taxonomic composition with comprehensive geochemical species to investigate the participation of distinct bacteria and archaea in sedimentary geochemical cycles in a sediment core (300 cm) from Pearl River Estuary (PRE). Geochemical properties (NO3-, dissolved Mn and Fe, SO42+, NH4+; dissolved inorganic carbon (DIC), δ13CDIC, dissolved organic carbon (DOC), total organic carbon (TOC), δ13CTOC, and fluorescent dissolved organic matter (FDOM)) exhibited strong depth variability of different trends. Bacterial 16S rRNA- and dsrB gene abundance decreased sharply with depth while archaeal and bathyarchaeotal 16S rRNA gene copies were relatively constant. This resulted in an increase in relative abundance of archaea from surface (11.6%) to bottom (42.8%). Network analysis showed that bacterial groups of Desulfobacterales, Syntrophobacterales and Gammaproteobacteria were significantly (P < 0.0001) associated with SO42- and dissolved Mn while archaeal groups of Bathyarchaeota, Group C3 and Marine Benthic Group D (MBGD) showed close positive correlations (P < 0.0001) with NH4+, δ13CTOC values and humic-like FDOM. Our study suggested that these bacterial groups dominated in redox processes relevant to sulfate or metal oxides, while the archaeal groups are more like to degrade recalcitrant organic compounds in anaerobic sediments.

中文翻译：

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珠江口沉积物中的不同细菌和古细菌分布反映了不同的地球化学过程。

微生物群落结构和代谢活动对海洋沉积物的生物地球化学过程具有深远的影响。功能性细菌（例如还原硝酸盐和硫酸盐的细菌）通过耦合适合相关能量代谢的特定反应来响应氧化还原梯度。但是，尚未观察到沉积古细菌的类似功能模式（除厌氧甲烷甲烷营养菌和产甲烷菌外）。我们将分类学组成与综合地球化学种类结合起来，以研究珠江口（PRE）沉积物核心（300厘米）中不同细菌和古细菌在沉积地球化学循环中的参与。地球化学性质（NO3-，溶解的Mn和Fe，SO42 +，NH4 +；溶解的无机碳（DIC），δ13CDIC，溶解的有机碳（DOC），总有机碳（TOC），δ13CTOC，和荧光溶解有机物（FDOM））表现出不同趋势的强烈深度变化。细菌16S rRNA和dsrB基因的丰度随深度而急剧下降，而古细菌和水生古细菌的16S rRNA基因拷贝相对恒定。这导致古细菌的相对丰度从表面（11.6％）到底部（42.8％）增加。网络分析表明，脱硫细菌，滑膜细菌和γ-变形杆菌细菌组与SO42-和溶解态锰显着相关（P <0.0001），而Bathyarchaeota，C3组和海洋底栖性D组（MBGD）的古细菌组显示出密切的正相关（P <0.0001） ），NH4 +，δ13CTOC值和类腐殖质FDOM。我们的研究表明，这些细菌群在与硫酸盐或金属氧化物有关的氧化还原过程中占主导地位，