Data_Sheet_1_Environmental heterogeneity shapes the C and S cycling-associated microbial community in Haima's cold seeps.pdf

Environmental heterogeneity in cold seeps is usually reflected by different faunal aggregates. The sediment microbiome, especially the geochemical cycling-associated communities, sustains the ecosystem through chemosynthesis. To date, few studies have paid attention to the structuring and functioning of geochemical cycling-associated communities relating to environmental heterogeneity in different faunal aggregates of cold seeps. In this study, we profiled the microbial community of four faunal aggregates in the Haima cold seep, South China Sea. Through a combination of geochemical and meta-omics approaches, we have found that geochemical variables, such as sulfate and calcium, exhibited a significant variation between different aggregates, indicating changes in the methane flux. Anaerobic methanotrophic archaea (ANME), sulfate-reducing, and sulfide-oxidizing bacteria (SRB and SOB) dominated the microbial community but varied in composition among the four aggregates. The diversity of archaea and bacteria exhibited a strong correlation between sulfate, calcium, and silicate. Interspecies co-exclusion inferred by molecular ecological network analysis increased from non-seep to clam aggregates and peaked at the mussel aggregate. The networked geochemical cycling-associated species showed an obvious aggregate-specific distribution pattern. Notably, hydrocarbon oxidation and sulfate reduction by ANME and SRB produced carbonate and sulfide, driving the alkalization of the sediment environment, which may impact the microbial communities. Collectively, these results highlighted that geofluid and microbial metabolism together resulted in environmental heterogeneity, which shaped the C and S cycling-associated microbial community.

冷泉（cold seeps）的环境异质性通常以不同的动物聚集体（faunal aggregates）为表征。沉积物微生物组（sediment microbiome），尤其是与地球化学循环相关的群落，通过化能合成作用维持该生态系统的运转。迄今为止，鲜有研究关注冷泉不同动物聚集体中与环境异质性相关的地球化学循环相关群落的构建机制与生态功能。本研究以南海海马冷泉（Haima cold seep）的4种动物聚集体为研究对象，解析了其微生物群落组成特征。通过结合地球化学检测与宏组学（meta-omics）分析方法，本研究发现硫酸盐、钙等地球化学变量在不同聚集体间存在显著差异，指示甲烷通量的变化。厌氧甲烷氧化古菌（Anaerobic methanotrophic archaea, ANME）、硫酸盐还原菌（sulfate-reducing bacteria, SRB）与硫氧化菌（sulfide-oxidizing bacteria, SOB）构成了微生物群落的优势类群，但在4种聚集体间的组成存在显著差异。古菌与细菌的多样性与硫酸盐、钙以及硅酸盐的含量存在显著相关性。通过分子生态网络分析（molecular ecological network analysis）推断得到的物种间互斥模式，从非冷泉聚集体到蛤类聚集体逐渐增强，并在贻贝聚集体中达到峰值。与地球化学循环相关的网络关联物种呈现出显著的聚集体特异性分布模式。值得注意的是，ANME与SRB介导的烃类氧化与硫酸盐还原反应会生成碳酸盐与硫化物，驱动沉积物环境发生碱化，进而可能对微生物群落产生影响。综合来看，本研究结果表明，地下流体（geofluid）与微生物代谢共同塑造了环境异质性，进而调控了碳循环与硫循环相关微生物群落的构建。