Table_1_Vertical Stratification of Dissolved Organic Matter Linked to Distinct Microbial Communities in Subtropic Estuarine Sediments.xlsx

Dissolved organic matter (DOM) provides carbon substrates and energy sources for sediment microbes driving benthic biogeochemical processes. The interactions between microbes and DOM are dynamic and complex and require the understanding based on fine-scale microbial community and physicochemical profiling. In this study, we characterized the porewater DOM composition in a 300-cm sediment core from the Pearl River estuary, China, and examined the interactions between DOM and archaeal and bacterial communities. DOM composition were highly stratified and associated with changing microbial communities. Compared to bacteria, the amplicon sequence variants of archaea showed significant Pearson correlations (r ≥ 0.65, P < 0.01) with DOM molecules of low H/C ratios, high C number and double bond equivalents, indicating that the distribution of archaea was closely correlated to recalcitrant DOM while bacteria were associated with relatively labile compounds. This was supported by the presence of auxiliary enzyme families essential for lignin degradation and bcrABCD, UbiX genes for anaerobic aromatic reduction in metagenome-assembled genomes of Bathyarchaeia. Our study demonstrates that niche differentiation between benthic bacteria and archaea may have important consequences in carbon metabolism, particularly for the transformation of recalcitrant organic carbon that may be predominant in aged marine sediments.

溶解有机物（DOM）为沉积物微生物提供了碳源和能量来源，驱动了底栖生物地球化学过程。微生物与DOM之间的相互作用动态且复杂，需要基于精细尺度微生物群落和物理化学分析的深入理解。在本研究中，我们对中国珠江口300厘米沉积物岩心中的孔隙水DOM组成进行了表征，并探讨了DOM与古菌和细菌群落的相互作用。DOM组成高度分层，并与微生物群落的变迁密切相关。与细菌相比，古菌的扩增子序列变异体与低H/C比率的DOM分子、高C数和双键当量表现出显著的Pearson相关系数（r ≥ 0.65，P < 0.01），表明古菌的分布与抗性DOM密切相关，而细菌则与相对易变化合物相关。这一观点得到了Bathyarchaeia的宏基因组组装基因组中存在木质素降解所必需的辅助酶家族以及bcrABCD、UbiX基因（用于厌氧芳香族还原）的支持。本研究表明，底栖细菌与古菌之间的生态位分化可能在碳代谢中具有重要的后果，尤其是在老年海洋沉积物中可能占主导地位的抗性有机碳的转化过程中。