Data Sheet 1_Microbial community structure and metabolic characteristics in sediments from five different deep-sea trenches.doc

Microbial community growth efficiency, defined as the ratio of production to substrate assimilation, could provide insights into carbon flow among microbes and the regulation of marine biogeochemical cycles. However, the metabolic characteristics of microbes in deep-sea trenches remain largely undetermined. In this study, the structural and metabolic characteristics of microbial communities in five deep-sea trenches were investigated using Illumina high-throughput sequencing, quantitative PCR, the 3H-leucine incorporation method, and electron transport system analysis. We found that microbial community structure and functional gene abundance exhibited significant inter-trench variations, indicating that geographic isolation and environmental filters are key drivers of microbial biogeography. Under atmospheric pressure (AP), significantly higher respiration rates in the Mariana (MT) and Yap (YT) trenches than in the Kermadec (KT), Diamantina (DT), and Wallaby-Zenith (WT) trenches showed that higher organic carbon input in the western Pacific supported more active heterotrophic metabolism. Crucially, the consistently lower prokaryotic growth efficiency (PGE) under high hydrostatic pressure (HHP) across all trenches indicated that, in situ, pressure fundamentally shifted carbon allocation from biomass production to maintenance respiration, drastically constraining deep-sea carbon conversion efficiency. This demonstrated that genomic potential alone was insufficient to predict carbon cycling rates, and that direct physiological measurements under in situ conditions were essential for accurate assessment. Our study provided preliminary insights into the processes and efficiency of microbial-driven carbon cycling in the deep biosphere.

微生物群落生长效率（microbial community growth efficiency）被定义为微生物生产量与底物同化量的比值，可为解析微生物间的碳流动以及海洋生物地球化学循环的调控机制提供重要参考。然而，深海海沟中微生物的代谢特征在很大程度上仍未明确。本研究采用Illumina高通量测序（Illumina high-throughput sequencing）、定量聚合酶链式反应（quantitative PCR）、³H-亮氨酸掺入法以及电子传递系统分析，对5个深海海沟的微生物群落结构与代谢特征展开研究。研究发现，微生物群落结构与功能基因丰度在不同海沟间存在显著差异，表明地理隔离与环境过滤是驱动微生物生物地理学（microbial biogeography）形成的关键因素。在常压（atmospheric pressure，AP）条件下，马里亚纳海沟（MT）与雅浦海沟（YT）的呼吸速率显著高于克马德克海沟（KT）、迪亚曼蒂纳海沟（DT）及沃勒比-泽尼特海沟（WT），这表明西太平洋较高的有机碳输入支撑了更为活跃的异养代谢。尤为关键的是，所有海沟在高静水压（high hydrostatic pressure，HHP）条件下的原核生物生长效率（prokaryotic growth efficiency，PGE）均持续偏低，这表明在原位环境中，压力从根本上改变了碳分配模式：将原本用于生物量合成的碳转向维持呼吸，大幅制约了深海碳转化效率。该结果证实，仅依靠基因组潜力无法准确预测碳循环速率，在原位条件下开展直接生理测量对于精准评估碳循环过程至关重要。本研究为深入理解深部生物圈中微生物驱动的碳循环过程与效率提供了初步参考。