Although volcanic ash deposition into oceans has been a frequent phenomenon for much of geologic history, the potential effects on deep-sea seabed metal-biogeochemical cycles remain enigmatic. In this study, we analyzed mineral compositions, microbial communities, and metal-related functional genes in a sediment core with volcanic ash layers from the Yap Trench in the western Pacific Ocean. The mineralogical analysis showed that volcanic activity introduced large amounts of Fe-rich igneous minerals, such as olivine, pyroxene, hornblende, grossularite, and biotite, into the trench seabed sedimentary environments. Furthermore, some differentiation in microbial communities was observed and potential Fe-metabolizing bacteria (such as Pseudomonas, Alteromonas, Marinobacter, Halomonas, Pseudoalteromonas, and Erythrobacter) were dominant in the volcanic ash layers. Moreover, compared with the background sediment metagenome, the volcanic ash metagenomes were enriched in pathways for siderophore synthesis and uptake, and metal resistant functional genes. These results suggest that volcanic ash can lead to changes in trench-sediment-based microbial communities and stimulate microbial Fe acquisition and other metal-related metabolism. In response, microorganisms could promote decomposition of the metal-rich volcanic minerals and metal release rates from them, subsequently enhancing the deep-sea metal-biogeochemical cycle.

尽管在许多地质历史中，火山灰沉积到海洋中都是一种常见现象，但对深海海底金属生物地球化学循环的潜在影响仍然难以捉摸。在这项研究中，我们分析了西太平洋Yap海沟中具有火山灰层的沉积岩芯中的矿物成分，微生物群落和与金属相关的功能基因。矿物学分析表明，火山活动将大量富铁的火成矿物引入了海床沉积环境，例如橄榄石，辉石，角闪石，块石和黑云母。此外，还观察到了微生物群落的一些分化，并发现了潜在的铁代谢细菌（如假单胞菌，链霉菌，马林杆菌，Halomonas，Pseudoalteromonas和Erythrobacter（）在火山灰层中占主导地位。此外，与背景沉积物基因组相比，火山灰的基因组丰富了铁载体合成和吸收的途径以及对金属有抗性的功能基因。这些结果表明，火山灰可导致基于沟槽沉积物的微生物群落的变化，并刺激微生物铁的获取和其他与金属有关的新陈代谢。作为响应，微生物可以促进富金属火山矿物的分解和金属从其中的释放速率，从而增强深海金属生物地球化学循环。