Seamounts are often covered with Fe and Mn oxides, known as ferromanganese (Fe–Mn) crusts. Future mining of these crusts is predicted to have significant effects on biodiversity in mined areas. Although microorganisms have been reported on Fe–Mn crusts, little is known about the role of crusts in shaping microbial communities. Here, we investigated microbial communities based on 16S rRNA gene sequences retrieved from Fe–Mn crusts, coral skeleton, calcarenite, and biofilm at crusts of the Rio Grande Rise (RGR). RGR is a prominent topographic feature in the deep southwestern Atlantic Ocean with Fe–Mn crusts. Our results revealed that crust field of the RGR harbors a usual deep-sea microbiome. No differences were observed on microbial community diversity among Fe–Mn substrates. Bacterial and archaeal groups related to oxidation of nitrogen compounds, such as Nitrospirae, Nitrospinae phyla, Candidatus Nitrosopumilus within Thaumarchaeota group, were present on those substrates. Additionally, we detected abundant assemblages belonging to methane oxidation, i.e., Methylomirabilales (NC10) and SAR324 (Deltaproteobacteria). The chemolithoautotrophs associated with ammonia-oxidizing archaea and nitrite-oxidizing bacteria potentially play an important role as primary producers in the Fe–Mn substrates from RGR. These results provide the first insights into the microbial diversity and potential ecological processes in Fe–Mn substrates from the Atlantic Ocean. This may also support draft regulations for deep-sea mining in the region.

海山通常覆盖着铁和锰的氧化物，称为锰铁 (Fe-Mn) 结壳。预计这些结壳的未来开采将对矿区的生物多样性产生重大影响。尽管已经报道了 Fe-Mn 结皮上存在微生物，但对结皮在塑造微生物群落中的作用知之甚少。在这里，我们基于从里奥格兰德海隆 (RGR) 地壳的 Fe-Mn 结壳、珊瑚骨架、方解石和生物膜中检索到的 16S rRNA 基因序列研究了微生物群落。RGR 是大西洋西南部深部具有 Fe-Mn 结壳的显着地形特征。我们的结果表明，RGR 的地壳场拥有一个常见的深海微生物群。Fe-Mn 底物之间的微生物群落多样性没有观察到差异。与氮化合物氧化相关的细菌和古菌群， Thaumarchaeota 组中的Candidatus Nitrosopumilus存在于这些基质上。此外，我们检测到大量属于甲烷氧化的组合，即 Methylomirabilales (NC10) 和 SAR324 (Deltaproteobacteria)。与氨氧化古菌和亚硝酸盐氧化细菌相关的化学自养菌可能在 RGR 的 Fe-Mn 底物中作为初级生产者发挥重要作用。这些结果首次提供了对大西洋 Fe-Mn 基质中微生物多样性和潜在生态过程的见解。这也可能支持该地区深海采矿的法规草案。