Soluble ligand‐bound Mn(III) can support anaerobic microbial respiration in diverse aquatic environments. Thus far, Mn(III) reduction has only been associated with certain Gammaproteobacteria. Here, we characterized microbial communities enriched from Mn‐replete sediments of Lake Matano, Indonesia. Our results provide the first evidence for the biological reduction of soluble Mn(III) outside the Gammaproteobacteria. Metagenome assembly and binning revealed a novel betaproteobacterium, which we designate ‘Candidatus Dechloromonas occultata.’ This organism dominated the enrichment and expressed a porin‐cytochrome c complex typically associated with iron‐oxidizing Betaproteobacteria and a novel cytochrome c‐rich protein cluster (Occ), including an undecaheme putatively involved in extracellular electron transfer. This occ gene cluster was also detected in diverse aquatic bacteria, including uncultivated Betaproteobacteria from the deep subsurface. These observations provide new insight into the taxonomic and functional diversity of microbially driven Mn(III) reduction in natural environments.

中文翻译：

---

对细菌 Mn(III) 还原的分类多样性和分子机制的新见解。

可溶性配体结合的 Mn(III) 可以支持不同水生环境中的厌氧微生物呼吸。到目前为止，Mn(III) 减少仅与某些Gammaproteobacteria相关。在这里，我们描述了从印度尼西亚马塔诺湖富含锰的沉积物中富集的微生物群落。我们的结果为Gammaproteobacteria之外的可溶性 Mn(III) 的生物还原提供了第一个证据。宏基因组组装和分箱揭示了一种新的 betaproteobacterium，我们将其命名为“ Candidatus Dechloromonas occultata”。这种生物体在富集过程中占主导地位，并表达了一种通常与铁氧化Betaproteobacteria相关的孔蛋白-细胞色素c复合物和一种新的富含细胞色素c的蛋白簇（Occ），包括一种假定参与细胞外电子转移的十一血红素。这种occ基因簇也在多种水生细菌中检测到，包括来自地下深处的未培养的Betaproteobacteria。这些观察结果为自然环境中微生物驱动的 Mn(III) 还原的分类和功能多样性提供了新的见解。