OBJECTIVE Heterotrophic manganese (Mn)-oxidizing microorganisms responsible for biogenic manganese oxide (Bio-MnOx) production are fastidious. Their enrichment is not easily accomplished by merely adding a soluble organic substrate to non-sterile mixed cultures. The objective of this study was to evaluate polycaprolactone (PCL), an aliphatic polyester, as an effective solid organic substrate for the enrichment of marine Mn-oxidizing microorganisms. RESULTS We successfully obtained marine microbial enrichment with the capacity for dissolved Mn removal and MnOx production using PCL as a solid organic substrate. The removal of dissolved Mn by the Mn-oxidizing enrichment culture followed first-order kinetics with a rate constant of 0.014 h-1. 16S rRNA gene amplicon sequencing analysis revealed that the Mn-oxidizing enrichment culture was highly dominated by operational taxonomic units related to the bacterial phyla Cyanobacteria, Planctomycetes, and Proteobacteria. CONCLUSIONS Our data demonstrate that PCL can serve as a potential substrate to enrich Mn-oxidizing microorganisms with the ability to produce MnOx under marine conditions.

中文翻译：

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以聚己内酯为固体有机底物富集海洋氧化锰微生物

目标 负责生物源氧化锰 (Bio-MnOx) 生产的异养氧化锰 (Mn) 微生物非常挑剔。仅通过向非无菌混合培养物中添加可溶性有机底物并不容易实现它们的富集。本研究的目的是评估聚己内酯 (PCL)，一种脂肪族聚酯，作为一种有效的固体有机底物，用于富集海洋氧化锰的微生物。结果我们使用PCL作为固体有机底物成功地获得了具有去除溶解锰和生产MnOx能力的海洋微生物富集。通过 Mn 氧化富集培养物去除溶解的 Mn 遵循一级动力学，速率常数为 0.014 h-1。16S rRNA 基因扩增子测序分析表明，Mn 氧化富集培养物高度受与细菌门蓝藻、浮游菌和变形菌相关的操作分类单元的支配。结论 我们的数据表明，PCL 可以作为一种潜在的底物，以丰富具有在海洋条件下产生 MnOx 能力的 Mn 氧化微生物。