Manganese oxidation and prokaryotic community analysis in a polycaprolactone-packed aerated biofilm reactor operated under seawater conditions
Manganese oxidation and prokaryotic community analysis in a polycaprolactone-packed aerated biofilm reactor operated under seawater conditions
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DOI：
10.1007/s13205-022-03250-y
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发表时间：
2022-07
期刊：
影响因子：
2.8
通讯作者：
Masataka Aoki;Yukina Miyashita;T. Miwa;T. Watari;Takashi Yamaguchi;Kazuaki Syutsubo;K. Hayashi
中科院分区：
文献类型：
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作者：
Masataka Aoki;Yukina Miyashita;T. Miwa;T. Watari;Takashi Yamaguchi;Kazuaki Syutsubo;K. Hayashi
生物锰氧化物（BioMnOx）在去除环境污染物和回收水环境中的微量金属方面受到越来越多的关注。然而，在快速生长的共存异养菌的存在下，富集用于BioMnOx生产的异养Mn（II）氧化微生物是具有挑战性的。在我们以前的工作中，我们发现，聚己内酯（PCL），一种可生物降解的脂肪族聚酯，可以作为一种有效的固体有机基质，以丰富锰氧化微生物群落在海水条件下。然而，利用PCL的海洋BioMnOx生产生物反应器系统尚未建立。因此，一个实验室规模的连续流PCL填充曝气生物膜（PAB）反应器运行238天，以评估其在海水条件下生产生物锰氧化物的可行性。反应器启动后，在不同进水Mn浓度（平均2.5-14.0 mg/L）和理论水力停留时间（0.19-0.77 d）条件下，Mn（II）的平均去除率为0.4-2.3 mg/L/d。16 S rRNA基因扩增子测序分析表明，在反应器中存在推定的Mn（II）氧化和PCL降解细菌谱系。两个高度占主导地位的操作单元（OTU）在包装的PCL相关的生物膜被分配到generaMarinobacterandPseudohoeflea，而属Lewinella和未分类的AlphaproteobacteriaOTU是高度占主导地位的含锰氧化物的黑色/深棕色沉淀物相关的生物膜中形成的反应器。激发-发射矩阵荧光光谱分析揭示了酪氨酸和色氨酸样组分的产生，其可作为反应器中的可溶性异养有机底物。我们的研究结果表明，PAB反应器是潜在的适用于在海水条件下的生物锰氧化物生产。
Biogenic manganese oxides (BioMnOx) have been receiving increasing attention for the removal of environmental contaminants and recovery of minor metals from water environments. However, the enrichment of heterotrophic Mn(II)-oxidizing microorganisms for BioMnOx production in the presence of fast-growing coexisting heterotrophs is challenging. In our previous work, we revealed that polycaprolactone (PCL), a biodegradable aliphatic polyester, can serve as an effective solid organic substrate to enrich Mn-oxidizing microbial communities under seawater conditions. However, marine BioMnOx-producing bioreactor systems utilizing PCL have not yet been established. Therefore, a laboratory-scale continuous-flow PCL-packed aerated biofilm (PAB) reactor was operated for 238 days to evaluate its feasibility for BioMnOx production under seawater conditions. After the start-up of the reactor, the average dissolved Mn removal rates of 0.4–2.3 mg/L/day, likely caused by Mn(II) oxidation, were confirmed under different influent dissolved Mn concentrations (2.5–14.0 mg/L on average) and theoretical hydraulic retention time (0.19–0.77 day) conditions. The 16S rRNA gene amplicon sequencing analysis suggested the presence of putative Mn(II)-oxidizing and PCL-degrading bacterial lineages in the reactor. Two highly dominant operational units (OTUs) in the packed PCL-associated biofilm were assigned to the generaMarinobacterandPseudohoeflea, whereas the genusLewinellaand unclassifiedAlphaproteobacteriaOTUs were highly dominant in the MnOx-containing black/dark brown precipitate-associated biofilm formed in the reactor. Excitation-emission matrix fluorescence spectroscopy analysis revealed the production of tyrosine- and tryptophane-like components, which may serve as soluble heterotrophic organic substrates in the reactor. Our findings indicate that PAB reactors are potentially applicable to BioMnOx production under seawater conditions.