We focused on the use of abiotic MnO2 to develop reactors for enriching manganese-oxidizing bacteria (MnOB), which may then be used to treat harmful heavy metal-containing wastewater and in the recovery of useful minor metals. Downflow hanging sponge (DHS) reactors were used under aerobic and open conditions to investigate the potential for MnOB enrichment. The results of an experiment that required a continuous supply of organic feed solution containing Mn(II) demonstrated that MnOB enrichment and Mn(II) removal were unsuccessful in the DHS reactor when plain sponge cubes were used. However, MnOB enrichment was successful within a very short operational period when sponge cubes initially containing abiotic MnO2 were installed. The results of a microbial community analysis and MnOB isolation revealed that MnOB belonging to Comamonadaceae or Pseudomonas played a major role in Mn(II) oxidation. Successful MnOB enrichment was attributed to several unidentified species of Chitinophagaceae and Gemmataceae, which were estimated to be intolerant of MnO2, being unable to grow on sponge cubes containing MnO2. The present results show that MnO2 exerted anti-bacterial effects and inhibited the growth of certain non-MnOB groups that were intolerant of MnO2, thereby enabling enriched MnOB to competitively consume more substrate than MnO2-intolerant bacteria.

中文翻译：

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MnO2对下流式悬挂海绵反应器中锰氧化细菌富集的抗菌作用


我们专注于使用非生物二氧化锰来开发富集锰氧化细菌（MnOB）的反应器，然后将其用于处理有害的含重金属废水和回收有用的微量金属。在有氧和开放条件下使用下流式悬挂海绵 (DHS) 反应器来研究 MnOB 富集的潜力。需要连续供应含有 Mn(II) 的有机进料溶液的实验结果表明，当使用普通海绵立方体时，DHS 反应器中 MnOB 富集和 Mn(II) 去除不成功。然而，当安装最初含有非生物 MnO2 的海绵立方体时，MnOB 富集在很短的操作期内就取得了成功。微生物群落分析和 MnOB 分离结果表明，属于丛毛单胞菌科或假单胞菌属的 MnOB 在 Mn(II) 氧化中起主要作用。 MnOB 的成功富集归因于几种身份不明的 Chitinophagaceae 和 Gemmataceae 物种，这些物种估计对 MnO2 不耐受，无法在含有 MnO2 的海绵立方体上生长。目前的结果表明，MnO2 发挥抗菌作用，并抑制某些不耐受 MnO2 的非 MnOB 基团的生长，从而使富集的 MnOB 能够比不耐受 MnO2 的细菌竞争性地消耗更多的底物。