Department of Civil and Environmental Engineering, Graduate School of Advanced Science and Engineering, Hiroshima University.
Western Region Industrial Research Center, Hiroshima Prefectural Technology Research Institute.
Microbes Environ. 2020;35(4). doi: 10.1264/jsme2.ME20052.
We focused on the use of abiotic MnO 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 MnO 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 MnO, being unable to grow on sponge cubes containing MnO. The present results show that MnO exerted anti-bacterial effects and inhibited the growth of certain non-MnOB groups that were intolerant of MnO, thereby enabling enriched MnOB to competitively consume more substrate than MnO-intolerant bacteria.
我们专注于利用非生物 MnO 开发用于富集锰氧化菌 (MnOB) 的反应器，这些反应器可用于处理有害的含重金属废水和回收有用的微量金属。在需连续供应含 Mn(II) 的有机进料溶液的条件下，采用下流式悬挂海绵 (DHS) 反应器，研究了 MnOB 富集的潜力。当使用普通海绵块时，实验结果表明 DHS 反应器中 MnOB 富集和 Mn(II)去除均不成功。然而，当最初含有非生物 MnO 的海绵块安装后，MnOB 富集在很短的运行期内就成功了。微生物群落分析和 MnOB 分离的结果表明，属于 Comamonadaceae 或 Pseudomonas 的 MnOB 在 Mn(II)氧化中起主要作用。成功的 MnOB 富集归因于几种未鉴定的几丁质分解菌科和芽单胞菌科，它们估计不能耐受 MnO，无法在含有 MnO 的海绵块上生长。目前的结果表明，MnO 发挥了抑菌作用，抑制了某些不耐 MnO 的非 MnOB 群体的生长，从而使富集的 MnOB 能够比不耐 MnO 的细菌更具竞争力地消耗更多的底物。
