Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University, Hangzhou, China.
Key Lab Water Pollut Control & Environm Secur Tec, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
Biodegradation. 2020 Dec;31(4-6):319-329. doi: 10.1007/s10532-020-09912-z. Epub 2020 Sep 11.
The strictly anaerobic serum bottles were applied to investigate methane oxidation coupled to chlorate (ClO) reduction (MO-CR) without exogenous oxygen. 0.35 mM ClO was consumed within 20 days at the reduction rate of 17.50 μM/d, over three times than that of ClO. Chlorite (ClO) was not detected throughout the experiment and the mass recovery of Cl was over 89%. Isotope tracing results showed most of CH was oxided to CO, and the electrons recovery reached to 77.6%. Small amounts of CH was consumed for DOC production probably through aerobic methane oxidation process, with oxygen generated from disproportionation reaction. In pMMO (key enzyme in aerobic oxidation of methane) inhibition tests, ClO reduction rate was slowed to 7. 0 μmol/d by 2 mM CH, real-time quantitative PCR also showed the transcript abundance of pMMO and Cld were significantly dropped at the later period of experiment, indicating that the O disproportionated from ClO was utilized to active CH. NC10 bacteria Candidatus Methylomirabilis, related closely to oxygenic denitrifiers M. oxyfera, was detected in the system, and got enriched along with chlorate reduction. Several pieces of evidence supported that NC10 bacteria promoted CH oxidation coupled to ClO reduction, these oxygenic denitrifiers may perform ClO disproportionation to produce O, and then oxidized methane intracellularly.
严格厌氧的血清瓶被应用于研究甲烷氧化偶联氯酸盐（ClO）还原（MO-CR）过程，在此过程中没有外源氧气的参与。在 20 天内，350μM 的 ClO 被消耗，其还原速率是 ClO 的三倍以上。在整个实验过程中未检测到亚氯酸盐（ClO），且 Cl 的质量回收率超过 89%。同位素示踪结果表明，大部分 CH 被氧化为 CO，电子回收率达到 77.6%。少量的 CH 可能通过好氧甲烷氧化过程被消耗，用于产生 DOC，其中氧气来源于歧化反应。在 pMMO（甲烷好氧氧化的关键酶）抑制试验中，2mM CH 将 ClO 还原速率减缓至 7.0μmol/d，实时定量 PCR 也表明，pMMO 和 Cld 的转录丰度在实验后期显著下降，表明 ClO 歧化产生的 O 被用于激活 CH。系统中检测到与好氧反硝化菌 M. oxyfera 密切相关的 NC10 细菌 Candidatus Methylomirabilis，并随着氯酸盐的还原而富集。有几个证据表明 NC10 细菌促进了 CH 氧化偶联的 ClO 还原，这些好氧反硝化菌可能进行 ClO 歧化以产生 O，然后在细胞内氧化甲烷。
