| ANAMMOX培养物中硫酸盐型氨氧化生物转化机制 |
| 摘要点击 1857 全文点击 599 投稿时间：2020-08-10 修订日期：2020-09-02 |
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| 中文关键词 ANAMMOX培养物 硫酸盐型氨氧化(SRAO) 氨氧化细菌(AOB) 异养硫酸盐还原细菌(SRB) 氧化还原电位(ORP) 溶解氧(DO) 功能基因 |
| 英文关键词 ANAMMOX consortia sulfate reduction ammonium oxidation (SRAO) ammonium oxidation bacteria (AOB) sulfate reduction bacteria (SRB) oxidation-reduction potential (ORP) dissolved oxygen (DO) functional genes |
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| 中文摘要 |
| 厌氧条件下，ANAMMOX培养物中发生的硫酸盐型氨氧化（SRAO）现象被认为是由ANAMMOX细菌（AnAOB）介导的自养生物转化过程.在这个过程中，作为电子供体的氨被电子受体硫酸盐氧化.在某一些自然环境中观察到的氨与硫酸盐转化现象也被认为是由于上述生物转化作用而导致的.然而，在不同研究中，关于氨与硫酸盐的转化摩尔比（N/S）、硫酸盐还原的中间产物和最终产物的认定均有存在较大差异.因此，氨和硫酸盐在ANAMMOX培养物中的转化机制仍不明确.为探明ANAMMOX污泥中SRAO现象背后的基质转化途径，在不同厌氧状态（微氧：-100 mV < ORP < 0 mV，0.5 mg·L-1 < DO < 1 mg·L-1；缺氧：-300 mV < ORP < -100 mV，0.2 mg·L-1 < DO < 0.5 mg·L-1；厌氧：ORP < -300 mV，DO < 0.2 mg·L-1）以及不同污泥组成（ANAMMOX污泥和混合污泥）的条件下开展连续流实验和批次实验.结果表明，SRAO现象只能在缺氧条件且存在异养硫酸盐还原细菌（SRB）的混合污泥中发生；在ANAMMOX污泥中无论处于哪种厌氧状态，均不会发生SRAO现象.微生物群落变化与功能基因表达分析表明，ANAMMOX污泥和混合污泥中均存在以Nitrosomonas和Nitrosospira为主的携带amoA基因的氨氧化细菌（AOB），可将氨氧化生成亚硝酸盐，为AnAOB代谢提供底物.Desulfomicrobium、Desulfovibrio以及Desulfonatronum等携带apsA基因的SRB只存在于混合污泥中，它们利用微生物衰亡释放的有机物将硫酸盐还原.AnAOB并不能以硫酸盐为电子受体氧化氨维持代谢.因此，在ANAMMOX污泥中观察到的SRAO现象（即氨与硫酸盐的同步转化）实际上是氨氧化、ANAMMOX和异养硫酸盐还原这3个过程联合的结果，上述生物转化过程分别由AOB、AnAOB和SRB完成. |
| 英文摘要 |
| Sulfate reduction with ammonium oxidation (SRAO) in laboratory ANAMMOX reactors was considered as an autotrophic process mediated by ANAMMOX bacteria (AnAOB), in which ammonium, as an electron donor, was oxidized by the electron acceptor sulfate. This process was developed based on the transformations of nitrogenous and sulfurous compounds observed in natural environments. Reported results vary widely for conversion mole ratios (ammonium/sulfate) as do intermediate and final products of the sulfate reduction. Thus, hypotheses surrounding biological conversion pathways of ammonium and sulfate in ANAMMOX consortia are implausible. In this study, continuous reactor experiments and batch tests were conducted under micro-aerobic (-100 mV < ORP < 0 mV, 0.5 mg·L-1 < DO < 1 mg·L-1), anoxic (-300 mV < ORP < -100 mV, 0.2 mg·L-1 < DO < 0.5 mg·L-1) and anaerobic (ORP < -300 mV, DO < 0.2 mg·L-1) conditions with different inoculated sludge (ANAMMOX sludge and mixed sludge) to verify the SRAO phenomena and identify possible pathways of substrate conversion. The key findings were that SRAO occurred only where SRB existed under anoxic condition, and was absent under anaerobic conditions with ANAMMOX consortia. The analysis of the microbial community and functional gene expression showed that ammonium oxidation by AAOB coupled with sequential ANAMMOX is possibly responsible for the loss of ammonium under anoxic condition. Organic substances released through microbial decay contributed to heterotrophic sulfate conversion by SRB. AnAOB do not possess the ability to oxidize ammonium with sulfate as the electron acceptor. SRAO could, in fact, involve a combination of aerobic ammonium oxidation, ANAMMOX, and heterotrophic sulfate reduction processes, which are mediated via AOB, AnAOB, and SRB. |
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