Wang Zhiyao, Ni Gaofeng, Maulani Nova, Xia Jun, De Clippeleir Haydée, Hu Shihu, Yuan Zhiguo, Zheng Min
Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
District of Columbia Water and Sewer Authority, 5000 Overlook Ave. SW, Washington, DC 20032, USA.
Water Res. 2021 May 15;196:117026. doi: 10.1016/j.watres.2021.117026. Epub 2021 Mar 9.
Recently, acidic (i.e. pH<5) nitrification in activated-sludge is attracting attention because it enables stable nitritation (NH → NO), and enhances sludge reduction and stabilization. However, the key acid-tolerant ammonia oxidizers involved are poorly understood. In this study, we performed stoichiometric and kinetic characterization of a new acid-tolerant ammonia-oxidizing bacterium (AOB) belonging to gamma-proteobacterium, Candidatus Nitrosoglobus. Ca. Nitrosoglobus was cultivated in activated-sludge in a laboratory membrane bioreactor over 200 days, with a relative abundance of 55.1 ± 0.5% (indicated by 16S rRNA gene amplicon sequencing) at the time of the characterization experiments. Among all known nitrifiers, Ca. Nitrosoglobus bears the highest resistance to nitrite, low pH, and free nitrous acid (FNA). These traits define Ca. Nitrosoglobus as an adversity-strategist that tends to prosper in acidic activated-sludge, where the low pH (< 5.0) and high levels of FNA (at parts per million levels) sustained and inhibited all other nitrifiers. In contrast, in the conventional pH-neutral activated-sludge process, Ca. Nitrosoglobus is less competitive with canonical AOB (e.g. Nitrosomonas) due to the relatively slow specific growth rate and low affinities to both oxygen and total ammonia. These results advance our understanding of acid-tolerant ammonia oxidizers, and support further development of the acidic activated-sludge process in which Ca. Nitrosoglobus can play a critical role.
最近，活性污泥中的酸性（即pH<5）硝化作用备受关注，因为它能实现稳定的亚硝化（NH → NO），并增强污泥的减量和稳定化。然而，人们对其中关键的耐酸氨氧化菌了解甚少。在本研究中，我们对一种属于γ-变形菌纲的新型耐酸氨氧化细菌（AOB）——“亚硝化oglobus菌属”进行了化学计量和动力学表征。“亚硝化oglobus菌属”在实验室膜生物反应器的活性污泥中培养了200多天，在表征实验时，其相对丰度为55.1 ± 0.5%（通过16S rRNA基因扩增子测序表明）。在所有已知的硝化菌中，“亚硝化oglobus菌属”对亚硝酸盐、低pH值和游离亚硝酸（FNA）具有最高的耐受性。这些特性将“亚硝化oglobus菌属”定义为一种逆境策略者，它倾向于在酸性活性污泥中繁盛，在这种环境中，低pH值（<5.0）和高水平的FNA（百万分之几的水平）持续存在并抑制了所有其他硝化菌。相比之下，在传统的pH中性活性污泥工艺中，由于其相对较慢的比生长速率以及对氧气和总氨的低亲和力，“亚硝化oglobus菌属”与典型的AOB（如亚硝化单胞菌）相比竞争力较弱。这些结果推进了我们对耐酸氨氧化菌的理解，并支持了酸性活性污泥工艺的进一步发展，在该工艺中“亚硝化oglobus菌属”可以发挥关键作用。
