Holben WE, Noto K, Sumino T, Suwa Y
Division of Biological Sciences, The University of Montana, Missoula, Montana 59812-1002, Japan.
Appl Environ Microbiol. 1998 Jul 1;64(7):2528-32. doi: 10.1128/AEM.64.7.2528-2532.1998.
Bacterial community structure and the predominant nitrifying activities and populations in each compartment of a three-compartment activated sludge system were determined. Each compartment was originally inoculated with the same activated sludge community entrapped in polyethylene glycol gel granules, and ammonium nitrogen was supplied to the system in an inorganic salts solution at a rate of 5.0 g of N liter of granular activated sludge-1 day-1. After 150 days of operation, the system was found to comprise a series of sequential nitrifying reactions (K. Noto, T. Ogasawara, Y. Suwa, and T. Sumino, Water Res. 32:769-773, 1998), presumably mediated by different bacterial populations. Activity data showed that all NH4-N was completely oxidized in compartments one and two (approximately half in each), but no significant nitrite oxidation was observed in these compartments. In contrast, all available nitrite was oxidized to nitrate in compartment three. To study the microbial populations and communities in this system, total bacterial DNA isolated from each compartment was analyzed for community structure based on the G+C contents of the component populations. Compartment one showed dominant populations having 50 and 67% G+C contents. Compartment two was similar in structure to compartment one. The bacterial community in compartment three had dominant populations with 62 and 67% G+C contents and retained the 50% G+C content population only at a greatly diminished level. The 50% G+C content population from compartment one hybridized strongly with amo (ammonia monooxygenase) and hao (hydroxylamine oxidoreductase) gene probes from Nitrosomonas europaea. However, the 50% G+C content population from compartment two hybridized strongly with the hao probe but only weakly with the amo probe, suggesting that the predominant ammonia-oxidizing populations in compartments one and two might be different. Since different activities and populations come to dominate in each compartment from an identical inoculum, it appears that the nitrification processes may be somewhat incompatible, resulting in a series of sequential reactions and different communities in this three-compartment system.
确定了三室活性污泥系统各隔室中的细菌群落结构以及主要的硝化活性和菌群。每个隔室最初接种的是 entrapped 在聚乙二醇凝胶颗粒中的相同活性污泥群落，以无机盐溶液的形式向系统中供应铵态氮，供应速率为 5.0 g N·升颗粒活性炭污泥⁻¹·天⁻¹。运行 150 天后，发现该系统包含一系列连续的硝化反应（K. 野藤、小笠原 T、诹访 Y 和角野 T，《水研究》32:769 - 773，1998），推测由不同的细菌种群介导。活性数据表明，所有的 NH₄-N 在隔室一和隔室二中被完全氧化（每个隔室约占一半），但在这些隔室中未观察到显著的亚硝酸盐氧化。相反，隔室三中所有可用的亚硝酸盐都被氧化成了硝酸盐。为了研究该系统中的微生物种群和群落，基于组成种群的 G+C 含量，对从每个隔室分离的总细菌 DNA 进行了群落结构分析。隔室一显示出 G+C 含量分别为 50%和 67%的优势种群。隔室二在结构上与隔室一相似。隔室三中的细菌群落具有 G+C 含量分别为 62%和 67%的优势种群，并且仅在极低水平保留了 G+C 含量为 50%的种群。来自隔室一的 G+C 含量为 50%的种群与欧洲亚硝化单胞菌的 amo（氨单加氧酶）和 hao（羟胺氧化还原酶）基因探针强烈杂交。然而，来自隔室二的 G+C 含量为 50%的种群与 hao 探针强烈杂交，但与 amo 探针仅弱杂交，这表明隔室一和隔室二中主要的氨氧化种群可能不同。由于从相同接种物开始，不同的活性和种群在每个隔室中占主导地位，因此硝化过程似乎在某种程度上不兼容，导致了这个三室系统中的一系列连续反应和不同群落。
