Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, 5 Yiheyuan Road, Beijing 100871, China.
J Biosci Bioeng. 2012 May;113(5):619-23. doi: 10.1016/j.jbiosc.2011.12.012. Epub 2012 Jan 31.
Characteristics of ammonium removal by a newly isolated heterotrophic nitrification-aerobic denitrification bacterium Agrobacterium sp. LAD9 were systematically investigated. Succinate and acetate were found to be the most favorable carbon sources for LAD9. Response surface methodology (RSM) analysis demonstrated that maximum removal of ammonium occurred under the conditions with an initial pH of 8.46, C/N ratio of 8.28, temperature of 27.9°C and shaking speed of 150rpm, where temperature and shaking speed produced the largest effect. Further nitrogen balance analysis revealed that 50.1% of nitrogen was removed as gas products and 40.8% was converted to the biomass. Moreover, the occurrence of aerobic denitrification was evidenced by the utilization of nitrite and nitrate as nitrogen sources, and the successful amplifications of membrane bound nitrate reductase and cytochrome cd(1) nitrite reductase genes from strain LAD9. Thus, the nitrogen removal in strain LAD9 was speculated to comply with the mechanism of heterotrophic nitrification coupled with aerobic denitrification (NH(4)(+)-NH(2)OH-NO(2)(-)-N(2)O-N(2)), in which also accompanied with the mutual transformation of nitrite and nitrate. The findings can help in applying appropriate controls over operational parameters in systems involving the use of this kind of strain.
本研究系统考察了一株新分离的异养硝化-好氧反硝化菌（Agrobacterium sp. LAD9）去除铵的特性。结果表明，琥珀酸盐和乙酸盐是最适合 LAD9 的碳源。响应面法（RSM）分析表明，在初始 pH 值为 8.46、C/N 比为 8.28、温度为 27.9°C、摇床转速为 150rpm 的条件下，铵的去除率最高，其中温度和摇床转速的影响最大。进一步的氮平衡分析表明，50.1%的氮以气体产物的形式去除，40.8%转化为生物量。此外，通过利用亚硝酸盐和硝酸盐作为氮源，以及从 LAD9 菌株中成功扩增出膜结合型硝酸盐还原酶和细胞色素 cd(1)亚硝酸盐还原酶基因，证实了好氧反硝化的发生。因此，推测 LAD9 菌株的氮去除符合异养硝化耦合好氧反硝化（NH(4)(+)-NH(2)OH-NO(2)(-)-N(2)O-N(2)）的机制，同时伴随着亚硝酸盐和硝酸盐的相互转化。这些发现有助于在涉及使用这种菌株的系统中，对操作参数进行适当的控制。
