异养硝化菌Alcaligenes faecalis strain NR 的 硝 化 性 能 及 其 酶 活 性

从膜生物反应器的活性污泥中分离出一株异养硝化细菌Alcaligenes faecalis strain NR，采用柠檬酸三钠为碳源、氯化铵为氮源研究其硝化性能，通过超声波破碎法对调控其硝化过程的2个关键酶--氨单加氧酶（AMO）和羟胺氧化酶（HAO）进行粗提，考察影响其提取率的主要因素（功率、工作与间歇时间、菌液浓度和总工作时间），并采用正交实验进行优化.结果表明：菌株NR具有产生亚硝酸盐和硝酸盐的能力；在30 °C和120 r/min的好氧条件下，当NH+4 N浓度为20、40和60 mg/L时，菌株NR在24 h内对NH+4 N的去除率分别为94.8%、93.5%和94.5%；粗酶提取的最佳工作条件为菌液光密度1.876，总工作时间600 s，工作和间歇时间4、6 s，功率300 W；在好氧条件下，测得AMO和HAO的酶比活力分别为0.011和0.016 U/mg protein.

Heterotrophic Nitrification Capability and its Enzyme Activity of Alcaligenes faecalis strain NR

A heterotrophic nitrifying bacterium, Alcaligenes faecalis strain NR, was isolated from a membrane bioreactor. Citrate and ammonium were used as the sole carbon and nitrogen sources respectively to investigate nitrification characteristics of the new isolate. Under the aerobic condition of 30 °C and 120 r/min, the removal rates of NH+4 N are 94.8%, 93.5% and 94.5% respectively when the initial concentrations are 20, 40 and 60 mg/L. And strain NR shows nitrification capability of producing nitrite and nitrate. To further understand the heterotrophic nitrification, enzyme assay was conducted. Sonication was used to obtain the key enzymes of AMO and HAO during nitrification process. Based on the single factor and orthogonal experimental results, the optimal ultrasonic conditions are: cell OD600 1.876, total working time 600 s, work/interval time 4, 6 s and power 300 W. The AMO and HAO enzyme activities under aerobic conditions are 0.011 U/mg protein and 0.016 U/mg protein respectively.