Diaphorobacter sp.PDB3菌好氧反硝化脱氮特性

研究了Diaphorobactersp.PDB3菌在发酵罐内好氧反硝化特性.经过分析比较确定柠檬酸钠是好氧反硝化最佳碳源，采用响应面法对影响好氧反硝化的条件（温度、pH值、发酵罐转速、碳氮比）进行优化，构建出好氧反硝化数学模型.本模型预测值与实测值相关性非常好，预测PDB3菌发酵罐内好氧反硝化最佳条件：pH值、碳氮比、温度、转速分别为7.3、8.1、30.1℃、299.9r/min，最佳好氧反硝化比速率为2.25h^-1.验证实验表明，PDB3菌在发酵罐内好氧反硝化比速率为2.12h^-1，误差仅为5.8%.通过氮平衡分析表明，29.0%的总氮去除量转化为胞内氮，氮损失占总氮去除量的67.3%，细胞主要通过好氧反硝化作用和细胞同化作用脱氮.荧光定量PCR分析测定好氧反硝化过程中脱氮基因（napA，nirS，cnorB，nosZ）的表达水平以进一步解释脱氮特征，为Diaphorobacter sp.PDB3菌的实际应用提供一定的理论依据.

The nitrogen removal characteristics of aerobic denitrification by Diaphorobacter sp. PDB3

The aerobic denitrification characteristics of Diaphorobacter sp. PDB3 in a fermentor were studied. The sodium citrate was determined as the best carbon source for aerobic denitrification. The response surface methodology was used to optimize the aerobic denitrification conditions (temperature, pH, rotation speed, C/N ratio), and the mathematical model of aerobic denitrification was constructed. The predicted value and the measured value correlated very well. The optimum conditions for the aerobic denitrification in the fermentation broth of strain PDB3 were pH 7.3, C/N ratio 8.1, temperature 30.1℃ and rotation speed 299.9r/min, respectively. The optimum specific aerobic denitrification rate was 2.25h^-1.The results showed that the specific aerobic denitrification rate of PDB3 strain in the fermentor was 2.12h^-1 and the error was only 5.8%. Finally, the nitrogen balance analysis showed that 29.0% of the total nitrogen removal was converted to intracellular nitrogen and nitrogen loss accounted for 67.3% of the total nitrogen removal. The nitrogen was mainly removed by aerobic denitrification and cellular assimilation.The expression level of denitrifying gene (napA, nirS, cnorB, nosZ) was determined by RT-qPCR analysis to further explain the nitrogen removal characteristics, and provide theoretical basis for the practical application of Diaphorobacter sp.PDB3.