一株好氧反硝化菌的降酚特性及反硝化关键酶活性

Phenol Degradation Characteristic of the Aerobic Denitrifying Strain Diaphorobacter sp.PD-7 and Its Key Denitrifying Enzymes Activity

为了研究菌株Diaphorobacter sp.PD-7在有氧条件下降解低浓度苯酚同时反硝化的特性,采用单因素试验,摇床转速180 r/min时,最佳降酚条件为200 mg/L乙酸钠和300 mg/L苯酚同时作为碳源,培养液初始p H为7.0,温度30℃,20 h内对初始浓度300 mg/L苯酚去除率达97.3%。培养液p H为中性时,硝酸盐还原酶(NAR)与亚硝酸盐还原酶(NIR)的最适反应温度分别为35℃、40℃。用米门方程对酶促反应动力学模拟,拟合曲线与实验测定值相关性良好,参数分别为Km=0.76μmol/L、vmax=42.02×10-3U/min和Km=1.49μmol/L、vmax=32.79×10-3U/min。推测NIR可能是该菌株反硝化过程中的限速酶,菌株PD-7主要通过细胞同化作用与反硝化作用脱氮,且该菌株有着完整的反硝化途径。

Single factor experiments was used to study the characteristic of simultaneous low concentration of phenol degradation of the strain Diaphorobacter sp. PD-7 and its denitrification. At the shaking speed of180 r/min,the optimum degradation condition were as follow： 200 mg/L soudium acetate and 300 mg/L phenol as carbon source at the same time,initial p H 7. 0,temperature 30 ℃. The strain degraded 97. 3% of 300 mg/L phenol in 20 h. The optimal reaction temperature of nitrate reductase（ NAR） and nitrite reductase（ NIR） were 35 ℃and 40 ℃,respectively,when the nutrient solution p H value is neutral. The process of enzymatic reaction was simulated using Michaelis-Menten equation. The fitted curve had a good correlation with test measured. The parameters were Km= 0. 76 μmol/L,vmax= 42. 02 × 10-3U/min,and Km= 1. 49 μmol/L,vmax= 32. 79 × 10-3U/min.Speculated that NIR may be the rate-limiting enzyme in the denitrification process,Strains PD-7 denitrified mainly through assimilation and denitrification denitrification,and the strain has a complete denitrification pathways.