一株苯酚降解菌的分离鉴定及响应面法优化其固定化

从太原市焦化厂废水活性污泥中分离、筛选出一株苯酚降解细菌,经生理生化反应和16S rRNA鉴定,该菌株为Diaphorobacter属细菌,命名为PD-07.代谢机制研究表明,苯酚可诱导该菌合成邻苯二酚2,3-加氧酶降解苯酚.为了提高该菌株对苯酚的降解率,以海藻酸钙为材料,对该菌株进行包埋固定化研究.首先采用Plackett–Burman实验设计筛选出影响固定化菌株苯酚降解率的关键因素,然后采用最陡爬坡实验逼近最大苯酚降解率响应区域.最后用Box–Behnken实验设计及响应面回归分析,应用二次方程对实验数据进行拟合得,拟合曲线与实验实测值相关性良好,最佳条件为海藻酸钠浓度3.83%(m/V)、CaCl2 0.3mol/L、菌胶比1:26.73、固定化时间2h、摇床转速180r/min、培养温度30℃、初始pH值7.2、液固比4.86:1,在此条件下苯酚降解率可达96.89%.

Isolation and identification of a phenol-degrading strain and optimization for its immobilization using response surface methodology

A phenol-degrading strain was isolated from the activated sludge of a cokes wastewater treatment facility in Taiyuan City. Based on its physiology, biochemical characters and the analysis of its 16S rRNA gene sequence, the isolated strain named PD-07 was identified as a member of the genus Diaphorobacter. Metabolic pathway research showed that the strain could be induced to synthesize intracellular catechol-2,3-dioxygenase.To improve the phenol degradation rate, a study of embedding immobilized strain was conducted with calcium alginate as material. Firstly, factors playing important roles in the phenol degradation rate of immobilized cell were selected based on Plackett-Burman design. Then the path of steepest ascent was undertaken to approach the optimal region of the phenol degradation rate. Finally, the optimal levels of those main factors were further optimized by using Box-Behnken design and response surface analysis. Quadratic equation was adopted to fit the test data. The fitting curve had a good correlation with the measured values. The optimal conditions were as follows: alginate concentration 3.83%(m/V), calcium chloride concentration 0.3mol/L, bacteria-cement ratio 1:26.73, immobilized time 2h, rotation rate 180r/min, culture temperature 30℃, initial pH value 7.2, liquid-solid ratio 4.86:1. Under the optimal conditions mentioned above, the phenol degradation rate reached 96.89%.