施氏假单胞菌PFS-4的筛选、优化固定及其对二氯喹啉酸的降解性能

Isolation,Immobilization and Characterization of Quinclorac-Degrading Strain Pseudomonas stutzeri PFS-4

从长期施用二氯喹啉酸的土壤中分离到1株能以二氯喹啉酸为碳源生长的菌株,命名为PFS-4。经16S rRNA基因序列和生理生化特性分析,将菌株PFS-4鉴定为施氏假单胞菌(Pseudomonas stutzeri)。以麦秆吸附-海藻酸钠包埋方式对菌株进行复合固定,采用正交实验对固定条件进行优化,研究温度、pH值、碳源对固定化菌剂降解二氯喹啉酸的影响;考察固定化菌剂对污水中二氯喹啉酸的去除效果,并对比分析游离菌及固定化菌剂去除能力的差异。结果表明,固定化菌剂制备的最佳条件为:海藻酸钠质量分数为5%,Ca Cl2为4%,菌胶比1∶2,交联时间5 h。在温度为30℃、pH值为7的条件下,经5 d培养,固定化菌剂对500 mg·L^(-1)二氯喹啉酸降解率为92.3%。在处理污水中二氯喹啉酸时,游离菌的降解能力受到极显著抑制(P<0.01),而对固定化菌剂降解率影响相对较小,去除率保持在64%以上。麦秆吸附-海藻酸钠包埋固定化菌剂对不良环境具有较好缓冲性,可用于微生物降解菌的开发利用。

Using quinclorac as carbon source,one strain,named PFS-4,was isolated from long-term contaminated soil. Strain PFS-4 was identified as Pseudomonas stutzeri based on physiological and biochemical characteristics and 16S rRNA sequence analysis. PFS-4 immobilization condition was optimized by orthogonal experiment,and then the effects of differ-ent temperature,initial pH,carbon and nitrogen sources on the degradation of quinclorac by the immobilized bacteria were examined. The performance of free bacteria and immobilized bacteria in actual wastewater were also detected. The results show that the optimal conditions for immobilization were as follows ： alginate concentration 5 %,calcium chloride 4 % ,bac-teria cement ratio 1-2, crosslinking time 5 h. The immobilized bacteria could effectively degrad 9 2 .3% of quinclorac （500 mg ？L 1） after 5 d inoculation at the condition of 30 丈 and pH 7 .0 . The results also revealed that the degradation rate decreased when treating actual wastewater. The degradation rate of free bacteria was significantly inhibited （ P〈0.01） when treating wastewater, on the contrary, immobilized bacteria were less affected and the removal rate remained above 64% . Therefore, wheat-straw adsorption-sodium alginate immobilized bacteria can be applied in quinclorac biodegradation treatment because of its good buffering to adverse circumstances.