低浓度环丙沙星对曝气生物滤池生物膜硝化过程及硝化微生物的作用影响

Effect of Low-concentration Ciprofloxacin on the Nitrification and Nitrifying Microorganisms of Biofilms in Biological Aerated Filter

以曝气生物滤池(BAF)作为研究对象,考察了低浓度环丙沙星(CIP)对其生物膜微生物硝化过程及其功能微生物的作用影响,采用荧光定量PCR方法定量检测分析了4种环丙沙星抗性基因(CIP-ARGs)在硝化作用过程中的丰度变化,并探讨了其与硝化微生物之间的相关关系.结果表明,CIP对生物膜氨氧化阶段影响较小,但对亚硝酸盐氧化阶段具有一定抑制作用.通过对氨氧化细菌(AOB)和亚硝酸盐氧化细菌(NOB,包括Nitrobacter和Nitrospira)的定量检测结果分析可知,CIP对生物膜亚硝酸盐氧化转化过程的抑制主要是通过对Nitrobacter和Nitrospira的抑制实现的.此外,CIP的加入对生物膜中aac和qepA抗性基因的变化影响较小,但对parC和oqxB的影响较大.通过相关性分析可知,Nitrobacter与parC之间具有显著相关性,Nitrospira与oqxB之间同样具有显著相关性,推测生物膜中不同硝化微生物的遗传因子中可能携带有CIP-ARGs.

Effect of low-concentration ciprofloxacin（ CIP） on nitrification and nitrifying microorganisms of biofilms was studied in biological aerated filters（ BAF）. Quantitative PCR（ q PCR） was used to determine the abundance variance of four ciprofloxacin resistance genes（ CIP-ARGs） during nitrification in biofilms. The correlations between the abundances of CIP-ARGs and nitrifying microorganisms were also discussed. The results showed that CIP had little influence on the ammonium oxidation process of biofilm microorganisms,whereas inhibition of the nitrite oxidation process was found. The quantitative results of ammonium-oxidizing bacteria（ AOB） and nitrite-oxidizing bacteria（ NOB） including Nitrobacter and Nitrospira indicated that the inhibition on the transformation of nitrite was resulted from the inhibition on Nitrobacter and Nitrospira. In addition,little influence of CIP on the relative abundance of aac and qepA in biofilms was found,but the influence on par C and oqxB was great. The abundance of Nitrobacter exhibited significant positive correlation with the abundance of par C. Similar significant correlation was also found between the abundances of Nitrospira and oqxB. It could be speculated that the genetic elements of different nitrifying microorganisms in biofilms possibly carried CIP-ARGs.