抗生素对耐药型反硝化菌反硝化过程及微生物群落结构的影响

Influence of Antibiotics on the Denitrification Process of Antibiotic Resistant Denitrifying Bacteria and the Analysis of Microbial Community Structure

城市污水中部分抗生素通过常规工艺处理的去除率较低,导致自然水环境中微生物耐药性增强.为降低抗生素对城镇受纳水体的生态危害,提出了利用耐药型反硝化菌的共代谢作用降解微量抗生素的风险控制技术.采用乙酸钠为电子供体,并保持氧氟沙星(OFLX)浓度为1μg·L^-1,逐步提高抗生素降解菌的优势生长,分别培养获得仅有乙酸钠和氮元素存在条件下的反硝化菌群(DnB1)、微量抗生素与乙酸钠、氮元素同时存在条件的反硝化菌群(DnB2).考察了抗生素通过反硝化共代谢的降解效果,抗生素对耐药型反硝化菌脱氮过程的影响,以及微生物群落结构的变化情况.结果表明DnB2相比于DnB1,对OFLX具有明显降解作用, DnB1和DnB2对OFLX的降解量分别为0.31μg·g^-1和16.14μg·g^-1.OFLX浓度的提高,会在短期内抑制DnB1反硝化活性.DnB2反硝化过程受OFLX影响较小.同时,使用Illumina MiSeq平台进行高通量测序,基于测序结果聚类形成的OTUs信息,对比分析各样品的多样性,结果表明,DnB1的微生物群落相对丰度和微生物群落多样性均要高于DnB2.

The removal rate of some antibiotics in urban sewage by conventional treatment is low, which leads to an increase in antibiotic resistant bacteria in natural water environments. To reduce the ecological harm of antibiotics to the water in towns, a risk control technique for degradation of microantibiotics by the co-metabolism of antibiotic resistant denitrifying bacteria was proposed. Using sodium acetate as an electron donor and maintaining the concentration of ofloxacin(OFLX) at 1 μg·g^-1, gradually increasing the dominant growth of antibiotic degradation bacteria, denitrifying bacteria(DnB1), trace antibiotics and sodium acetate, and denitrifying bacteria(DnB2) with the presence of sodium acetate and nitrogen elements were cultured. The degradation effect of antibiotics through denitrification and the effects of antibiotics on denitrification of resistant denitrifying bacteria and the changes to the microbial community were investigated. The results showed that DnB2 had a significant degradation effect on OFLX compared to DnB1. The degradation to OFLX by DnB1 and DnB2 was 0.31 μg·g^-1 and 16.14 μg·g^-1, respectively. Increased OFLX concentration inhibited DnB1 denitrification activity in the short term. The denitrification process of DnB2 was less affected by OFLX. At the same time, high-throughput sequencing using the Illumina MiSeq platform was used. Based on the operational taxonomic unit information formed by the clustering of sequencing results, the diversity of each sample was compared and analyzed. The research results show that the relative abundance and diversity of the microbial community of DnB1 are higher than those of DnB2.