城市河道沉积物中残留医用抗生素对反硝化潜势的抑制作用及机制

研究了南明河贵阳城区段中沉积物的5种残留医用抗生素对沉积物反硝化潜势的影响,并采用荧光定量PCR及高通量测序方法检测了5种反硝化过程中的关键功能基因丰度以及编码nirS基因的细菌群落结构,探讨了抗生素残留影响反硝化潜势的微生物学机制.结果表明,南明河沉积物中5种目标抗生素中,诺氟沙星(norfloxacin,NFX)的浓度最高((537.13±212.69) ng·g~(-1)),并且对沉积物中反硝化潜势有显著抑制效果(p0.05).进一步分析表明,NFX对反硝化潜势的抑制作用主要是通过抑制编码nirS细菌主导的亚硝酸盐还原阶段而实现的.本研究揭示了城市河道沉积物中的残留抗生素可能会削弱河道的反硝化脱氮能力从而加重河流氮污染状况,为评估抗生素污染的微生态效应提供了依据.

The inhibition effects of residual antibiotics on denitrification in the urban river sediments

This study investigated the effects of five typical antibiotics on denitrification rates in the sediments of Nanming River in Guiyang city. Through the quantitative Real-time PCR and high-throughput sequencing technologies, abundances of five key denitrifying genes and nirS encoding bacterial communities were also characterized to explore the antibiotics effects on denitrification. Among the five targeting antibiotics, the average concentration of the norfloxacin (NFX) is the highest (537.13±212.69) ng·g^-1, and it significantly inhibited denitrification rates in the sediments. The NFX was able to strongly inactivated nirS carrying bacteria which dominated the nitrite reduction process, leading to the decrease of denitrification rates. In general, this study sheds light on the impacts of residual antibiotics on denitrification that may deteriorate the nitrogen pollution in urban rivers. These findings lay a foundation for further research concerning micro-ecological risks of antibiotics pollution.