17α-乙炔雌二醇胁迫下零价铁对硝化污泥中抗性基因的影响

Effect of zero valent iron on antibiotic resistance gene in nitrifying sludge under 17α-ethinylestradiol stress

采用硝化污泥序批式反应器去除17α-乙炔雌二醇(EE2),基于宏基因组测序技术考察了零价铁(ZVI)对硝化污泥去除17α-乙炔雌二醇(EE2)过程中抗生素抗性基因(ARGs)的影响,结合菌群结构分析了其潜在影响机制.结果表明,硝化污泥处理EE2过程中ARGs丰度提高了724.42TPM(每百万转录本中来自于某基因的转录本数目),但ZVI削减了此过程中的ARGs丰度增长趋势,EE2及ZVI改变了ARGs亚型的分布,但对ARGs类型及亚型种类无明显影响.EE2使得硝化污泥中属于高风险等级(Q1及Q2)的ARGs丰度增加了555.75TPM及151.08TPM,ZVI降低了硝化污泥中的抗性风险.多重耐药是硝化污泥中丰度占比最大的高风险(Q1和Q2等级)ARGs类型,占比高达49.23%.微生物群落是硝化污泥中ARGs的重要驱动因子,鞘脂单胞菌属(Sphingopyxis)等菌属与多种ARGs显著正相关,可能是多种ARGs的共同潜在宿主.

The prevalence of antibiotic resistance genes(ARGs)has been widely concerned by the worldwide researchers.However,the effect of zero valent iron(ZVI)on ARGs in nitrifying sludge has been rarely studied.A nitrifying sludge sequencing batch reactor was used to remove 17α-ethinylestradiol(EE2).The effect of ZVI on ARGs in the process of EE2 removal by nitrifying sludge was investigated based on metagenome sequencing,and the potential mechanism was analyzed by combining with the structure of bacterial community.The results showed that the abundance of ARGs increased by 724.42TPM(transcripts per million)during the removal of EE2,and ZVI reduced the increasing trend of ARGs abundance.EE2 and ZVI changed the distribution of ARGs subtypes,but had no significant effect on the types and subtypes amount of ARGs.The abundance of ARGs belonging to high-risk ranks(Q1 and Q2)increased by 555.75,151.08TPM in the treatment of EE2,but ZVI reduced the resistance risk.Multidrug was the most abundant high-risk(Q1 and Q2 rank)ARGs in nitrifying sludge,accounting for 49.23%.Microbial community was an important driving factor for ARGs in nitrifying sludge.Some bacteria,such as Sphingopyxis,were significantly associated with multiple ARGs positively,and might be the common potential hosts of multiple ARGs.This study provides a scientific basis and theoretical guidance for ZVI to reduce ARGs and resistance risks in the treatment of emerging pharmaceutical contaminants by biological nitrogen removal process.