酚类化合物对污水处理系统中细菌抗性基因的影响机理及应对策略研究

Nowadays, the biosafety of the biological wastewater treatment systems has received growing concerns. Previous studies have shown that the bacterial antibiotic resistance genes (ARG) widely occur in wastewater treatment bioreactors. Even in some bioreactors treating antibiotic-free wastewater, the diversity and abundance of ARGs are also very high. The ARG in the bioreactors could pose potential risks to human beings. However, the affecting factors and mechanisms of the diversity and abundance of ARG in bioreactor still remain largely unknown, and no coping strategies were reported. According to the applicant’s previous preliminary study and the surveys of natural environments conducted by other researchers, there could be significant associations between the ARG and the presence of refractory and toxic organic matters. In this project, phenolic compounds will be used as the target refractory and toxic organic matters, and both advanced molecular technologies and conventional environmental microbiology methods will be jointly applied to investigate the relationships between ARG and refractory organic matter degrading process. On one hand, the relationships between ARG and phenolic compounds will be investigated and the effects of concentration, toxicity and biodegradability of phenolic compounds will be identified to elucidate the influence of phenolic compounds on the ARG in bioreactors. On the other hand, relevant pretreatment methods and bioaugmentation approaches will be explored based on the information obtained in this study to control and reduce the levels of ARG in bioreactors, meanwhile the control and reduction mechanisms will also be revealed. The outcomes of this project are expected to provide theoretical and practical supports for reducing the risks of the biological wastewater treatment processes.

目前污水生物处理的安全性受到越来越多的关注，研究表明，携带抗性基因（ARG）的细菌在污水处理反应器中普遍存在，即使污水中不含抗生素，反应器中仍存在大量的ARG，这对人类健康具有潜在风险。然而，目前对于反应器中ARG的影响机理尚不明确，控制方法及应对策略未见报道。申请人通过前期探索及分析文献中对环境样品的调查结果发现难降解有毒有机物的存在可能与细菌ARG显著相关。本项目拟从酚类物质着手，联合采用前沿分子生物学技术以及传统的环境微生物学方法对反应器中难降解有毒有机物对ARG的影响机理进行深入探索。一方面研究反应器中酚类有机物的存在与ARG之间的关系，明确不同酚类有机物的浓度、毒性及生物可降解性与ARG丰度和多样性之间的关联，阐明酚类有机物对ARG的影响机理；另一方面基于有机物预处理和生物强化技术，探索在酚类物质存在条件下有效控制反应器中ARG的方法和机理，为降低污水处理系统的风险提供科学依据。

携带抗生素抗性基因（ARGs）的细菌在污水生物处理反应器中普遍存在，对人类健康有着潜在的风险。然而，目前对于反应器中ARGs的影响因素及机理尚不明确，控制方法及应对策略鲜有报道。本项目研究了酚类化合物在污水处理反应器中的降解过程与ARGs的丰度及多样性之间的关联及酚类化合物对ARGs传播的影响机理。研究发现对氨基苯酚（PAP）和对硝基苯酚（PNP）可显著增加污水生物处理系统中ARGs的丰度和多样性，这类物质可改变了反应器中的微生物群落结构，从而导致了同时携带ARGs和芳香族化合物降解基因（ADGs）的细菌的增加。全基因组数据分析表明ARGs和ADGs在微生物基因组上存在着普遍的共现性，67.6%携带ADGs 的细菌也同时携带ARGs，携带ADGs的细菌所携带ARGs的数量是仅携带ARGs的细菌的两倍以上。研究过程中我们还构建了ARGs属间和属内水平转移模型，研究了酚类物质对ARGs水平转移的影响。结果表明，PNP、PAP和苯酚都可以显著增加ARGs的属间和属内水平转移频率，通过细菌培养和平板计数实验还发现接合质粒具有较高的稳定性，并且宿主细菌具有较高多样性。供体和受体中ROS的产生，细胞膜通透性增加及相关调控基因的表达是导致ARGs转移的主要因素。此外，本研究还提出了一种使用臭氧来对含酚类物质的废水进行预处理从而有效的控制生物反应器中ARGs丰度的方法，废水经臭氧预处理后芳香度显著下降，可使污水生物反应器中ARGs的相对丰度降低70％以上。