纳米金属对污水处理系统中磺胺耐药基因和耐药菌的影响及其机理

Effects and mechanisms of metallic nanoparticles on the fate of sulfanilamide antibiotic resistance genes and resistant bacteria in wastewater treatment system

细菌耐药性和纳米材料污染为新兴环境问题。细菌耐药性遗传载体——耐药基因(ARGs)广泛存在于污水处理系统中,且已被证明与金属纳米材料密切相关。采用实时荧光定量PCR技术,探究了纳米零价铁(nZVI)和纳米氧化锌(nZnO)对污水处理系统中磺胺类耐药菌(ARB)和ARGs的分布特征的影响。结果表明,50 mg·L^(-1)nZVI和nZnO暴露均有利于削减磺胺ARB浓度数。与对照组相比,nZVI和nZnO暴露后污泥中sul1丰度增加了0.25%~16.21%,而sul2出现明显削减(1.51%~15.47%)。此外,50 mg·L^(-1)nZVI会导致游离态胞外ARGs大幅削减。nZVI和nZnO暴露通过富集污水处理系统中的intI^(1)、改变细胞膜通透性和调节细菌转录能力促进sul1的增殖。本研究结果阐明了典型纳米金属对污水处理系统中ARB和不同形态ARGs消长的影响及其机制,可为制定有效调控和全面削减污水处理系统中耐药污染策略提供参考。

Antibiotic resistance and nanomaterials contaminants are important emerging environmental issues worldwide.Antibiotic resistance vectors-antibiotic resistance genes(ARGs) widely exist in wastewater treatment systems and have been proved to be closely related to metal nanoparticles.The influences of nano zero valent iron(nZVI) and nano zinc oxide(nZnO) on the distribution of antibiotic resistant bacteria(ARB) and different forms of ARGs in wastewater treatment system were investigated by quantitative real-time PCR.The results showed that 50 mg·L^(-1) nZVI and nZnO exposure was beneficial to the reduction of ARB concentration.Compared with the control group,the abundance of sull in the sludge after exposure to nZVI and nZnO increased by 0.25%~16.21%,while sul2 decreased significantly(1.51%~15.47%).In addition,50 mg·L^(-1) nZVI led to a significant reduction in free extracellular ARGs.nZVI and nZnO exposure can promote the proliferation of sull by enriching intI1,changing the permeability of cell membrane and regulating the transcription ability of bacteria.The present study was helpful for clarifying the effects and mechanisms of metal nanoparticles on the fate of ARB and different forms of ARGs in the wastewater treatment system,which may lay the foundation for effective regulation and mitigation strategies of antibiotic resistance in the wastewater treatment system.