固定床吸附磺胺嘧啶过程中微生物抗性及群落变化

Microbial resistance and community changes during the adsorption of sulfadiazine through fixed bed

以磷酸改性咖啡渣生物炭(PABC-700)为吸附剂填充固定床,系统分析进水流速、吸附剂填充高度以及初始浓度对PABC-700固定床动态吸附磺胺嘧啶(SDZ)规律的影响,进而对受SDZ长期选择压力下固定床内微生物抗性及群落变化进行了评估.结果表明,PABC-700固定床对水中SDZ的动态吸附行为符合Yoon-Nelson和Adams-Bohart模型.利用qPCR技术分析了sul1和sul2两种抗性基因的丰度变化,结果表明,固定床长期运行会导致出水中磺胺类抗生素抗性基因的增殖,且随着体系中SDZ浓度的升高,生物炭上sul1及sul2的丰度也呈现出升高趋势,暴露于1.0mg/L磺胺嘧啶组的sul1及sul2表达量可达对照组的1.97及1.53倍.利用Miseq PE300测序对固定床反应器长期运行条件下进出水及生物炭表面的微生物群落结构分析,结果表明,固定床上微生物群落多样性较对照组发生显著衰减,出水与固定床上的细菌群落结构具有显著相关性,且滤后出水中条件致病菌分枝杆菌属的增殖需要引起重视.

The fixed bed was filled with phosphoric acid modified coffee residue biochar(PABC-700)for the dynamic adsorption of sulfadiazine(SDZ)in water.The effects of influent flow rate,adsorbent filling height and initial concentration on the adsorption properties of sulfadiazine were systematically analyzed,and the microbial resistance and community change in the fixed bed under the long-term selective pressure of SDZ were then evaluated.The results showed that the dynamic adsorption behavior of PABC-700fixed bed for SDZ in water conformed to Yoon-Nelson and Adams-Bohart models.The resistance gene abundance changes of sul1 and sul2 according to the results obtained from qPCR showed that the long-term operation of the fixed bed would lead to the proliferation of sulfonamides resistance genes in the effluent.With the increase of SDZ concentration in the system,the abundance of sul1 and sul2 on biochar also showed an increasing trend.The expression of sul1 and sul2 in the group exposed to 1.0mg/L sulfadiazine was 1.97 and 1.53times that of the control group.The microbial community structure on the surface of biochar,as well as the inlet and outlet of the water after the long-term operation were analyzed using Miseq PE300sequencing technology.The results showed that the microbial community diversity on the fixed bed was significantly attenuated compared with the control group,and there was a significant correlation between the purified effluent and the bacterial community structure on the fixed bed biochar.More attention should be paid to the proliferation of conditional pathogenic bacteria Mycobacterium in filtered effluent.