不同预处理方式对剩余污泥中活菌菌群及ARGs的影响

Impact of different pretreatments on ARGs and live microbial communities in excess sludge

剩余污泥作为抗生素抗性基因(ARGs)的储库,对其进行预处理有助于后续厌氧消化(AD),同时控制ARGs进入AD后的传播风险.本文采用叠氮碘化丙锭(PMA)处理手段,来研究不同预处理方式对活菌菌群及携带ARGs的影响.研究结果显示,热碱、热水解和微波预处理对污泥ARGs去除效果较优,分别为3.32log、3.13log和2.95log;超声波预处理对活菌ARGs仅去除0.58log.在热水解预处理时间延长过程中,菌群大量死亡出现在1~2h间,4h后去除率达2.42log.变形菌门是污泥中最主要的优势菌门,厚壁菌门、绿弯菌门在微波、热水解预处理后实现较大提升.相关性结果显示,sulI与tetC高度相似,且同时与多个科属的微生物成显著正相关,推测其宿主范围较广,且sulI与tetC在预处理中较好的去除率说明其宿主菌对预处理耐受性差;erm B、tetA与占比较高的菌群没有正相关.多数ARGs携带菌对热水解、热碱和微波不耐受,污泥预处理能够降低ARGs丰度,适当延长低温热水解预处理时间,才能有效削减污泥中的ARGs.

Pretreatment can not only facilitate the subsequent anaerobic digestion(AD)of excess sludge,but also may decrease the abundance of antibiotic resistance genes(ARGs)and reduce the risk of ARGs spreading during AD.In this study,the impact of different pretreatments on ARGs and live microbial communities in excess sludge was investigated based on propidium monoazide(PMA)treatment.The results showed that the removal of ARGs by thermo-alkaline,thermal hydrolysis,and microwave pretreatments were 3.32logs,3.13logs,and 2.95logs,respectviely.The ultrasonic wave pretreatment only removed 0.58logs of the ARGs.With the time extension of thermal hydrolysis,the microorganisms was dramatically removed during 1~2hours.The removal of ARGs was 2.42 logs with thermal hydrolysis extended to 4 hours.Proteobacteria was the dominant bacteria in the raw excess sludge.With the pretreatment of microwave and thermal hydrolysis,Firmicutes and Chloroflexi was greatly improved.The correlation analysis showed that sulI and tetC was very similar that significant positive correlated with several families of microorganisms,which indicated various kinds of the potential host bacteria.However,the good removal of sulI and tetC during pretreatment indicated the poor tolerance of their hosts to the pretreatments.No significant positive correlation was found between ermB and microbial communities,and only few families correlated with tetA.Most ARGs carrying bacteria have little resistance with thermo-alkaline,thermal hydrolysis,and microwave pretreatments,and it is necessary to extend the pretreatment time of thermal hydrolysis appropriately to effectively reduce the ARGs in sludge.