污泥臭氧氧化处理过程中活菌抗药基因丰度的消减

臭氧氧化技术是一种广泛应用的污泥减量技术，然而臭氧处理能否对污泥中的抗生素抗药基因进行有效消减还不清楚。采用单叠氮溴化丙锭（propidium monoazide，PMA）预处理结合定量PCR（qPCR）方法对污泥臭氧减量过程中不同臭氧消耗量下活性污泥活菌中的四环素、氨基糖苷和大环内酯3大类共21种抗药基因的变化进行了研究。结果表明：臭氧氧化可以有效消减活性污泥活菌中21种抗药基因的绝对丰度（每毫升污泥的抗药基因拷贝数），在臭氧消耗量0.31 g·g-1（TSS）情况下抗药基因总量降低了75.44%；尽管绝对丰度下降，污泥臭氧氧化处理过程中大量抗药基因的相对丰度（抗药基因拷贝数与细菌16S rRNA基因拷贝数的比例）逐渐增加，表明臭氧处理后污泥中耐药菌占总活菌比例可能增加，具有一定的抗性传播风险；Ⅰ型整合子是抗药基因水平转移的重要遗传元件，其绝对丰度同样随着臭氧消耗量增加而降低，而相对丰度逐渐上升。

Reduction of antibiotic resistance genes in viable bacterial communities of sludge during ozonation treatment

Ozonation is a widely used in sludge reduction. However, it is not clear whether ozone can effectively reduce antibiotic resistance genes in sludge. In this paper, we used the propidium monoazide (PMA) modified quantitative polymerase chain reaction (qPCR) method to study the changes of 21 antibiotic resistance genes in activated sludge during ozonation treatment. The results showed that ozone oxidation could effectively reduce the absolute abundances (resistance genes' copies in 1 mL sludge) of 21 antibiotic resistant genes in activated sludge, and their total amount decreased by 75.44% under the ozone consumption of 0.31 g·g-1(TSS). Despite the decline in absolute abundance, relative abundances (resistance gene' copies/16S rRNA gene's copies) of most resistance genes in sludge increased during sludge ozonation, indicating that the proportion of antibiotic resistant bacteria in the sludge might increased.The absolute abundance of class I integron, an important genetic element for the horizontal transfer of resistance genes, also decreased with the increase of ozone consumption, while its relative abundance increased.