基于活体微生物揭示蚯蚓对污泥耐药基因转归的影响

Effects of earthworms on the antibiotic resistance genes of vermicompost from dewatered sludge revealed by active microbes

为削减污泥蚯蚓堆肥产物中耐药基因(ARGs),以无蚯蚓组为对照,采用叠氮溴化丙锭对蚯蚓堆肥样品进行预处理,探究蚯蚓对污泥中活微生物种群及其ARGs的影响.结果显示,与对照组相比,蚯蚓堆肥产物中有机物矿化度与降解量分别显著提升82.5%与5.2%(P<0.05).并且接种蚯蚓使其产物中放线菌门的丰度显著增加了65.6%(P<0.05),而厚壁菌门和拟杆菌门的丰度分别显著降低了74.7%和34.6%(P<0.05).相较于对照组,蚯蚓堆肥致使sul1、sul2、erm F和tet M基因丰度分别显著减少了66.5%、82.8%、72.8%和77.6%(P<0.05),但erm B的丰度显著增加了5.7倍(P<0.05).蚯蚓堆肥产物中int I1基因丰度比对照组显著降低了67.2%(P<0.05),蚯蚓处理后ARGs总绝对丰度为4.19×10^(13)copies/g,ARGs总去除率为82.6%,比对照组高45.4%.研究表明,蚯蚓可通过改变活细菌种群结构,减少ARGs潜在活体宿主的丰度,进而降低其传播扩散的潜在风险.

To eliminate the abundances of ARGs in sludge vermicompost,this study aimed to reveal the underlying effects of earthworms on the active bacterial community structure and their ARGs involved in vermicomposting systems for sludge recycling.For this,vermicomposting with and without earthworms was set up in parallel.Moreover,the dyeing pretreatment for samples with propidium monoazide(PMA)was adopted to screen out the DNA of active bacteria.The results showed that the electrical conductivity of sludge vermicompost was significantly increased by 82.5%(P<0.05),the degradation rate of organic matter was increased by 5.2%(P<0.05).Compared with the control treatment,the abundance of Actinobacteria significantly increased by 65.6%(P<0.05),while the abundance of Firmicutes and Bacteroidetes significantly decreased by 74.7%and 34.6%,respectively.Meanwhile,vermicomposting led to the selected ARGs abundances of tetM,sul1,sul2,ermB and ermF significantly decreased by 66.5%,82.8%,72.8%and 77.6%(P<0.05),while the abundance of ermB significantly increased by 5.7times(P<0.05)in active bacteria,compared to the counterpart.The abundance of intI1gene in vermicompost products significantly reduced by 67.2%compared with the control treatment.The total absolute abundance of ARGs was 4.19×10^(13) copies/g,and the total removal rate of ARGs was 82.6%,45.4%higher than that of the counterpart.This study suggests that earthworms can reduce the abundance of dominant hosts of ARGs by modifying the active microbial community structure of sludge,thus reducing the associated dissemination risks of the spread of ARGs.