宏基因组学揭示蚯蚓对污泥中抗生素抗性基因的影响

Effects of Earthworms on Antibiotic Resistance Genes during Vermicomposting of Dewatered Sludge by Metagenomic Analysis

污泥蚯蚓堆肥是一种极具潜力的污泥资源化技术.对污泥蚯蚓堆肥前后样品进行宏基因组测序,揭示蚯蚓对污泥中抗生素抗性基因(ARGs)、遗传元件及其潜在宿主的影响.总16SrDNA序列经拼接、组装、注释与比对分析后得到有效的ARGs数据.结果显示,蚯蚓污泥堆肥系统中存在139种ARGs,分属30个大类,主要为β-内酰胺类、氨基糖苷类、大环内酯类、四环素类等.与无蚯蚓组相比,蚯蚓堆肥组中ARGs总丰度降低了41.5%.相比而言,蚯蚓堆肥能够有效削减tetX、sul2、sul1、ermF、ermT、tet36、aph6-Id、adeF等优势ARGs的丰度,以及遗传元件质粒和接合子的种类,但对转座子降低效果不明显.同时,蚯蚓堆肥能够增加ARGs变形菌宿主的丰度而降低厚壁菌宿主的丰度.研究表明:微生物种群的转换和遗传元件的减少是蚯蚓堆肥减轻ARGs污染的主要原因.

Vermicomposting is considered as a potential technique for sludge recycling.This study aimed to reveal the effects of earthworms on antibiotic resistance genes (ARGs),mobile genetic elements and their possible hosts in dewatered sludge through sequencing for the metagenomes of sludge samples collected before and after vermicomposting.Reliable data of ARGs were obtained through matching,assembling,annotating and comparing of the total 16S rDNA sequences.The results showed that there were 139 ARGs in vermicomposting system,which belonged to 30 categories,mainly including beta-lactamides,aminoglycosides,macrolides and tetracycline.Compared to the counterpart without earthworms,the total abundance of ARGs in vermicomposting treatments decreased by 41.5%.In contrast,vermicompostingt can effectively reduce the abundance of dominant ARGs,such as tetX,sul2,sul1,ermF,ermT,tet36,aph6-Id and adeF,as well as the types of genetic element plasmids and zygotes,but it has no obvious effect on the reduction of transposon.Meanwhile,vermicomposting can increase the abundance of ARGs proteobacteria host and decrease the abundance of firmicutes host.The results show that the transformation of microbial population and the decrease of genetic elements are the main reasons for vermicomposting to reduce ARGs pollution.