基于宏基因组技术分析MBR膜清洗后污泥中抗性基因

污水处理厂作为抗生素抗性基因（antibiotic resistance genes，ARGs）的重要储存库，是自然界ARGs的主要来源之一.膜生物反应器（membrane bioreactor，MBR）被认为是一种能够有效去除污水处理厂中ARGs的技术工艺.MBR膜截留的废水中胶体、颗粒物、悬浮物及微生物代谢物中存在着大量的病原菌与抗性基因，而目前关于膜清洗后污泥中抗性基因的分布特征和规律尚不明确.本文采用宏基因组技术对MBR膜清洗后污泥中抗性基因进行了分析.结果显示，膜清洗后污泥中共检测出39门，其中优势菌门为Proteobacteria、Nitrospirae和Actinobacteria，优势菌属为Nitrospira、Pseudomonas和Bradyrhizobium.污泥样品含有的病原菌属占所有菌属的10.54%，其中Pseudomonas属相对丰度最高，占到所有菌属的3.94%.样品中共注释出17类ARGs和16类金属抗性基因（metal resistance genes，MRGs，15类单金属抗性基因和1类多重金属抗性基因）.其中，多药类抗生素抗性基因相对丰度最高，占49.08%.金属抗性基因中多重金属类抗性基因相对丰度最高，占该污泥样品的34.58%，单金属抗性基因中对铜的抗性基因数量最多，占19.99%.该膜清洗后污泥中微生物群落最主要的功能通路为代谢相关，并存在大量与人类疾病相关的代谢通路相关基因，其中涉及细菌耐药和细菌传染疾病的基因数量最多，分别为占人类疾病相关的代谢通路已注释序列的34.50%和16.62%.由此可见，膜清洗后污泥中蕴藏着丰富的ARGs、MRGs以及病原菌属，具有潜在的环境健康风险，需要加强对膜清洗后污泥中ARGs、MRGs以及病原菌的管控.本文为选择合适的技术工艺有效去除膜清洗后污泥中ARGs、MRGs以及病原菌提供指导.

Metagenomic Analysis of Resistance Genes in Membrane Cleaning Sludge

Wastewater treatment plants (WWTPs) are considered important reservoirs of antibiotic resistance genes (ARGs) and function as the main sources of ARGs in the environment. Membrane bioreactors (MBRs) have been recognized as effective tools for removing ARGs in WWTPs.There are a large number of pathogens and resistance genes in colloids, particulate matter, suspended matter, and microbial metabolites in intercepted wastewater by MBR. However, the distribution characteristics of resistance genes in membrane cleaning sludge remains unclear. In this study, resistance genes of membrane cleaning sludge were analyzed using a metagenomic technique. The results showed that there were 39 phyla in the membrane cleaning sludge. Proteobacteria, Nitrospirae, and Actinobacteria were the dominant phyla. The dominant genera were Nitrospira, Pseudomonas, and Bradyrhizobium. The pathogens accounted for 10.54% of all bacteria in the sample, among which Pseudomonas had the highest abundance, accounting for 3.94%. A total of 17 types of antibiotic resistance genes and 16 types of metal resistance genes (MRGs) (15 types of single metal resistance genes and 1 types of multi-heavy metal resistance gene) were identified. Multidrug resistance genes had the highest abundance, accounting for 49.08%. Multi-heavy metal resistance genes were the most abundant, accounting for 34.58%. The copper resistance genes were the most abundant of the single metal resistance genes, accounting for 19.99%. The most important functional pathway of microbial community in the membrane cleaning sludge was metabolic related, and many genes identified were related to human diseases. The numbers of genes related to bacterial resistance and bacterial infectious diseases were the largest, accounting for 34.50% and 16.62%, respectively. These results indicate that there were abundant ARGs, MRGs, and pathogens in the membrane cleaning sludge, which has potential environmental health risks. It is necessary to strengthen the control of ARGs, MRGs, and pathogens in membrane cleaning sludge to provide guidance for selecting appropriate technologies for effectively removing ARGs, MRGs, and pathogens.