摘要

    过度使用或滥用抗生素作为兽药和生长促进剂会加速抗生素耐药性，对世界公共卫生构成严重威胁。猪粪液作为重要的抗生素抗性基因（ARG）的库受到了广泛的关注，但是关于猪场中与ARGs相关的移动遗传元件（MGEs）的发生，持久性和结局，尤其是它们的变化模式和信息，知之甚少。在大型养猪废水处理系统（PWWTS）中进行清除。在这项研究中，我们搜索了猪场中MGE和相关ARG的存在和分布，并通过实时定量PCR（qPCR）解决了全尺寸PWWTS中它们的命运和季节性变化。我们的结果表明，在猪粪和猪场废水中普遍存在1类整合素，2类整合素和结合质粒。猪粪液中这些MGE水平的清晰模式，即intI1> intI2> traA（p <0.01），冬季的绝对丰度均高于夏季的0.07–2.23原木。值得注意的是，MGEs和ARGs通过PWWTSs的各种处理单元盛行，并且从猪场排放的经处理废水中存在相当数量的水（MGEs高达101–107拷贝/ mL，ARGs高达103–108拷贝/ mL）。在大多数ARG丰度和MGE水平之间存在显着相关性（p <0.05），例如tetQ和traA（r = 0.775），sul1和intI1（r = 0.847），qnrS和inI2（r = 0.859）。 ARGs-水平转移。因此，猪粪和养猪废水中MGEs和ARGs的高流行和富集，也暗示猪粪液可能是ARGs水平转移的热点。

    The overuse or abuse of antibiotics as veterinary medicine and growth promoters accelerates antibiotic resistance, creating a serious threat to public health in the world. Swine liquid manure as an important reservoir of antibiotic resistance genes (ARGs) has received much attention, but little information is known regarding the occurrence, persistence and fate of ARGs-associated mobile genetic elements (MGEs) in swine farms, especially their change patterns and removal in full-scale piggery wastewater treatment systems (PWWTSs). In this study, we searched the presence and distribution of MGEs and associated ARGs in swine farms, and addressed their fate and seasonal variation in full-scale PWWTSs by real-time quantitative PCR (qPCR). Our results revealed class 1 integrons, class 2 integrons and conjugative plasmids were prevalent in pig feces and piggery wastewater. A clear pattern of these MGE levels in swine liquid manure was also observed, i.e., intI1 > intI2 > traA (p < 0.01), and their absolute abundances in winter were all higher than that in summer with 0.07–2.23 logs. Notably, MGEs and ARGs prevailed through various treatment units of PWWTSs, and considerable levels of them were present in the treated effluent discharged from swine farms (up to 101–107 copies/mL for MGEs and 103–108 copies/mL for ARGs). There were significant correlations between most ARG abundance and MGE levels (p < 0.05), such as tetQ and traA (r = 0.775), sul1 and intI1 (r = 0.847), qnrS and inI2 (r = 0.859), suggesting the potential of ARGs—horizontal transfer. Thus the high prevalence and enrichment of MGEs and ARGs occurred in pig feces and piggery wastewater, also implicating that swine liquid manure could be a hotspot for horizontal transfer of ARGs.

    https://www.nature.com/articles/s41598-020-72149-6