摘要

       抗生素耐药基因（ARGs）已成为全球关注的健康问题。大量的研究工作已经投入到水生生态系统中的ARGs。然而，尽管ARGs在空气中传播的作用更大，但其在空气中的传播模式仍不清楚。本研究旨在探讨高污染空气中ARGs及其相应亚型细菌载体在空气中的时间分辨传播。在北京市低（14-93μg/m3）和高PM2.5（36-205μg/m3）污染时间（6天以上，共69个空气样本）期间，使用大容量采样器（1 m3/min）每4 h连续（白天和夜间）采集时间分辨空气样本（各20 m3，共3个样本）。对39个ARGs亚型进行16srRNA序列分析。对北京和石家庄两地的可培养纯菌株进行了Sanger序列分析，并进行了高通量ARG亚型检测。空气中ARGs及其亚型的相对丰度昼夜差异较大（丰度高达3倍），而blaTEM基因是导致ARGs丰度的主要原因。在一个清晨，在高污染的空气中，多重耐药NDM-1基因被检测到高达总ARG丰度的30%。作为NDM-1和vanB基因的主要载体，耐盐芽孢杆菌也能传播更多的ARG亚型。在另一方面，tnpA和intI1在空气中的可培养芽孢杆菌中的含量差异很大，而sul3基因在空气中的可培养芽孢杆菌中广泛存在。主成分分析（PCA）显示不同PM2.5污染事件的基因共现网络不同，如tnpA和intI1基因转移和整合，发现高PM2.5污染事件的基因共现网络更为丰富。这项研究强调了时间分辨的ARGs在空气中传播对公共健康的严重威胁。在高PM2.5污染事件期间，迫切需要开展进一步的工作来追踪ARGs的来源，以便对其进行优化控制。

        Antibiotic resistance genes (ARGs) have emerged as a global health concern. A large volume of work has already been devoted to ARGs in aquatic ecosystems. However, ARG dispersal patterns in air remain to be largely unknown despite of its greater role in transmission. This work aims to investigate time-resolved airborne spread of ARGs and their corresponding subtype bacterial carriers in highly polluted air. Time-resolved air samples (20 m³ each with three samples) were collected using a high volume sampler (1 m³/min) every 4 h continuously (both day and night) during low (14-93 μg/m³) and high PM_2.5 (36-205 μg/m³) pollution times (over 6 days with a total of 69 air samples) in Beijing. All air samples were subjected to 16S rRNA sequence analysis for 39 ARG subtypes. Pure culturable bacterial isolates from Beijing and Shijiazhuang were Sanger sequenced for species identification and also subjected to high throughput ARG subtype detection. ARG and its subtype relative abundances in the air were observed to differ greatly (up to 3 folds for abundance) both day and night, and the blaTEM gene was found to lead the ARG abundance. For an early morning time, the multi-drug resistant NDM-1 gene was detected up to 30% of total ARG abundance in highly polluted air. Identified as a major NDM-1 and vanB gene carrier, Bacillus halotolerans were also shown to disseminate more ARG subtypes. On another front, tnpA and intI1 were shown to vary greatly in abundance, while the sul3 gene was found widespread among the culturable Bacillus isolates in the air. Principal component analysis (PCA) showed different gene co-occurrence networks for different PM_2.5 pollution episodes, e.g., tnpA and intI1 for gene transfer and integration, respectively, were found more abundant for the high PM_2.5 pollution episode. This study highlights a serious yet previously unidentified public health threat from time-resolved airborne spread of ARGs. Further work is urgently warranted to track the sources of ARGs for their optimized control during high PM_2.5 pollution episodes.

        https://www.sciencedirect.com/science/article/pii/S0160412019302089?via%3Dihub