摘要

       抗生素抗性基因 (ARG) 已成为全球关注的健康问题。大量工作已经致力于水生生态系统中的 ARG。然而，尽管 ARG 在传播中的作用更大，但空气中的 ARG 传播模式在很大程度上仍然未知。这项工作旨在研究 ARGs 及其相应亚型细菌载体在高污染空气中的时间分辨空气传播。在低 (14–93μg/m3) 和高 PM2.5 期间，每 4 小时连续（白天和黑夜）使用大容量采样器（1 立方米/分钟）收集时间分辨空气样本（每个 20 立方米，每份 3 个样品）。北京 5 (36–205μg/m3) 污染时间（超过 6 天，共 69 个空气样本）。所有空气样本都进行了 39 个 ARG 亚型的 16S rRNA 序列分析。来自北京和石家庄的纯可培养细菌分离物进行桑格测序以进行物种鉴定，并进行高通量 ARG 亚型检测。观察到空气中 ARG 及其亚型相对丰度在白天和晚上都有很大差异（丰度高达 3 倍），并且发现 blaTEM 基因导致 ARG 丰度。在清晨时间，在高度污染的空气中检测到高达 30% 的 ARG 总丰度的耐多药 NDM-1 基因。作为主要的 NDM-1 和 vanB 基因载体，耐盐芽孢杆菌也被证明传播更多的 ARG 亚型。另一方面，tnpA 和 intI1 的丰度差异很大，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 污染事件的不同基因共现网络，例如，分别用于基因转移和整合的 tnpA 和 intI1，在高 PM2.5 污染事件中更为丰富。这项研究突出了 ARG 的时间分辨空气传播所带来的严重但以前未确定的公共卫生威胁。迫切需要进一步的工作来追踪 ARGs 的来源，以便在 PM2.5 高污染事件期间对其进行优化控制。

       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 PM2.5 (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 PM2.5 pollution episodes, e.g., tnpA and intI1 for gene transfer and integration, respectively, were found more abundant for the high PM2.5 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 PM2.5 pollution episodes.

https://www.sciencedirect.com/science/article/pii/S0160412019302089