摘要

抗生素抗性基因（ARG）已成为全球健康关注的焦点。已经为水生生态系统中的ARG投入了大量工作。然而，尽管ARG在传播中起着更大的作用，但它在空气中的散布方式仍是未知之数。这项工作旨在调查ARGs及其对应的亚型细菌携带者在高污染空气中的时间分辨空中传播。时间分辨的空气样品（每份20µm3，每份三个样品）使用高容量采样器（1µm3 / min）在低（14–93µg / m3）和高PM2浓度下连续（白天和晚上）每4µh收集一次。在北京，污染时间为5（36–205μg/ m3）（6天之内，总共有69个空气样本）。对所有空气样品进行39种ARG亚型的16S rRNA序列分析。对北京和石家庄的纯可培养细菌分离株进行Sanger测序以进行物种鉴定，并进行高通量ARG亚型检测。白天和晚上，空中ARG及其亚型的相对丰度差异很大（丰度高达3倍），并且发现blaTEM基因导致了ARG丰度。在一个清晨的时间里，在高度污染的空气中检测到多药耐药性NDM-1基因高达总ARG丰度的30％。被鉴定为主要的NDM-1和vanB基因载体的卤代芽孢杆菌也显示出传播更多的ARG亚型。在另一方面，tnpA和intI1的丰度差异很大，而sul3基因则在空气中可培养的芽孢杆菌中广泛分布。主成分分析（PCA）显示了针对不同PM2.5污染事件的不同基因共现网络，例如用于基因转移和整合的tnpA和intI1在高PM2.5污染事件中分别更为丰富。这项研究强调了时间分辨的ARGs的空中传播对人类健康的严重威胁，但此前尚未确定。迫切需要做进一步的工作来追踪ARGs的来源，以便在高PM2.5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