BACKGROUND Mass transit environments, such as subways, are uniquely important for transmission of microbes among humans and built environments, and for their ability to spread pathogens and impact large numbers of people. In order to gain a deeper understanding of microbiome dynamics in subways, we must identify variables that affect microbial composition and those microorganisms that are unique to specific habitats. METHODS We performed high-throughput 16S rRNA gene sequencing of air and surface samples from 16 subway stations in Oslo, Norway, across all four seasons. Distinguishing features across seasons and between air and surface were identified using random forest classification analyses, followed by in-depth diversity analyses. RESULTS There were significant differences between the air and surface bacterial communities, and across seasons. Highly abundant groups were generally ubiquitous; however, a large number of taxa with low prevalence and abundance were exclusively present in only one sample matrix or one season. Among the highly abundant families and genera, we found that some were uniquely so in air samples. In surface samples, all highly abundant groups were also well represented in air samples. This is congruent with a pattern observed for the entire dataset, namely that air samples had significantly higher within-sample diversity. We also observed a seasonal pattern: diversity was higher during spring and summer. Temperature had a strong effect on diversity in air but not on surface diversity. Among-sample diversity was also significantly associated with air/surface, season, and temperature. CONCLUSIONS The results presented here provide the first direct comparison of air and surface bacterial microbiomes, and the first assessment of seasonal variation in subways using culture-independent methods. While there were strong similarities between air and surface and across seasons, we found both diversity and the abundances of certain taxa to differ. This constitutes a significant step towards understanding the composition and dynamics of bacterial communities in subways, a highly important environment in our increasingly urbanized and interconnect world. Video abstract.

中文翻译：

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地铁微生物组：季节性动态以及空气和表面细菌群落的直接比较。

背景技术诸如地铁之类的公共交通环境对于微生物在人类和建筑环境之间的传播以及它们传播病原体和影响大量人群的能力而言尤其重要。为了更深入地了解地铁中的微生物组动态，我们必须确定影响微生物组成的变量以及特定栖息地特有的微生物。方法 我们对挪威奥斯陆 16 个地铁站四个季节的空气和表面样本进行了高通量 16S rRNA 基因测序。通过随机森林分类分析，然后进行深入的多样性分析，确定了跨季节以及空气和地表之间的区别特征。结果空气和表面细菌群落之间以及不同季节之间存在显着差异。高度丰富的群体通常无处不在；然而，大量流行率和丰度较低的类群仅存在于一个样本基质或一个季节中。在高度丰富的科和属中，我们发现其中一些在空气样本中是独一无二的。在表面样本中，所有高度丰富的群体在空气样本中也得到了很好的体现。这与整个数据集观察到的模式一致，即空气样本具有明显更高的样本内多样性。我们还观察到季节性模式：春季和夏季多样性较高。温度对空气多样性有很大影响，但对地表多样性没有影响。样本间多样性也与空气/表面、季节和温度显着相关。结论 这里提出的结果首次对空气和表面细菌微生物组进行了直接比较，并首次使用独立于培养的方法评估了地铁的季节性变化。虽然空气和地表之间以及不同季节之间存在很强的相似性，但我们发现某些类群的多样性和丰度有所不同。这是了解地铁中细菌群落的组成和动态的重要一步，地铁是我们日益城市化和互联的世界中非常重要的环境。视频摘要。