Abstract

Background:

Exposure to a diverse environmental microbiome is thought to play an important role in “educating” the immune system and facilitating competitive exclusion of pathogens to maintain human health. Vegetation and soil are key sources of airborne microbiota––the aerobiome. A limited number of studies have attempted to characterize the dynamics of near surface green space aerobiomes, and no studies to date have investigated these dynamics from a vertical perspective. Vertical stratification in the aerobiome could have important implications for public health and for the design, engineering, and management of urban green spaces.

Objectives:

The primary objectives of this study were to: a) assess whether significant vertical stratification in bacterial species richness and evenness (alpha diversity) of the aerobiome occurred in a parkland habitat in Adelaide, South Australia; b) assess whether significant compositional differences (beta diversity) between sampling heights occurred; and c) to preliminarily assess whether there were significant altitudinal differences in potentially pathogenic and beneficial bacterial taxa.

Methods:

We combined an innovative columnar sampling method at soil level, 0.0, 0.5, 1.0, and $2.0\mathrm{m}$, using passive petri dish sampling to collect airborne bacteria. We used a geographic information system (GIS) to select study sites, and we used high-throughput sequencing of the bacterial 16S rRNA gene to assess whether significant vertical stratification of the aerobiome occurred.

Results:

Our results provide evidence of vertical stratification in both alpha and beta (compositional) diversity of airborne bacterial communities, with diversity decreasing roughly with height. We also found significant vertical stratification in potentially pathogenic and beneficial bacterial taxa.

Discussion:

Although additional research is needed, our preliminary findings point to potentially different exposure attributes that may be contingent on human height and activity type. Our results lay the foundations for further research into the vertical characteristics of urban green space aerobiomes and their implications for public health and urban planning. https://doi.org/10.1289/EHP7807

中文翻译：

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城市绿地空气生物群落的垂直分层

 抽象的

 背景：

人们认为，接触多样化的环境微生物组在“教育”免疫系统和促进竞争性排除病原体以维持人类健康方面发挥着重要作用。植被和土壤是空气微生物群（需氧生物组）的关键来源。有限的研究试图描述近地表绿色空间空气生物群落的动态特征，并且迄今为止还没有研究从垂直角度研究这些动态。空气生物群的垂直分层可能对公共卫生以及城市绿地的设计、工程和管理产生重要影响。

 目标：

本研究的主要目标是： a ) 评估南澳大利亚阿德莱德公园栖息地中需氧生物群落的细菌物种丰富度和均匀度（α 多样性）是否存在显着的垂直分层； b ) 评估采样高度之间是否存在显着的成分差异（β多样性）； c ) 初步评估潜在致病菌和有益菌类群是否存在显着的海拔差异。

 方法：

我们在土壤水平上结合了创新的柱状采样方法，0.0、0.5、1.0 和$\mathrm{<span\; data-immersive-translate-walked="e4cbd65e-3797-4e06-bdea-05d4a62319db">2.0</span>}\mathrm{<span\; data-immersive-translate-walked="e4cbd65e-3797-4e06-bdea-05d4a62319db">米</span>}$，使用被动培养皿采样来收集空气传播的细菌。我们使用地理信息系统 (GIS) 选择研究地点，并使用细菌 16S rRNA 基因的高通量测序来评估需氧生物组是否发生显着的垂直分层。

 结果：

我们的结果提供了空气细菌群落的α和β（组成）多样性垂直分层的证据，多样性大致随高度而降低。我们还发现潜在致病和有益细菌类群存在显着的垂直分层。

 讨论：

尽管还需要进行更多研究，但我们的初步研究结果表明，潜在的不同暴露属性可能取决于人类身高和活动类型。我们的研究结果为进一步研究城市绿地空气生物群落的垂直特征及其对公共卫生和城市规划的影响奠定了基础。 https://doi.org/10.1289/EHP7807