Dispersal of airborne microorganisms is an important ecological process, resulting in the distribution of bacteria to all habitats on Earth. Investigation of this process is limited by the ability to collect uncontaminated high-altitude microbial samples for use with next-generation sequencing approaches. Here, we describe the design of a Remote Airborne Microbial Passive sampling system. Troubleshooting experiments demonstrate that the samplers collect adequate DNA for bacterial 16S rRNA (ribosomal RNA) amplicon-based Mi-Seq sequencing at 2 and 150 m from the ground. When samplers are closed, they retain only a low number of sequences, and may be used as a negative control. We also demonstrate that the optimal amount of collection dishes to include in the sampler is 8, and that freezing collection dishes at −80°C is an alternative to immediate DNA extraction. Samplers may be used to address a variety of ecological and human health-related questions.

Land use influences the composition of near-surface airborne bacterial communities, and bacteria can be transported through the atmosphere at global scales. The atmosphere mixes vertically, but rigorously assessing whether the effects of land use on atmospheric communities extends to higher altitudes requires examining communities from multiple altitudes collected at a stable location and timeframe. In this study, we collected near-surface (<2 m) and higher-altitude (150 m) air samples from three sites in an agricultural/developed location and a forested/undeveloped location. We used bacterial 16S rRNA amplicon sequencing to compare communities and predict functionality by altitude. Higher-altitude and near-surface communities did not differ in composition within each location. Communities collected above the undeveloped location were equally variable at both altitudes; higher-altitude samples from the developed location predominantly contained Firmicutes and were less variable than near-surface samples. We also compared airborne taxa to those present in soil and snow. Communities from higher-altitude samples above the developed location contained fewer overlapping taxa with soil and snow sources, and overlapping Operational Taxonomic Units (OTUs) among the three sources differed by location. Our results suggest that land use affects the composition of both near-surface and higher-altitude airborne bacterial communities and, therefore, may influence broad bacterial dispersal patterns. This small-scale pilot study provides a framework for simultaneously examining local and regional airborne microbial communities that can be applied to larger studies or studies using different types of samplers.

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