Diversity of airborne bacteria in samples collected using different devices for aerosol collection

Bacteria are ubiquitous in the atmosphere, where they form a highly diverse community, albeit low in abundance. Several approaches are available for collecting airborne particles, though few comparative studies have been conducted to date. This study examined how different sampling strategies affect the apparent composition of the airborne community. Three devices were tested: an impactor, a liquid impinger, and a Teflon membrane filter. Comparative studies were conducted at one mountainous location in Norway and one seaside location in Sweden. At both locations, microbial samples were collected in parallel using the sampling devices. DNA extraction, construction of 16S rRNA gene clone libraries, and subsequent sequencing were used to identify the bacteria. The comparison between clone libraries retrieved using the different devices indicated good agreement regarding dominant species, overall diversity, and distribution of species among phylogenetic groups. Among the less common species, there were few shared sequences in different clone libraries, likely due to the high diversity of the assessed samples. Bacteria belonging to the Bacteroidetes and Proteobacteria phyla dominated at both locations, and the most common genera were Sphingomonas sp. and Pantoea sp. Chloroplast-like 16S rRNA gene sequences were detected in all samples.