Wednesday, August 14, 2019: 2:50 PM
L005/009, Kentucky International Convention Center
Kathryn Docherty1, Kenneth Domingue2, Rebecca L. Hale3, Thomas Kerber2, Kristina Lemmer2, Margaret Mooney2 and Allison Spring1, (1)Biological Sciences, Western Michigan University, Kalamazoo, MI, (2)Mechanical and Aerospace Engineering, Western Michigan University, Kalamazoo, MI, (3)Biological Sciences, Idaho State University, Pocatello, ID
Background/Question/Methods: Airborne transport of microbial communities is a key component of the global ecosystem because it serves as a mechanism for dispersing microbial life between all surface habitats on the planet. Our current understanding of airborne microbial distribution is derived from samples collected near the ground, yet little is understood about how urban expansion may change the types of microbes that enter the atmosphere in the greatest abundance. We hypothesized that airborne bacterial communities would be more homogenous above urban sites, and that this effect would extend to higher altitudes. To test this hypothesis, we sampled at minimally disturbed natural sites and paired urban sites in four different North American ecosystems in the spring. Additionally, we compared these communities to those collected in winter. To collect higher-altitude airborne samples, we constructed a remote-controlled airborne sampling platform and attached them to tethered helikites at three replicate sites within each natural or urban location. We collected samples from 150 m, 30 m and 2 m above the ground, as well as from soil transects and plant surfaces at each site. We extracted DNA and examined airborne, soil and plant-associated bacterial communities using 16S rRNA amplicon-based Illumina Mi-Seq sequencing. Communities were visualized using principal coordinates analysis and community differences were analyzed using permutational analysis of variance.
Results/Conclusions: Bacterial communities collected in the air within each ecosystem (desert, short-grass steppe, coniferous forest, deciduous forest) harbored taxa that were distinctive to each ecosystem. However, our results demonstrate that urbanization homogenizes soil, plant and overlying airborne bacterial communities, regardless of the ecosystem-type where samples are collected. This effect extends into airborne samples collected higher in the atmosphere, suggesting that urbanization can have broad-reaching effects on bacterial distribution patterns. The season when samples were also influenced community composition, with more taxa associated with anthropogenic activities present in the air during the winter time point. Overall these results support the urban homogenization hypothesis and add a new, vertical, dimension.
