The microbial ecotone of the built environment and the interplay of microbial sources of indoor air bacteria in single-family homes in Oregon.
Suzanne L. Ishaq1,*, Roo Vandegrift1, Jeff Kline1, Ashkaan Fahimipour1, Jason Stenson1, Gulcan Cil2, Ryann Crowley2, Hannah Wilson1, Dale Northcutt1, Erica Hartmann3, Deb Johnson-Shelton2, G.Z. Brown1, Jessica Green1, Kevin Van Den Wymelenberg1
1 Institute for Health in the Built Environment, University of Oregon, Eugene, OR, USA
2 Oregon Research Institute, Eugene, OR, USA
3 Northwestern University, Chicago, IL, USA
*Corresponding email: firstname.lastname@example.org
Category: Managing Microbial Communities
Keywords: indoor microbiome; weatherization; occupancy; building operation; built environment; health
Two major drivers of microbial diversity in the built environment are the outdoor environment and occupants, including humans, pets, and plants. The strength and relative contributions of these microbial sources determines whether the indoor microbiome is more human- or outdoor-associated. Whether indoor bacterial diversity or numerical patterns have health impacts for humans remains unclear.
Week-long indoor and outdoor settled dust, and home survey data, were collected from 66 single-family homes in Portland, Oregon, US, before and after a home-specific weatherization treatment, whereby homes were sealed from the outside to improve energy efficiency. We determined treatment effects on indoor bacterial communities using Illumina amplicon sequencing of the V3-V4 regions of the 16S rRNA gene. Paired-end sequences were processed using the DADA2 statistical inference algorithm, with the Silva ver. 128 taxonomy database, and analyzed in the statistical programming environment, R.
Weatherization had minor effects on the bacterial community. Shannon diversity was elevated in older homes, and those with pets, living plants, indoor compost, and increased use of windows. Pets were associated with increasingly heterogeneous indoor bacterial communities, while homes containing houseplants or compost were more similar to each other than expected by chance. Taxonomic community dissimilarity between indoor and outdoor air, (i.e. unweighted Jaccard distances), decreased when plants or compost were present indoors, with increasing window use, and in homes with more south-facing windows or doors in the sampling room. In contrast, pets and occupant densities had little effect, possibly reflecting uneven occupancy patterns.