Indoor potted plants have little effect on office dust fungal communities

Reflecting the predominance of time we spend indoors, there is increasing interest in understanding and achieving healthy indoor microbiomes. Introducing more plants into urban environments, e.g., through living architecture, is one possible way to increase indoor microbial diversity. However, more research is needed to establish how and the degree to which indoor plants affect the indoor microbiome, particularly indoor fungal communities. In this study, we explore whether plant and indoor air microbiomes interact with each other. We hypothesized that fungi found in the plants’ soil would be detected in the settled dust samples and that rooms with plants will have more diverse fungal communities. We conducted a longitudinal study of single-occupancy offices with and without plants, (1) quantifying total fungal and bacterial levels in airborne settled dust and (2) comparing the fungal composition. We found that the fungal community composition and total abundance was consistent over time and across the offices that we measured, suggesting a strong building-specific effect. Both relative humidity and dewpoint in the rooms had a statistically significant correlation with the fungal community composition. Plant status had no effect on the alpha or beta diversity, nor the network structure, of the office’s fungal community. A small fraction of the highly abundant soil ASVs were found in the dust samples (0.6 ± 1.5 %), while a larger fraction of the highly abundant dust ASVs were found in the soil samples (27.1 ± 17.4 %), suggesting a small degree of bidirectional exchange between their fungal communities. Future studies with more plants are necessary to evaluate whether this trend persists with more plant material. Overall, our study suggests that typical numbers of office house plants are unlikely to modify indoor air quality by changing the indoor fungal community.