Influence of housing characteristics on bacterial and fungal communities in homes of asthmatic children

Abstract

Variations in home characteristics, such as moisture and occupancy, affect indoor microbial ecology as well as human exposure to microorganisms. Our objective was to determine how indoor bacterial and fungal community structure and diversity are associated with the broader home environment and its occupants. Next-generation DNA sequencing was used to describe fungal and bacterial communities in house dust sampled from 198 homes of asthmatic children in southern New England. Housing characteristics included number of people/children, level of urbanization, single/multifamily home, reported mold, reported water leaks, air conditioning (AC) use, and presence of pets. Both fungal and bacterial community structures were non-random and demonstrated species segregation (C-score, P < 0.00001). Increased microbial richness was associated with the presence of pets, water leaks, longer AC use, suburban (vs. urban) homes, and dust composition measures (P < 0.05). The most significant differences in community composition were observed for AC use and occupancy (people, children, and pets) characteristics. Occupant density measures were associated with beneficial bacterial taxa, including Lactobacillus johnsonii as measured by qPCR. A more complete knowledge of indoor microbial communities is useful for linking housing characteristics to human health outcomes. Microbial assemblies in house dust result, in part, from the building's physical and occupant characteristics.

Keywords: Asthma; Bacteria; Beneficial microbes; Fungi; Indoor microbiome; Next generation DNA sequencing.

Figure 1

A,B,C,D. Rarefaction curves for (A) fungi and (B) bacteria, (C) a comparison of fungal and bacterial richness, and (D) dust composition analysis for total concentration of bacteria, fungi, human, and dog (Canis lupus familiaris) cells. (A,B) Lines are randomly displayed in various shades of gray for improved visualization. (A,B,C) Fungi were normalized to 450 sequences per sample and bacteria were normalized to 2500 sequences per sample prior to analysis. (C) R = 0.30, p = 0.0002.

Figure 2

A–O. Morisita Horn distance comparison for fungi for occupancy, housing characteristics, and dust composition measures. The p-values on bar graphs compare the within group average (represented by the bar) to the between group average (represented by the solid line). Error bars and dotted lines represent standard error. Bars significantly below the solid line indicate low variation in community composition (more similar communities).

Figure 3

A–O. Unweighted Unifrac distance comparison for bacteria for occupancy, housing characteristics, and dust composition measures. The p-values on bar graphs compare the within group average (represented by the bar) to the between group average (represented by the solid line). Error bars and dotted lines represent standard error. Bars significantly below the solid line indicate low variation in community composition (more similar communities).