Insights into the Profile of the Human Expiratory Microbiota and Its Associations with Indoor Microbiotas

Abstract

Microorganisms residing in the human respiratory tract can be exhaled, and they constitute a part of environmental microbiotas. However, the expiratory microbiota community and its associations with environmental microbiotas remain poorly understood. Here, expiratory bacteria and fungi and the corresponding microbiotas from the living environments were characterized by DNA amplicon sequencing of residents’ exhaled breath condensate (EBC) and environmental samples collected from 14 residences in Nanjing, China. The microbiotas of EBC samples, with a substantial heterogeneity, were found to be as diverse as those of skin, floor dust, and airborne microbiotas. Model fitting results demonstrated the role of stochastic processes in the assembly of the expiratory microbiota. Using a fast expectation–maximization algorithm, microbial community analysis revealed that expiratory microbiotas were differentially associated with other types of microbiotas in a type-dependent and residence-specific manner. Importantly, the expiratory bacteria showed a composition similarity with airborne bacteria in the bathroom and kitchen environments with an average of 12.60%, while the expiratory fungi showed a 53.99% composition similarity with the floor dust fungi. These differential patterns indicate different relationships between expiratory microbiotas and the airborne microbiotas and floor dust microbiotas. The results here illustrated for the first time the associations between expiratory microbiotas and indoor microbiotas, showing a potential microbial exchange between the respiratory tract and indoor environment. Thus, improved hygiene and ventilation practices can be implemented to optimize the indoor microbial exposome, especially in indoor bathrooms and kitchens.

Metabolic changes of VOCs in human caused by wearing masks: a preliminary study based on electronic nose

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Perspectives on Sampling and New Generation Sequencing Methods for Low-Biomass Bioaerosols in Atmospheric Environments

“…Table 2 lists some of the recent discoveries in bioaerosols based on the application of amplicon sequencing technologies. For example, aerosol studies incorporating amplicon technologies evidenced that installing good ventilation and air filters in a given building improved the air quality by altering the fungal and bacterial composition of the indoor aerosols 29 , 63 , 64 . Other studies evidenced the transportation of microorganisms in a bioaerosol from one place to another by determining the microbial community structures and compositions by amplicon-NGS analyses 15 , 22 , 65 , 66 .…”

Contribution of Particulates to Airborne Disease Transmission and Severity: A Review

“…Human activity can directly produce bioaerosols consisting of particles such as skin and hair debris, microorganisms (bacterial cells and fungal spores), or other dust (e.g., from clothing and flooring). In both indoor and outdoor environments, the number of humans is positively correlated with the ambient bioaerosol concentration and also influences airborne microbiota. , For instance, in a study examining bioaerosol emissions during different human activities, coarse FBAPs were found to be 5–6 times more prevalent during walking (averaging 0.9 ± 0.3 million particles per person-h) compared to sitting . The type and cleanliness of the floor also significantly affect particle resuspension and deposition .…”