Daylight exposure modulates bacterial communities associated with household dust

Area of Science:

• Microbiology
• Environmental Science
• Building Science

Background:

• Indoor dust harbors diverse microbial communities.
• The impact of light, particularly sunlight transmitted through windows, on these microbial communities is not well understood.
• Understanding light's effect on dust microbes is crucial for built environment health.

Purpose of the Study:

• To investigate the effects of light exposure and specific wavelengths on the structure of the indoor dust microbiome.
• To quantify changes in bacterial community composition, abundance, and viability under different light conditions.

Main Methods:

• Household dust was placed in controlled model rooms with windows transmitting visible, ultraviolet, or no light.
• Bacterial communities were analyzed for taxonomic composition, absolute abundance, and viability.
• Computational models and ecological sampling simulations were used to interpret results.

Main Results:

• Light exposure reduced viable bacteria and altered community structure compared to dark conditions.
• Visible and ultraviolet light showed minor differences, primarily affecting dead human-derived taxa.
• Daylighting led to the loss of dominant microbial groups and apparent increases in rare taxa, possibly due to selective inactivation or limited growth.

Conclusions:

• Indoor dust harbors viable bacteria sensitive to changes in abiotic conditions like light.
• Sunlight filtered through windows possesses bactericidal properties similar to ultraviolet light at relevant dosages.
• These findings have implications for building design and indoor air quality.