Sunshine can kill some dust-dwelling bacteria

Allowing sunlight in through windows can kill bacteria that live in dust, according to a study published in the open access journal Microbiome.

Researchers at the University of Oregon found that in dark rooms 12% of bacteria on average were alive and able to reproduce (viable). In comparison only 6.8% of bacteria exposed to daylight and 6.1% of bacteria exposed to UV light were viable.

Dust kept in the dark contained organisms closely related to species associated with respiratory diseases, which were largely absent in dust exposed to daylight.

The authors found that a smaller proportion of human skin-derived bacteria and a larger proportion of outdoor air-derived bacteria lived in dust exposed to light that in than in dust not exposed to light. This may suggest that daylight causes the microbiome of indoor dust to more strongly resemble bacterial communities found outdoors.

The researchers made eleven identical climate-controlled miniature rooms that mimicked real buildings and seeded them with dust collected in residential homes. The authors applied one of three glazing treatments to the windows of the rooms, so that they transmitted visible, ultraviolet or no light. After 90 days, the authors collected dust from each environment and analysed the composition, abundance, and viability of the bacteria present.

See:

Ashkaan K. Fahimipour, Erica M. Hartmann, Andrew Siemens, Jeff Kline, David A. Levin, Hannah Wilson, Clarisse M. Betancourt-Román, GZ Brown, Mark Fretz, Dale Northcutt, Kyla N. Siemens, Curtis Huttenhower, Jessica L. Green, Kevin Van Den Wymelenberg. Daylight exposure modulates bacterial communities associated with household dust. Microbiome, 2018; 6 (1) DOI: 10.1186/s40168-018-0559-4

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology