The dust in our homes contains more than 5,000 different species of bacteria and around 2,000 species of fungi, according to a team of scientists who investigated microbial communities found in the dust collected from inside and outside approximately 1,200 homes in the continental U.S.
This false-color image shows household dust under a microscope. Image credit: NIAID.
The findings, published today in the journal Proceedings of the Royal Society B, highlight the degree to which these microorganisms can tell a story about the homes they inhabit.
“Every day, we are surrounded by a vast array of organisms in our homes, most of which we can’t see,” said study senior author Dr Noah Fiere of the University of Colorado, Boulder.
“We live in a microbial zoo, and this study was an attempt to catalog that diversity.”
Dr Fiere and co-authors examined roughly 1,200 homes across the continental U.S., homes that represent a broad range of home designs and span many climatic zones.
With help of volunteers and citizen scientists, they collected indoor and outdoor dust samples at each site.
According to the team, on average, each home contains more than 5,000 different species of bacteria and around 2,000 species of fungi.
Fungal communities tend to be more predictive of a home’s location while bacterial communities provide clues about the identity of its residents.
“Geography is the best predictor of fungi in your home. The reason is that most fungi blow in from outdoors via soil and leaves,” Dr Fiere said.
“A home in the upper Midwest, for instance, will harbor distinct fungi compared to a home in the Southeast,” he explained.
When it comes to bacteria, however, where you live may be less important than whom you live with.
From the dust samples, scientists could confidently predict which homes had pets such as cats or dogs and, to a slightly lesser extent, the gender ratio of the residents.
Homes with only male occupants, for example, will have a different bacterial makeup than those with both male and female occupants.
“One of the key takeaways is that if you want to change what you breathe inside your house, you would either have to move very far away or change the people and the pets you live with,” said study lead author Albert Barbaran, also from the University of Colorado, Boulder.
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Albert Barberan et al. 2015. The ecology of microscopic life in household dust. Proceedings of the Royal Society B, vol. 282, no. 1814; doi: 10.1098/rspb.2015.1139
