Every city in the world has its own distinct community of microbes, and these communities do not differ much from how offices are located in the same city, a new study revealed.
Scientists recognize that buildings and rooms are crawling with microbes – tiny living organisms that include bacteria, archaebacteria, protists and some fungi – and that these invisible roommates may affect human health.
Led by microbiologist Gregory Caporaso, researchers from Northern Arizona University investigated what drives the composition of microbes inside nine various offices across three different cities.
Caporaso and his colleagues collected microbial samples in San Diego, California; Toronto, Canada and Flagstaff, Arizona, which are all chosen for their diverse climates.
The team covered microbial sampling plates with swatches of drywall, carpet and ceiling tile, as well as sensors that could help them monitor factors of the environment such as equilibrium relative humidity on surfaces, occupancy, available light and temperature.
They then installed the collection plates on walls, floors, and office ceilings. This went on for more than a year.
With the help of a special gene sequencing technique, researchers found that each of the three cities has its own unique, specific microbial signature. What's more, collection plates from offices in the same city were more similar to one another than the ones in other cities.
Caporaso said this was interesting because the cities were different in usage patterns, ventilation and size. He said their findings suggest that geography is more crucial than any of the factors measured in the study when it comes to driving the composition of bacterial communities.
The microbial communities in Flagstaff were richer than those in Toronto or San Diego, while the microbial communities in both cities were actually quite similar. Researchers have yet to understand why this is the case.
Additionally, Caporaso and his team found that 25 percent to 30 percent of the office microbial communities had bacteria from human skin, while human nasal bacteria appeared to be a tiny but consistent part of microbial communities. The largest percentage is from the environment.
Caporaso believes the findings of their study, which is featured in the journal mSystems, may help scientists make use of microbial connections to construct and design buildings with healthier microbiomes in balance with the environment.
The goal would be to build healthier places where we spend most of our days.
"This is a benchmark study," said microbial ecologist Jack Gilbert from University of Chicago.
In the meantime, the team will move on to study and simulate flooding events to determine how fungal communities in built settings change over time.
Photo: Michael Mayer| Flickr
