Each city has its own unique types of microbial communities, however, microbes don’t differ among buildings located in the same city, according to a new study directed by Northern Arizona University in Flagstaff. Researchers also suggest that human skin is a relevant component of the built environment surface.
Researchers analyzed samples of microbes from nine different offices in three cities, to understand how the behavior of these tiny living organisms, changes depending on places and interactions.
A theory also proposes that office floors have more microbes than other surfaces in offices, probably due to soil and materials dragged by workers. Detailed results were published this week in mSystems, a journal from the American Society for Microbiology (ASM).
At the same time, the lack of “extreme conditions like flooding” may be leading to an accumulation of microbes on surfaces in the built environment , which are not carrying out an active process, said senior study author Gregory Caporaso, PhD and assistant professor of biological sciences.
What is the built environment and which is its impact?
According to the Centers for Disease Control and Prevention, the built environment includes all of the physical parts where humans develop, describing it as “a public issue” that can affect the health of Americans.
Understanding microbiology of the built environment is fundamental to future research efforts. Professor Caporaso said in a press release issued Tuesday, that researchers should include routine monitoring of microbial communities, to identify changes that could have an incidence on human health.
Study details and other theories
Professor Caporaso and his team observed three offices during one year in Flagstaff, San Diego, and Toronto, to study how microbes establish in built environments over time, said the ASM in a press release.
They set up three sample plates in three different places: the floor, the ceiling tile, and the wall. Each of them containing two or three swatches of painted drywall, ceiling tile and carpet, alongside sensors developed to register parameters of the environment.
Parameters included equilibrium relative humidity on the surfaces of the samples, available light, occupancy, and temperature, said the ASM. Later, each sample was collected in four-week periods to be analyzed in laboratories, with gene sequencing techniques that can detect bacterial and fungal communities.
Results would appear to show that floor samples restrained always more microbes than wall or ceiling surfaces, regardless of the material. Moreover, taking the plates for sampling did not alter the microbial communities considerably.
Findings also suggest that cities have their unique types of microbial communities. Professor Caporaso said that this appears interesting, since even among the same cities, the offices selected were different from each other.
“The offices we studied differed from each other in terms of size, usage patterns, and ventilation systems suggesting that geography is more important than any of these features in driving the bacterial community composition of the offices within the ranges that we studied,” said Caporaso.
It appears that offices in Flagstaff had richer microbial communities than offices located in San Diego or Toronto. However, researchers require further investigation to explain why it occurs, since they are unclear by now, said Caporaso.
Researchers also collected samples of human skin, nasal, oral, and fecal microbiome from 11 workers from different offices in the three cities, to determine if specific office workers or body sites were sources of microbes, found in the sample plates.
They concluded that in all offices, human skin was the main contributor to microbial communities. It appears that between 25-30 percent of the built environment surface, derived from human skin.
Another human contributor to microbial communities is the human nasal microbiome, explained the ASM. However, the main source of microbial communities in the offices, was from non-human sources like the environment.