Local germs

A somewhat interesting finding:

Cities have their own distinct microbial fingerprints 

When Chris Mason’s daughter was a toddler, he watched, intrigued, as she touched surfaces on the New York City subway. Then, one day, she licked a pole. “There was a clear microbial exchange,” says Mason, a geneticist at Weill Cornell Medicine. “I desperately wanted to know what had happened.”

So he started swabbing the subway, sampling the microbial world that coexists with people in our transit systems. After his 2015 study revealed a wealth of previously unknown species in New York City, other researchers contacted him to contribute. Now, Mason and dozens of collaborators have released their study of subways, buses, elevated trains, and trams in 60 cities worldwide, from Baltimore to Bogotá, Colombia, to Seoul, South Korea. They identified thousands of new viruses and bacteria, and found that each city has a unique microbial “fingerprint.”...

The researchers also found a set of 31 species present in 97% of the samples; these formed what they called a “core” urban microbiome. A further 1145 species were present in more than 70% of samples. Samples taken from surfaces that people touch—like railings—were more likely to have bacteria associated with human skin, compared with surfaces like windows. Other common species in the mix were bacteria often found in soil, water, air, and dust.

But the researchers also found species that were less widespread. Those gave each city a unique microbiome—and helped the researchers predict, with 88% accuracy, which city random samples came from, they report today in Cell.