Cities have their own microbial fingerprints | Science

When Chris Mason’s daughter was a toddler, she was intrigued to see her touching the surface of the New York City Subway. Then one day she licked Paul. “There was a definite microbial exchange,” says Mason, a geneticist at Weill Cornell Medicine. “I desperately wanted to know what happened.”

So he started wiping the subway and sampled the world of microbes that coexist with people in our transportation system.After his 2015 study revealed Abundant species previously unknown In New York City, other researchers contacted him to contribute. Currently, Mason and dozens of collaborators are presenting research on subways, buses, elevated trains and trams in 60 cities around the world, from Baltimore to Bogotá, Colombia and Seoul, South Korea. They identified thousands of new viruses and bacteria and discovered that each city had its own “fingerprint” of microorganisms.

The study is “great,” said Adam Roberts, a microbiologist at the Liverpool School of Tropical Medicine who was not involved in the study. Although a small study examined individual cities and transportation systems, the new project is much larger than any previous project and can investigate new questions, he says. “They did a great job of putting this all together. I think this data will be analyzed over the next few decades.”

To take a global snapshot of transport microbial flora around the world, Mason and his collaborators first needed to understand how to consistently collect samples. They settled on the wipes common to transportation everywhere, including benches, turnstile ticket gates, and ticket offices. Scientists wiped the surface for 3 minutes. This was long enough to get enough DNA, but not long enough to be strange to researchers and bystanders.

Returning to the lab, the researchers analyzed the DNA. They found that about 45% did not match known species. Nearly 11,000 viruses and 1302 bacteria were new to science.

Researchers also found that 97% of the samples had a set of 31 species. These formed what they called the “core” urban microbial flora. In addition, 1145 species were present in more than 70% of the samples. Samples taken from surfaces that are touched by humans, such as railings, were more likely to carry bacteria associated with human skin than surfaces such as windows. Other common species of the mixture were bacteria commonly found in soil, water, air and dust.

However, researchers have also discovered less prevalent species. They gave each city a unique microbiome, and helped researchers predict, With 88% accuracy, Derived from a random sample of the city, they report today cell..In New York City, for example, they found a lot Carnobacteriaceae check, A lactic acid bacterium with high low temperature resistance. More research suggests that unique urban fingerprints like these could be useful in forensic medicine, Mason says.

The main value of the study is not in its findings (mapped) Here) As much as open data available at metagraph.ethz.chSays Noah Fierer, a microbiologist at the University of Colorado at Boulder, who was not involved in the study. It will give other researchers the opportunity to delve into new questions. “Different cities have different microbial communities,” says Fierer. “That’s not surprising. Why is the question for me?”

And while some may be worried about the microbes hiding in our city, Mason says the results represent a relatively safe situation. For example, antimicrobial resistance genes were present at much lower levels in transport samples than in human gut or hospital samples, he says.

Instead, Mason sees the opportunity of “awe and excitement for the mass transit system as an unexplored source of extraordinary biodiversity.” Newly discovered species have potential for drug research, he said, and extensive mapping and monitoring of urban microbiota benefits public health, allowing researchers to discover new pathogens early. Helps to.

Until recently, monitoring urban microbiota was a “strange” idea and was exorbitantly expensive, Mason said. But now people can see how useful it is. Mason says that if researchers around the world were analyzing RNA samples, they might have seen the emergence of a pandemic coronavirus. “What if you’ve been watching for a long time?”