The unexpected natural “gps” on the sole of our shoes

As every man has his own fingerprint, so every city has its own “microbial»Imprint, the microbial map, that is, that differentiates it from the others.

This has been investigated by new international scientific research, the largest genetic study of urban microbiomes (viruses and bacteria) ever conducted internationally, and shows that it is possible, with proper analysis, to draw useful conclusions.

The more than 900 collaborating researchers, led by Christopher Mason, a professor of genetics at New York’s Weill Cornell Medical College, published in the journal Cell Cell Biology, analyzed 4,728 air samples from 60 , from London, Stockholm and New York to Rio de Janeiro, Shanghai and Tokyo. Samples were taken over three years, mainly by public transport. This was followed by their genetic analysis for viruses, bacteria and other microorganisms. This is the most complete to date list of urban microbial ecosystems.

Each city has its own molecular “echo”

“Every city has its own molecular ‘echo’ of microbes that identifies it. If you gave me your shoe, I could tell you with about 90% accuracy from which city in the world you came “said Mason.

The microbial “profiles” of European and North American cities differ significantly from those of the developed cities of East Asia. In general, the closer two cities are, the more similar their microbial “footprints” look. Cities near Ecuador have greater microbial biodiversity, while coastal cities have several water-related germs.

It was found that, in addition to the distinct microbial “signature” of each city, there is one a nucleus of 31 microbial species that is common to almost all cities (97%). Almost half of these common species are bacteria that live in the human body, mainly in the skin. In total, the researchers found 4,246 known species of urban microorganisms, two-thirds of which were bacteria and the rest fungi, viruses and other microbes. To their great surprise, they also discovered 10,928 new viruses and 748 new species of bacteria, hitherto unknown.

The bigger a city is, the more complex and diverse its microbiome is. The origin and functions of many of these microorganisms remain unknown, although, according to scientists, they are not a source of particular concern. The vast majority of them do not appear to be pathogenic and do not pose a risk to humans.

The investigation began in 2013, when for the first time in the world Mason began collecting and analyzing microbial samples from the New York subway. Following the publication of his first findings, he was approached by scientists from all over the world who wanted to do something similar in their own cities. Thus, he developed a research protocol and the research acquired an international character.

In 2015, Mason formed the International Research Consortium International MetaSUB Consortium and June 21 was established as World Cities Sampling Day. In 2020 amid a pandemic an effort was launched to investigate the spread of the coronavirus SARS-CoV-2 in cats. At the same time, MetaSUB researchers in Switzerland have created an open global genetic database (MetaGraph), which records all genomes of urban germs.

The findings of this type of research can also have useful practical applications, from criminology (if a suspect recently visited a particular city based on the analysis of the microbiome in his shoes) to the development of new drugs. “People often think that biodiversity is abundant in a rainforest and new molecules can be found for medical treatments, but the same goes for a handle on the subway or a bench in the city. “, Mason said.

The study was conducted before Covid-19 lockdown the cities of the world, so the next step of the researchers will be to see if the pandemic has affected the microbial footprint of each city. The research consortium has already launched the MetaCOV program to look for possible changes in the microbial genomes and to isolate the presence of coronavirus in urban environments (ATM machines, waste, hospitals, means of transport, etc.).