Cities have their own unique collection of bacteria and viruses

In a new study from the University of Maryland School of Medicine (UMSOM), researchers have found that each city has its own unique collection of bacteria and viruses. The findings are based on the analysis of 4,728 samples from cities on six continents taken over the course of three years.

The experts sequenced and analyzed samples collected from both public transit systems and hospitals in 60 cities around the world. 

The research, which was conducted by an international team of experts, is considered to be the largest-ever global study of urban microbiomes. The microbial species identified include thousands of viruses and bacteria and two newly identified single-cell organisms.

Study co-author Dr. Lynn Schriml is an associate professor in the Department of Epidemiology & Public Health at the Institute for Genome Sciences (IGS), at UMSOM, who led the study sampling efforts for Baltimore’s transit systems. 

“Baltimore’s distinct microbial signature reveals a unique, fascinating, and diverse world, providing insights into geographical variation and previously unknown microbial genomes,” said Dr. Schriml.

Study senior author Dr. Christopher Mason is a professor at Weill Cornell Medicine and the director of the WorldQuant Initiative for Quantitative Prediction.

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

The researchers are now looking at how the COVID-19 pandemic may have affected the microbiome fingerprint of each city. 

In 2020, the team launched the MetaCOV project in 2020 to investigate the change in urban metagenomes and isolate the presence of the SARS-CoV-2 virus in urban environments, such as ATM machines, hospitals, and transit systems.

In addition to distinct microbial signatures in various cities, the analysis revealed a core set of 31 species that were found in 97 percent of samples across the sampled urban areas, according to the researchers.

The study is published in the journal Cell.

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By Chrissy Sexton, Earth.com Staff Writer