In an audaciously remarkable attempt to characterize the microbial population found in New York City, a team of researchers from Weil Cornell Medical School have produced a map of microbes or a "pathomap" of the heavily travelled New York City subway.
Assistant Professor Christopher Mason, the principal investigator of the study and a geneticist at the Weil Cornell Medical College, recruited researchers and grad students to swab surfaces of metal handrails, turnstiles, ticket kiosks, and other commonly touched places in New York's subway system. It took them 18 months for collecting samples and using techniques described in the publication to identify the microbiome and come up with the pathomap. They analyzed over 10 billion DNA fragments.
The researchers detected about 637 known bacterial, fungal, viral and other known animal microbes a vast majority of which are non-pathogenic and represent common bacteria found in human body. More strikingly, about half of the DNA studied were unidentified i.e. they did not match any organism known at the National Centre for Biotechnology Information or Centre for Disease Control Prevention, underscoring the scientific potential of these king of studies.
"Our data show evidence that most bacteria in these densely populated, highly trafficked transit areas are neutral to human health, and much of it is commonly found on the skin or in the gastrointestinal tract," says Dr. Mason.
However, 12 percent of the microbes they sampled were associated with human disease. 27 percent of the samples they collected contained antibiotic-resistant bacteria, two samples had DNA fragments of Bacillus anthracis (anthrax) and three samples had plasmid of Yernisia pestis (Bubonic plague).
Mason clarifies that there is no need to be worried. The presence of DNA fragments does not mean that the microbes are alive and furthermore they were not found to be infectious when culture experiments were done.
"These apparently virulent organisms are not linked to widespread sickness or disease," said Dr. Mason. "They are instead likely just the co-habitants of any shared urban infrastructure and city, but wider testing is needed to confirm this." He goes on to add that lack of reported medical cases and the presence of the DNA fragments testify to how good our immune system is and how well we adapt to changing environments.
The authors explain that creating a pathomap is not just to quench scientific curiosity. By continuing the study over a course of time, researchers can compare microbial population and predict whether certain diseases or biological weapons have spread. They also believe that maps like these could be a baseline to guide the construction of so-called probiotic buildings. For instance, some bacteria in the subway can help clean up hazardous chemicals while some are vital to the immune system. The team looks forward to the day when they understand patterns of microbial behavior well enough so they could create places where those helpful germs would want to live.
REFERENCES AND FUTHER READINGS
https://www.cell.com/pb/assets/raw/journals/research/cell-systems/do-not-delete/CELS1_FINAL.pdf
https://www.pathomap.org/
https://www.nytimes.com/2015/02/06/nyregion/among-the-new-york-city-subways-millions-of-riders-a-study-finds-many-mystery-microbes.html?_r=0
