[upbeat instrumental music]
- [Narrator] This is a subway pole,
a turnstile,
a seat.
And this is what's underneath.
- We did see some geodermatophilus species,
which can survive on rocks and hot environments.
We've also seen staphylococcus epidermis.
The most common species was a cutibacter acne,
which is something that's a normal skin flora bacteria
that is really just being shed off of our human bodies
into the transit system.
Hello, I am Christopher Mason,
a professor of genomics, physiology, and biophysics
at Weill Cornell Medicine.
- [Narrator] Dr. Mason and his team started swabbing
subway stations in 2013.
- We set up an app, a tracking system,
developed a protocol,
and we went on and swabbed every single subway station
in triplicate across New York City.
- [Narrator] They're looking to discover and categorize
the microbiome found in city subways.
- The microbiome is the collection of microorganisms
that are either in, on, or all around you,
and they include bacteria, viruses, fungi, parasites,
really any little organism that you can't quite see
but that has a strong, a really powerful feature
of mediating health and disease.
There are large cities today
where we just don't have a sense of what they look like
or even many environments,
really most of the world's environments,
we don't have a microbial or macroscopic view
of the biology that's there.
- [Narrator] So, what do cities actually look like
underneath the microscope?
[bell dinging]
- We normally swab at least three services for each city,
which is consistently the turnstiles,
the kiosks, and the benches.
Like, for example, in New York City,
there was geobacillus thermoleovorans,
which is this really hardy microbe that can survive
on rocks and soil and even be desiccated or dried out
and, you know, really it takes a licking
and keeps on ticking.
It goes on fine, like, I think, New Yorkers.
We can see that, you know, these really hardy microbes
have evolved for the harsh surfaces of the cities.
[upbeat instrumental music]
[bell dinging]
In Naples, we could actually see
a lot of Mediterranean microbes that have already been found
that isolated in the shores of Italy
or in Greece that could pop up in the cities.
But then we could see, you know, other food-related microbes
that would pop up as well.
So, certain kinds of yeast that are associated
even with cooking pizza and sort of baking bread.
We could sometimes pick up more in Naples
than in other cities.
That was kind of interesting to see.
[upbeat instrumental music]
[bell dinging]
We started sampling before, during, and after
the 2016 Olympics, and we could actually see, you know,
this change because a million people swarmed into Rio
and started to actually add their microbiome to the city.
So we've seen the burst of new species emerging
as there's a mass increase of humans coming into a city.
And so, that disrupted a bit of what the city looks like
at the microbial perspective,
but it also added some diversity to what's present.
So I actually think that the Olympics serve
not only as a gathering for sports and human endeavors,
but also gives this interesting, you know, addition,
like a probiotic to a city, essentially in a way.
[upbeat instrumental music]
[bell dinging]
Tokyo actually has the greatest amount of novel peptides
or new sort of biology that we've discovered
from any of the cities so far.
And why this is is not entirely clear.
So there's a chance that, you know,
some of the novel biology that we find there
is because it's been so isolated from the rest of the world
at earlier centuries.
And so, you know, that's a hypothesis,
so we have to really test that,
but we're trying to not really blend microbial ecology,
modern genetics, plus history
to get a more comprehensive view
of what's happening in the cities and in their people.
Tokyo also had a range of new phages
or these viruses that attack bacteria
that we didn't see anywhere else in the world,
including some phages that are specific for C. acne
or a very common skin microbe.
So, you know, we can actually see that these ecosystems
on the surface and on the skin of people in these cities
really have their own geography
and their own specificity wherever you are in the world.
- [Narrator] While each city
has a unique microbial footprint,
Dr. Mason and his team have identified
a core set of commonalities that cities share.
[bell dinging]
- Across all the systems we've analyzed,
there's actually 31 species of bacteria and microbes
that are really consistently found.
We find them in 97% of every swab that we take.
So, on the one hand, there's this core set of microbes
that includes things like cutibacter acne
or geodermatophilus species.
Humans have evolved a tolerance for milk
over the past few 10,000 years
and this even is reflected in the subway.
Some of the species of lactobacillus are showing up,
things that you find in milk or in dairy products,
that we can also see riding on people's hands and skin,
and then show up in the cities.
We've seen a good number of extremophiles in the subway
in particular some that can survive
in say the cooling waters of nuclear power plants,
like deinococcus radiodurans is one
or other bacteria that are known to survive on stone
or survive under high UV light or a lot of radiations.
The subway system and the city's surfaces enrich for
and probably select for these hardier microbes
that can survive on rough surfaces
full of toxins and radiation.
But at the same time, we find that there's a lot of species
that are very unique to one part of the world,
that even give us a forensic capacity to tell, you know,
what city did you come from?
And if you look at your shoe, for example,
we can tell what about 90% certainty
where in the world you came from
just from the microbes that you're carrying with you.
[upbeat instrumental music]
- [Narrator] With subways teeming with bacteria,
should commuters start to worry about the microbes
they'll encounter on the subway?
- There is some good news in that there is not an avalanche
of pathogens waiting to greet you at the subway systems.
A pathogen is an organism that is known to cause
an infection and a disease.
We seen no evidence of wealth of harmful pathogens,
or really even that many opportunistic pathogens,
in the city centers or transit systems.
But rather we've actually seen
it seemed to be a relatively safe environment.
And even if we look at things like antibiotic resistance
or these antimicrobial resistance genes,
what you'll find in the subway and transit systems
is often less than what you'd find in the soil
or even in your own stomach.
From the first study, my favorite fact then and now
is actually that about half of the DNA that we sequenced
matched no known species.
It had never been seen before.
A new species means that it has to be at least 20% divergent
from anything that's been seen before,
meaning if it was a 100-page book of the genetic code,
at least 20 pages would be completely new
and never been seen before.
But evolution is conservative.
So actually, a lot of pieces of DNA
that we have are bacteria or viruses
get recycled and reused.
- [Narrator] Their subway swabs uncovered
over 11,000 new bacteria and viruses.
- There was all this unknown life
really under our fingertips.
But then other species we could see
looked like they were bacteria
that were associated more with rats,
or sometimes we'd actually see the rat DNA itself.
Actually, we could see cucumber DNA.
We can see plants and animals.
We can see more plant DNA closer to the parks, for example.
So, we could actually see this entire ecosystem of life
really reflected in the surfaces of the subway.
We've also seen a lot of new CRISPR arrays.
These are basically the bacterial immune systems
that are defending against other viruses,
and they also could serve as a new way to understand
how do the CRISPR systems work,
can you use them for new actually therapies or drugs
or even treatments.
CRISPR is even being used right now for gene therapies.
And so, finding these new bacterial functions
could potentially lead the way towards new medicines.
- [Narrator] So, for commuters riding subways
around the world, you might not wanna touch the poles,
turnstiles, and seats like you used to,
but the microbes underneath our fingers serve a purpose.
- I would actually think it's okay to grab the subway pole.
If anything, the ecosystem we discovered
shows that there's a very consistent core microbiome
that humans probably have evolved with
and essentially probably could use the exposure
to that environment.
So, instead of being afraid of the subway,
you could even go in with reckless abandon
and grab it with some confidence.
Or at least I do at this point.
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