а что это такое?
also, что такое subway?
http://www.nytimes.com/2015/02/06/nyregion/among-the-new-york-city-subways-millions-of-riders-a-study-finds-many-mystery-microbes.html
Have you ever been on the subway and seen something that you did not
quite recognize, something mysteriously unidentifiable?
Well, there is a good chance scientists do not know what it is either.
Researchers at Weill Cornell Medical College released a study on
Thursday that mapped DNA found in New York’s subway system — a crowded,
largely subterranean behemoth that carries 5.5 million riders on an
average weekday, and is filled with hundreds of species of bacteria
(mostly harmless), the occasional spot of bubonic plague, and a universe
of enigmas. Almost half of the DNA found on the system’s surfaces did
not match any known organism and just 0.2 percent matched the human genome.