Not a surprise to me but yikes nonetheless:

In the first comprehensive study of the DNA on dollar bills, researchers at New York University’s Dirty Money Project found that currency is a medium of exchange for hundreds of different kinds of bacteria as bank notes pass from hand to hand.

By analyzing genetic material on $1 bills, the NYU researchers identified 3,000 types of bacteria in all—many times more than in previous studies that examined samples under a microscope. Even so, they could identify only about 20% of the non-human DNA they found because so many microorganisms haven’t yet been cataloged in genetic data banks.

Easily the most abundant species they found is one that causes acne. Others were linked to gastric ulcers, pneumonia, food poisoning and staph infections, the scientists said. Some carried genes responsible for antibiotic resistance.

“It was quite amazing to us,” said Jane Carlton, director of genome sequencing at NYU’s Center for Genomics and Systems Biology where the university-funded work was performed. “We actually found that microbes grow on money.”