Researchers at the New York University's Dirty Money Project analyzed DNA on $1 bills and found some 3,000 types of bacteria -- many times more than studies using a microscope found.
Jane Carlton, director of genome sequencing at NYU's Center for Genomics and Systems Biology told the Wall Street Journal: "It was quite amazing to us. We actually found that microbes grow on money."
Carlton and colleagues used high-speed gene sequencing and computerized database analysis from 80 $1 bills to identify lifeforms via their DNA.