Alex Pasternack describes the work of Sorin Popescu:

You shouldn’t put money in your mouth, obviously, mainly because it has lots of gross stuff on it. We just can’t see it. That is, until Sorin Popescu, a 23-year-old pharmacy student from Romania, harvested some of the bacteria and created an art project called "demonstrating the evil that money carries with it." It’s called Life on Money, as in life on Mars, but also, I think, the idea of this is your life on money, with all of the infectiousness that implies.

More images here.