Physicists from the Sapienza University of Rome have used free-swimming, light-driven E. coli bacteria to propel tiny 3D printed micromotors in a process that resembles how running water rotates a watermill. Bacteria, unicellular microorganisms that are essential to global ecology (but which can also cause disease in living things), have traditionally had a bad rap with humans.
from 3ders.org - http://www.3ders.org