So far experiments have been done on E. coli bacterial cells, Tobacco Mosaic Virus cells, as well as human and hamster cells.

BBC: Cell infected with HIV

The machine let the E. coli multiply, mixed them with the DNA strands, and applied an electric shock to open up the bacterial cells and let the DNA get inside.

FORBES: Putting Evolution to Work

Zeneca ordered a "wet" copy of a promising gene, in the form of a clone -- a colony of bacterial cells whose members all carry the desired snippet of DNA. These bacterial guinea pigs can then be used to try out antibacterial chemicals.

FORBES: Biology in silico

The idea would be to treat cancer the same way doctors now fight lethal bacterial infections, hitting cancer cells early with the equivalent of multiple antibiotics.

FORBES: Swiss Army Medicine

The lungs have their own anti-bacterial action, produced by a liquid which overlays the cells lining the lung.

BBC: Sugar spray 'prevents lung infections'