E. coli bacterium and nanoparticles. Illustration of metal nanoparticles interacting with an Escherichia coli bacterium. E. coli has been investigated as a medium for storing and encrypting data in bacterial DNA (deoxyribonucleic acid). Bacterial biostorage systems could hold vast amounts of data, and the concept could also be used to create biological barcodes. The nanoparticles could also be attacking and destroying the bacterium. E. coli bacteria are a normal part of the intestinal flora in humans and other animals, where they aid digestion. However, some strains can produce a toxin that leads to severe illness, or even death. Normal strains can also produce infections in those with weakened immune systems.