Bioengineered Assassins

[Daedalus]

This bioengineered bacterium is actually pretty cool, and has many practical applications. The most beneficial, of course, is the ability to fight disease, but we could also see bio-weapons being made with such a technique.

Synthetic biologist Matthew Chang at Nanyang Technological University in Singapore has armed Escherichia coli bacteria with a ‘seek and kill’ system that targets cells of Pseudomonas aeruginosa, an invasive bacterium that causes pneumonia and other illnesses.

The researchers inserted genes into E. coli to make a killing peptide called microcin S (MccS). This is smaller than pyocin, so the E. coli can secrete it, rather than delivering the payload in a single suicidal burst. That means that fewer of the modified bacteria are required to treat an infection.

The team then loaded the engineered bacterium with genes to make a nuclease called DNase I. This efficiently slices through the protective biofilm that envelops P. aeruginosa colonies by breaking down the nucleic acids that help to hold the biofilm together.

The researchers programmed their E. coli so that it cunningly keeps its powder dry until it is close to its mark. It can detect a P. aeruginosa messenger molecule used for a process called quorum sensing, by which the invader assesses its own population density. Each E. coli generates a protein that latches on to a quorum-sensing molecule, forming a complex that activates its weapons systems.