Engineered particles produce toxins deadly to targeted bacteria

The global rise in antibiotic resistance is a growing threat to public health, damaging our ability to fight deadly infections such as tuberculosis.

In a paper published online in the journal Nano Letters, researchers at MIT, the Broad Institute of MIT and Harvard, and Harvard University reveal that they have developed a new means of killing harmful bacteria.

The researchers have engineered particles, known as "phagemids," capable of producing toxins that are deadly to targeted bacteria.

Bacteriophages—viruses that infect and kill bacteria—have been used for many years to treat infection. But bacteriophages can also cause potentially harmful side effects. They kill bacteria by lysing the cell, or causing it to burst. But this is problematic, as it can lead to the release of nasty toxins from the cell. These toxins can lead to sepsis and even death in some cases.

The researchers used synthetic biology techniques to develop a platform of particles called phagemids. These particles infect bacteria with small DNA molecules known as plasmids, which are able to replicate independently inside a host cell. Once inside the cell, the plasmids are engineered to express different proteins or peptides—molecules made up of short chains of amino acids—that are toxic to the bacteria.