Bacteria can be genetically tricked into self-destructing

Making bacteria’s defenses attack themselves may lead to antibiotics that can destroy bad microbes without harming good ones. One potential smart antibiotic killed a strain of E. coli while leaving untouched a strain that has DNA 99 percent identical to the affected strain’s, researchers at North Carolina State University in Raleigh report January 28 in mBio.

Bacteria defend themselves against virus attacks using a primitive immune system known as the CRISPR-Cas system. CRISPRs are short pieces of RNA that serve as “wanted” posters, helping bacteria recognize dangerous viruses. Enzymes known as Cas proteins then dismember the virus’s genetic material.

Chase Beisel and colleagues engineered CRISPRs so that they called attention to the DNA of a particular strain of E. coli, instead of viral DNA. In lab dishes growing that strain of E. coli and a close relative, the researchers wiped out nearly all of the targeted strain.