Genetic tweaks to tuberculosis could speed up discovery of a new vaccine

“OK, smell this,” says Jeff Wagner, a Harvard postdoc of immunology and infectious disease. He’s pointing to the two flasks of bacteria in front of me. I breathe cautiously from the first vial of yellowish broth. Nothing. “Now this one,” he says, with an identical looking sample. And I’m hit with it: a distinct mint aroma like someone melted down a pack of breath mints.

These minty bacteria are genetically engineered relatives of Mycobacterium tuberculosis, the bacterium that kills 1.5 million people each year. Thankfully this strain — Mycobacterium smegmatis — is harmless. But it’s a close enough cousin that scientists can use it as a proxy for the real thing.

And though a mint-scented bacterium might seem like a silly achievement, it’s part of a serious strategy by a team