Body odor. The smell of B.O. is unmistakable. And the culprit behind that signature stench is a molecule called thioalcohol. Our noses are so attuned to it, we can pick up quantities as small as one part per trillion. But here's the mystery: How does that stinky substance get there in the first place?

Well, it turns out bacteria named Staphylococcus hominis is the major perpetrator, along with a few of its relatives. Their genes code for enzymes that snip the molecules in our sweat to pieces—creating the offensive thioalcohols, along with bits of food for the bacteria. Hey, bacteria gotta eat, too, right? 

When innocuous E. coli bacteria were given the genes that our B.O. perpetrators have naturally, they, too, could achieve the stank. These findings were presented at the annual meeting of the Society for General Microbiology, in Birmingham, in the U.K. [Daniel Bawdon et al, Battling body odour: transport and catabolism of malodour precursors by the underarm microbiota]

Not surprisingly, this work was partially funded by Unilever. Because now that we've identified these microbial targets, the researchers say, it might be possible to design more effective deodorants. Which, instead of crippling all underarm bacteria, dispatch only the most dastardly denizens. Smells like profit to me.

—Christopher Intagliata

[The above text is a transcript of this podcast.]