“I was not always someone who would have advertised probiotics,” Michael Otto told BioWorld. And it’s easy to see why. At this point, probiotics are more often dubious wellness offerings than evidence-based therapeutics. Part of the issue is that the mechanisms by which probiotics are supposed to exert their effects are mostly vague. Molecular mechanisms that could account for claimed health benefits are few and far between. But Otto, who is chief of the pathogen molecular genetics section at the National Institutes of Allergy and Infectious Disease, and his colleagues have identified one such molecular mechanism.