Japanese research reveals the cause of bad breath

Researchers from Osaka University find that a metabolite produced by the commensal oral bacterium Streptococcus gordonii activates another bacterial species, Fusobacterium nucleatum, to produce the malodorous compound methyl mercaptan.

Bad breath is caused by volatile compounds that are produced when bacteria in the mouth digest substances like blood and food particles. One of the smelliest of these compounds is methyl mercaptan (CH₃SH), which is produced by microbes that live around the teeth and on the surface of the tongue. However, little is known about which specific bacterial species are involved in this process.

Takeshi Hara, lead author of the study, explained, “Most previous studies investigating CH₃SH-producing oral bacteria have used isolated enzymes or relatively small culture volumes. In this study, we aimed to create a more realistic environment in which to investigate CH₃SH production by major oral bacteria.”