The production of malodour by humans is mediated by bacterial transformation of naturally secreted, non-odorous molecules. Specifically in the underarm (axilla), malodour arises due to biotransformation by the microbiota of dipeptide-conjugated thioalcohols, particularly S-[1-(2-hydroxyethyl)-1-methylbutyl]-(l)-cysteinylglycine (Cys-Gly-3M3SH). This molecule, secreted by the axilla, has a well-established role in malodour when metabolized to free thioalcohol by bacteria. We present Cys-Gly-3M3SH biotransformation data from a library of skin-isolated corynebacteria and staphylococci and report a significant variation in thioalcohol generation across individual bacterial species. Staphylococcus hominis, Staphylococcus haemolyticus and Staphylococcus lugdunensis were particularly efficient Cys-Gly-3M3SH transformers. In contrast, Staphylococcus epidermidis and Corynebacterium tuberculostearicum, both highly prevalent axillary commensals, are low producers of 3M3SH. We also identify significant differences between the ability of several isolates to biotransform Cys-Gly-3M3SH compared to S-benzyl-l-Cys-Gly, a dipeptide-linked version of a commonly used malodour precursor substrate. Finally, using traditional biochemical assays we subsequently establish that Cys-Gly-3M3SH is actively transported into S. hominis, rather than passively diffusing across the membrane. This work significantly enhances our knowledge of Cys-Gly-3M3SH biotransformation by physiologically important bacteria in the axillary microbiota.
- body odour