Suppression of microbial metabolic pathways inhibits the generation of the human body odor component diacetyl by Staphylococcus spp.

Takeshi Hara,Hironori Shimizu,Hiroshi Matsui,Vasu D Appanna

doi:10.1371/journal.pone.0111833

Abstract

Diacetyl (2,3-butanedione) is a key contributor to unpleasant odors emanating from the axillae, feet, and head regions. To investigate the mechanism of diacetyl generation on human skin, resident skin bacteria were tested for the ability to produce diacetyl via metabolism of the main organic acids contained in human sweat. l-Lactate metabolism by Staphylococcus aureus and Staphylococcus epidermidis produced the highest amounts of diacetyl, as measured by high-performance liquid chromatography. Glycyrrhiza glabra root extract (GGR) and α-tocopheryl-l-ascorbate-2-O-phosphate diester potassium salt (EPC-K1), a phosphate diester of α-tocopherol and ascorbic acid, effectively inhibited diacetyl formation without bactericidal effects. Moreover, a metabolic flux analysis revealed that GGR and EPC-K1 suppressed diacetyl formation by inhibiting extracellular bacterial conversion of l-lactate to pyruvate or by altering intracellular metabolic flow into the citrate cycle, respectively, highlighting fundamentally distinct mechanisms by GGR and EPC-K1 to suppress diacetyl formation. These results provide new insight into diacetyl metabolism by human skin bacteria and identify a regulatory mechanism of diacetyl formation that can facilitate the development of effective deodorant agents.

Highlights

Human body odor can be attributed to the bacterial metabolism of odorless compounds secreted from the eccrine, apocrine, and sebaceous glands
To find resident skin bacteria capable of diacetyl formation, nine strains of human skin bacteria (Staphylococcus and Corynebacterium spp.) with the relevant metabolic pathways were screened based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database [31]
Using sodium pyruvate as the substrate, diacetyl was produced by S. aureus and S. epidermidis (Table 1), with the former having the highest capacity for diacetyl formation

Summary

Introduction

Human body odor can be attributed to the bacterial metabolism of odorless compounds secreted from the eccrine, apocrine, and sebaceous glands. Secretions from different body parts–such as the axillae, feet, and scalp–have distinct odors [1,2,3,4]. Many deodorant manufacturers claim that their products are designed to prevent human body odor and stress sweating for as long as possible [5]. For the effective control of body odor, the characterization of different odor-causing elements–including the responsible bacteria and their metabolites–as well as the analysis of active deodorant components are essential. An understanding of how body odor is produced from complex bacterial metabolic processes is of great interest to biologists

Methods

Results

Conclusion