Trends in Microbiology
ReviewHuman MicrobiomeDaily battle against body odor: towards the activity of the axillary microbiota
Section snippets
Characteristics of the human axilla as a microbial habitat
The human skin exhibits a diversity of ecological niches varying in moisture, the availability of nutrients, and the presence of host- and bacteria-derived antimicrobial peptides 1, 2. In general, skin regions can be classified as dry, sebaceous, or moist environments with specifically adapted organisms establishing a distinct microbial profile characteristic for each topographical region [3]. Comprehensive 16S rDNA profiling of the cutaneous microbiota (see Glossary) in the course of the Human
Origin and composition of human axillary odor
In the past decade intensive research on axillary sweat and the resulting body odor was driven mainly by the cosmetic industry and led to the identification of a variety of characteristic odorous compounds (Figure 1). These include sulfanylalkanols, steroid derivatives, and volatile short-chain fatty acids, whose combination and ratios account for the intensity of human axillary odor 13, 14. The highest impact on axillary odor derives from volatile sulfur compounds, which exhibit a low
Composition of the microbiota of the axillary skin
Investigations of the cutaneous microbiota at various skin sites were performed by employing high-throughput 16S ribosomal DNA (rDNA) amplicon sequencing 38, 39. These studies demonstrate that the composition of the skin microbiota correlates to the well-structured topographical landscape of the skin analogous to the several sub-habitats found in all naturally occurring ecosystems [40]. The most dominant four phyla were found to be Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes 38
First clues of the active axillary microbiota
A major shortcoming of DNA-based ‘omic’ techniques such as 16S rDNA amplicon sequencing and metagenomics is the inability to discriminate between living microorganisms, representing the active resident fraction of the skin microbiota, and persisting bacteria transiently colonizing a habitat after contamination from a foreign source 3, 46. In the case of the axillary microbiota, it is well-established that microbial activity is responsible for body-odor formation and, therefore, the
Future perspectives: towards a metatranscriptome of the axillary microbiota
The concept of a core microbiome with specific metabolic functions emphasizes the requirement to analyze the active microbial community of the human axilla at a functional level. To characterize unknown enzymatic functions as well as active metabolic processes involved in body-odor formation, metatranscriptomic analyses of the axillary microbiota are required in the future (Figure 3). However, such an approach has not been reported so far, which also might be due to the restricted amount of
Acknowledgment
E.F. and H.B. are recipients of scholarships from the CLIB Graduate Cluster Industrial Biotechnology.
Glossary
- Anosmia
- the inability to perceive odor.
- Axilla
- the hollow beneath the junction of the arm and shoulder (armpit).
- Diversity
- number and abundance distribution of distinct taxa of microorganisms.
- Lipid-auxotrophic
- used to describe corynebacteria lacking the ability to synthesize fatty acids de novo owing to a missing fatty acid synthase gene. These species are therefore also lipophilic.
- Lipid-catabolizing
- used to describe corynebacteria with the ability to degrade a variety of fatty acids, for instance via
References (50)
Microbial ecology of human skin in health and disease
J. Investig. Dermatol. Symp. Proc.
(2001)The microbiology of the human axilla and its relationship to axillary odor
J. Invest. Dermatol.
(1981)Formulation and stability of a novel artificial human sweat under conditions of storage and use
Toxicol. In Vitro
(2010)- et al.
The sequential action of a dipeptidase and a β-lyase is required for the release of the human body odorant 3-methyl-3-sulfanylhexan-1-ol from a secreted Cys-Gly-(S) conjugate by Corynebacteria
J. Biol. Chem.
(2008) A specific bacterial aminoacylase cleaves odorant precursors secreted in the human axilla
J. Biol. Chem.
(2003)- et al.
Genetic influences on human body odor: from genes to the axillae
J. Invest. Dermatol.
(2010) Production of malodorous steroids from androsta-5,16-dienes and androsta-4,16-dienes by Corynebacteria and other human axillary bacteria
J. Steroid Biochem. Mol. Biol.
(2003)Skin microbiome: genomics-based insights into the diversity and role of skin microbes
Trends Mol. Med.
(2011)Microbiology of the skin and the role of biofilms in infection
Int. Wound J.
(2011)- et al.
The skin microbiome
Nat. Rev. Microbiol.
(2011)
Topographical and temporal diversity of the human skin microbiome
Science
Characterization of the microflora of the human axilla
Int. J. Cosmet. Sci.
Sweaty skin, background and assessments
Int. J. Dermatol.
A short history of sweat gland biology
Int. J. Cosmet. Sci.
Steroid analysis of human apocrine secretion
Steroids
Formulation and stability of a novel artificial sebum under conditions of storage and use
Int. J. Cosmet. Sci.
Anatomy and physiology of the skin
J. Dermatol. Nurses’ Assoc.
A broad diversity of volatile carboxylic acids, released by a bacterial aminoacylase from axilla secretions, as candidate molecules for the determination of human-body odor type
Chem. Biodivers.
Gender-specific differences between the concentrations of nonvolatile (R)/(S)-3-methyl-3-sulfanylhexan-1-ol and (R)/(S)-3-hydroxy-3-methyl-hexanoic acid odor precursors in axillary secretions
Chem. Senses
Analysis of characteristic odors from human male axillae
J. Chem. Ecol.
Body odour of monozygotic human twins: a common pattern of odorant carboxylic acids released by a bacterial aminoacylase from axilla secretions contributing to an inherited body odour type
J. R. Soc. Interface
A functional ABCC11 allele is essential in the biochemical formation of human axillary odor
J. Invest. Dermatol.
Preference for human body odors is influenced by gender and sexual orientation
Psychol. Sci.
MHC-correlated odour preferences in humans and the use of oral contraceptives
Proc. Biol. Sci.
Skin microbiota: a source of disease or defense?
Br. J. Dermatol.
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Association of HLA-DPB1, NLRP10, OVOL1, and ABCC11 with the axillary microbiome in a Japanese population
2022, Journal of Dermatological ScienceCitation Excerpt :Afterward, correlation of rs17822931 with development of apocrine glands and a strong genetic association with the axillary odoriferous phenotype have been shown [8–11]. In the axillary region, apocrine glands, eccrine glands, and sebaceous glands are mixed; volatile organic compounds and their precursors with specific amino acids are excreted and compose the axillary odor complex [12,13]. The trans (E) isomer of 3-methyl-2-hexenoic acid (E3M2H, fatty acid odor) was identified as a representative odorant.
Exploring the interrelationship between the skin microbiome and skin volatiles: A pilot study
2023, Frontiers in Ecology and Evolution