A pilot study of 80 healthy Chinese participants across four age cohorts (centered at 10, 30, 50, and 70 years) mapped bacterial and fungal communities on both sun-exposed and non-sun-exposed skin sites using DNA sequencing. A random forest classifier trained on this combined microbiome data identified four key markers — the fungus Lactarius, and bacteria Chryseobacterium, Gordonia, and Psychrobacter — achieving an AUC of 0.97 for age-group classification. Notable biological shifts included Malassezia dominance peaking at age 30 then declining, species-level transitions from M. globosa in children to M. arunalokei in elderly, and bacterial succession from diverse childhood genera toward Cutibacterium dominance in young adulthood.
The gut microbiome has monopolized aging biomarker research for over a decade, yet skin is the body's largest organ and its most direct interface with environmental stressors, UV radiation, and hormonal flux. This study's insistence on including fungi — routinely excluded from microbiome profiling — is methodologically important and long overdue. The Malassezia species-level switching across age is particularly intriguing, as these lipid-dependent yeasts are implicated in seborrheic dermatitis and atopic conditions that track with age. However, the 80-person sample is modest, the cohort is ethnically homogeneous, and age groups are widely spaced, limiting mechanistic inference. Whether these microbial shifts drive aging physiology or merely reflect it remains entirely open. Incremental but directionally significant — skin mycobiome deserves a seat at the longevity-biomarker table.
