Skin is the largest organ in the human body.
Skin is a protective barrier that regulates body temperature and is our first line of defense against foreign pathogens, including bacteria and viruses.
Microbiota
The skin microbiota is a complex and dynamic ecosystem composed of bacteria, fungi, archaea and viruses that coexist with the host in a finely regulated balance (Byrd et al., 2018). Beyond its role in disease, the microbiota is increasingly recognized as a key determinant of skin quality and appearance.
Through interkingdom interactions, microorganisms communicate with each other and with the host via biochemical and biophysical signaling pathways, contributing to the regulation of immune responses, barrier integrity and cellular function (Chen et al., 2018). These mechanisms play a fundamental role not only in maintaining skin health, but also in preserving physiological skin conditions associated with a healthy and youthful appearance.
Disease & the market
In addition to structural and immunological effects, recent evidence highlights the role of microbial-derived metabolites as active modulators of skin physiology. Among these, bacterial porphyrins—produced by commensal species such as Cutibacterium acnes—have been shown to influence melanogenesis and oxidative processes. These compounds can act as photosensitizers, generating reactive oxygen species upon light exposure and contributing to pigmentation changes and age-related alterations, a process recently referred to as Porphyr’ageing (Meunier et al., 2026;Bouslimani et al., 2019).
Alterations in the composition and functionality of the skin microbiota (dysbiosis) can therefore impact not only inflammation and barrier function, but also pigmentary balance and oxidative stress, leading to visible changes in skin condition, including increased sensitivity, dryness, uneven texture and premature aging (Krishnan et al., 2021). Environmental factors, lifestyle and external treatments can further disrupt this delicate ecosystem and modulate microbial metabolic activity.
Traditional aesthetic approaches primarily focus on correcting visible imperfections or targeting structural components of the skin, often without addressing the underlying biological balance or the contribution of microbial metabolites. As a result, their effects may be temporary or incomplete.
Cosmetic products based on bacteria of the genus Lactobacillus, which are not typical members of the resident skin microbiota, may exhibit limited metabolic activity on the skin surface due to the relatively oxygen-rich environment, low availability of fermentable substrates, and strong microbial competition (O’Neill et al., 2016); consequently, the production of bioactive metabolites is reduced, and effects observed in vitro may not be fully reproducible in vivo.
Recent advances in microbiome science have introduced a new paradigm in aesthetic medicine: supporting the skin’s natural ecosystem rather than altering it. By targeting the skin microbiota, its interkingdom interactions and its metabolic outputs, it is possible to promote a more physiological, balanced and long-lasting improvement in skin appearance (Wallen-Russell, 2019).
This emerging approach highlights the potential of microbiome-based solutions to redefine aesthetic care, bridging the gap between cosmetic outcomes and biological skin health, and incorporating the control of microbiota-driven processes such as oxidative stress and microbiome-mediated pigmentation.
References
1. Bouslimani, A., et al. (2019). The role of skin microbiota in cutaneous aging: Focus on metabolites and signaling pathways. Frontiers in Genetics, 10, 1107.
2. Byrd, A. L., Belkaid, Y., & Segre, J. A. (2018). The human skin microbiome. Nature Reviews Microbiology, 16(3), 143-155.
3. Chen, Y. E., Fischbach, M. A., & Belkaid, Y. (2018). Skin microbiota–host interactions. Nature, 553(7689), 427-436.
4. Krishnan, R. S., et al. (2021). The skin microbiome in skin aging and its potential as a target for aesthetic medicine. Journal of Cosmetic Dermatology, 20(12), 3785-3792.
5. Meunier, Marie et al. “Bacterial porphyrins in healthy skin: Microbiota components impact melanogenesis and age-related processes leading to Porphyr’ageing.” International journal of cosmetic science vol. 48,1 (2026): 186-199. doi:10.1111/ics.70014
6. O’Neill, C. A., et al. (2016). Is the skin microbiome the new frontier in health and disease? Biological Sciences, 371(1707), 20150218.
7. Wallen-Russell, C. (2019). The role of every-day cosmetics in altering the skin microbiome: A study of 12 volunteers. Cosmetics, 6(1), 4.
References
1. Banueth, G., et al. (2021). The role of the skin microbiome in veterinary dermatology: A review. Veterinary Sciences, 8(9), 189.
2. Bhaduri, P., et al. (2022). Staphylococcus pseudintermedius: An update on its role in canine skin infections. Journal of Veterinary Medical Science, 84(3), 321-330.
3. Bradley, C. W., et al. (2016). Longitudinal evaluation of the skin microbiome and association with microenvironment and disease in canine atopic dermatitis. Journal of Investigative Dermatology, 136(6), 1182-1190.
4. Hoffmann, A. R., et al. (2014). The feline skin microbiota: The extent to which site and health status influence bacterial and fungal communities. PLOS ONE, 9(3), e93011.
5. Marsella, R., et al. (2011). Transepidermal water loss and skin hydration as a function of the anatomical site in normal and atopic dogs. Veterinary Dermatology, 22(6), 510-520.
6. Olivry, T., et al. (2015). Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Veterinary Research, 11(1), 1-15.
7. Pucheu-Haston, C. M., et al. (2015). Review: The role of the skin barrier in the pathogenesis of atopic dermatitis in dogs. Veterinary Dermatology, 26(2), 143-e31.
8. Ross, A. A., et al. (2019). Characterization of the skin microbiota of healthy domestic dogs and cats. Microbiome, 7(1), 1-14.
9. Santoro, D., et al. (2015). Clinical and microbiological effects of a topical treatment in dogs with atopic dermatitis and superficial pyoderma. Veterinary Dermatology, 26(3), 193-e40.
10. Simou, C., et al. (2005). Adherence of Staphylococcus pseudintermedius to canine corneocytes: A comparison of atopic and healthy dogs. Veterinary Dermatology, 16(6), 385-391.