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Personalized Beauty? Start Paying Attention to your Skin Microbiome by Mérieux NutriSciences

11 January 2023

Human skin is a complex ecosystem with various micro-environmental conditions and microbial communities, and it is the home to millions of bacteria, fungi and viruses which compose its microbiota. It is extremely important to the skin health, and it plays an essential role in protecting it against external infectious or toxic substances and allergens.

Skin microbial communities are site-, individual-, and ethno-specific, and they are largely stable over time, despite skin’s exposure to different external environments. Various factors, including the use of antibiotics, cosmetics, soaps, personal care products, and living conditions such as lifestyles and nutrition habits can influence the skin microbiome.


Various factors can disrupt the balance of microbiota and cause skin dysbiosis. Described as an imbalance between the microbiota and its host, dysbiosis can be considered a form of impaired homeostasis in which the microbiota is shifted towards a less complex, less varied pathological spectrum.


Researchers have suggested that the fragile balance of the skin microbiota may have a strong influence on the functional differences between healthy skin and diseased or damaged skin, and that strong treatments can deeply alter the microbiota and compromise the health of the skin.It becomes important to maintain the microbiota equilibrium to preserve the best skin physiology, also choosing biome-friendly cosmetic products.


The skin microbiota in-vitro approach: our outstanding expertise on disease models.


POINT 1. Be safe – Check the formula composition

  • Skin cytotoxicity evaluation: the potential cytotoxicity of the formulation assessed through a skin in vitro
  • Skin irritation evaluation: the potential irritation of the formulation assessed through OECD test N. 439 – In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method.


POINT 2. Respect your microbes – Check the formula skin compatibility

  • Bacteriostatic or bactericidal activity of the cosmetic formulation: to investigate if the formulation at its highest non-irritant concentration negatively affects bacteria growth, its bacteriostatic and bactericidal activity will be assessed following a standard MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) assays.
  • Formulation impact on bacteria growth kinetic: the impact of the formulation on skin bacteria growth is evaluated by combining a broth culture and a spread plate seeding approach.


POINT 3. Evidence-based effect – Prove the real effect of the product

  • Skin microbes’ competition for active substances in the formulation: depending on the effect of cosmetic formulation on bacterial strains growth kinetics, it is evaluated the potential competition between different skin microbe strains for active substances as energy sources.
  • 3D in vitro skin model for skin microbes’ colonization: it is evaluated the bacterial strains colonization potential and growth kinetic on in vitro skin model specifically designed for each application. Skin colonization and growth of different bacteria, as single strains or in combination, will be assessed both in the presence and in the absence of the cosmetic formulation.


The skin microbiota approach on human skin: our outstanding expertise on normal and sensitive skin.


Our experts dedicated to skin microbiota projects have developed a sound strategy to provide a complete service that prove the real effect of beauty products that claim for microbiota or microbiome, through the design of specific protocol that fits customized needs.


STEP 1. The selection of the right panel

The right panel of volunteers is screened and selected according to skin bacterial communities. Screening results to select the right panel for specific efficacy test services are based on the total bacterial count through a direct collection of skin microbiota on volunteers.


STEP 2. Test your product effect on a selected panel

Thanks to a customizable evaluation on skin microbiota before and after product application, we can prove the product effect on selected volunteers with an integrated and multi-tool approach. Our integrated & multi-tool approach exploits the synergies of different techniques to investigate:

  • how a product works on skin microbiota
  • the clinical proof of your product effect on the selected panel




Innovation is the engine of cosmetics. The continuous research and the development of technology have always been part of the DNA of cosmetics. New claims, new production processes, new ingredients, new actives, new formulations, new products are continuously designed and developed to meet the needs and demands of the consumers of today and tomorrow. Efficacy tests give real data to support all these innovations.