A New Model to Investigate the Effects of Cosmetics on Skin Microorganisms In Vitro

Abstract

The use of prebiotic substances in cosmetic products in order to improve skin appearance by influencing the skin microbiome has become quite common. As known from the food industry, prebiotic cosmetics aim for specific support of beneficial microorganisms, while others, especially pathogenic bacteria, are sought to be inhibited. To develop such products and evaluate their efficacy, it is crucial to understand the mode of action of prebiotic substances already before an in vivo use phase, e.g., by applying appropriate lab methods. We describe the development of a suitable in vitro model in order to test the efficacy of prebiotic substances incorporated in different types of formulas. A leather surface inoculated with different bacterial species of the human residential skin microbiota proved effective in simulating the action of prebiotic agents on the skin. It could be shown that the growth of bacteria was positively or negatively influenced by cosmetic formulas containing prebiotic substances. Thus, the model allows the investigation of prebiotic agents in cosmetic formulas with respect to their efficacy on a skin-like surface.