How are probiotics obtained?

Naturally present in the body, microorganisms such as bacteria, viruses, and yeasts make up the microbiota. Found in the digestive system but also in the skin, this is a complex ecosystem whose diversity is generally correlated with human health: the richer it is, the better the individual's health will be. In the skin, an imbalance of the microbiota can be associated with the development of certain dermatoses such as rosacea, eczema or even psoriasis.

To address this, it may be relevant to boost the populations of microorganisms through external supplementation. This is where probiotics come into play. According to the definition given by the World Health Organisation (WHO) and the Food and Agriculture Organization of the United Nations (FAO), probiotics are "live microorganisms which, when consumed in adequate amounts, have a health effect on the host". At the skin level, probiotics can particularly strengthen the barrier function but also reduce inflammatory phenomena by participating in the regulation of the immune system.

Probiotics are industrially produced from a colony of identical cells that originate from a mother bacterial cell. This process begins with the meticulous selection of specific bacterial strains, most often lactic bacteria such as the Bifidobacterium and the Lactobacillus, acting as a moisturiser in cosmetics. These strains are cultivated from frozen seeds in a suitable nutrient medium where they multiply and grow under controlled conditions.

The bacteria are then subjected to successive fermentations in order to increase the volume ofinoculum required for commercial production. They are transferred to large fermenters where they continue to grow through the addition of water, nitrogen sources, carbohydrates, salts and micronutrients. Once the fermentations are completed, the bacterial cells are concentrated using several techniques such as centrifugation.

The preservation of bacteria requires a specific approach that halts ongoing chemical and cellular reactions. Thus, to stabilise the populations of microorganisms, stabilising solutions such as cryoprotectants or lyoprotectants can be added. In addition to protecting the cells during their storage and transport, freezing and lyophilisation methods ensure the longevity and balance of the bacteria. The resulting lyophilisate is then ground to produce a finely milled powder that can be mixed with excipients and other functional ingredients. This powder probiotic can then be used to manufacture various finished formats such as capsules, tablets or creams.

Throughout the manufacturing process, numerous quality control tests are conducted on in-process samples as well as on the final product to ensure its quality, safety, and compliance with regulatory standards. This rigorous procedure is necessary to ensure that the resulting probiotics are of high quality, stable, and effective, thus meeting customer expectations in terms of health and product performance.

• OUWEHAND A. & al. The Production and Delivery of Probiotics: A Review of a Practical Approach. Microorganisms (2019).

• YU J. & al. Application and mechanism of probiotics in skincare: A review. Journal of Cosmetic Dermatology (2022).