Microbial Surfactants to the Rescue

Abstract

Industrial BiotechnologyVol. 19, No. 3 EditorialFree AccessMicrobial Surfactants to the RescueRichard A. GrossRichard A. GrossIndustrial BiotechnologySearch for more papers by this authorPublished Online:15 Jun 2023https://doi.org/10.1089/ind.2023.29315.rgrAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Industrial Biotechnology provides the cosmetics industry with exciting, cost-competitive, safe and efficacious ingredients.The complexity of the relationship between skin epidermal cells and skin bacteria enables various types of beneficial synergistic relationships. In fact, skin's oily, moist, and dry surface regions provide an environment where microorganisms can thrive. One square centimeter of human skin contains about one billion different microorganisms that include fungi, bacteria, yeast and viruses. For a microorganism to thrive in the skin microbiota, they must provide benefits to the host. One such advantage provided by some bacteria is activation of the innate immune system. Some preferred members of the skin microflora produce antimicrobial compounds to help the skin ward off infections and curb propagation by pathogens. Such benefits highlight the importance of skin care products that promote the overall health of human skin.Presently, synthetic surfactants dominate the market for foaming and emulsifying agents in skincare products even though numerous reports have documented that such chemical surfactants and associated formulations are harmful to skin flora, triggering irritation and allergies. These deleterious effects can occur when surfactants interact negatively with lipids and proteins in skin. Furthermore, after multiple applications, the non-biodegradability of many synthetic surfactants results in accumulation that solubilizes essential skin lipids found within cells of the epidermis.Industrial Biotechnology is coming to the rescue with a family of naturally degradable, skin-safe compounds that work synergistically to provide benefits to skin flora, enhancing skin health. Numerous microbes efficiently produce natural surfactants in a wide range of structures and that fulfill important skin functions. Important examples of microbial surfactants include surfactin, a member of the lipopeptide family, as well as compounds characterized as glycolipids. Notable members of the glycolipid family include sophorolipids, rhamnolipids, and mannoslyerythritol lipids (MELs).It is important to note that microbial surfactants were designed to benefit the microbes that make them; this is why important work is underway to modify natural surfactants by simple and scalable approaches to improve their cost performance. Approaches to modify natural surfactants must meet “green chemistry” metrics or be carried out by physiological changes during fermentations. Recombinant microbial surfactant strains designed to prepare alternative microbial surfactant structures have been developed, though these strains are often not used as they are genetically modified organisms and thus unwelcome by some populations of the world community.The idea at play is that, even though the skin environment has evolved to be a healthy, self-contained ecosystem, the addition of bioactive compounds that enhance a healthy skin microbiome and can come to the aid of skin under environmental duress, is an attractive prospect. Microbial surfactants provide a plethora of natural, practical, and tunable options to explore.Microbial surfactants provide several important physiochemical qualities. For one, they consist of fatty acid structures that hydrate dry skin surfaces, function as antioxidants, and hinder free radical production caused by UV light. Also, biosurfactants consist of natural molecules such as peptides, carbohydrates and hydroxylated lipids that are analogous and therefore compatible with cell membrane components. Furthermore, the mobility of molecular entities through skin cell membranes is determined by their interfacial interactions with skin membrane components. The similarity of cell membrane and glycolipid components allow the latter to have high permeability through skin. Their incorporation into skin membranes can be used to regulate skin barrier properties. For example, the latter can promote skin repair processes and hair regeneration. In vitro experiments with MELS, sophorolipids and rhamnolipids have demonstrated their compatibility with human skin.Also, biosurfactant possess valuable interfacial phenomena such as promoting foaming, solubilization, emulsification and wetting properties that make them valuable constituents in lotions, powders, creams, shampoos, and other cosmetic formulations.Some examples of cosmetic products that contain microbial derived biosurfactants include Sopholiance™ S, a line of shower gels, face cleaners and deodorants produced by Givaudan Active Beauty (Paris, France); Relipidium™, a BASF (Monheim, Germany) product face and body moisturizer; and skin-care products (cleansers, moisturizers, UV filters) manufactured by Kanebo Cosmetics (Tokyo, Japan).Numerous reports document the antimicrobial properties of natural and modified biosurfactants. While, in many cases, the mechanism of action has not been defined, interactions with the cell membrane potentiate bioactivities that are detrimental to pathogens. Modified sophorolipids have been identified that provide effective virucidal and spermicidal activity with antiadhesive properties blocking adhesion of pathogenic microorganisms.Microbial-derived surfactants also function to disrupt biofilms, which is an important step in treating infections. Microbes that cause infections on skin produce exopolysaccharides and other substances that act as a shield against bacteria. This extracellular matrix protects bacteria, causing infections, as therapeutics now need to pass through high viscosity biofilms to kill the invading microbe. Biofilms are associated with skin diseases that include chronic wounds, impetigo, and acne vulgaris. Examples of organisms that cause skin infections and protect themselves by producing a biofilm include Cutibacterium acnes, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Hence, microbial-derived surfactants are effective because they disrupt biofilms by infiltrating the matrix, exposing individual microorganisms that then become easier to eliminate. Another important class of cosmetic products are moisturizers. While shampoos and body wash provide a feel-good effect when applied, prolonged contact with these products can harm the stratum corneum (outermost skin layer). Problems incurred include increasing the solubility of cell lipids and causing protein denaturation. Microbial-derived surfactants have been identified, tested, and found to be effective at moisturizing skin while providing better skin compatibility than currently used surfactants in moisturizer formulations. MELS, a member of the family of glycolipids produced by species of Candida, is a beneficial microbial surfactant moisturizer ingredient. MELS were tested using 3D skin models that were pretreated to exhibit dried skin and corresponding loss of cell viability. Treatment with a MEL analogue (MEL-A) resulted in about a 90% improvement in skin viability.Other skin irritations can occur due to skin disorders that result in inflammation and dry/itchy/scaly skin patches. This is often attributed to a deficiency in ceramide sphingolipids, which function as polar lipids in the stratum corneum responsible for skin barrier functions like maintaining cell adhesion and epidermal differentiation. While the best treatment would be to apply ceramides to affected skin areas, these are expensive. MELs have been used in place of ceramides, providing a cost-effective alternative treatment option. Overall, MELs are skin care ingredients that promote healthy skin microbiota through multiple pathways. Also, the analogue MEL-C is an effective radical scavenger. It follows that MELs are effective ingredients in skin-whitening formulations. These products have shown promise in treating hyperpigmentation by inhibiting melanocyte formation.In conclusion, the human skin is a responsive ecosystem that must effectively interact with changing environmental conditions. The skin functions as a primary barrier that is regularly challenged by toxins and pathogenic microorganisms. Results thus far support that the large family of microbial surfactants can play a critical role in protecting and nourishing the skin. The production of microbial-derived surfactants in virtually every known case provides a mixture of congeners, consisting of a family of analogues that differ in small but significant ways that can affect performance. Studies determining the effectiveness of microbial surfactant ingredients in cosmetic formulations have often used the natural mixture of congeners. This is cost-effective but troublesome since it is difficult to prepare microbial surfactant products with consistent mixture compositions. However, the presence of a mixture provides ideas developed by nature on how product properties can be tuned.Furthermore, post-modification of microbial surfactants provides a route to convert a product mixture into a more uniform combination of constituents. Modifications also provide opportunities to improve natural design that was optimized by evolution to serve microorganisms and not humans. There remains a major opportunity to relate structure and mechanism for the broad family of microbial surfactants and the complexity of skin biology.We are at the beginning of a journey where mechanistic insights will inform design principles that lead to more effective, naturally derived microbial surfactants for numerous applications, including cosmetic ingredients. Progress will rely on harnessing the power of Industrial Biotechnology to increase microbial surfactant yields from lower-cost substrates such as agro-industrial wastes and co-products. Easing of constraints in the use of genetically modified organisms will enable fine-tuning of product structures without the need for post-fermentation modification. Also, downstream processing must be integrated with innovations in upstream process development to truly optimize the biomanufacturing route.FiguresReferencesRelatedDetails Volume 19Issue 3Jun 2023 InformationCopyright 2023, Mary Ann Liebert, Inc., publishersTo cite this article:Richard A. Gross.Microbial Surfactants to the Rescue.Industrial Biotechnology.Jun 2023.95-96.http://doi.org/10.1089/ind.2023.29315.rgrPublished in Volume: 19 Issue 3: June 15, 2023PDF download