The skin microbiome plays a critical role in maintaining skin health, but imbalances involving pathogenic bacteria like Staphylococcus aureus and Staphylococcus epidermidis can lead to common skin issues such as acne, dermatitis, and wound infections. As the demand for microbiome-friendly, natural cosmetic products grows, lactic acid bacteria (LAB) have emerged as attractive candidates due to their skin-beneficial properties. However, most LAB strains used in skincare are derived from fermented foods, with limited exploration of plant-based strains. In this context, the authors investigated the dermatological potential of a novel LAB strain, Pediococcus pentosaceus THG-219, isolated from ginseng—a medicinal plant known for its pharmacological properties—to assess its safety and efficacy as a functional cosmetic ingredient.
Methods
LAB was isolated from ginseng extract using culture methods and identified via 16S rRNA sequencing. The antimicrobial activity of the strain and its fractions was tested against S. aureus and S. epidermidis using broth microdilution and disk diffusion assays. Cytotoxicity was assessed on human keratinocytes (HaCaT) and intestinal epithelial cells (Caco-2). Biofilm inhibition, adhesion to host cells, and pathogen exclusion were also evaluated. A Galleria mellonella larval model was used to test in vivo safety and antibacterial efficacy, and the strain’s tolerance to acid, bile, and heat was examined.
Key Findings
- P. pentosaceus THG-219 showed strong antimicrobial activity, with MIC values of 0.625 mg/mL (against S. aureus) and 1.25 mg/mL (against S. epidermidis), superior to the reference strain.
- Ethyl acetate (EA) fractionation enhanced antimicrobial potency, increasing inhibition zones in disk diffusion assays.
- The strain inhibited biofilm formation and caused visible structural damage to pathogenic cells under SEM.
- THG-219 displayed no cytotoxicity up to 100 µg/mL in HaCaT and Caco-2 cells.
- It exhibited strong adhesion to host cells and inhibited pathogen adhesion by over 40%.
- In vivo testing using G. mellonella larvae confirmed safety and improved survival rates following bacterial infection, especially against S. aureus.
- The strain demonstrated high acid (54% survival at pH 2.5), bile (31% survival), and thermal tolerance (50% survival at 70°C).
This study introduces P. pentosaceus THG-219, a ginseng-derived LAB strain, as a safe and effective antimicrobial candidate for cosmetic applications. Its ability to combat pathogenic bacteria, support host cell colonization, and endure harsh environmental conditions highlights its potential as a multifunctional ingredient in skincare formulations. The novelty lies in its plant-based origin, high adhesion, enhanced antimicrobial effects after fractionation, and validation through an ethical in vivo model. Future research should focus on isolating active metabolites, exploring formulation strategies, and conducting clinical trials to advance its integration into dermatological products.
Link to the study: https://www.mdpi.com/2076-2607/13/5/1093
