The increasing demand for natural cosmetic products is indicative of a growing awareness of the potential adverse environmental and health implications associated with synthetic compounds. Synthetic preservatives, which are commonly employed in cosmetics to prevent microbial contamination, have been implicated in the occurrence of allergic reactions and contribute to environmental pollution. This has led to a growing demand for safer and more sustainable alternatives. Natural preservatives, particularly bioactive compounds derived from microorganisms, have emerged as a promising substitute due to their biodegradability and compatibility with consumer safety standards.

Of particular interest are bioactive metabolites produced by yeasts, which have gained attention for their ability to inhibit the growth of pathogenic microorganisms.

This study investigated the antimicrobial potential of peptides produced by the yeasts Saccharomyces cerevisiae and Wickerhamomyces anomalus as natural preservatives in a cosmetic emulsion formulation. Antimicrobial efficacy was evaluated using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and a 48-hour challenge test against common pathogenic microorganisms including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans. The results showed that the 2-10 kDa peptidic fraction derived from S. cerevisiae metabolism achieved MICs as low as 450 µg/mL for E. coli and 56.25 µg/mL for S. aureus. Similarly, metabolites from W. anomalus exhibited MICs of 450 µg/mL against E. coli and 575 µg/mL against S. epidermidis. The 48-hour challenge test showed a significant reduction in microbial growth when the peptide fractions were applied, particularly against E. coli and S. aureus.

This study highlights the potential of yeast-derived bioactive metabolites as sustainable and effective alternatives to synthetic preservatives in cosmetics.