The skin’s microbial ecosystem plays a vital role in maintaining its health, and an imbalance can lead to skin conditions such as acne and seborrheic dermatitis (SD). Traditional treatments for these conditions, like antibiotics, can increase drug resistance in pathogens. Probiotic therapy offers a potential solution by restoring microbial balance and improving the skin barrier. The researchers investigated the ability of probiotic metabolites to inhibit Malassezia furfur (M. furfur) and Cutibacterium acnes (C. acnes), pathogens associated with SD and acne. The goal was to identify effective probiotic strains and their key metabolites for alleviating these skin conditions.
Methods
This study examined the fermentation growth inhibition of 18 commercial probiotic strains on M. furfur and C. acnes in vitro. Supernatants from the probiotic strains were tested for inhibitory effects. Active metabolites were identified using ammonium sulfate precipitation, dialysis, and HPLC analysis. Pathogen growth inhibition was measured by observing the optical density at 600 nm (OD600) over 72 hours.
Key Findings
•Inhibitory Effects of 18 Probiotic Strains:
◦Bifidobacterium lactis (B. lactis) and Lacticaseibacillus rhamnosus (L. rhamnosus) strains showed significant inhibition of M. furfur and C. acnes.
◦B. lactis maintained high inhibition over 72 hours, while L. rhamnosus decreased to around 60%.
◦B. lactis strain HN019 exhibited the highest efficacy, with over 90% inhibition after 72 hours.
•Antibacterial Proteins and Peptides
◦Samples with a 10,000 Da molecular weight cut-off (MWCO) showed no inhibition, while samples with a 200 Da MWCO did.
◦ Crude protein extracts of Bi07 and HN019 also exhibited an inhibitory effect at approximately 40% to 50% against M. furfur.
◦The crude protein extract of B420 inhibited C. acnes by 61% at 48 hours, while no inhibition was observed in the crude protein extracts of other strains.
◦The 48-hour inhibition rate of the supernatant from the Bi07 crude protein extracts was 40%, and that of HN019 was 28% against C. acnes.
•Inhibitory Effects of Organic Acids:
◦Neutralized supernatants partially inhibited pathogens, with 40% to 80% inhibition at 48 hours.
◦Lactic acid and acetic acid were the most abundant organic acids.
◦Organic acid mixtures from the four strains had significant inhibition effects, ranging from 53% to 95%.
◦Synergistic effects of organic acid combinations lowered the MIC, with strain-dependent effects.
The study demonstrated that fermented supernatants from selected probiotics inhibited M. furfur and C. acnes, with active compounds under 10,000 Da showing bacteriostatic properties. Utilizing a 10,000 Da MWCO membrane filtration method enhances production efficiency. This study indicates the potential of using specific probiotic strains, like B. lactis HN019, to develop targeted treatments for skin conditions. The extended measurement period and exploration of synergistic metabolite effects provide a novel contribution for developing probiotic-based skincare.
Link to the study: https://www.mdpi.com/2079-9284/12/1/3
