Lyophilized Cell-Free Supernatants of Lacticaseibacillus paracasei T0901 Isolated from Fermented Palm Sap Exhibit Antiacne and Antimelanogenic Activities in B16F10 Melanoma Cells

Acne vulgaris is a common chronic inflammatory skin condition. Conventional acne treatments are often limited by adverse effects, driving interest in alternative therapies. This study explored the multifunctional bioactivities of a lyophilized cell-free supernatant (LCFS) derived from Lacticaseibacillus paracasei T0901, isolated from fermented palm sap, with a focus on its antimicrobial, antibiofilm, and antimelanogenic potential for dermatological applications. Antimicrobial activity was evaluated using agar well diffusion and broth microdilution assays against acne-associated pathogens, while antibiofilm effects were quantified via crystal violet staining. Antimelanogenic activity was assessed in α-melanocyte-stimulating hormone (α-MSH)-stimulated B16F10 melanoma cells by measuring melanin content and tyrosinase activity. Whole-genome sequencing was performed to identify genes linked to observed bioactivities, and molecular docking was used to predict metabolite–protein interactions. The LCFS exhibited strong inhibitory activity against acne-associated bacteria, with inhibition zones of C. acnes (10.67 ± 0.58 mm), S. epidermidis (21.00 ± 0.00 mm), and S. aureus (20.00 ± 0.00 mm), and a minimum inhibitory concentration of 25 mg/mL. Biofilm formation was significantly reduced by 62.98 ± 3.54%. In α-MSH-stimulated B16F10 cells, LCFS treatment (10 mg/mL) significantly decreased melanin content (73.23 ± 2.36%) and intracellular tyrosinase activity (68.19 ± 6.29%) relative to control. Genomic analysis revealed antioxidant-related genes (sodA, trxB, nox), pigmentation regulators (mco, fcbD), and buk (butyrate kinase), supporting the observed bioactivities. Molecular docking further demonstrated strong binding affinities of LCFS-derived metabolites to tyrosinase and MITF, suggesting modulation of melanogenic pathways. Collectively, these results indicate that L. paracasei T0901 produces safe postbiotic compounds with potent antimicrobial, antibiofilm, and antimelanogenic activities, highlighting its promise as a multifunctional ingredient in probiotic-based skincare formulations.