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 <i>Lacticaseibacillus paracasei</i> 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 <i>C. acnes</i> (10.67 ± 0.58 mm), <i>S. epidermidis</i> (21.00 ± 0.00 mm), and <i>S. aureus</i> (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 (<i>sodA</i>, <i>trxB</i>, <i>nox</i>), pigmentation regulators (<i>mco</i>, <i>fcbD</i>), and <i>buk</i> (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 <i>L. paracasei</i> T0901 produces safe postbiotic compounds with potent antimicrobial, antibiofilm, and antimelanogenic activities, highlighting its promise as a multifunctional ingredient in probiotic-based skincare formulations.