A different approach to vaginal-derived probiotics: anti‑quorum sensing and anti‑biofilm activities of exopolysaccharides

Aims This study aimed to characterize the physicochemical properties of exopolysaccharides (EPS) produced by vaginal Lactobacillus casei L2, Lactobacillus plantarum L4, Lactobacillus crispatus L5, and Lactobacillus rhamnosus L17 strains and to evaluate their antimicrobial, antibiofilm, anti-quorum sensing (anti-QS), and antiproliferative activities under in vitro conditions.Methods EPS production was quantified using the phenol–sulfuric acid method, with glucose as a standard. Antimicrobial activity was assessed against selected Gram-positive and Gram-negative bacteria. Antibiofilm activity was evaluated by quantitative assays and visualized using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Anti-QS activity was determined using Chromobacterium violaceum ATCC 12,472 as an indicator strain. Antiproliferative effects were analyzed in the MDA-MB-231 breast cancer cell line.Results All EPS preparations exhibited varying degrees of antimicrobial and antibiofilm activity, with L17 demonstrating the strongest biofilm inhibition. EPS derived from L2 and L17 strains showed marked quorum sensing inhibitory effects. In the MDA-MB-231 cell line, EPS from L2 and L17 reduced cell viability in a dose-dependent manner, with maximal inhibition observed at 85 µg/mL.Conclusions These findings demonstrate that EPS derived from vaginally derived Lactobacillus spp. species possess strain-dependent biological activities, particularly in antibiofilm effect and regulation of quorum sensing. Further structural and mechanistic studies are needed to elucidate their functional potential.