Abstract
Lactic acid bacteria (LAB) are a promising source of postbiotics with potential applications in the cosmetic industry; however, strains isolated from fermented vegetables are rarely studied. This study aimed to characterize the bioactivity of postbiotics produced by Lactiplantibacillus pentosus B1 isolated from fermented beetroot juice. An organic extract (ELCFS) and a lyophilizate (LLCFS) were prepared from cell free supernatant of B1 and assessed for antimicrobial activity (MIC, MBC), biofilm inhibition and eradication ability against Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes and Cutibacterium acnes. Stability (temperature, time) and cytotoxicity were also examined. Metabolite composition was determined by GC-MS. MIC values were 10 g/L for ELCFS and 10-20 g/L for LLCFS. ELCFS completely inhibited biofilm formation at 10 g/L, and LLCFS at 25 g/L; partial inhibition was observed at lower concentrations (e.g., E. coli-32.99% at 1 g/L ELCFS; S. aureus and S. pyogenes-74.01% and 95.67%, respectively, at 5 g/L). Complete eradication of mature biofilm was obtained at 2.5 g/L (ELCFS) and 12.5 g/L (LLCFS), while a significant partial effect was observed from 0.04 g/L ELCFS for E. coli (29.3%) and 0.2 g/L LLCFS for S. pyogenes (23.2%). C. acnes showed the lowest sensitivity. A reduction in viability of eucaryotic cells was observed at ≥ 5 g/L ELCFS (90.32%) and 12.5-50 g/L LLCFS (55.87-89.20%). Importantly, concentrations causing partial inhibition and eradication of biofilm did not show cytotoxicity towards fibroblasts. The preparations were thermostable and retained activity over time; only incubation of ELCFS at elevated temperature significantly reduced its antimicrobial activity against the C. acnes strain. GC-MS analysis revealed five organic acids, with lactic acid dominating. The results confirm the potential of L. pentosus B1 as a source of stable, effective, and safe postbiotics for cosmetology applications.