Comparative evaluation of postbiotics and parabiotics derived from Lactiplantibacillus plantarum: functional properties and cytotoxicity

In the present study, postbiotics and parabiotics of Lactiplantibacillus plantarum were prepared and comparatively evaluated for their functional composition, antimicrobial activity, antioxidant capacity, and cytotoxicity. Fourier-transform infrared spectroscopy analysis showed that postbiotics were predominantly enriched with soluble bioactive metabolites, including organic acids and peptides, whereas parabiotics retained structural cellular components. Postbiotics demonstrated significantly superior antimicrobial activity, with 1.5 to 1.7-fold larger inhibition zones on Escherichia coli and Listeria monocytogenes , and achieved significant bacterial reduction within 3 h compared to 9–12 h for parabiotics. Both biotics maintained stable antimicrobial activity over eight weeks of storage. Antioxidant assessment of postbiotics and parabiotics revealed comparable DPPH radical scavenging capacities (IC₅₀: 0.54 vs. 0.62 mg/mL), whereas postbiotics exhibited significantly higher ferric reducing power (FRAP: 59.9 vs. 32.1 µmol Fe 2 ⁺/L). Moreover, postbiotics exerted higher dose-dependent cytotoxicity against colorectal cancer (HT-29) cells (< 50% viability) but retained relatively high cell viability (> 70%) in normal fibroblasts. Fluorescence staining further confirmed selective apoptosis induction. These findings highlight postbiotics as multifunctional bioactive preparations with superior antimicrobial, antioxidant, and selective anticancer properties, supporting their potential application as natural bio-preservatives and functional ingredients in food and nutraceutical systems.