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Response surface analysis and anti-inflammatory activity of a potential postbiotic exopolysaccharide produced by probiotic Lacticaseibacillus paracasei K56

Year: 2025

Type: article

Abstract: Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) have been extensively studied, but the potential postbiotic activities of the EPSs are not well characterized. A probiotic strain of Lacticaseibacillus paracasei K56 previously characterized by strong postbiotic activities was investigated by response surface analysis for production of an EPS, designated K56-EPS, and by testing EPS for anti-inflammatory effects in a LPS-induced RAW264.7 macrophage inflammation model. The optimal protocol for EPS production (76.27 mg/L) in skim milk employed 8.7 % ( w /w) inoculum for 34.2 h fermentation at 33.9 °C, followed by extraction with 6 % ( w / v ) TCA and treatment of the culture supernatant with 4 volumes of ethanol at 4 °C for 24 h. The chromatographically purified K56-EPS had a monosaccharide composition of rhamnose, glucosamine hydrochloride, galactose, and glucose in a molar ratio of 0.387:0.053:0.188:0.371, with a molecular weight of 3.39 × 10 5 Da. Furthermore, K56-EPS (200 μg/mL) effectively suppressed expression of key genes within the TLR4/ NF-κB signaling pathway and inhibited the nuclear translocation of the NF-κB p65 protein to interrupt transcriptional activation of inflammatory mediators. Higher dose of K56-EPS (400 μg/mL) was shown to significantly attenuate phagocytosis, reduce acid phosphatase (ACP) activity, decrease nitric oxide (NO) release, and downregulate TNF-α, IL-6, IL-1β, and IL-10 cytokine levels ( p < 0.05). Therefore, K56-EPS demonstrated prominent in vitro anti-inflammatory activity with significance as a potential novel postbiotic of LAB for applications in functional dairy foods.

Source: Journal of Functional Foods

DOI: 10.1016/j.jff.2025.107126