The aim of this study was to evaluate the probiotic properties of lactic acid bacteria (LAB) isolated from kimchi and antioxidant and anti-inflammatory activities of heat-killed LAB strains. Regarding probiotic properties, Lactiplantibacillus plantarum SMF398 and L. plantarum SMF470 isolated from kimchi can survive under artificial gastric condition and adhere strongly to HT-29 cells. The SMF398 and SMF470 strains showed strong antimicrobial activity and co-aggregation against pathogenic bacteria. The heat-killed cells of LAB (1 mg/mL) were prepared by heating at 121℃ for 15 min. MTT assay revealed that the heat-killed cells (1 mg/mL) of SMF398 and SMF470 were not toxic to HT-29 cells. The heat-killed SMF398 and SMF470 showed significantly higher DPPH and ABTS radical scavenging activities as well as βcarotene bleaching inhibitory activity than the heat-killed L. plantarum ATCC14917, a control probiotic strain (p<0.05). In lipopolysaccharide-induced RAW264.7 cells, the heat-killed SMF398 and SMF470 significantly reduced the nitric oxide production by 30.92% and 22.81%, respectively (p<0.05). Furthermore, the heat-killed SMF398 and SMF470 significantly decreased the gene expression levels of tumor necrosis factor-α, interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2 up to 58.02%, 67.70%, 53.44%, 45.90%, respectively (p<0.05). These results suggest that the heat-killed L. plantarum SMF398 and L. plantarum SMF470 might be useful as antioxidant and anti-inflammatory agents.

This study aimed to determine the probiotic properties of lactic acid bacteria (LAB) isolated from kimchi and to develop a probiotic starter culture for yogurt supplemented with red ginseng extract powder (RGE). Two LAB strains were selected by analysis of acid resistance, bile resistance and antioxidant activity, and identified as Lactiplantibacillus plantarum SY46 and Levilactobacillus brevis SY65 by 16S rRNA sequencing. Both strains showed similar or higher auto-aggregation, co-aggregation, antimicrobial activity, and antioxidant activity compared to Lacticaseibacillus rhamnosus GG, a commercial probiotic strain. The yogurt samples, which were supplemented with 5% or 10% RGE and fermented with the mixed culture of SY46 and SY65, exhibited pH values of 4.28-4.46 and titratable acidity of 1.25-1.53%, and their viable cell counts were over 9.0 Log CFU/mL. The antioxidant effects using DPPH radical scavenging and β-carotene bleaching assay were significantly increased with increasing RGE concentrations (p<0.05). Overall, yogurts fermented with 5% or 10% RGE were acceptable in terms of pH, titratable acidity, cell viability and antioxidant effect. These results might provide useful information for the development of ginseng dairy products with probiotic properties.

This study aimed to optimize the fermentation condition of black bean using probiotic lactic acid bacteria (LAB) and to evaluate characteristics and antioxidant activity of LAB fermented and heat-treated black bean. Two LAB strains were selected by analysis of acid resistance, bile resistance, antimicrobial activity, and antioxidant activity, and identified as Lactiplantibacillus plantarum CH9 and Lactiplantibacillus plantarum SU18 by 16S rRNA sequencing. Both strains showed similar or higher acid resistance, bile resistance and antimicrobial activity, compared to Lacticaseibacillus rhamnosus GG, a commercial probiotic strain. The heat-killed cells of CH9 and SU18 strains showed significantly (p<0.05) higher DPPH and ABTS radical scavenging activities than live cells. Fermentation of black bean (30%) treated with Alcalase using the two selected strains was found to be optimal condition, increasing viable cell count of LAB up to 10.8 Log CFU/g. During the fermentation, the titratable acidity of Alcalase-treated black bean was notably increased with concomitant decrease in the pH. LAB fermentation significantly (p<0.05) increased antioxidant activity based on DPPH and ABTS radical scavenging activities as well as total phenol content. In addition, total phenol content and antioxidant activity were significantly (p<0.05) enhanced by heat processing (121C, 15 min) of the fermented products. These findings are expected to be useful for the development of various LAB-fermented foods containing heat-killed probiotics.