This study aimed to investigate the effects of antioxidant and anti-inflammatory activities of heat-killed lactic acid bacteria (LAB) produced under different temperature conditions. Regarding probiotic properties, Limosilactobacillus fermentum SMF743 and Lactiplantibacillus plantarum SMF796 isolated from kimchi showed strong acid and bile salt resistance, adhesion activity onto HT-29 cells, and antimicrobial activity against pathogenic bacteria. Based on the results of thermal death time and temperature, heat-killed LAB cells (1 mg/mL) were prepared by heating at 70oC (180 min), 80oC (120 min), 100oC (30 min), and 121oC (15 min). The heat-killed SMF743 and SMF796 showed significantly higher DPPH and ABTS radical scavenging activities than live cells (p<0.05). The heat-killed SMF743 and SMF796 at 70oC or 121oC revealed stronger DPPH and ABTS radical scavenging activities and inhibition of nitric oxide production than those at 80oC or 100oC. Furthermore, heat-killed SMF743 and SMF796 at 121oC significantly reduced the gene expression levels of tumor necrosis factor-, inducible nitric oxide synthase, and cyclooxygenase- 2 up to 53.33%, 58.67%, and 83.67%, respectively, in lipopolysaccharide (LPS)-induced RAW264.7 cells (p<0.05). These results suggest that heat-killed L. fermentum SMF743 and L. plantarum SMF796 can be used as natural antioxidants and anti-inflammatory agents.

This study was conducted to evaluate the effect of lactic acid bacteria (LAB) inoculation to domestically-cultivated Italian ryegrass (IRG) on silage fermentation and in vitro ruminal fermentation. There were six treatments based on the LAB inoculants: 1) no addition of LAB (negative control: NC), additions of 2) commercially-available LAB (positive control: PC), 3) Lactobacillus plantarum (LPL), 4) L. paracasei (LPA), 5) L. acidophilus (LA), and 6) L. pentosus (LPT). All treatments were inoculated at a concentration of 106 CFU/g and ensiled for 3, 7, 21, and 42 days in triplicate and analyzed for nutritive values when ensiling was terminated. Day 42 silage from all treatments were also examined for in vitro ruminal fermentation. After 42 days, LAB-inoculated silages had higher (P<0.05) lactic acid concentration compared to the NC. In terms of nutritive values, the silages treated with LPA, LA, and LPT showed higher (P<0.05) crude protein and lower (P<0.05) neutral detergent fiber and acid detergent fiber content compared to the rest of the treatment. In vitro ruminal dry matter degradability was not affected by LAB addition. However, LAB-treated IRG had shown higher (P<0.05) ammonia-N compared with that of the NC. LPA had shown the highest (P<0.05) volatile fatty acid concentration among the LAB examined. In conclusion, the addition of a single strain of LAB appeared to produce a quality IRG silage compared with the NC and the PC. Among the strains examined, LPA seemed to be superior to the others.