Characteristics and immuno-modulatory effects of Enterococcus faecium JS1-8 isolated from Kimchi

Abstract

Characteristics and immuno-modulatory effects of Enterococcus (E.) faecium JS1-8 isolated from Kimchi were investigated for potential probiotic use. We measured their acid, bile, and heat tolerances, adhesion properties in Caco- 2 cells, antimicrobial activity against pathogenic bacteria, and bacteriocin-like substance-producing activity. Immunomodulatory effects of E. faecium JS1-8 were measured by determination of nitric oxide (NO), nuclear factor-κB (NF- κB), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) production in RAW 264.7 cells or RAW BLUE cells. JS1-8 survived at pH 2.0 for 2 hr and showed tolerance to 0.3% oxgall bile salt, and it survived after exposure for 5 min at 80°C. JS1-8 showed high antimicrobial inhibition zones to Staphylococcus aureus (460 mm), Listeria monocytogenes (310 mm), Salmonella enteritidis (280 mm), and E. coli (150 mm). Bacteriocin-like substance produced by JS1-8 showed a broad spectrum of activity against Listeria monocytogenes KCCM 40307 and Lactobacillus sake KCCM 40264. Low concentration (1 × 10 7 CFU/mL) of heat-killed E. faecium JS1-8 induced statistically higher production of NO than Lactobacillus rhamnosus GG (LGG), which is a well-known immuno-modulatory lactic acid bacteria. Low and high (5 × 10 7 CFU/mL) concentrations of JS1-8 induced statistically higher production of NF-κB than that produced by LGG. We also found that JS1-8 increased production of pro-inflammatory cytokines such as IL-1β and TNF-α in a concentration-dependent manner. As a result, E. faecium JSI-8 could be used as a useful probiotic for controlling pathogens and enhancing host immune responses.