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. Immuno-modulatory 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 × 107 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 × 107 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.

Introduction
 Materials and Methods
  Bacterial strains
  Scanning electron microscopic observation
  Bacteriocin like substance producing activity
  Acid, bile salt and heat tolerance
  Antimicrobial activity
  Adhesion property to Caco-2 cells
  Activation of macrophages cells
  Measurement of NO production
  Cytokine measurements by ELISA (IL-1β and TNF-α)
  NF-κB Assay
  Statistical analysis
 Results
  Characteristics of Enterococcus faecium JS1-8 for probiotic use
  Bacteriocin- like substance produced by E. faecium JS1-8
  NO, NF-κB and cytokine production in RAW 264.7 or RAW BLUE cells
 Discussion
 Acknowledgements
 ORCID
 References

• Su-Bin Ahn(College of Veterinary Medicine, Chungbuk National University, Cheongju 362-763, Korea)
• Ho-Eun Park(College of Veterinary Medicine, Chungbuk National University, Cheongju 362-763, Korea)
• Sang-Myeong Lee(Division of Biotechnology, College of Environmental & Bioresource Sciences, Chonbuk National University, Iksan 570-752, Korea)
• So-Young Kim(Functional Food & Nutrition Division, Department of Agrofood Resources, National Academy of Agricultural Science, Rural Development Administration, Wanju 565-851, Korea)
• Wan-Kyu Lee(College of Veterinary Medicine, Chungbuk National University, Cheongju 362-763, Korea) Corresponding author