Lactic acid bacteria (LAB) were reported to comprise the majority of the bacterial population in mukeunji, a long-fermented kimchi. This current study investigated the probiotic abilities of LAB isolated from mukeunji. Forty bacterial strains from mukeunji were identified by SDS-PAGE gel patterns, which were further tested for acid and bile tolerance. An assessment of the immuneboosting effects of these strains in RAW264.7 cells was also carried out by measurement of secreted proinflammatory cytokines. Heat-killed LAB were also tested for their contribution to cytokine production because certain LAB are not durable in the digestive tract. Immune-boosting strains were further characterized by SDS-PAGE of whole-cell protein and 16S rRNA gene sequencing, resulting in the identification of Lactobacillus plantarum, L. sakei, Weissella cibaria, and Pediococcus parvulus. These data and the fact that mukeunji is highly consumed in Korea, together, highlight the need of detailed epidemiological and animal feeding studies.
Keywords: cytokine; lactic acid bacteria; macrophage; mukeunji; probiotics.