Probiotic effects of kimchi-derived lactic acid bacteria (LAB), Lactobacillus plantarum PNU (KCCM 11532P) and Leuconostoc mesenteroides PNU (KCCM 11353P), were observed. In addition, fermentation characteristics and health functionalities of kimchi by inoculating kimchi LAB starters were studied. We manufactured single LAB starter kimchi (Lab. plantarum pnuK, Lab. plantarum 3099K, Leu. mesenteroides pnuK), mixed LAB starter kimchi (Lab. plantarum pnu/Leu. mesenteroides pnuK, Lab. plantarum 3099/Leu. mesenteroides pnuK) with inoculum size of 1.0×106 CFU/g, as well as naturally fermented kimchi (NK), and fermented them for 6 days at 15°C to observe effects of kimchi LAB starter on fermentation characteristics of kimchi. In this study, we evaluated inhibitory effects of starter-kimchi on AOM/DSS induced colitis-associated colon cancer (CAC) using 6-week-old Balb/c male mice.
The Lab. plantarum PNU and Leu. mesenteroides PNU have tolerance in simulated gastric juice, small intestinal juice and heat conditions. Also it shows high adhesion to human intestinal epithelial cell and antioxidant/anticancer effects.
The pH and acidity of the early phase of fermentation were not different, but kimchi with the starters showed rapid changes in the pH and acidity 2 days after fermentation. As the fermentation progressed, the level of total aerobic bacteria and Lactobacillus sp. increased similarly with or without Lab. plantarum (LP) inoculation. However, the level of Leuconostoc sp. was high in kimchi inoculated with Leu. mesenteroides starter. In the sensory evaluation test, kimchi with starters received higher overall acceptability scores than those of NK, especially mixed starter added kimchi earned the highest score.
In DPPH and hydroxyl radical scavenging activity, kimchi with the starters exhibited higher activity than that of NK. In the MTT assay of HCT-116 and HT-29 human colon cancer cells, NK showed inhibition rates of 63.4 and 51.9%, but LPpnuK achieved 77.1 and 68.8%, respectively. This study showed that inoculating starters in kimchi increased in vitro antioxidant and anticancer activities, and single starter (LP) added kimchi revealed higher functionality than the kimchi with mixed starter.
Also, suppression of colon cancer was observed in all kimchi-administered groups in AOM/DSS induced colitis-associated colon cancer (CAC) mice, and weight-to-length ratio of colon and occurrence of tumor were the lowest in starter-added kimchi-administered groups. The groups showed less changes in histochemical investigation, compared with control group. Concentrations of serum pro-inflammatory cytokines were found the lowest from starter-added kimchi-administered group. Kimchis with the starters effectively up-regulated the gene expressions of the pro-apoptotic gene of Bax, but down-regulated Bcl-2 in the colon tissue. They promoted expressions of p53 and p21, and suppressed expressions of inflammation-related genes, iNOS and COX-2, compared with NK-administered group.
Taken together, it is expected that these kimchi-derived LAB may be used as probiotic source. And these results also suggest that these kimchi starters help to improve quality and health functionality of kimchi, however, more detailed studies and needed for the development of starters of kimchi.