Whole genome sequences of Lactococcus lactis KCKM 0851 isolated from green onion kimchi.

Lactococcus lactis KCKM 0851 isolated from green onion kimchi is a probiotic candidate and can be used as a starter culture for kimchi and dairy products. The whole-genome data of this strain will help us understand its genetics and metabolic characteristics.

Production, Characterization, and Antioxidant Activities of an Exopolysaccharide Extracted from Spent Media Wastewater after Leuconostoc mesenteroides WiKim32 Fermentation.

Bacterial exopolysaccharides (EPSs) are important alternatives to plant polysaccharides in fermented products and exhibit antioxidant activity, which is particularly desirable for functional foods. This study evaluated the use of spent media wastewater (SMW) derived from kimchi fermentation for the production of an EPS and analyzed the characterization and antioxidant activity of the resulting EPS. The EPS concentration and conversion yields of sequential purification were 7.7-9.0 g/L and 38.6-45.1%, respectively. Fourier transform infrared spectra and NMR spectra indicated that the EPS was a linear glucan with α-(1 → 6) linkages. The EPS also exhibited thermal tolerance to high temperatures. In vitro antioxidant activity analyses indicated the scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, thiobarbituric acid reactance (TBAR), and ferric ion reducing antioxidant power (FRAP) values of 71.6-79.1, 28.2-33.0%, and 0.04-0.05 mM FeCl3, respectively. These results reveal that the EPS extracted from SMW has potential as a thermally tolerant, nontoxic, and natural antioxidant for industrial applications.

Mixed starter of Lactococcus lactis and Leuconostoc citreum for extending kimchi shelf-life.

To develop a starter culture system for improving the shelf-life and quality of kimchi, we prepared a mixed starter composed of Lactococcus lactis and Leuconostoc citreum. Two strains, L. lactis WiKim0098 and Leu. citreum WiKim0096, showed high antimicrobial activity and mannitol productivity, respectively. These lactic acid bacteria (LAB) were introduced as a starter into kimchi following cultivation in foodgrade liquid medium. Two kimchi samples, with and without starter, were fermented for 12 days at 10°C. Compared to the control kimchi without starter, a lower initial pH and higher number of LAB were observed in kimchi with starter at 0 day. However, the starter in kimchi prolonged the period taken by kimchi to reach to pH 4.2 by approximately 1.5-fold compared to that in the control kimchi. To estimate the effect of the starter on the flavor of kimchi, metabolite changes were evaluated by gas chromatography/mass spectrometry. In starter fermented kimchi, the levels of mannitol and amino acid, which are associated with the flavor of kimchi, were increased following fermentation. The amount of mannitol was confirmed by high-performance liquid chromatography analysis, showing concentrations of 3.4 and 5.1 mg/ml for the control and starter fermented kimchi, respectively. Thus, mixed starter inoculated with L. lactis WiKim0098 and Leu. citreum WiKim0096 may extend the shelf-life of kimchi and improve its sensory characteristics.

Lactobacillus curvatus WiKim38 isolated from kimchi induces IL-10 production in dendritic cells and alleviates DSS-induced colitis in mice.

Probiotics such as lactobacilli and bifidobacteria have healthpromoting effects by immune modulation. In the present study, we examined the immunomodulatory properties of Lactobacillus curvatus WiKim38, which was newly isolated from baechu (Chinese cabbage) kimchi. The ability of L. curvatus WiKim38 to induce cytokine production in bone marrow-derived dendritic cells (BMDCs) was determined by enzyme-linked immunosorbent assay. To evaluate the molecular mechanisms underlying L. curvatus Wikim38-mediated IL-10 production, Western blot analyses and inhibitor assays were performed. Moreover, the in vivo anti-inflammatory effects of L. curvatus WiKim38 were examined in a dextran sodium sulfate (DSS)-induced colitis mouse model. L. curvatus WiKim38 induced significantly higher levels of IL-10 in BMDCs compared with that induced by LPS. NF-κB and ERK were activated by L. curvatus WiKim38, and an inhibitor assay revealed that these pathways were required for L. curvatus WiKim38-induced production of IL-10 in BMDCs. An in vivo experiment showed that oral administration of L. curvatus WiKim38 increased the survival rate of mice with DSS-induced colitis and improved clinical signs and histopathological severity in colon tissues. Taken together, these results indicate that L. curvatus Wikim38 may have health-promoting effects via immune modulation, and may thus be applicable for therapy of various inflammatory diseases.

Starter cultures for kimchi fermentation.

Kimchi is a traditional Korean vegetable product that is naturally fermented by various microorganisms present in the raw materials. Among these microorganisms, lactic acid bacteria dominate the fermentation process. Natural fermentation with unsterilized raw materials leads to the growth of various lactic acid bacteria, resulting in variations in the taste and quality of kimchi, which may make it difficult to produce industrial-scale kimchi with consistent quality. The use of starter cultures has been considered as an alternative for the industrial production of standardized kimchi, and recent trends suggest that the demand for starter cultures is on the rise. However, several factors should be carefully considered for the successful application of starter cultures for kimchi fermentation. In this review, we summarize recent studies on kimchi starter cultures, describe practical problems in the application of industrial-scale kimchi production, and discuss the directions for further studies.