• Korean Journal of Microbiology
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• v.41 no.1
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• pp.18-23
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• 2005

The purpose of this work was to investigate the physiological characteristics of Lactobacillus sp. JK-8 isolated from a shrimp aquaculture pond. The strain JK-8 was grown on MRS media, and morphological and physiological characteristics of the strain were examined. The bacterium was identified as a strain of the genus Lactobacillus on the basis of BIOLOG test. Strain JK-8 produced both lactic acid and acetic acid, which were responsible for the pH decrease during growth. Concentrations of lactic acid and acetic acid increased to 192.8 mM and 43.6 mM, respectively, and the initial pH 7.0 of the cultures decreased to 3.8 at the end of incubaction. The bacteriocidal effect against eight target bacteria was examined with 5-fold concentrated culture supernatants. All bacteria tested in this work were completely killed within 3 hrs after treatment with the culture supernatant. The bacteriocidal effects were clearly observed, only when the pH of the culture supernatants were not adjusted. HPLC was used to reslove lactic acid and acetic acid in the culture solution, and GC-MS was used to verify the metabolites.

• Journal of Life Science
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• v.14 no.4
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• pp.636-643
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• 2004

D-Xylose isomerase produced by Lactococcus sp. JK-8, isolated from kimchi, was purified 17-fold of homogeneity, and its physicochemical properties were determined. Although the N-terminal amino acid sequence of D-xylose isomerase was analysed to Ala-Tyr-Phe-Asn-Asp-Ile-Ala-Pro-Ile-Lys, it was not similar to that of Lactobacillus enzyme. The molecular weight of the purified enzyme was estimated to be 180 kDa by gel filtration, 45 kDa by SDS-PAGE and the enzyme was homotetramer. The optimum pH of the enzyme was around 7 and stable between pH 6 and 8. The optimum reaction temperature was 7$0^{\circ}C$ and stable up to 7$0^{\circ}C$ in the presence of 1 mM $Mn^{2+}$. Like other D-xylose isomerases, this enzyme required divalent cation, such as $Mg^{2+}$, $Co^{2+}$, or $Mn^{2+}$ for the activity and thermostability. $Mn^{2+}$was the best activator. Substrate specificity studies showed that this enzyme was highly active on D-xylose. The enzyme had an isoelectric point of 4.8, and fm values for D-xylose was 5.9 mM.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.9
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• pp.1140-1147
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• 2007

A recipe for diet kimchi containing 20% of sea tangle to Korean cabbage kimchi (SK) was developed for weight reduction purpose. The fermentation process of SK showed typical Lactobacillus sp. growth pattern like other kimchis. The effects of SK on weight reduction was studied in high fat diet (HFD) fed rats (n=40). Diet groups used for the animal study were HFD, HFD supplemented either with Korean cabbage kimchi used as experimental control (HCK), or with SK (HSK), or with J-kimchi (JK) which was purchased at market (FJK). The effect of kimchi on preventing obesity in rat fed HFD was found to be obvious by means of reducing visceral fat contents and improving serum lipid profiles through enhancing the lipid excretion in the feces (p<0.05). Leptin concentration of rat was significantly decreased by kimchi consumption (p<0.05). This result can be interpreted that adipocytes in these animals were fewer than that of HFD group. The plasma bililubin concentration was lower in kimchi group than HFD, meaning that returning bile from ileum to the liver was reduced. When the observe beneficial effects of kimchi on preventing obesity were compared among kimchi groups, SK only reduced the relative visceral fat contents significantly than other kimchi groups (p<0.05). Besides this, other parameters such as plasma lipid profiles, feces lipids, leptin, and bililubin concentration were not significantly different, even though the most beneficial effect on these parameters was observed from SK. In conclusion, long term consumption of SK seems to have a beneficial effect on the prevention of obesity through enhancing the excretion of lipids in the feces. The dietary fiber content of SK was increased by 7% compared to CK when 20% of sea tangle was added.