• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.785-791
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• 2021

Many lactic acid bacteria (LAB) have probiotic properties that exert various health benefits. In this study, the reduction potential of nitrogen oxide compounds and ferric ions by six LAB, including Lactobacillus kimchicus, L. lactis, L. casei, L. plantarum, L. rhamnosus GG, and Leuconostoc mesenteroides were evaluated. The L. kimchicus strain produced a substantial amount of nitrite reduced from nitrate added to the media, whereas the other five LAB strains did not. L. kimchicus also showed the most potent reducing activity of ferric to ferrous ions. However, the reduction potential of the autoclaved L. kimchicus was little pronounced. The scavenging activities of viable LAB or their cell lysates against different radicals were not consistent with the potency of the LAB's reducing ability. The present results indicate that L. kimchicus has a strong reduction potential for nitrogen oxides in viable status, and that this ability can be used as a probiotic property for various health benefits.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.15-15
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• 2010

Ginseng contained many different kinds of saponin which was the most valuable for people, but its yield cannot satisfy the demand using traditional extract methods. Enzyme transformation is a conformable and highly performed method which was fit for today. A ${\beta}$-glucosidase producing bacterium ($DCY51^T$) was isolated from Korean fermented-vegetable food kimchi. The 16S rRNA gene sequence analysis revealed that the strain $DCY51^T$ belongs to the genus Lactobacillus. The highest sequence similarity was found with Lactobacillus paracollinoides LMG $22473^T$ and Lactobacillus collinoides LMG $9194^T$ with levels of 16S rDNA similarity of 97.4% and 97.3%, respectively. Based on the above results the strain $DCY51^T$ placed in the genus Lactobacillus and proposed a new species, Lactobacillus kimchicus sp. nov. $DCY51^T$ (= KCTC $12976^T$ = JCM $15530^T$). It was culture solution reacted with Red Ginseng extract and $Rb_1$, respectively. The medium of bacteria was the liquid of MRS, the temperatures of growing and reacting between bacteria liquid and saponin were samely $37^{\circ}C$, there spective reacting time were 12 hours and 48 hours. Thus we got different saponins, and TLC and HPLC analysis showed that: enzyme respectively reacted with $Rb_1$ and Red Ginseng extract got the transformed saponin, respectively. The polarity position in TLC was a little higher than Rd; and the polarity position was the same as that of Compound K's, the saponin obtained from HPLC and other experimental results was not Compound K. The constitution of its saponin was hoped to be further confirmed.

• Korean Journal of Food Science and Technology
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• v.53 no.2
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• pp.204-212
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• 2021

Resazurin, an oxidized blue dye, is reduced to resorufin, showing a peak absorbance change and emitting fluorescence due to the metabolic activity of living cells. In this study, the growth of Lactobacillus rhamnosus GG (LGG) and the redox potential of living probiotic bacteria were evaluated based on changes in the absorbance or fluorescence of resazurin. Fluorescence analysis is a more accurate and sensitive method for quantifying viable LGG than the colorimetric absorbance measurement of resazurin change. Fluorescence measurement could detect LGG of 6.5-9.5 log CFU/mL within 30 min with R2=0.99. No significant effect of further reduction of resorufin to dihydroresorufin by LGG was observed. Various probiotics showed different resazurin-reducing activities, and L. kimchicus had the highest reducing activity among the six probiotics tested. These findings suggests that fluorescence measurement in a resazurin-based assay is useful for analyzing bacterial growth and the redox potential of living probiotics.

• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.404-413
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• 2022

The process of manufacturing craft beer involves a wide variety of spontaneous microorganisms, acting in different stages of the brewing process, that contribute to the distinctive characteristics of each style. The objective of this work was to compare the structure of microbial communities associated with two different craft beer styles (Doppelbock and Märzen lagers), at a late maturation stage, and to identify discriminative, or style-specific taxa. Bacterial and fungal microbial communities were analyzed by Illumina sequencing of 16S rRNA gene of prokaryotes and the ITS 2 spacer of fungi (eukaryotes). Fungal communities in maturating beer were dominated by the yeast Dekkera, and by lactic acid (Lactobacillus and Pediococcus) and acetic acid (Acetobacter) bacteria. The Doppelbock barrels presented more rich and diverse fungal communities. The Märzen barrels were more variable in terms of structure and composition of fungal and bacterial communities, with occurrence of exclusive taxa of fungi (Aspergillus sp.) and bacteria (L. kimchicus). Minority bacterial taxa, differently represented in the microbiome of each barrel, may underlie the variability between barrels and ultimately, the distinctive traits of each style. The composition of the microbial communities indicates that in addition to differences related to upstream stages of the brewing process, the contact with the wood barrels may contribute to the definition of style-specific microbiological traits.