• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1216-1222
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• 2017

To develop starters for the production of functional foods or materials, lactic acid bacteria producing ${\gamma}-aminobutyric$ acid (GABA) were screened from jeotgals, Korean fermented seafoods. One isolate producing a high amount of GABA from monosodium $\text\tiny{L}$-glutamate (MSG) was identified as Enterococcus avium by 16S rRNA gene sequencing. E. avium M5 produced $18.47{\pm}1.26mg/ml$ GABA when incubated for 48 h at $37^{\circ}C$ in MRS broth with MSG (3% (w/v)). A gadB gene encoding glutamate decarboxylase (GAD) was cloned and overexpressed in E. coli BL21 (DE3) using the pET26b (+) expression vector. Recombinant GAD was purified through a Ni-NTA column and the size was estimated to be 53 kDa by SDS-PAGE. Maximum GAD activity was observed at pH 4.5 and $55^{\circ}C$and the activity was dependent on pyridoxal 5'-phosphate. The $K_m$ and $V_{max}$ values of GAD were $3.26{\pm}0.21mM$ and $0.0120{\pm}0.0001mM/min$, respectively, when MSG was used as a substrate. Enterococcus avium M5 secretes a lot of GABA when grown on MRS with MSG, and the strain is useful for the production of fermented foods containing a high amount of GABA.

• Journal of Microbiology
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• v.40 no.2
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• pp.156-160
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• 2002

The whole gal/lae operon genes of Lactococcus lactis ssp. lactis 7962 were reported as follows: galA-galM-galK-galT-lacA -lacZ-galE. The galK gene encoding a galactokinase involved in one of the Leloir pathways for galactose metabolism was found to be 1,197 bp in length and encodes a protein of 43,822 Da calculated molecular mass. The deduced amino acid sequence showed over 50% homology with GaIK proteins from several other lactic acid bacteria. The galK gene was expressed in E. coli and the product was identified as a 43 kDa protein which corresponds to the estimated size from the DNA sequence. The galactokinase activity of recombinant 5. coli was about 8 times greater against that of the host strain and more than 3 times higher than the induced L. lactis 7962.

• KSBB Journal
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• v.10 no.5
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• pp.553-560
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• 1995

A lactic aci bacteria producing antibacterial substance was isolated from pig feces. This strain was identified as a genus Lactobacillus, through its morphological, cultural and physiological characteristics. Lactobacillus sp. KJ-5 isolated showed the strong inhibitory effect on the growth of Salmonella paratyphi. The production of antibacterial substance was growth associated form during the batch culture of Lactobacillus sp. KJ-5 and the maximum production was obtained at the culture temperature of $37^{\circ}C$ as well as optimum temperature of cell growth. The antibacterial activity of the filtrate of culture broth was decreased by adjusting the pH 6.2 and was not affected by catalase treatment. The antibacterial substance was partially purified by methanol and acetone extraction, whtch exhibited three spots in the thin-layer chromatography and one of them showed an antibacterial activity, This substance also showed the maximum absorption of UV at 270nm and an antibacterial activity was completely inactivated by the treatment of proteolytic enzymes.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.287-296
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• 2007

A Lactobacillus paraplantarum strain producing a bacteriocin was isolated from kimchi using the spot-on-the lawn method and named L. paraplantarum C7 [15]. The bacteriocin, paraplantaricin C7, was found to inhibit certain Lactobacillus strains, including L. plantarum, L. pentosus, and L. delbrueckii subsp. lactis. It also inhibited Enterococcus faecalis, yet did not inhibit most of the other LAB (lactic acid bacteria) tested. The maximum level of paraplantaricin C7 activity was observed under the culture conditions of $25^{\circ}C$ and a constant pH of 4.5. Paraplantaricin C7 retained 90% of its activity after 10 min of treatment at $100^{\circ}C$ and remained stable within a pH range of 2-8. Based on a culture supernatant, paraplantaricin C7 was purified by DEAE-Sephacel column chromatography and $C_{18}$ reverse-phase HPLC. SDS-PAGE and activity staining were then conducted using the purified paraplantaricin C7, and its molecular mass determined to be about 3,800 Da. The 28 N-terminal amino acids from the purified paraplantaricin C7 were determined, and the structural gene encoding paraplantaricin C7, ppnC7, was cloned by PCR using degenerate primers based on the N-terminal amino acid sequence. The nucleotide sequences for ppnC7 and other neighboring orfs exhibited a limited homology to the previously reported plantaricin operon genes. Paraplantaricin C7 is a novel type II bacteriocin containing a double glycine leader sequence.

• Journal of Microbiology and Biotechnology
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• v.23 no.1
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• pp.64-68
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• 2013

Previous studies have shown that lactic acid bacteria can inhibit inflammatory responses, but the mechanisms are very little known. In this study, transaction and expression of three proinflammatory factors, iNOS, PTGS-2, and IL8, which are closely related to the inflammatory response, were investigated by luciferase reporter assay and RTPCR in HT-29 cells treated by Lactobacillus acidophilus. The results showed that the live L. acidophilus sharply down-regulated the transcription of these three genes. Because there was a NF-${\kappa}B$ binding site located at -265 bp, -225 bp, and -95 bp upstream of the iNOS, PTGS-2, and IL8 promoters, respectively, we further addressed the effects of NF-${\kappa}B$ on transaction of the three promoters by cotransfection. As was expected, NF-${\kappa}Bs$ remarkably upregulated the activity of the reporter gene and, no effect of NF-${\kappa}B$s on IL-8 promoter transaction was found after NF-${\kappa}B$ binding site mutation of the IL8 promoter in HT-29 cells. In conclusion, the live L. acidophilus decreased the transcriptional activity of NF-${\kappa}B$ and, in turn, inhibited the transaction of NF-${\kappa}B$ on the three proinflammatory factors mentioned above.

• Food Science of Animal Resources
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• v.32 no.4
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• pp.404-408
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• 2012

This study was performed to investigate the effects of laying productivity and egg quality according to providing germinated and fermented soybean (GFS) as feed additive. Among the strain, we selected Monascus purpureus KCCM 12002 so that inoculated in soybean and fermented for 48 h at $20^{\circ}C$. A total of two-hundred forty 70-wk-old Hy-Line Brown layers were divided into four groups (4 treatment${\times}$6 replication${\times}$10 birds each) and fed diets containing 0 (as control) (T1), 0.5% (T2), 1.0% (T3) or 2.0% GFS (T4) for 6 wk. The laying productivity, egg quality and blood property in the egg yolk were experimented. There were no significant differences in the laying productivity, relative liver and spleen weights, egg yolk color and eggshell strength among another groups. The eggshell color, eggshell thickness and haugh unit significantly increased in the GFS-supplemented group (p<0.05) compared to control. However, no significant differences were observed in the blood property after supplementation. The amount of lactic acid bacteria present during storage increased by providing of GFS (p<0.05) compare to control group. Our study results suggested that GFS can be used as a favorable feed additive and feedstuff for the productivity of high quality eggs and promoted relative industry.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.117-125
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• 2022

Until recently, four types of cellobiose-fermenting Saccharomyces cerevisiae strains have been developed by introduction of a cellobiose metabolic pathway based on either intracellular β-glucosidase (GH1-1) or cellobiose phosphorylase (CBP), along with either an energy-consuming active cellodextrin transporter (CDT-1) or a non-energy-consuming passive cellodextrin facilitator (CDT-2). In this study, the ethanol production performance of two cellobiose-fermenting S. cerevisiae strains expressing mutant CDT-2 (N306I) with GH1-1 or CBP were compared with two cellobiose-fermenting S. cerevisiae strains expressing mutant CDT-1 (F213L) with GH1-1 or CBP in the simultaneous saccharification and fermentation (SSF) of cellulose under various conditions. It was found that, regardless of the SSF conditions, the phosphorolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-2 with CBP showed the best ethanol production among the four strains. In addition, during SSF contaminated by lactic acid bacteria, the phosphorolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-2 with CBP showed the highest ethanol production and the lowest lactate formation compared with those of other strains, such as the hydrolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-1 with GH1-1, and the glucose-fermenting S. cerevisiae with extracellular β-glucosidase. These results suggest that the cellobiose-fermenting yeast strain exhibiting low energy consumption can enhance the efficiency of the SSF of cellulosic biomass.

• Journal of Convergence for Information Technology
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• v.11 no.5
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• pp.223-231
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• 2021

The antioxidant activity of Chrysanthemum indicum L. extract (CIL) was investigated by fermenting lactic acid bacteria with the CIL from 64% and 80% ethanol extraction and measuring the total phenolic contents (TPC), flavonoid, 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power (RP), and linoleic acid auto-oxidation inhibitory activity. CIL was confirmed to inhibit bacterial auto-oxidation. TPC was increased in strains 3109 and 3237, while flavonoid decreased in all strains. DPPH was increased in strains 3074 and 3109 fermented with 64% CIL and all the strains with 80% CIL. RP was increased and linoleic acid auto-oxidation inhibitory activity decreased in all the strains fermented with 64% or 80% CIL. Among the 4 strains, strain 3109 had the highest DPPH and RP; thus, it was most effective in increasing CIL's antioxidant efficacy through the fermentation process.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.358-366
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• 2024

The lactic acid bacteria, including Latilactobacillus sakei and Latilactobacillus curvatus, have been widely studied for their preventive and therapeutic effects. In this study, the underlying mechanism of action for the antioxidant and immunostimulatory effects of two strains of heat-treated paraprobiotics was examined. Heat-treated L. sakei KU15041 and L. curvatus KU15003 showed higher radical scavenging activity in both the 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assays than the commercial probiotic strain LGG. In addition, treatment with these two strains exhibited immunostimulatory effects in RAW 264.7 macrophages, with L. curvatus KU15003 showing a slightly higher effect. Additionally, they promoted phagocytosis and NO production in RAW 264.7 cells without any cytotoxicity. Moreover, the expression of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 was upregulated. These strains resulted in an increased expression of inducible nitric oxide synthase and cyclooxygenase-2. Moreover, the nuclear factor-κB and mitogen-activated protein kinase signaling pathways were stimulated by these strains. These findings suggest the potential of using L. sakei KU15041 and L. curvatus KU15003 in food or by themselves as probiotics with antioxidant and immune-enhancing properties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.386-395
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• 2016

To develop a functional fermentation food from Rubus coreanus Miquel (Bokbunja) and chlorella mixtures, optimal lactic acid fermentation conditions were established, and quality properties based on physicochemical evaluation such as chemical compositions, free sugars, organic acids, and antibacterial activities were investigated. Regarding optimal fermentation strain selection, formation of lactic acid was best in Lactobacillus plantarum among the experimental strains (10 kinds), and the optimal fermentation temperature was $37^{\circ}C$. In addition, overall acceptability in the sensory evaluation was highest in the 5% chlorella mixture sample. Therefore, quality properties of the prepared sample under the established optimal fermentation conditions were investigated. Moisture, total sugar (dry basis), crude fiber (dry basis), and pH of fermented Rubus coreanus Miquel juice (RCM) with 5% chlorella mixture (RCM-C5) were reduced by 4.90%, 14.15%, and 0.32%, respectively, as compared with non-fermented RCM. Meanwhile, crude protein, crude fat, and crude ash (dry basis) of RCM-C5 were elevated by 13.75%, 0.18%, and 0.73%, respectively, as compared with RCM. The yellowness (b value) of color values was greater in RCM-C5 compared to RCM. The free sugar and organic acid contents of RCM-C5 were elevated by 0.97% and 616.30 mg%, respectively, as compared with RCM. In addition, the gram positive bacterium Staphylococcus aureus was elevated by 5.83% while gram negative bacteria Escherichia coli and Salmonella Typhimurium were elevated by 2.94% and 4.67%, respectively, as compared with RCM. In conclusion, the quality properties of RCM and chlorella lactic acid fermentation mixtures were improved compared with the general RCM product. Consequently, it is possible to apply fermented RCM as a functional fermentation food.