• Journal of Microbiology and Biotechnology
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• 제12권3호
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• pp.389-397
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• 2002

Bacteriocin-producing lactic acid bacteria were isolated from kimchi. One isolate producing the most efficient bacteriocin was identified and named Lactococcus lactis B2, based on the biochemical properties and 16S rDNA sequences. The B2 bacteriocin inhibited many different Gram positive bacteria including Lactococcus, Lactobacillus, Leuconostoc, Enterococcus, Streptococcus, and Staphylococcus, but did not inhibit Gram-negative bacteria. The bacteriocin was maximally produced at temperatures between $25^{\circ}C\;and\;30^{\circ}C$ and at the initial pH of 7.0. Ninety $\%$ of the activity remained after 10 min of heat treatment at $121^{\circ}C,\;and\;100\%$, after 1 h exposure to organic solvents. The bacteriocin was purified from culture supernatant by ammonium sulfate precipitation, CM Sepharose column chromatography, ultrafiltration, and finally, by reverse-phase HPLC. A 1.58-kb fragment was amplified from B2 chromosome by using a primer set designed from the published nisA sequence. Sequencing result showed that the fragment contained the whole nisZ and 5' portion of nisB, whose gene product was involved in postmodification of nisin. The upstream sequence, however, was completely different from those of reported nisin genes.

• 한국미생물·생명공학회지
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• 제19권6호
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• pp.619-623
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• 1991

Lactococcus lactis ssp. lactis ML8(L.lactis ML8)의 nisin 생산과 저항 특성을 구명하기 위하여 배지의 종류 및 pH가 nisin의 역가에 미치는 영향, 균체의 생육에 따른 nisin의 생산특성, nisin이 균체생육에 미치는 영향 및 $Ca^[2+}$ 이온의 존재가 균주의 nisin 저항성에 미치는 영향을 조사하였다. Nisin의 역가를 Micrococcus flacus에 대하여 항생효과를 나타내는 성질을 이용하여 agar diffusion법으로 측정하였을 때, M.flavus 생육에 대한 저해직경은 nisin 농도 (0.5`20 unit/ml)의 log치에 비례하였다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.53-60
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• 2000

Strain BH5 was isolated from naturally fermented Kimchi and identified as a bacteriocin producer, which has bactericidal activity against Micrococcus flavus ATCC 10240. Strain BH5 was identified tentatively as Lactococcus lactis by the API test and some characteristics. Lactococcus lactis BH5 showed a broad spectrum of activity against most of the non-pathogenic and pathogenic microorganisms tested by the modified deferred method. The activity of lacticin BH5, named tentatively as the bacteriocin produced by Lactococcus lactis BH5, was detected at the mid-log growth phase, reached its maximum during the early stationary phase, and decreased after the late stationary phase. Lacticin BH5 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms as tested by the spot-on-lawn method. Its antimicrobial activity on sensitive indicator cells was completely disappeared by protease XIV or ${\alpha}$-chymotrypsin. The inhibitory activities of lacticin BH5 were detected during treatments up to 100$^{\circ}C$ for 30 min. Lacticin BH5 was very stable over a pH range of 2.0 to 9.0 and was stable with all the organic solvents examined. The cell concentration and bacteriocin production in strain BH5 were maximum when grown at 30$^{\circ}C$ in a modified MRS medium supplemented with 0.5% tryptone, 1.0% yeast extract, and 0.5% beef extract as nitrogen sources. It demonstrated a typical bactericidal mode of inhibition against Micrococcus flavus ATCC 10240. Lacticin BH5 was purified through ammonium sulfate precipitation, ethanol precipitation, and CM-Sepharose column chromatography. The apparent molecular mass of lacticin BH5 was estimated to be in the region of 3.7 kDa, by the direct detection of bactericidal activity after SDS-PAGE. Mutant strain NO141 which was isolated by nitrosoguanidine mutagenesis produced about 4 fold more bacteriocin than the wild type.

• 한국미생물·생명공학회지
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• 제22권3호
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• pp.240-245
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• 1994

Relation the phage defense mechanism of phage resistant Lactococcus lactis subsp. cremoris ATCC 11602-A1 to its cell wall components was investigated. To determine whether teichoic acid which is known to be one of the phage receptor site present on the cell wall, phage adsorption was examined after treatment 5% TCA(60%$\CIRC $C) and concanavalin A to the cell wall of A1 and parent strain. However, the adsorption rate of two strains did not change. Total amount of phosphate after TCA treatment did not change in both strains, but a difference between the two strains was observed. Ribitol and glycerol, components of teichoic acid, could not be detected in the cell walls of two strains by GC analysis. These results suggest that although teichoic acid was not present in the cell walls of both strains, the composition of cell wall of two strains was not identical. Measurement of amount of protein and SDS-polyacryamide gel electrophoresis were carried out to examine the involvement of cell wall protein in phage resistance, showing that protein is nothing to do with phage adsorption of parent strain, but phage resistance of A1 is related to protein. Cell wall carbohydrates of A1 contained rhamnose, glucose, and galactose. Total amount of carbohydrate of 1% SDS-treated A1 cell wall was reduced to the level of parent strain. The results suggest that phage resistance of A1 was due to the presence of a higher level of carbohydrates then parent strain, and to interaction of carbohydrate and protein.

• 한국축산식품학회지
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• 제28권4호
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• pp.457-462
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• 2008

Lactococcus lactis NK34, isolated from jeotgal (Korean traditional fermented fish), produces bacteriocin against bovine mastitis pathogens such as Staphylococcus aureus 7, S. aureus 8, Staphylococcus chromogenes 10, S. chromogenes 19, Staphylococcus hominis 9, Streptococcus uberis E290, Enterococcus faecium E372, Streptococcus agalactiae ATCC 13813, Pseudonocardia autotrophia KCTC 9455, and Staphylococcus simulans 78. Lacticin NK34 was inactivated by protease XIV but not by protease IX, protease XIII, proteinase K, $\acute{a}$-chymotrypsin, trypsin, and pepsin. Also, lacticin NK34 was stable over a pH range of 2 to 9 for 4 hr and withstood exposure to temperatures of 30-$100^{\circ}C$ for 30 min. Lacticin NK34 showed bactericidal effects against S. simulans 78. This bacteriocin was purified using ammonium sulfate precipitation, ion exchange chromatography, ultrafiltration, and hydrophobic chromatography. Tricin-SDS-PAGE of purified bacteriocin gave the same molecular weight (3.5 kDa) as nisin. The gene encoding this bacteriocin was amplified by PCR using nisin gene-specific primers. It showed similar sequences to this nisin Z gene. These results indicate that lacticin NK34 is a nisin-like bacteriocin, and could be used as an antimicrobial alternative for livestock.

• The Korean Journal of Physiology and Pharmacology
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• 제28권2호
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• pp.153-164
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• 2024

This study aimed to identify metabolic biomarkers and investigate changes in intestinal microbiota in the feces of healthy participants following administration of Lactococcus lactis GEN-001. GEN-001 is a single-strain L. lactis strain isolated from the gut of a healthy human volunteer. The study was conducted as a parallel, randomized, phase 1, open design trial. Twenty healthy Korean males were divided into five groups according to the GEN-001 dosage and dietary control. Groups A, B, C, and D1 received 1, 3, 6, and 9 GEN-001 capsules (1 × 10¹¹ colony forming units), respectively, without dietary adjustment, whereas group D2 received 9 GEN-001 capsules with dietary adjustment. All groups received a single dose. Fecal samples were collected 2 days before GEN-001 administration to 7 days after for untargeted metabolomics and gut microbial metagenomic analyses; blood samples were collected simultaneously for immunogenicity analysis. Levels of phenylalanine, tyrosine, cholic acid, deoxycholic acid, and tryptophan were significantly increased at 5-6 days after GEN-001 administration when compared with predose levels. Compared with predose, the relative abundance (%) of Parabacteroides and Alistipes significantly decreased, whereas that of Lactobacillus and Lactococcus increased; Lactobacillus and tryptophan levels were negatively correlated. A single administration of GEN-001 shifted the gut microbiota in healthy volunteers to a more balanced state as evidenced by an increased abundance of beneficial bacteria, including Lactobacillus, and higher levels of the metabolites that have immunogenic properties.

• 대한소아치과학회지
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• 제27권2호
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• pp.185-191
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• 2000

Streptococcus mutans가 치태를 형성할 때, 유산구균 1370 (Streptococcus lactis 1370)이 생산하는 수용성 글루캔이 영향을 미친다. 본 연구에서는 여러 인자에 의한 수용성 글루캔 형성 정도를 유산구균 1370배양 상청액의 흡광도로 측정하여 다음과 같은 결과를 얻었다. 1. 5% 자당이 첨가된 M17 broth에서 유산구균 1370 배양 상청액의 흡광도는 높고 Streptococcus mutans 배양 상청액의 흡광도는 낮았으나, 통계학적인 유의성은 없었다. 2. M17 broth에 10% 자당을 첨가하여 유산구균 1370을 배양할시 배양 상청액의 흡광도는 첨가하지 않을 때보다 높았다. (p<0.05), 배지 pH가 5에서보다 7에서 배양 상청액의 흡광도가 더 높았다(p<0.05). 3. $32^{\circ}C,\;37^{\circ}C,\;42^{\circ}C$중 $37^{\circ}C$에서 배양시 배양 상청액의 흡광도가 가장 높았으나 통계학적인 유의성이 없었고, 호기성 배양시보다 혐기성 배양시 배양 상청액의 흡광도가 더 높았다(p<0.05). 4. 배지의 $CaCl_2$ 농도가 1.0mM에서 (p<0.05), KCl 농도가 2.5mM에서 (p<0.05) 배양 상청 액의 흡광도가 높았다. 5. M17 broth에 5% 자당을 첨가한 배지에 유산구균 1370을 접종하여 배양한 배양 상청액과 배지를 1:3으로 가한 비커와이어 검사에서 Streptococcus mutans에 의하여 형성된 인공치태 무게는 5.6mg으로 5% 자당을 첨가하지 않을 때의 103.0mg에 비교하여 현저히 감소하였다 (p<0.05). 이상의 결과를 요약하면 유산구균 1370에 의한 수용성 글루캔의 형성은 자당이 함유된 배지나 세균 증식이 잘 되는 조건에서 증가하였으며, 수용성 글루캔이 Streptococcus mutans에 의한 인공치태 형성을 억제하였다.

• Fisheries and Aquatic Sciences
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• 제18권3호
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• pp.333-339
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• 2015

Red lip mullet Chelon haematocheilus (body weight = $468{\pm}91g$) which became sick during an outbreak of disease at mariculture facilities at Cheonsu Bay, Korea, during July-August 2013, were examined to identify the cause of the disease. Diseased mullets displayed green liver syndrome, and Lactococcus garvieae were isolated from their internal organs. Argulus sp., Trichodina sp., and/or Vibrio spp. were also discovered in some infected fish. Histopathological examination revealed that fatty liver syndrome with hepatocyte degeneration, reflected in heterokaryons, inflammatory lesions, and melanomacrophage centers ($MMC_S$), had caused fibrosis around the kidney, spleen, and blood vessels. After the outbreak, visceral fat and green liver syndrome in the mullets were consistently observed throughout the year in the same mariculture facilities, indicating that the cultured mullets suffered a chronic metabolic disorder. Although Vibrio spp. were also isolated from some individuals, L. garvieae, which is known to be a causative agent of red lip mullet mortality, was isolated from all diseased individuals. This is the first report of L. garvieae infection in cultured red lip mullet.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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• pp.840-843
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• 2000

The structure of gal/lac operon of Lactococcus lactis ssp. lactis ATCC7962 was partially characterized and the gene (galM) encoding galactose mutarotase was cloned together with the order; galA-galM-galK-galT. The galM was found to be 1,027 bp in length and encoded the protein of 37,609 Da calculated molecular mass. The deduced amino acid sequence showed a homology with GalM proteins from several other microorganisms. Thus, the galM gene was expressed in Escherichia coli and the product was identified as a 38 kDa protein which corresponded to the size estimated from DNA sequence. mutarotase activity of the IPTG inducedrecombinant was 2.7 times increased against that of the host strain.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.786-790
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• 2006

Cellular components of Lactococcus lactis ssp. lactis (heat-killed whole cells, cytoplasm, and cell walls) were tested for their in vivo immunopotentiating activity. Peritoneal macrophages from mice orally administered with heat-killed whole cells exhibited significantly greater phagocytic activity than the groups administered with cell-wall fraction or cytoplasm fraction. The cytotoxicity of natural-killer cells was the highest in the group administered with whole cells, and the production of cytokines ($IFN-\gamma$, IL-2, and IL-12) in spleen cells was significantly higher, when cellular components were injected, and it tended to be higher in the cell-wall and cytoplasm groups than in the whole-cell group. Interestingly, the cytokine production of Peyer's patch cells was high, when cytoplasm fractions were administered. These results demonstrate that whole cells and cytoplasm and cell-wall fractions of L. lactis ssp. lactis have immunopotentiating activities, which are related to the stimulation of Peyer's patches.