• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.550-556
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• 1994

For an extension of the palatable stage in Kimchi which was limited by further lowering pH as the fermentation proceeds, the starter culture of bacteriocin-producing Enterococcus faecium DU 0267 obtained from Kimchi was added at the preparation time, and pH, bacteriocin activity, growth of lactic acid bacterial group and gas production in Kimchi were examined during the fermentation at 10, 20 and 30$\circ$C . The pH of Kimchi fell rapidly to 4.0~4.2 in the early fermentation stage, and then, has gone down very slowly throughout further fermentation. The lactic acid bacte- ria, particularly lactobacilli and leuconostoc, were remarkably slower in its growth than those in the control. Although the patterns of these change during fermentation at different temperatures were similar, these effects by the addition of starter were enhanced at 10 and 20$\circ$C. The bacteriocin activity was increased rapidly during log phase of the bacteriocin producer strain in the early fermentation stage of Kimchi and reached their maximum after fermentation at 10$\circC, for 8 days and at 20 or 30$\circ$C for 2 days. Thereafter, the activity disappeared quickly. The gas production by fermentation was also suppressed considerably, and their volume produced after fermentation at 20$\circ$C for 14 days corresponded to 60% of those of the control.

• Food Science of Animal Resources
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• v.35 no.1
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• pp.137-142
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• 2015

A lactic acid bacterium presenting antimicrobial activity against a Lactobacillus acidophilus strain used for eradication of acid inhibition was isolated from a natural cheese. The 16S rRNA gene sequence of the isolate best matched with a strain of L. rhamnosus and was designated L. rhamnosus CJNU 0519. The antimicrobial activity of the partially purified bacteriocin of CJNU 0519 was abolished when treated with a protease, indicating the protein nature of the bacteriocin. The partially purified bacteriocin (rhamnocin 519) displayed a narrow antimicrobial activity against L. acidophilus, Listeria monocytogenes, and Staphylococcus aureus among several tested bacterial and yeast strains. Rhamnocin 519 in particular showed strong bactericidal action against L. monocytogenes.

• The Korean Journal of Ecology
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• v.22 no.1
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• pp.45-50
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• 1999

A bacteriocin-producing strain was isolated from kimchi at the early stage of kimchi fermentation. It was identified as Lactococcus lactis by morphological, cultural and physiological characteristics and partial sequence of 16S rDNA. The bacteriocin from isolate had antimicrobial activity against gram positive pathogenic bacteria, such as Listeria monocytogenes. Staphylococcus aureus and several strains of lactic acid bacteria but not to gram negative bacteria, Yersinia enterocolitica. The bacteriocin was sensitive to protease, protease ⅩⅣ, a-chymotrypsin and pepsin but not to lipase, trypsin and lysozyme. The bacteriocin activity was stable at pH 2-11 and temperature of 100 for 10 min. Thus, Listeria monocytogenes could be inhibited by Lactococcus lactis at early stage of fermentation.

• Preventive Nutrition and Food Science
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• v.2 no.2
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• pp.101-108
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• 1997

A lactic acid bacterium LAB3113, isolated from traditionally fermented Kimchi was found to produce bacteriocin whose activity was very specific toward lactobacilli and not effective against any other bacteria. Lactobacilli affected by the inhibitory substance included Lactobacillus delbrueckii-lactis, L. johnsonii, L. gsseri, and L. curvatus. Based upon biochemical and physiological characteristics, LAB3113 was classified as Lactococcus lactis, and its bacteriocin was named as lactococcin K3113. Lactococcus lactis. LAB3113 produced bacteriocin at th early stage of growth and the concentration of the bacteriocin did not decrease even after alt stationalry phase. Optimal temperature of bacteriocin production was $25^{\circ}C$ at the initial pH 7.0. Partially purified lactococcin K3113 was completely inactivated by protease, but not affected by lipase, lysozyme and RNase. The bacteriocin was very heat-stable even after autoclaving for 20 min. It was also stable in pH changes, an was not affected by th presence of solvents. lacotococcin K3113 appeared to act in bactericidal mode against L. delbrueckii-lactis ATCC4797. Molecular weight of lactococcin K3113 was calibrated as 10,500 dal by SDS-PAGE an activity staining. Lactococcus lactis LAB3113 had four residential plasmids of 3.7kb, 11.2kb, 15.5kb, and 48kh in molecular sizes. Plasmid profile analysis of mutant strain revealed that 15.5 kb plasmid was re-sponsible for the production of lactococcin K3113 and its immunity to the bacteriocin.

• 한국유가공학회:학술대회논문집
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• 1996.11a
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• pp.30-34
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• 1996

Twenty seven strains of Lactobacillus acidophilus among 92 isolated from fecal contents of humans, pigs, calves, chickens, rodents and turkeys demonstrated inhibitory attributed to bacteriocin(s). The bacteriocin(s) were heat stable and nondialyzable proteinous compounds and exhibited narrow inhibitory spectra of activity. Neither hydrogen peroxide nor low pH were responsible for inhibitory action. All of the producer strains were resistant to their own bacteriocin or bacteriocin(s) produced by other strains. The bacteriocins from several strains from different host species were purified for further characterization. The bacteriocin(s) all exhibited similar characteristics.

• Microbiology and Biotechnology Letters
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• v.22 no.3
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• pp.266-270
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• 1994

A bacteriocin was isolated from the supernatant fluid of M17G broth culture of Lactococcus sp. HY 449 strain, which showed strong inhibitory activity against the growth of selective indicator strain, Lactobacillus fermentum IFO3023. When the bacteriocin wasa added to the growing indicator cells or cell suspensions, viable cells and optical density were density were decreased, indicating bacteriolytic mode of action. Electron microscopic observation of indicator cells treated with bacteriocin revealed apparent damages on the cell surface and eventual lysis of cell walls.

• Journal of Microbiology
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• v.43 no.4
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• pp.370-374
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• 2005

Bacteriocin ST311LD is approximately 2.3 kDa in size. Low levels of bacteriocin activity were recorded in BHI and M17 broth (800 AU/ml) and in $10\%$ (w/v) soy milk (3,200 AU/ml). No bacteriocin pro-duction was recorded in $10\%$ (w/v) molasses, despite good growth. Optimal levels (12,800 AU/ml) were detected in MRS broth which had been supplemented with tryptone (20.0 g/l), saccharose (5.0 or 10.0 g/l) or vitamin C (1 ppm). Increased potassium levels did not result in higher levels of activity, and glycerol (1.0 g/l) inhibited the production of bacteriocin ST311LD.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.1
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• pp.150-165
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• 2002

The purpose of this study was to evaluate bacteriocin activity against human flora. Lactobiocin, a bacteriocin produced by Lactococcus sp. HY 449, inhibited the growth of Starphylococcus epidermidis, Starphylococcus aureus, Streptoccoccus pyogenes and Propionibacterium acnes. When crude bacteriocin was added to indicator cells during logarithmic growth, the optical density(O.D 650nm) of cells without bacteriocin increase after 5h of incubation. Whereas in the presence of bacteriocin, the O.D of cell suspensions decreased. The similar patterns were observed for absorbance readings at 280 nm and 260 nm. The release of cellular components when cell were treated with Lactobiocin suggests some degree of membrane damage or cell lysis. Scanning electron microscopy of cells following treatments with Lactobiocin in PBS buffer revealed disruptures of cell morphology. These results indicate that bacteriocin appears to cause cell lysis of tested strains. In cytotoxicity on human fibroblast, LD$\_$50/ of Lactobiocin was ca. 50 mg/ml and no change was observed cell proliferation at the same concentration. Any irritation and allergic reaction did not observed when evaluated by human patch test for Lactobiocin.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.49-57
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• 2005

Enterococcus faecium MJ-14, having strong antilisterial activity, was isolated from Korean fermented food, Meju. MJ-14 showed the same phenotypic characteristics, but different sugar utilization, as reference strain, E. faecium KCCM12118. It could utilize D-xylose, amygdaline, and gluconate, whereas E. faecium KCCM12118 could not. Optimal condition for bacteriocin production by E. faecium MJ-14 was at $37^{\circ}C$ and pH 7.0. Bacteriocin activity appeared in mid exponential phase and increased rapidly up to stationary phase. Activity was significantly promoted in MRS broth containing 3.0% glucose, 1.5% lactose, 2.0% peptone, or 1.5% tryptone. Bacteriocins effectively inhibited Enterococcus faecalis and Listeria spp. of Gram-positive bacteria, and Helicobacter pylori of Gram-negative bacteria, but did not inhibit yeasts and molds. They were stable against heat (for 30 min at $100^{\circ}C$), pH (3.0-9.0), long-term storage (for 60 days at 4 or $-20^{\circ}C$), and enzymatic digestion by catalase, proteinase K, papain, lysozyme, trypsin, chymotrypsin, and lipase, etc. Bacteriocin activity was completely inhibited by protease and pepsin, and 50% by ${\alpha}$-amylase. Studies on PCR detection of enterocin structural genes revealed bacteriocins are identical to enterocins A and B.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.131-137
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• 2021

This study aimed at isolating lactic acid bacteria with anti-MRSA (methicillin-resistant Staphylococcus aureus) bacteriocin activity from fermented shrimp. We selected three strains, named Weissella sp. S1, S2, and S3, using analysis based on 16S rRNA gene sequences. All strains showed appropriate growth in an MRS medium containing 5% (w/v) NaCl and showed antibacterial activities against Bacillus cereus, Escherichia coli, Staphylococcus aureus, and MRSA. The strains exhibited similar growth rates at 0-5% NaCl, with approximate reduction in growth rate observed at 9% NaCl. Weissella sp. S1, S2, and S3 exhibited maximum growth rates at pH 7, 9, and 8, respectively. The crude bacteriocin was prepared from Weissella sp. S3 and subjected to characterization. The remaining activities after 30 min of exposure at each temperature were 100%, beyond 75%, and 49% at 4℃ and 37℃, 50℃ and 70℃, and 100℃, respectively. The remaining activities after 24 h of exposure at each pH were 100%, 75%, and 49% at pH 3 and 5, 7 and 9, and 10, respectively. Use of 50% (v/v) ethanol or isopropanol treatment did not diminish the antibacterial activity of the bacteriocin, while the 50% (v/v) hexane treatment reduced the activity by 51%. The molecular weight of the bacteriocin was nearly 6 kDa that was quantified using tricine-SDS-PAGE. Our findings suggest that Weissella sp. S3 may be considered a probiotic and useful source of antimicrobial substances in the development of bio-preservatives for food or in MRSA treatment.