• Korean Journal of Microbiology
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• v.54 no.4
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• pp.398-409
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• 2018

In the present study, biogenic amine-forming Bacillus spp. and bacteriocin-producing lactic acid bacteria (LAB) isolated from Doenjang were generally identified through 16S rRNA gene sequencing, and the physicochemical and microbiological characteristics of cheonggukjang prepared using the isolated strains were investigated. Biogenic amine-producing bacteria from the samples were identified as Bacillus licheniformis DB102, B. subtilis DB203, B. stearothermophilus DB206, B. pumilus DB209, B. subtilis DB310, B. coagulans DB311, B. cereus DB313, B. amyloliquefaciens DB714, B. amylolique-faciens DB915, B. licheniformis DB917, B. cereus DB1019, B. subtilis DB1020, B. megaterium DB1022. The bacteriocin-producing LAB showed antibacterial effect against biogenic amine-producing Bacillus spp. were identified as Lactobacillus plantarum DLA205, L. brevis DLA501, L. fermentum DLA509, L. acidophilus DLA703, and Enterococcus faecalis DLA804. The bacteriocin produced by the LAB significantly decreased the viable numbers and the amine production ability of the biogenic amine-forming Bacillus spp. in a concentration dependent manner. Therefore, the pH, ammonia nitrogen and biogenic amine content of cheonggukjang prepared by mixed culture of the LAB and Bacillus spp. were significantly decreased compared to the control group.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.847-850
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• 2005

The aim of this study was to increase production of leucocin A, a kind of bacteriocin, in a transformed variety of S. cerevisiae. We investigated optical density, total secreted protein, protease activity, and antibacterial activity for the transformed S. cerevisiae in different carbon sources. The production of leucocin A growth-associated, and antibacterial activity, according to carbon source, was in the order of sucrose, glucose, glycerol, and fructose. Antibacterial activity was $10.6\%$ higher in the presence of sucrose than glucose. This is the first report regarding the effect of carbon sources on the production of leucocin A in transformed S. cerevisiae, as far as we ascertain. Our results could prove useful in the industrial production of natural preservatives.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1303-1309
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• 2004

In order to extend shelf-life of the packaged or coated foods, an antibacterial edible film was developed. Antimicrobial activities of 9 bacteriocin-like substance (BLS)­producing strains were evaluated after growing them on defatted soybean meal medium (DSMM). Bacillus subtilis was selected among those, because it showed the biggest inhibition zone against 6 problem bacteria in food. The antimicrobial edible film, containing $0.32\%$ of BLS, was produced from the fermented soybean meal with B. subtilis at the optimum condition of pH 7.0-7.5 and $33^{\circ}C$ for 33 h. The antimicrobial activity of the film was over $50\%$ of the maximum activity after film production with heat treatment at $90^{\circ}C$ and pH adjustment to 9. When the soy protein film with BLS was applied on the agar media containing E. coli, the growth inhibition was much higher than the ordinary soy protein film. These results indicate that the soy protein film with BLS from B. subtilis can be used as a new packaging material to extend the shelf-life of foods.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.153-160
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• 2010

The present study was carried out for the isolation of bacteriocin-producing enterococci from indigenous sources. Gram-positive enterococci are known for having the ability to produce enterocins with good antimicrobial potential. A total of 34 strains were isolated from processed dairy products of Pakistan and seven out of them were found to be member of genus Enterococcus on selective enumeration. Biochemical and molecular characterization revealed that four of these isolates (IJ-03, IJ-07, IJ-11, and IJ-12) were Enterococcus faecalis and three (IJ-06, IJ-21, and IJ-31) were Enterococcus faecium. Local processed cheese was the source of all enterococcal isolates, except E. faecium IJ-21 and IJ-31, which were isolated from indigenous yoghurt and butter samples, respectively. Bacterial isolates were sensitive to commonly used antibiotics except methicillin and kanamycin. They also lacked critical virulence determinants, mainly cytolysin (cyl), gelatinase (gel), enterococcal surface protein (esp), and vancomycin resistance (vanA and vanB). Polymerase chain reaction amplification identified that enterocin A and P genes were present in the genome of E. faecium IJ-06 and IJ-21, whereas the E. faecium IJ-31 genome showed only enterocin P genes. No amplification was observed for genes that corresponded with the enterocins 31, AS-48, L50A, and L50B, and ent 1071A and 1071B. There were no signals of amplification found for E. faecalis IJ-11, indicating that the antimicrobial activity was because of an enterocin different from those checked by PCR. Hence, the indigenous bacterial isolates have great potential for bacteriocin production and they had antibacterial activity against a variety of closely related species.

• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.597-604
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• 2006

In order to extend the shelf-life of packaged or coated foods, an antibacterial edible film containing 1.8% of BLS was developed from the defatted corn germ meal, which had been fermented with Bacillus subtilis under the optimum condition of pH 7.0-7.5 and $33^{\circ}C$ for 33 h. Water vapor permeability of the fermented film $(88.3mg/cm^2\;h)$ was higher than those of the normal corn germ films $(75.8mg/cm^2\;h)$. Protein solubility of the fermented film was also higher than ordinary corn germ film at the pH range of 3-10. The fermented corn germ film had higher tensile strength and lower % elongation (elongation rate) than the ordinary corn germ film. The antimicrobial activity of the film was more than 50% of the maximum activity after film production with heat treatment at $90^{\circ}C$ and pH adjustment to 9. When the corn germ protein film with bacteriocin-like substance was applied on the mashed sausage media containing E. coli, the bacterial growth inhibition was higher than the ordinary corn protein film.

• Korean Journal of Microbiology
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• v.55 no.3
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• pp.258-267
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• 2019

The purpose of this study was to investigate the effect of lactic acid bacteria (LAB) on the growth and biogenic amines (BA) formation of Enterobacter aerogenes CIH05 in skim milk and soymilk. Lactobacillus acidophilus GK20, Lactobacillus paracasei GK74, and Lactobacillus plantarum GK81 isolated from mustard kimchi did not produce BA in the decarboxylation broth. L. paracasei GK74 exhibited the highest cell viability and antimicrobial compounds producing ability in fermented skim milk and soymilk samples, while the lowest producer was L. plantarum GK81. The production yield of lactic acid, hydrogen peroxide, and bacteriocin was dependent on the species of Lactobacillus and the type of culture medium. As LAB the number of viable cells of E. aerogenes CIH05 were higher in skim milk than in soymilk. When mixed culture with L. acidophilus GK20 and L. paracasei GK74 and treated with bacteriocin solution (300 AU/ml) obtained from these strains in milk media, the cell growth and cadaverine and histamine contents of E. aerogenes CIH05 were significantly (P < 0.05) lower than the respective values in control sample.

• Journal of Animal Science and Technology
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• v.49 no.5
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• pp.621-632
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• 2007

The aim of this study was to isolate and characterize bacteriocin-producing bacteria from the intestine of duck to use as probiotics for livestock. A total of 416 strains were isolated from the small intestine and cecum of ducks and 13 isolates were finally selected after determinging inhibitory activity against pathogenic indicators by spot-on-lawn method. The selected strains were identified as Lactobacillus salivarius JWS 58, Lactobacillus plantarum JWS 1354, Pediococcus pentosaceus JWS 939, 7 strains of enterococci, and 3 strains of Escherichia coli. Lact. salivarius JWS 58, Ent. faecium JWS 833, and Ped. pentosaceus JWS 939 showed a strong inhibitory activity against Listeria monocytogenes. E. coli JWS 108 inhibited the growth of E. coli and Staphylococcus aureus. Lact. salivarius JWS 58 strain survived almost 50% in pH 2.5 phosphate buffer for 2 hr. Ped. pentosaceus JWS 939 and Lact. plantarum JWS 1354 showed strong amylolytic activity. These results suggest that a combination of bacteriocins or multispecies probiotics of the selected strains has a strong potential of alternative to antibiotics in livestock production.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.1035-1043
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• 1999

Bacteriocins are natural antimicrobial compounds produced by many microorganisms associated with foods, so that there is currently much interest in their use as food biopreservatives. Goal of this study was to partially evaluate lacticin NK24 as a food biopreservative by showing antimicrobial activity of L. lactis NK24 and lacticin NK24 against food-borne spoilage and pathogenic bacteria, respectively. Lactic acid bacteria NK24 isolated from jeot-gal, Korean fermented fish foods, was tentatively identified as Lactococcus lactis and showed broad spectrum of activity against all of spoilage and pathogenic bacteria tested by deferred method. Bacteriocin production in jar fermenter was detected at the mid-log growth phase, and reached the maximum at the early stationary phase, but decreased after the stationary phase. Lacticin NK24 was partially purified by 75% ammonium sulfate precipitation followed by subsequent dialysis. This partially purified lacticin NK24 showed antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Clostridium perfringens, some bacilli, Listeria monocytogenes, Listeria ivanovii, Sphin-gomonas pausimobilis, Escherichia coli and Pseudomonas aeruginosa. Thus, lacticin NK24 examined in this study show promise as a biopreservative be-cause of their broad spectrum of activity.

• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.125-131
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• 1993

The s-type pyocin, one kind of bacteriocins, is a bactericidal substabce of protein nature produced by certain Pseudomonas aeruginosa and is active against some other strains of the same or closely related species. Among many Pseudomonas aeruginosa strains collected from the patients at the Hospitals in Seoul and Taegu cities, some Pseudomonas aeruginosa pyocinogeny were determined by pyocin typing. As a result, Pseudomonas aeruginosa 90-2-2205 was selected as the S-type pyocin producing microorganism due to its highest antimicrobial and protease sensitivity.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 1994.06a
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• pp.17-22
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• 1994

Food additives are minor components which are used to enhance nutritive or sensory values, and to improve shelf life of foods. In foods, natural additives are preferred over artificial or synthetic materials because of concern on food safety. Many biotechnological techniques have been applied to the production of food additives since the biotechnology has been utilized to prodyce many flavor components such as glutamate, 5'-nucleotides, esters, 2,3-bytadione, pyrazines, terpenes, and lactones. Natural flavors, fragrances, sweetners, and colorants can be produced by plant cell culture. Many lactic acid bacteria produce bacteriocins such as nisin or diplococcin. These bacteriocins are used as safe preservatives in foods and many researches on the improvenment of bacteriocin productivity by genetic engineering are in progress.