• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.588-594
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• 1998

Lactic acid bacteria were isolated from Kimchi and screened for bacteriocin production. Strain SE1, identified as Lactobacillus curvatus sp., showed the strongest inhibitory activity against Lactobacillus delbrueckii subsp. delbrueckii. The bacteriocin was inactivated by amyloglucosidase, trypsin, or protease K treatment. However, it maintained its activity under heat treatment at $100^{\circ}C$ for 60 min. The production of the bacteriocin had a growth-related mode and decreased around the early-stationary phase. The optimum temperature for the growth of L. curvatus SE1 was $37^{\circ}C$; however, the optimum temperature for bacteriocin production was $30^{\circ}C$. The bacteriocin activity was decreased by treatment with methanol, butanol, acetone, or chloroform, however, it was not affected by treatment with ethanol, iso-propanol, or cyclohexane. The inhibitory activity of bacteriocin was stable over a wide range of pHs (2 to 11). The bacteriocin from L. curvatus SE1 killed the indicator strain by a bactericidal mode of action. The bacteriocin from L. curvatus SE1 was partially purified by ethanol precipitation and ion exchange chromatography. SDS-polyacrylamide gel electrophoresis was used to determine the molecular weight of the bacteriocin by the bacteriocin activity test. The apparent molecular mass of the bacteriocin produced by L. curvatus SE1 was about 14 kDa.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.1064-1079
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• 2018

In this study, the antimicrobial activity of a bacteriocin produced by Enterococcus faecalis KT11, isolated from traditional Kargı Tulum cheese, was determined, and bacteriocin KT11 was partially characterized. The results showed that bacteriocin KT11 was antagonistically effective against various Gram-positive and Gram-negative test bacteria, including vancomycin- and/or methicillin-resistant bacteria. The activity of bacteriocin KT11 was completely abolished after treatment with proteolytic enzymes (proteinase K, ${\alpha}$-chymotrypsin, protease and trypsin), which demonstrates the proteinaceous nature of this bacteriocin. Additionally, bacteriocin KT11 remained stable at pH values ranging from 2 to 11 and after autoclaving at $121^{\circ}C$ for 30 min. In addition, the activity of bacteriocin KT11 was stable after treatment with several surfactants (EDTA, SDS, Triton X-100, Tween 80 and urea) and organic solvents (chloroform, propanol, methanol, ethyl alcohol, acetone, hexane and ethyl ether). Cell-free supernatant of E. faecalis KT11 was subjected to ammonium sulfate precipitation and then desalted by using a 3.5-kDa cut-off dialysis membrane. The bacteriocin activity was determined to be 711 AU/mL in the dialysate. After tricine-SDS-PAGE analysis, one peptide band, which had a molecular weight of ~3.5 kDa, exhibited antimicrobial activity. Because the bacteriocin KT11, isolated from E. faecalis KT11, exhibits a broad antimicrobial spectrum, heat stability and stability over a wide pH range, this bacteriocin can be used as a potential bio-preservative in foods. Additionally, bacteriocin KT11 alone or in combination with conventional antibiotics may provide a therapeutic option for the treatment of multidrug-resistant clinical pathogens after further in vivo studies.

• Food Science of Animal Resources
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• v.35 no.4
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• pp.473-478
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• 2015

The aim of this study was to screen and In vitro characterize the properties of bacteriocin produced by lactic acid bacteria isolated from Vietnamese fermented pork (Nem chua). One hundred and fifty LAB were isolated from ten samples of Nem chua and screened for bacteriocin-producing lactic acid bacteria. Antimicrobial activity of bacteriocin was carried out by spot on lawn method against both gram positive and gram negative bacteria. One isolate, assigned as KL-1, produced bacteriocin and showed inhibitory activity against Lactobacillus sakei, Leuconostoc mesenteroides and Enterococcus faecalis. To characterize the bacteriocin-producing strain, optimum temperature, incubation period for maximum bacteriocin production and identification of bacteriocin-producing strain were determined. It was found that the optimum cultivation temperature of the strain to produce the maximum bacteriocin activity (12,800 AU/mL) was obtained at 30℃. Meanwhile, bacteriocin production at 6,400 AU/mL was found when culturing the strain at 37℃ and 42℃. The isolate KL-1 was identified as L. plantarum. Antimicrobial activity of cell-free supernatant was completely inhibited by proteolytic enzyme of trypsin, alpha-chymotrypsin and proteinase K. Bacteriocin activity was stable at high temperature up to 100℃ for 10 min and at 4℃ storage for 2 d. However, the longer heating at 100℃ and 4℃ storage, its activity was reduced.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.7-12
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• 1994

One bacterial strain, that had made the largest inhibition zone at the antagonism assay and also that lost the inhibition activity by the protease treatment, was isolated from raw milk. That strain was identified as Streptococcus salivarius subsp. thermophilus. The specific growht rate of this strain was maximum at 45$\circ $C. However, at this temperature the strain produced no bacteriocin. The bacteriocin activity was quite stable even at high temperature. Moreover, the activity of the vacteriocin was sensitive to proteases. but not to $\alpha $-amylase, DNase I, or RNase.

• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.94-99
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• 1989

Seven gtrains of Lactobacillus produce bacteriocin being active for Lacidophilus. All strains producing bacteriocin were found to be L. acidophilus except with one strain of L. gasseri. The maximum activity of bacteriocin produced by Lactobacillus strains was obtained at a middle or late stage of the log phase, or a early stage of the stationary phase. After the maximum was reached, however, the activity was rapidly decreased. The bacteriocins were inactivated easily by the treatment with proteolytic enzymes but not with nucleolytic enzymes, suggesting that the bacteriocin was proteinaceous. The bacteriocins were different from the other previously reported lactobacillus bacteriocin in their flexibility to the treatment at 10$0^{\circ}C$. Bacteriocins of L. acidophilus ATCC 9857 and 4357 decreased in activity by the treatment with diethylether, presumably the bacteriocin contained of a lipid component. It sums likely that L. acidophilus A4 bacteriocin adsorb to a regularly arrayed layer of the cell wall.

• Journal of Food Hygiene and Safety
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• v.10 no.2
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• pp.65-71
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• 1995

Bacteriocins from lactic acid bacteria have attracted much attention in recent years because of their useful worth in increasing safety and extending shelf life of foods. These substances show an inhibitory effect against some food spoilage bacteria and food-borne pathogens. The inhibitory effect fo the bacteriocin produces by lactic acid bacteria against Listeria monocytogenes(L. monocytogenes) was examined in this study. The culture supernatants of 5 kinds of bacteria among the 10 kinds of testes lactic acid bacteria had the inhibitory activity against Listeria sp., various Gram positive and Gram negative bacteria. Bacteriocin produced by Lactobacillus plantarum(Lact. plantarum) LMG 7945 was the most active toward L. monocytogenes. Bacteriocin production of the Lact. plantarum LMG 7945 cultured on MRS broth was increased late logarithmic phase over early stationary phase. This bacteriocin was stable at heat treatment and acidic pH relatively; The activity was retained after heating at 121$^{\circ}C$ for 15min and was active in the pH range of 2~4 but was lost above pH 5.

• Journal of Microbiology and Biotechnology
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• v.7 no.6
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• pp.409-416
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• 1997

Leuconostoc sp. LAB145-3A isolated from kimchi produced a bacteriocin which was active against food pathogens, such as Listeria monocytogenes, Enterococcus faecalis, and E. faecium. Bacteriocin production occurred during the early exponential phase of growth and was stable upto the late stationary phase of growth. Optimum conditions for bacteriocin production were $37^{\circ}C$ with an initial pH of 7.0. The bacteriocin of LAB145-3A was sensitive to proteases, but stable for solvents, pH change and heat treatment. It was stable even at autoclaving temperature for 15 min. The bacteriocin exhibited a bactericidal mode of action against Lactobacillus curvatus LAB170-12. The bacteriocin produced by Leuconostoc sp. LAB145-3A was purified by CM-cellulose cation exchange column chromatography and Sephadex G-50 gel filtration. The purification resulted in an approximate 10,000-fold increase in the specific activity. Approximately 4% of the initial activity was recovered. Purified bacteriocin exhibited a single band on the SDS-PAGE with an apparent molecular weight of 4,400 daltons. This bacteriocin was named leucocin K. Leuconostoc sp. LAB145-3A had two residential plasmids with molecular sizes of 23 kb and 48 kb. A comparison of plasmid profiles between LAB145-3A and its mutants revealed that the 23 kb plasmid (pCA23) was responsible for bacteriocin production and immunity to the bacteriocin in Leuconostoc sp. LAB145-3A.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.164-171
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• 2021

Listeria monocytogenes is a representative foodborne pathogen and causes listeriosis. Enterococcus faecium CJNU 2524 was confirmed to produce a bacteriocin with anti-listerial activity. To establish optimal culture conditions for the production of the bacteriocin from E. faecium CJNU 2524, different media (MRS and BHI broth) and temperatures (25℃, 30℃, and 37℃) were investigated. The results showed that the optimal culture conditions were MRS broth and 25℃ or 30℃ temperatures. The crude bacteriocin was stable in a broad range of pH conditions (2.0-10.0), temperatures (60℃-100℃), and organic solvents (methanol, ethanol, acetone, acetonitrile, and chloroform). The bacteriocin activity was abolished when treated with protease but not α-amylase or lipase, indicating the proteinaceous nature of the bacteriocin. Finally, the bacteriocin showed a bactericidal mode of action against L. monocytogenes. Therefore, it can be a biopreservative candidate for controlling L. monocytogenes in dairy and meat products.

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.523-528
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• 1998

We isolated microorganism secreting antimicrobial substance from tomato and identified as Enterococcus faecium. This substance was completely inactivated by pretense treatment and retained activity after catalase treatment. This result indicated that the antimicrobial activity of this substance was due to proteinaceous substance known as bacteriocin. The bacteriocin inhibited growth of Gram positive bacteria, such as Listeria monocytogenes, Leuconostoc mesenteroides, Lactobacillus plantarum, Streptococcus agalactiae, Streptococcus pyrogenes, and Gram negative bacteria, such as Pseudomonas aeruginosa. Purification of the bacteriocin was achieved by ethanol precipitation, ion exchange chromatography on CM Sepharose CL-6B, and gel filtration on Sephacryl S-100 HR. After these purification steps, the specific activity of the bacteriocin was increased 35.8 fold compared with culture broth. Purified bacteriocin was shown single band on SDS-PAGE and molecular weight was estimated 51 kDa. The residual activity of this bacteriocin was 3.3% at 10$0^{\circ}C$ for 60 min, and this bacteriocin was stable at pH 2~7.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.503-508
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• 2004

The antimicrobial substance produced by Lactobacillus bulgaricus was inactivated by protease. It showed inhibitory activity against Staphylococcus aureus ATCC6538, Streptococcus agalactiae ATCC14364, some Gram-positive and Gram-negative bacteria, and characteristics of a bacteriocin. The optimal temperature and culture time for the production of bacteriocin were $30^{\circ}C$ and 10 h, respectively, in the culture of L. bulgaricus. The bacteriocin production started in the exponential phase and reached a maximum at the early stationary phase. Using Staph. aureus ATCC6538 and Strep. agalactiae ATCC14364, known as common bovine mastitis pathogens, as indicator strains for determination of the bacteriocin activity, the antimicrobial activity of the bacteriocin was found to be stable in acidic and neutral pH's (2- 7) even at lOOT, whereas it was lost at high pH (10- 11) and $100^{\circ}C$. The mode of action for the antimicrobial activity was bacteriocidal, and the molecular weight determined by SDS-PAGE and overlay method was 14 kDa.