• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.1026-1034
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• 2016

In the current study, a total of 135 enterococci strains from different sources were screened for the presence of the enterocin-encoding genes entA, entP, entB, entL50A, and entL50B. The enterocin genes were present at different frequencies, with entA occurring the most frequently, followed by entP and entB; entL50A and L50B were not detected. The occurrence of single enterocin genes was higher than the occurrence of multiple enterocin gene combinations. The 80 isolates that harbor at least one enterocin-encoding gene (denoted "Gene⁺ strains") were screened for antimicrobial activity. A total of 82.5% of the Gene⁺ strains inhibited at least one of the indicator strains, and the isolates harboring multiple enterocin-encoding genes inhibited a larger number of indicator strains than isolates harboring a single gene. The indicator strains that exhibited growth inhibition included Listeria innocua strain CLIP 12612 (ATCC BAA-680), Listeria monocytogenes strain CDC 4555, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 6538, Salmonella enteritidis ATCC 13076, Salmonella typhimurium strain UK-1 (ATCC 68169), and Escherichia coli BAC 49LT ETEC. Inhibition due to either bacteriophage lysis or cytolysin activity was excluded. The growth inhibition of antilisterial Gene⁺ strains was further tested under different culture conditions. Among the culture media formulations, the MRS agar medium supplemented with 2% (w/v) yeast extract was the best solidified medium for enterocin production. Our findings extend the current knowledge of enterocin-producing enterococci, which may have potential applications as biopreservatives in the food industry due to their capability of controlling food spoilage pathogens.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.4
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• pp.296-303
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• 2005

A strain named as HJ35 was isolated from the skin of sixty-five men and fourteen women for acne therapy, in order to find an effective antimicrobial agent against Propionibacterium acnes. Isolate HJ35 was identified as Enterococcus faecium based on 16 rDNA sequence and produced enterocin HJ35 having antimicrobial activities against most lactic acid bacteria, En­terococcus spp., Staphylococcus aureus, S. epidermidis, Clostridium perfringens, some bacilli, Mi­crococcus flavus, Listeria monocytogenes, L. ivanovii, Escherichia coli, Pseudomonas fluorescens and Propionibacterium acnes, in the modified well diffusion method. Especially, enterocin HJ35 showed a bactericidal activity against Propionibacterium acnes P1. The antimicrobial activity of enterocin HJ35 was disappeared completely with the use of protease XIV. But enterocin HJ35 activity is very stable at high temperature (up to $100^{\circ}C$ for 30 min), in wide range of pH (3.0${\~}$9.0), and by treatment with organic solvents. The apparent molecular mass of enterocin HJ35 was estimated to be approximately 4${\~}$4.5 kDa on detection of its bactericidal activity after SDS-PAGE. In batch fermentation of E. faecium HJ35, enterocin HJ35 was produced at the mid­log growth phase, and its maximum production was obtained up to 2,300 AU/mL at the late stationary phase. By employing fed-batch fermentation, the enhanced production of enterocin HJ35 was achieved up to 12,800 AU/mL by feeding with 10 g/L glucose or 6 g/L lactate.

• 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.

• Korean Journal of Microbiology
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• v.54 no.2
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• pp.171-173
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• 2018

Enterococcus faecium was commonly used as a probiotics and feed additives to human and animals because of their beneficial effects. We sequenced the genome of E. faecium JB00008 (KACC 92186P) isolated from a Korean fermented soybean paste (Cheonggukjang) that showed antibacterial activity against Escherichia coli. A 2,847,295-bp draft genome was obtained, and it has in 37.84% G + C content in 34 contigs (length, ${\geq}500bp$).

• Microbiology and Biotechnology Letters
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• v.46 no.3
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• pp.288-299
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• 2018

Food bio preservation is of major interest in the food industry. Many types of antimicrobial compounds can be produced by lactic acid bacteria (LAB), including bacteriocins. Bacteriocins increase the shelf-life of food by decreasing some food-borne diseases. In this study, a multi-coding sequence of bacteriocin genes was used for primer design to produce bacteriocin genes in Enterococcus faecium AH2 strain and Pediococcus pentosaceus AH1. Multi-coding sequences were aligned to detect conserved sequences in the bacteriocin gene. Eight genes encoding proteins involved in bacteriocin production were isolated and sequenced, including six from E. faecium AH2 (entA, entI, entF, entR, orfA2, orfA3) and two from P. pentoceseus AH1 (papA, pedB), and all gene sequences were deposited in the Gen Bank database under accession numbers LC064146-LC064151, LC101300, and LC101789, respectively. P. pentosaceus AH1 and E. faecium AH2 strains displayed bacteriocin activities of $2610AU\;mL^{-1}$ and $690AU\;mL^{-1}$ and inhibition zones of 26 mm and 19 mm, respectively. Overexpression of entA in E. faecium AH2 increased the bacteriocin and antimicrobial activities.

• 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.