• 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.

• 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.