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Isolation and characterization of large spectrum and multiple bacteriocin‐producing E nterococcus faecium strain from raw bovine milk
Author(s) -
Gaaloul N.,
Braiek O.,
Hani K.,
Volski A.,
Chikindas M.L.,
Ghrairi T.
Publication year - 2015
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12699
Subject(s) - raw milk , isolation (microbiology) , enterococcus faecium , bacteriocin , microbiology and biotechnology , strain (injury) , enterococcus , biology , bacteria , bovine milk , antibiotics , food science , antimicrobial , genetics , anatomy
Aims To assess the antimicrobial properties of lactic acid bacteria from Tunisian raw bovine milk. Methods and Results A bacteriocin‐producing Enterococcus faecium strain was isolated from raw cow milk with activity against Gram‐positive and Gram‐negative bacteria. Antimicrobial substances produced by this strain were sensitive to proteolytic enzymes and were thermostable and resistant to a broad range of pH (2–10). Mode of action of antimicrobial substances was determined as bactericidal. Maximum activity was reached at the end of the exponential growth phase when checked against Listeria ivanovii BUG 496 (2366·62 AU ml −1 ). However, maximum antimicrobial activity against Pseudomonas aeruginosa 28753 was recorded at the beginning of the exponential growth phase. Enterococcus faecium GGN7 was characterized as free from virulence factors and was susceptible to tested antibiotics. PCR analysis of the micro‐organism's genome revealed the presence of genes coding for enterocins A and B. Mass spectrometry analysis of RP‐HPLC active fractions showed molecular masses corresponding to enterocins A (4835·77 Da) and B (5471·56 Da), and a peptide with a molecular mass of 3215·5 Da active only against Gram‐negative indicator strains. The latter was unique in the databases. Conclusions Enterococcus faecium GGN 7 produces three bacteriocins with different inhibitory spectra. Based on its antimicrobial properties and safety, Ent. faecium GGN 7 is potentially useful for food biopreservation. Significance and Impact of the Study The results suggest the bacteriocins from GGN 7 strain could be useful for food biopreservation.