title: Isolation and characterization of large spectrum and multiple bacteriocin-producing Enterococcus faecium strain from raw bovine milk.
abstract: OBJECTIVE
  To assess the antimicrobial properties of lactic acid bacteria from Tunisian raw bovine milk.
  
  
  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 GGN7 produces three bacteriocins with different inhibitory spectra. Based on its antimicrobial properties and safety, Ent. faecium GGN7 is potentially useful for food biopreservation.
  
  
  CONCLUSIONS
  The results suggest the bacteriocins from GGN7 strain could be useful for food biopreservation.
authors.affiliation: UR12-ES03 Department of Biochemistry, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia.
authors.forename: N
authors.initials: N
authors.lastname: Gaaloul
authors.forename: O
authors.initials: O
authors.lastname: ben Braiek
authors.forename: K
authors.initials: K
authors.lastname: Hani
authors.forename: A
authors.initials: A
authors.lastname: Volski
authors.forename: M L
authors.initials: ML
authors.lastname: Chikindas
authors.forename: T
authors.initials: T
authors.lastname: Ghrairi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology*; D001430:Bacteriocins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology*; D016984:Enterococcus faecium / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008892:Milk / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins
keywords: Enterococcus; bacteriocins; cow milk; enterocins; high-performance liquid chromatography; lactic acid bacteria