title: Genetic Characterization of Lactic Acid Bacteria Isolated from Tunisian Milk Waste and their Antimicrobial Activity Against some Bacteria Implicated in Nosocomial Infections.
abstract: BACKGROUND
  A total of 94 lactic acid bacteria (LAB) were isolated from Tunisian artisanal (Ricotta cheese's whey) and industrial (bactofugate) milk waste, identified and then screened for their antimicrobial activity against some bacteria implicated on nosocomial infections.
  
  
  OBJECTIVE
  Bacterial genera and species identification was performed using molecular tools. The antimicrobial activity was tested against 7 strains of Gram-negative bacteria and 4 strains of Gram-positive bacteria as well as 6 yeasts.
  
  
  METHODS
  The Crude extract was found to have a narrow antimicrobial spectrum on Gram-positive bacteria mainly Listeria monocytogenes. Among the strains which showed antibacterial activity, four were determined to be bacteriocins-producers. They were identified as Lactococcus lactis.
  
  
  RESULTS
  Brain Heart Infusion (BHI) Agar was found more adapted than Man, Rogosa and Sharpe (MRS) to investigate the antimicrobial activity of L. actococcus lactis against L. isteria monocytogenes. The genetic determinants encoding the antimicrobial peptides were targeted by specific PCR.
  
  
  CONCLUSIONS
  All L. lactis bacteriocin producing strains possessed the Nisine Z gene (nisZ) except for one, which contained both Nisine A and Nisine Z genes (nisA and nisZ). They have been identified as antilisterial agentS.
authors.affiliation: Higher institute of Biotechnology of Monastir, University of Monastir, Tunisia. ghodhbanehanen@gmail.com.
authors.forename: Hanen
authors.initials: H
authors.lastname: Ghodhbane
authors.forename: Valentina
authors.initials: V
authors.lastname: Alessandria
authors.forename: Mejdi
authors.initials: M
authors.lastname: Snoussi
authors.forename: Lobna
authors.initials: L
authors.lastname: Elleuch
authors.forename: Ismail
authors.initials: I
authors.lastname: Trabelsi
authors.forename: Chedly
authors.initials: C
authors.lastname: Abdelly
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Sabatier
authors.forename: Luca
authors.initials: L
authors.lastname: Cocolin
authors.forename: Imed
authors.initials: I
authors.lastname: Regaya
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001430:Bacteriocins / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D003428:Cross Infection / Q000382:microbiology*; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006801:Humans; D056546:Lactobacillales / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D013294:Lactococcus lactis / Q000737:chemistry / Q000302:isolation & purification; D008089:Listeria monocytogenes / Q000187:drug effects; D008892:Milk / Q000382:microbiology*; D009561:Nisin / Q000235:genetics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014416:Tunisia; D014866:Waste Products; D000067796:Whey / Q000382:microbiology; D015003:Yeasts / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D014866:Waste Products; D009561:Nisin