title: Characterization of bacteriocins from two Lactococcus lactis subsp. lactis isolates.
abstract: In this study, bacteriocins from two Lactococcus lactis subsp. lactis isolates from raw milk samples in Turkey designated OC1 and OC2, respectively, were characterized and identified. The activity spectra of the bacteriocins were determined by using different indicator bacteria including Listeria, Bacillus and Staphylococcus spp. Bacteriocins were tested for their sensitivity to different enzymes, heat treatments and pH values. Loss of bacteriocin activities after alpha-amylase treatment suggested that they form aggregates with carbohydrates. Molecular masses of the purified bacteriocins were determined by SDS-PAGE. PCR amplification was carried out with specific primers for the detection of their structural genes. As a result of these studies, the two bacteriocins were characterized as nisin and lacticin 481, respectively. Examination of plasmid contents of the isolates and the results of plasmid curing and conjugation experiments showed that in L. lactis subsp. lactis OC1 strain the 39.7-kb plasmid is responsible for nisin production, lactose fermentation and proteolytic activity, whereas the 16.0-kb plasmid is responsible for lacticin 481 production and lactose fermentation in L. lactis subsp. lactis OC2 strain.
authors.affiliation: Department of Biotechnology, Middle East Technical University, Ankara, Turkey.
authors.forename: Oya
authors.initials: O
authors.lastname: Akçelik
authors.forename: Cagla
authors.initials: C
authors.lastname: Tükel
authors.forename: Gülay
authors.initials: G
authors.lastname: Ozcengiz
authors.forename: Mustafa
authors.initials: M
authors.lastname: Akçelik
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents; D001407:Bacillus / Q000187:drug effects; D001430:Bacteriocins / Q000032:analysis* / Q000235:genetics / Q000494:pharmacology; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000737:chemistry* / Q000235:genetics; D008087:Listeria / Q000187:drug effects; D008892:Milk / Q000382:microbiology; D008970:Molecular Weight; D009561:Nisin / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D013210:Staphylococcus / Q000187:drug effects; D000516:alpha-Amylases / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; C082508:lacticin 481; D009561:Nisin; D000516:alpha-Amylases