title: Detection, cellular localization and antibacterial activity of two lytic enzymes of Pediococcus acidilactici ATCC 8042.
abstract: OBJECTIVE
  In Pediococcus acidilactici ATCC 8042, two activities of peptidoglycan hydrolase (PGH) with lytic effect against Micrococcus lysodeikticus and Staphylococcus aureus have been detected. This work intends to elucidate the growth phase of maximum lytic activity, the localization and the effectiveness of the activity against pathogenic Gram-negative and Gram-positive bacteria.
  
  
  RESULTS
  Cells were grown in MRS medium and collected at different growth stages, and the proteins were extracted. The highest PGH activity was found during the logarithmic growth phase in the protein fraction bound to the cell membrane. From this fraction, two distinct proteins bands (110- and 99-kDa) in SDS-PAGE were partially purified with a three-step procedure. Both bands showed lytic activity against M. lysodeikticus. Mass spectrometry analysis (LC/ESI-MS/MS) indicated that the 110-kDa band corresponded to a protein of unknown function. The 99-kDa band corresponded to a N-acetylmuramidase that harboured catalytic sites with N-acetylmuramoyl-L-alanine amidase and N-acetylglucosaminidase activities. Both proteins are reported in the Ped. acidilactici 7_4 genome. The fraction containing the concentrated proteins (110 and 99 kDa) inhibited the growth of several pathogenic strains as: Bacillus cereus, Listeria monocytogenes and Salmonella typhimurium. The growth of S. aureus was diminished by 3 logarithmic units as early as 0.5 h of growth, while inhibition of Escherichia coli and Ped. acidilactici was observed after 18 and 8 h, respectively (both in one logarithmic unit). The minimum inhibitory concentration against S. aureus was 10 μg ml(-1).
  
  
  CONCLUSIONS
  Pediococcus acidilactici harbours at least two lytic enzymes, one of them recognized as PGH for the first time, which exert antibacterial activity against several bacterial strains.
  
  
  CONCLUSIONS
  Both PGH activities have a broad growth inhibition spectrum and could be used to control pathogenic bacteria. Because this activity comes from a lactic acid bacterium, it could be safely used in manufacturing processes of fermented foods.
authors.affiliation: Departamento de Alimentos y Biotecnología, Facultad de Química, Universidad Nacional Autónoma de México, México, DF, México.
authors.forename: I
authors.initials: I
authors.lastname: García-Cano
authors.forename: L
authors.initials: L
authors.lastname: Velasco-Pérez
authors.forename: R
authors.initials: R
authors.lastname: Rodríguez-Sanoja
authors.forename: S
authors.initials: S
authors.lastname: Sánchez
authors.forename: G
authors.initials: G
authors.lastname: Mendoza-Hernández
authors.forename: A
authors.initials: A
authors.lastname: Llorente-Bousquets
authors.forename: A
authors.initials: A
authors.lastname: Farrés
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics / Q000378:metabolism*; D010376:Pediococcus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D053719:Tandem Mass Spectrometry
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D006026:Glycoside Hydrolases; C026255:endo-N-acetylmuramidase; D009238:N-Acetylmuramoyl-L-alanine Amidase