title: In situ production of human β defensin-3 in lager yeasts provides bactericidal activity against beer-spoiling bacteria under fermentation conditions.
abstract: OBJECTIVE
  To examine the use of a natural antimicrobial peptide, human β-defensin-3 (HBD3), as a means of preventing spoilage from bacterial contamination in brewery fermentations and in bottled beer.
  
  
  RESULTS
  A chemically synthesised HBD3 peptide was tested for bactericidal activity against common Gram-positive and Gram-negative beer-spoiling bacteria, including species of Lactobacillus, Pediococcus and Pectinatus. The peptide was effective at the μmol l(-1) range in vitro, reducing bacterial counts by 95%. A gene construct encoding a secretable form of HBD3 was integrated into the genome of the lager yeast Saccharomyces pastorianus strain CMBS-33. The integrated gene was expressed under fermentation conditions and was secreted from the cell into the medium, but a significant amount remains associated with yeast cell surface. We demonstrate that under pilot-scale fermentation conditions, secreted HBD3 possesses bactericidal activity against beer-spoiling bacteria. Furthermore, when added to bottled beer, a synthetic form of HBD3 reduces the growth of beer-spoiling bacteria.
  
  
  CONCLUSIONS
  Defensins provide prophylactic protection against beer-spoiling bacteria under brewing conditions and also in bottled beer.
  
  
  CONCLUSIONS
  The results have direct application to the brewing industry where beer spoilage due to bacterial contamination continues to be a major problem in breweries around the world.
authors.affiliation: Moyne Institute for Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, College Green, Dublin, Ireland.
authors.forename: T C
authors.initials: TC
authors.lastname: James
authors.affiliation: Moyne Institute for Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, College Green, Dublin, Ireland.
authors.forename: L
authors.initials: L
authors.lastname: Gallagher
authors.affiliation: School of Food and Nutritional Science, University College Cork, Cork, Ireland.
authors.forename: J
authors.initials: J
authors.lastname: Titze
authors.affiliation: Moyne Institute for Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, College Green, Dublin, Ireland.
authors.forename: P
authors.initials: P
authors.lastname: Bourke
authors.affiliation: Moyne Institute for Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, College Green, Dublin, Ireland.
authors.forename: J
authors.initials: J
authors.lastname: Kavanagh
authors.affiliation: School of Food and Nutritional Science, University College Cork, Cork, Ireland.
authors.forename: E
authors.initials: E
authors.lastname: Arendt
authors.affiliation: Moyne Institute for Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, College Green, Dublin, Ireland.
authors.forename: U
authors.initials: U
authors.lastname: Bond
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000494:pharmacology*; D001483:Base Sequence; D001515:Beer / Q000382:microbiology*; D004271:DNA, Fungal / Q000737:chemistry; D005285:Fermentation; D006801:Humans; D007777:Lactobacillaceae / Q000187:drug effects* / Q000254:growth & development; D007778:Lactobacillus / Q000187:drug effects / Q000254:growth & development; D008969:Molecular Sequence Data; D045852:Pectinatus / Q000187:drug effects*; D010376:Pediococcus / Q000187:drug effects / Q000254:growth & development; D010865:Pilot Projects; D012331:RNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D012440:Saccharomyces / Q000235:genetics / Q000378:metabolism*; D023083:beta-Defensins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; C422950:DEFB103A protein, human; D004271:DNA, Fungal; D012331:RNA, Fungal; D023083:beta-Defensins
keywords: Peptides; brewery; fermentation biotechnology; lactic acid bacteria; microbial contamination