title: Evaluation of damage induced by Kwkt and Pikt zymocins against Brettanomyces/Dekkera spoilage yeast, as compared to sulphur dioxide.
abstract: OBJECTIVE
  Over the last few decades, the use of zymocins as biological tools to counteract contamination by spoilage yeast in beverages and food has been widely studied. This study examined the damage induced by the Kwkt and Pikt, two zymocins produced by Kluyeromyces wickerhamii and Wickerhanomyces anomalus, respectively, with antimicrobial activity against Brettanomyces/Dekkera wine-spoilage yeast.
  
  
  RESULTS
  The physiological and biochemical characterization of both of these proteins revealed that only Pikt showed a strict relationship between β-glucosidase activity and killer activity. The minimum inhibitory concentrations and minimum fungicidal concentrations of Kwkt and Pikt showed inhibitory activities against Brettanomyces/Dekkera yeast. Cytofluorimetric evaluation of cell death was based on both cell membrane permeability and cell metabolism, using fluorescence techniques under increasing zymocin levels over different incubation times. The antimicrobial actions of Kwkt and Pikt were also compared with the mode of action of sulphur dioxide. In this last case, the induction of the viable but noncultivable (VBNC) state was confirmed, with the consequent recovery of Brettanomyces yeast after medium replacement. In contrast, Kwkt and Pikt caused irreversible death of these yeast, without recovery of sensitive cells.
  
  
  CONCLUSIONS
  Kwkt and Pikt could be proposed as fungistatic or fungicide biocontrol agents in winemaking to control the colonization and development of Brettanomyces/Dekkera yeasts.
  
  
  CONCLUSIONS
  These data support the potential use of zymocins to reduce wine contamination as an alternative to sulphur dioxide that act on sensitive cells. Differently from sulphur dioxide, that could induce a reversible VBNC state, Kwkt and Pikt determine the irreversible damage on sensitive yeasts, ensuring the complete control of spoilage Brettanomyces yeast.
authors.affiliation: Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Oro
authors.affiliation: Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ciani
authors.affiliation: Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Bizzaro
authors.affiliation: Dipartimento Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Comitini
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D055168:Brettanomyces / Q000187:drug effects*; D055167:Dekkera / Q000187:drug effects*; D055646:Killer Factors, Yeast / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D013458:Sulfur Dioxide / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D055646:Killer Factors, Yeast; C058975:zymocin; D013458:Sulfur Dioxide
keywords: Brettanomyces/Dekkera; antimicrobials; irreversible mode of action; viable but noncultivable; zymocins