title: In vitro antimycotic activity of a Williopsis saturnus killer protein against food spoilage yeasts.
abstract: The in vitro antimycotic activity of a purified killer protein (KT4561) secreted by a strain of Williopsis saturnus was tested against 310 yeast strains belonging to 21 food spoilage species of 14 genera (Candida, Debaryomyces, Dekkera, Hanseniaspora, Issatchenkia, Kazachstania, Kluyveromyces, Pichia, Rhodotorula, Saccharomyces, Schizosaccharomyces, Torulaspora, Yarrowia and Zygosaccharomyces). Minimum inhibitory concentration (MIC) determinations showed that over 65% of the target strains were susceptible to concentrations < or = 32 microg/ml of KT4561. Three conventional food-grade antimicrobial agents were used as controls: 41, 33 and 40% of the target strains were sensitive to < or = 512 mg/ml of ethyl 3-hydroxybenzoate (E214), potassium sorbate (E202) or potassium metabisulphite (E224), respectively. The susceptibility of food spoilage yeasts towards KT4561, E214, E202 and E224 was species- and strain-dependent. In most cases KT4561 exhibited MIC values several orders of magnitude lower (100 to 100,000 times) than those observed for E214, E202 and E224. With only a few exceptions, the activity of KT4561 was pH-, ethanol-, glucose- and NaCl-independent. The present study demonstrates the potential of this yeast killer protein as a novel and natural control agent against food spoilage yeasts.
authors.affiliation: Dipartimento di Biologia Applicata-Sez, Microbiologia and Industrial Yeasts Collection DBVPG, Università di Perugia, Perugia 06121, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Goretti
authors.forename: Benedetta
authors.initials: B
authors.lastname: Turchetti
authors.forename: Morena
authors.initials: M
authors.lastname: Buratta
authors.forename: Eva
authors.initials: E
authors.lastname: Branda
authors.forename: Lanfranco
authors.initials: L
authors.lastname: Corazzi
authors.forename: Ann
authors.initials: A
authors.lastname: Vaughan-Martini
authors.forename: Pietro
authors.initials: P
authors.lastname: Buzzini
mesh_terms: D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D005516:Food Microbiology; D005656:Fungal Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D055646:Killer Factors, Yeast; D008826:Microbial Sensitivity Tests; D009183:Mycotoxins / Q000302:isolation & purification / Q000494:pharmacology*; D055320:Williopsis / Q000737:chemistry*; D015003:Yeasts / Q000187:drug effects*
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; C496274:KT4561 protein, Williopsis saturnus; D055646:Killer Factors, Yeast; D009183:Mycotoxins