title: Killer toxin from several food-derived Debaryomyces hansenii strains effective against pathogenic Candida yeasts.
abstract: Candida yeasts are the dominant fungi in the healthy human microbiome, but are well-known for causing disease following a variety of perturbations. Evaluation of fungal populations from the healthy human gut revealed a significant negative correlation between the foodborne yeast, Debaryomyces hansenii, and Candida species. D. hansenii is reported to produce killer toxins (mycocins) effective against other yeast species. In order to better understand this phenomenon, a collection of 42 D. hansenii isolates was obtained from 22 cheeses and evaluated for killer activity against Candida albicans and Candida tropicalis over a range of temperatures and pH values. Twenty three strains demonstrated killer activity against both C. albicans and C. tropicalis, which was pH- and temperature-dependent, with no killer activity observed for any strain at pH6.5 or higher, or at ≥ 35 °C (physiological conditions in the human gastrointestinal tract). A cell-free mycocin preparation showed transient killer activity against C. albicans at 35 °C and a cheese sample containing a killer D. hansenii strain demonstrated sustained killer activity against both C. albicans and C. tropicalis. Together, these observations raise the possibility that D. hansenii could influence Candida populations in the gut.
authors.affiliation: Department of Food Science and Technology, University of Nebraska-Lincoln, 1901 North 21st St, Lincoln, NE 68588-6205, USA.
authors.forename: Nabaraj
authors.initials: N
authors.lastname: Banjara
authors.affiliation: Department of Biological Sciences, University of Nebraska-Lincoln, 1901 Vine St, Lincoln, NE 68588-0665, USA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Nickerson
authors.affiliation: Department of Food Science and Technology, University of Nebraska-Lincoln, 1901 North 21st St, Lincoln, NE 68588-6205, USA.
authors.forename: Mallory J
authors.initials: MJ
authors.lastname: Suhr
authors.affiliation: Department of Food Science and Technology, University of Nebraska-Lincoln, 1901 North 21st St, Lincoln, NE 68588-6205, USA. Electronic address: hhallen-adams2@unl.edu.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Hallen-Adams
mesh_terms: D000898:Antibiosis / Q000502:physiology*; D002175:Candida / Q000187:drug effects*; D002611:Cheese / Q000382:microbiology; D005516:Food Microbiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009183:Mycotoxins / Q000494:pharmacology*; D004718:Saccharomycetales / Q000737:chemistry*; D013696:Temperature
chemical_list: D009183:Mycotoxins
keywords: Cheese; Killer yeast; Microbiome; Mycocin; Probiotic