title: Nectar yeasts of the Metschnikowia clade are highly susceptible to azole antifungals widely used in medicine and agriculture.
abstract: The widespread use of azole antifungals in medicine and agriculture and the resulting long-persistent residues could potentially affect beneficial fungi. However, there is very little information on the tolerance of non-target environmental fungi to azoles. In this study, we assessed the susceptibility of diverse plant- and insect-associated yeasts from the Metschnikowia clade, including several ecologically important species, to widely used medical and agricultural azoles (epoxiconazole, imazalil, ketoconazole and voriconazole). A total of 120 strains from six species were tested. Minimum inhibitory concentrations (MICs) were determined by the EUCAST broth microdilution procedure after some necessary modifications were made. The majority of species tested were highly susceptible to epoxiconazole, ketoconazole and voriconazole (>95% of strains showed MICs ≤ 0.125 mg l(-1)). Most strains were also very susceptible to imazalil, although MIC values were generally higher than for the other azoles. Furthermore, certain Metschnikowia reukaufii strains displayed a 'trailing' phenotype (i.e. showed reduced but persistent growth at antifungal concentrations above the MIC), but this characteristic was dependent on test conditions. It was concluded that exposure to azoles may pose a risk for ecologically relevant yeasts from the Metschnikowia clade, and thus could potentially impinge on the tripartite interaction linking these fungi with plants and their insect pollinators.
authors.affiliation: Department of Animal Health, Faculty of Veterinary Medicine, Universidad Complutense de Madrid, E-28040 Madrid, Spain Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, B-2860 Sint-Katelijne-Waver, Belgium.
authors.forename: Sergio
authors.initials: S
authors.lastname: Álvarez-Pérez
authors.affiliation: Estación Biológica de Doñana, CSIC, E-41092 Sevilla, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: de Vega
authors.affiliation: Plant Population and Conservation Biology, Biology Department, KU Leuven, B-3001 Heverlee, Belgium.
authors.forename: María I
authors.initials: MI
authors.lastname: Pozo
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, B-2860 Sint-Katelijne-Waver, Belgium.
authors.forename: Marijke
authors.initials: M
authors.lastname: Lenaerts
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, B-2860 Sint-Katelijne-Waver, Belgium.
authors.forename: Ado
authors.initials: A
authors.lastname: Van Assche
authors.affiliation: Estación Biológica de Doñana, CSIC, E-41092 Sevilla, Spain.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Herrera
authors.affiliation: Plant Population and Conservation Biology, Biology Department, KU Leuven, B-3001 Heverlee, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Jacquemyn
authors.affiliation: Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, B-2860 Sint-Katelijne-Waver, Belgium bart.lievens@kuleuven.be.
authors.forename: Bart
authors.initials: B
authors.lastname: Lievens
mesh_terms: D000383:Agriculture / Q000379:methods; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D007313:Insecta / Q000382:microbiology; D008511:Medicine / Q000379:methods; D055163:Metschnikowia / Q000187:drug effects* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010944:Plants / Q000382:microbiology
chemical_list: D000935:Antifungal Agents; D001393:Azoles
keywords: EUCAST; Metschnikowia clade; azoles; broth microdilution; floral nectar; insect pollinators