Diversity and molecular determination of wild yeasts in a central Washington State vineyard

Abstract

Yeasts were isolated from grapes collected from a research vineyard at the WSU-IAREC, located at Prosser, WA. Species determination was based on cultural features, microscopic morphology, physiological tests and analysis of ITS and D1/D2 rDNA sequence data. Fifty-three species were found distributed among five fungal subphyla, a greater number than expected based on similar published studies. Within Saccharomycotina, 13 species in the genera Candida, Hanseniaspora, Metschnikowia, Meyerozyma, Pichia, Wickerhamomyces and Yamadazyma were determined. Isolates within the Metschnikowia pulcherrima clade appeared to possess considerable diversity. Pucciniomycotina was represented by 12 species, in Curvibasidium , Rhodosporidium, Rhodotorula, Sporidiobolus and Sporobolomyces . Five phylogenetically distinct species in the subphylum could not be assigned to any described species. Isolates in Ustilaginomycotina were placed in Pseudozyma except for a single strain determined to be Rhodotorula bacarum .Within Agaricomycotina, 17 species in the genera Cryptococcus, Cystofilobasidium , Hannaella, Holtermanniella and Mrakiella were determined. Seven species of yeast-like Pezizomycotina were found, representing classes Leotiomycetes, Dothideomycetes and Sordariomycetes. Isolates of Aureobasidium pullulans represented three phylogenetically distinct subspecific lineages.Seventeen species identified in this study were previously unreported from wine grapes and 18 species were unreported from North America. Several strains appear to represent undescribed species, including the recently described Curvibasidium rogersii .