Autochthonous microbial population in a Niagara Peninsula icewine must

Abstract We have characterized the microbial population in icewine musts from three locations in an Ontario vineyard. More than 3×10 3 colony forming units (cfus) were isolated from icewine must from the 1999 vintage. The cfus were enumerated and representative colonies were selected and identified using classical morphological, auxanographic and physiological tests. Species distribution and frequency of microbes in icewine musts were compared with those found in an earlier study. In icewine must, bacteria accounted for 2% of the total cfus enumerated. Acetobacter and Gluconobacter were not found. The only fermentative yeast found was Hanseniaspora . The rest of the yeasts were non-fermentative Basidiomycetous yeasts that would have little effect on fermentations. Ninety percent of the mold cfus were the Basidiomycetous non-fermentative Aureobasidium pullulans . We conclude that in this sample, the autochthonous micro flora may possibly have some effect on the grapes in the vineyard but have only a minor role in the fermenting must.