Culturing Saccharomyces cerevisiae for [GAR+] prion detection.

To ascertain whether the [GAR⁺] prion state was detectable in wine fermentations, yeast were cultured for the prion as performed previously (121). Yeast peptone-based medium containing the designated carbon source was used, such as YPD (1% yeast extract, 2% peptone, 2% agar, 2% glucose), YPG (1% yeast extract, 2% peptone, 2% agar, 2% glycerol), or GGM [1% yeast extract, 2% peptone, 2% agar, 2% glycerol, 0.05% d-(+)-glucosamine hydrochloride]. Yeast from fermentations were inoculated into each well of a 96-well plate containing 200 μl liquid YPD    plus 34 g/ml chloramphenicol, and then yeast were grown at 30°C for 48 h. Yeast were pinned to YPG or GGM plates and grown at 30°C for 4 days.