Abstract 032
A New Medium For the Detection of Wild Yeast in Brewing Culture Yeast
J. Amer. Soc. Brew. Chem. 45: 135-140, 1987
J. De Angelo and K.J. Siebert
83 characteristics of 469 yeast spp. were entered into a data base management program to theoretically determine the number of spp. which exhibit positive, negative or variable growth for a specific trait. 41 pure cultures were incubated in various media (YM agar, lysine, copper sulphate, XMACS, cycloheximide) for 7 days at 27°C (YM incubated at 37°C). XMACS medium contained a combination of 5 C-sources (xylose, mannitol, adonitol, cellobiose and sorbitol), theoretically determined, to permit growth of 394 (84%) known yeast spp. Of 23 non-Saccharomyces cerevisiae, 14 grew on XMACS or lysine medium, 5 grew on cycloheximide and 21 grew on copper-sulphate medium. None of the 18 S. cerevisiae strains grew on cycloheximide or lysine media, 10 grew on XMACS and 12 on copper-sulphate medium. In 76 samples of pitching yeast (collected from 3 different breweries over 2 months) examined in these 5 media, wild yeasts were detected in 15 samples with XMACS, which is significantly higher than the 2 samples in cycloheximide and the 6 in lysine or copper sulphate media.
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