Evaluation of Multinitrogen Source Media for Wild Yeast Detection in Brewing Culture Yeast. C. P. Martin and K. J. Siebert, The Stroh Brewery Company, Detroit, MI 48207. J. Am. Soc. Brew. Chem. 50:0134, 1992.

A multinitrogen source medium called CLEN (employing cadaverine, lysine, ethylamine, and nitrate as the sole nitrogen sources) was developed based on published data. Theoretically, CLEN would support the growth of a greater number of wild yeast species (415 of 469 or 88%) than would lysine medium (355 or 76%). A comparison of means of detecting wild yeast (growth on CLEN, lysine agar, XMACS [xylose, mannitol, adonitol, cellobiose, and sorbitol] agar, Lin's agar, yeast-maltose agar with cycloheximide, copper sulfate agar, and yeast-maltose agar at 37° C) was made with known pure cultures of a variety of yeast species and with brewery production yeast cultures. CLEN supported the growth of more yeast species and the growth of larger numbers of wild yeast in brewery samples than did lysine medium. Growth on CLEN was more rapid than that on lysine agar. None of the media tested is capable of detecting all wild yeast; several in combination are needed for a thorough examination.

Keywords: Media, Microbiology, Nitrogen source, Plating, Wild yeast, Saccharomyces