NITROGENOUS CONSTITUENTS OF BREWING MATERIALS: X. UTILIZATION OF THE PURINES AND AMINO ACIDS OF WORT BY VARIOUS YEASTS

From a consideration of the composition of wort with respect to purines and amino acids during parallel fermentations, the various yeasts examined appeared to fall into four groups as follows: (a) brewing yeasts which assimilated a large proportion (more than 75%) of both the purines, guanine and particularly adenine, originally present in the wort; (b) other species of Saccharomyces and also Torulopsls colliculosa, which took up less adenine (ca. 60%); (c) a few yeasts which utilized only one‐third of the adenine; and (d) the film‐forming yeasts which actually formed extra‐cellular adenine while utilizing guanine preferentially. The behaviour of the yeasts towards amino acid nitrogen showed some parallelism with that towards adenine, except with those yeasts which possess high proteolytic activity towards wort proteins as is the case with Piehia membranaefaciens and Hansenula sub‐pelliculosa.