The Effect of Nitrogenous Substances on the Time of Flocculation of Saccharomyces cerevisiae

The point in the growth cycle at which a strain of brewer’s yeast became potentially flocculent could be delayed by supplementing the medium with ammonia, basic amino acids, glutamine, asparagine, γ-aminobutyric acid or urea. Other amino acids were ineffective. β-Alanine and 2-chloro-4-aminobenzoic acid led to an abnormally early appearance of potential flocculence. No development of flocculence occurred in the absence of glucose. It is suggested that the maintenance of non-flocculence is dependent upon the presence in the cell wall of a nitrogenous compound; potential flocculence will develop when this compound is not synthesized at a rate sufficient to maintain its concentration in the wall. The nitrogenous nutrients which delay flocculation would then act by enhancing this rate of synthesis.