[Cysteine effects on yeast growth]

The effect of cysteine on yeasts with different requirements for exogenous pantothenic acid was studied during their cultivation in the synthetic nutrient medium. Cysteine added at a concentration of 4X10(-4) M and 6X10(-4) M inhibited the growth of Saccharomyces cerevisiae of the Krasnodarsk race and Candida utilis BKM y-74 to a great extent and that of Saccharomycodes ludwigii BKM y-1176 to a lesser extent. The inhibitory effect of cystein was reversed by pantothenic acid, beta-alanine, aspartate and aspartic acid. It is assumed that cysteine inhibits metabolic utilization of pantothenic acid.