Vitamin requirements and induced nutritional imbalances as criteria in speciating psychrophobic yeasts

Vitamin requirements, determined by two different methods, and other nutritional characteristics of 46 psychrophobic and 30 non-psychrophobic yeasts were investigated. Vitamin requirements and induced nutritional imbalances emerged as criteria for definingCandida slooffii. Strains of this species behaved uniformly. Variations in vitamin requirements of strains ofSaccharomyces telluris, Torulopsis bovina andTorulopsis pintolopesii were confirmed. The choline requirement exhibited by several strains (by as many as 86% inS. telluris) was evident on a simple defined medium without methionine, but not on Wickerham's vitamin-free basal medium. The group of choline-requiring strains comprised strains responding similarly to choline or methionine, and some strains growing with choline but not with methionine on short incubation. Other frequently required vitamins were biotin, pantothenate, thiamine, nicotinic acid, pyridoxine, and inositol. Fellow of the John Simon Guggenheim Memorial Foundation. Fellow of the National Research Council (Brasil).