Orotic acid in the nutrition of a strain of Lactobacillus bulgaricus.

In an investigation of the nutrition of various strains of Lactobacillus bulgaricusl an organism was obtained that would not grow on a complex medium containing casein hydrolysate, purines, pyrimidines, vitamins, a yeast extract, and clarified tomato juice. A wide diversity of natural products was tested for their ability to support the growth of L. bulgaricus 09, but only whey or related productsa supported maximal growth of the organism. Fractionation of these milk products led to the isolation of a biologically active crystalline compound which was identified as erotic acid. When erotic acid was added to the basal medium and the tomato juice and yeast extract were omitted, no growth was obtained. Caswell et al. (1) reported that the tomato juice used in their medium for the estimation of vitamin Blz with Lactobacillus lactis Dorner could be replaced by a mixture of fumaric acid and ethyl sodium oxalacetate. With L. bulgaricus 09 this mixture does not support optimal growth of the organism. If citric acid is added in addition to the fumaric acid and ethyl sodium oxalacetate, satisfactory growth is obtained.