Growth-Promoting Activity of L-Lyxoflavin for Lactobacillus lactis ∗ †

Abstract

Summary

L-lyxoflavin had 16% of the activity of riboflavin in promoting growth of Lactobacillus lactis in a 40-hour assay. The activity increased to 43% after 6 days of incubation. Growth with L-lyxoflavin occurred in the presence or absence of riboflavin and there was no evidence of competitive inhibition. L-lyxoflavin inhibited riboflavin competitively in the growth of Lactobacillus casei, in Snell's riboflavin assay medium, with an inhibition index of 50, but the inhibition became stimulation in a synthetic medium when optimum amounts of riboflavin were present. D-lyxoflavin, D-araboflavin, gal-actoflavin, and α-ribazole were inactive in promoting growth of either L. lactis or L. casei while 5,6-dimethylbenzimidazole was inactive for L. lactis. Riboflavin phosphate and isoriboflavin had riboflavin activity for both organisms.