Vitamin B2 activity of 7,8-dimethyl-10-(2,3,4-trihydroxy-4-formylbutyl)isoalloxazine in Lactobacillus casei.

The microbial activities of vitamin B2-aldehyde and vitamin B2-acid, produced by Schizophyllum commune, a Basidiomycete, were studied. Lactobacillus casei ATCC No. 7469 was used as a test microorganism. B2-aldehyde exhibited a good response curve in the growth of L. casei. B2-acid had neither a stimulatory nor an inhibitory effect on the growth. When B2-aldehyde was incubated with the homogenate of L. casei, it was converted to riboflavin. The flavin formed from B2-aldehyde by the homogenate not only exhibited an equivalent response curve to authentic riboflavin in the growth of L. casei, but also showed the same Rf value as authentic riboflavin in any paper chromatogram, as far as tested. Hence, the microbial activity of B2-aldehyde for L. casei seems to be ascribable to riboflavin which is a reduction product of B2-aldehyde.