摘要:It was ascertained by paper partition chromatography, ultraviolet spectrum, and bioassay with L. casei that the green fluorescent substance, G compound, isolated from the mycelium of Er. ashbyii readily reacts with diacetyl or with acetoin to form riboflavin. These results established the structure 8-ribityl-6, 7-dimethyllumazine, formerly proposed by the author for the G compound. On the other hand, a large quantity of acetoin was detected in the mycelium and the culture filtrate, and comparing the amount with those of riboflavin and G compound in these materials, the assumption was made that the biosynthesis of riboflavin by Er. ashbyii might be effected by condensation of acetoin with G compound at the position of the methyl groups.