Abstract
Using Aerobacter aerogenes and Eremothecium ashbyii, chemically synthesized 4-N-ribitylamino-5-aminouracil was converted enzymically into riboflavin via 6, 7-dimethylribolumazine in the presence of acetoin. It is proposed that acetoin is enzymically oxidized to diacetyl and then it is cyclized spontaneously with diaminouracil compound forming lumazine compound. This reaction step does not require any energy-rich compound such as ATP in contrast to riboflavin synthesis from 6, 7-dimethylribolumazine. It was shown in Er. ashbyii that acetoin is formed from two molecules of acetaldehyde in the presence of cocarboxylase.
