Rapid preparation of isotopolog libraries by in vivo transformation of 1)C-glucose. Studies on 6,7-dimethyl-8-ribityllumazine, a biosynthetic precursor of vitamin B2.

An Escherichia coli strain engineered for expression of the ribABGH genes of Bacillus subtilis was shown to produce 100 mg of the riboflavin precursor 6,7-dimethyl-8-ribityllumazine per liter of minimal medium. Growth of the recombinant strain in medium supplemented with [U-13C6]glucose and/or 15NH4Cl as single sources of carbon and/or nitrogen afforded 6,7-dimethyl-8-ribityllumazine universally labeled with 13C and/or 15N. The yield of [U-13C13]-6,7-dimethyl-8-ribityllumazine based on [U-13C6]glucose was 25 mg/g. Fermentation with [1-13C1]-, [2-13C1]-, or [3-13C1]glucose afforded mixtures of 6,7-dimethyl-8-ribityllumazine isotopologs, predominantly with 13C enrichment of single carbon atoms. The isotope-labeled samples enabled a comprehensive NMR analysis of 6,7-dimethyl-8-ribityllumazine. Isotopolog libraries of a wide variety of microbial metabolites can be produced by the same experimental approach.