D-glucose enhanced 5-aminolevulinic acid production in recombinant Escherichia coli culture.

In this study, we introduced a new strategy, feeding D-glucose, to overproduce extracellular 5-aminolevulinic acid (ALA) in the recombinant Escherichia coli. We investigated that the D-glucose concentration is dependent on extracellular ALA production. The results indicated that increasing D-glucose concentration in bacteria culture enhanced final cell density and ALA yield and simultaneously decreased the activities of ALA synthase (ALAS) and ALA dehydratase (ALAD); then, the inhibitory effect of D-glucose on ALAS activity was relieved with the metabolism of D-glucose. when 4.0 g/L D-glucose was added at late exponential phase; 1.46 g/L ALA was achieved in shaking culture, which is 47% or 109% higher than the ALA yields with 30 mM levulinic acid of ALAD inhibitor or no inhibitor. In jar fermenter, final extracellular ALA concentration reached 3.1 g/L by feeding with D-glucose.