Enhancement of 5-aminolevulinate production with recombinant Escherichia coli using batch and fed-batch culture system

Abstract

5-Aminolevulinate (ALA) production with recombinant Escherichia coli Rosetta (DE3)/pET28a(+)- hemA was studied. In batch fermentation, the addition of glucose and glycine was effective to improve ALA production. Then the fed-batch fermentation was conducted with continuous feeding of precursors. When the concentrations of succinic acid and glycine were 7.0 g/l and 4.0 g/l, respectively, in the feeding, the ALA yield reached 4.1 g/l. But the molar yield (ALA/glycine) was decreased in the fed-batch fermentation compared to batch fermentation. And it was found that the pH control during fed-batch cultivation was very important for the cell growth and ALA production. A two-stage pH value controlling strategy was suggested, in which, the pH value in the first 6 h was regulated at pH 5.9, after then at pH 6.2, and the ALA yield was as high as 6.6 g/l via fed-batch fermentation.