5-aminolevulinic acid (5-ALA) affords various positive health effects, including benefits for conditions such as diabetes. Biological fermentation holds potential for efficiently mass-producing biomolecules, including 5-ALA, yet it generally results in a mixture of target molecules and impurities, including byproducts. Pyrazine-2,5-dipropionic acid (PY), a dimer of 5-ALA, can easily form in 5-ALA production and is one of its major impurities. In this study, we developed an integrated purification process for 5-aminolevulinic acid phosphate (5-ALAP) produced via biological fermentation. The process consists of 16 stages, including impurity removal (ion-exchange resins) and crystallization. Three types of ion-exchange resin (IER) columns were combined to remove impurities such as byproducts and pigment. Comprehensive condition setting for crystallization was carried out to reduce the amount of residual poor solvent in the 5-ALAP crystals. The obtained crystals contained significantly fewer impurities (<0.05% vs. 5-ALAP), such as PY, compared with their commercially available counterparts. The residual poor solvent in the 5-ALAP crystals was reduced to below 1000 ppm under the crystallization conditions. We confirmed the high scalability of the purification method developed in this study. Therefore, this article provides an industrially applicable purification process for fermentatively produced 5-ALA.
Iwata et al. (Mon,) studied this question.