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KMID : 0545120120220121653
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Journal of Microbiology and Biotechnology
2012 Volume.22 No. 12 p.1653 ~ p.1658
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Porphyrin Derivatives from a Recombinant Escherichia coli Grown on Chemically Defined Medium
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Lee Min-Ju
Chun Se-Jin
Kim Hye-Jung
Kwon An-Sung
Jun Soo-Youn
Kang Sang-Hyeon
Kim Pil
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Abstract
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We have reported previously that a recombinant Escherichia coli co-expresses aminolevulinic acid (ALA) synthase, an NADP-dependent malic enzyme, and a dicarboxylate transporter-produced heme, an iron-chelated porphyrin, in a succinate-containing complex medium. To develop an industrially plausible process, a chemically defined medium was formulated based on M9 minimal medium. Heme synthesis was enhanced by adding sodium bicarbonate, which strengthened the C4 metabolism required for the precursor metabolite, although a pH change discouraged cell growth. Increasing the medium pH buffering capacity (100mM phosphate buffer) and adding sodium bicarbonate enabled the recombinant E. coli to produce heme at rates 60% greater than those in M9 minimal medium. Adding growth factors (1 mg/l thiamin, 0.01 mg/l biotin, 5 mg/l nicotinic acid, 1 mg/l pantothenic acid, and 1.4 mg/l cobalamin) also induced positive heme production effects at levels twice of heme production in M9-based medium. Porphyrin derivatives and heme were found in the chemically defined medium, and their presence was confirmed by liquid chromatography/mass spectroscopy (LC/MS). The formulated medium allowed for the production of 0.6 μM heme, 29 μM ALA, 0.07 μM coproporphyrin I, 0.21 μM coproporphyrin III, and 0.23 μM uroporphyrin in a 3 L pH-controlled culture.
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KEYWORD
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heme, porphyrins, recombinant E. coli, chemically defined medium
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