title: Porphyrin derivatives from a recombinant Escherichia coli grown on chemically defined medium.
abstract: 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 microM heme, 29 microM ALA, 0.07 microM coproporphyrin I, 0.21 microM coproporphyrin III, and 0.23 microM uroporphyrin in a 3 L pH-controlled culture.
authors.affiliation: Department of Biotechnology, The Catholic University of Korea, Bucheon, Korea.
authors.forename: Min Ju
authors.initials: MJ
authors.lastname: Lee
authors.forename: Se-Jin
authors.initials: SJ
authors.lastname: Chun
authors.forename: Hye-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: An Sung
authors.initials: AS
authors.lastname: Kwon
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Jun
authors.forename: Sang Hyeon
authors.initials: SH
authors.lastname: Kang
authors.forename: Pil
authors.initials: P
authors.lastname: Kim
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D019149:Bioreactors / Q000382:microbiology*; D002853:Chromatography, Liquid; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways; D010710:Phosphates / Q000737:chemistry; D011166:Porphyrins / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D017693:Sodium Bicarbonate / Q000737:chemistry; D014815:Vitamins
chemical_list: D003470:Culture Media; D010710:Phosphates; D011166:Porphyrins; D014815:Vitamins; D017693:Sodium Bicarbonate