title: Autotrophic production of stable-isotope-labeled arginine in Ralstonia eutropha strain H16.
abstract: With the aim of improving industrial-scale production of stable-isotope (SI)-labeled arginine, we have developed a system for the heterologous production of the arginine-containing polymer cyanophycin in recombinant strains of Ralstonia eutropha under lithoautotrophic growth conditions. We constructed an expression plasmid based on the cyanophycin synthetase gene (cphA) of Synechocystis sp. strain PCC6308 under the control of the strong P(cbbL) promoter of the R. eutropha H16 cbb(c) operon (coding for autotrophic CO(2) fixation). In batch cultures growing on H(2) and CO(2) as sole sources of energy and carbon, respectively, the cyanophycin content of cells reached 5.5% of cell dry weight (CDW). However, in the absence of selection (i.e., in antibiotic-free medium), plasmid loss led to a substantial reduction in yield. We therefore designed a novel addiction system suitable for use under lithoautotrophic conditions. Based on the hydrogenase transcription factor HoxA, this system mediated stabilized expression of cphA during lithoautotrophic cultivation without the need for antibiotics. The maximum yield of cyanophycin was 7.1% of CDW. To test the labeling efficiency of our expression system under actual production conditions, cells were grown in 10-liter-scale fermentations fed with (13)CO(2) and (15)NH(4)Cl, and the (13)C/(15)N-labeled  cyanophycin was subsequently extracted by treatment with 0.1 M HCl; 2.5 to 5 g of [(13)C/(15)N]arginine was obtained per fed-batch fermentation, corresponding to isotope enrichments of 98.8% to 99.4%.
authors.affiliation: Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Lütte
authors.forename: Anne
authors.initials: A
authors.lastname: Pohlmann
authors.forename: Evgeny
authors.initials: E
authors.lastname: Zaychikov
authors.forename: Edward
authors.initials: E
authors.lastname: Schwartz
authors.forename: Johannes R
authors.initials: JR
authors.lastname: Becher
authors.forename: Hermann
authors.initials: H
authors.lastname: Heumann
authors.forename: Bärbel
authors.initials: B
authors.lastname: Friedrich
mesh_terms: D001120:Arginine / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D002245:Carbon Dioxide / Q000378:metabolism; D020118:Cupriavidus necator / Q000378:metabolism*; D005285:Fermentation; D015870:Gene Expression; D006859:Hydrogen / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods*; D060847:Metabolic Engineering; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D046939:Synechocystis / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; C024250:cyanophycin; D002245:Carbon Dioxide; D006859:Hydrogen; D001120:Arginine; D010453:Peptide Synthases; C113257:cyanophycin synthase, bacteria