title: Reaction engineering studies for the production of 2-hydroxyisobutyric acid with recombinant Cupriavidus necator H 16.
abstract: Recombinant Cupriavidus necator H 16 with a novel metabolic pathway using a cobalamin-dependent mutase was exploited to produce 2-hydroxyisobutyric acid (2-HIBA) from renewable resources through microbial fermentation. 2-HIBA production capacities of different strains of C. necator H 16 deficient in the PHB synthase gene and genetically engineered to enable the production of 2-HIBA from the intracellular PHB precursor (R)-3-hydroxybutyryl-CoA were evaluated in 48 parallel milliliter-scale stirred tank bioreactors (V = 11 mL). The effects of media composition, limitations, pH, and feed rate were studied with respect to the overall process performances of the different recombinant strains. 2-HIBA production was at a maximum at nitrogen limiting conditions and if the pH was controlled between 6.8 and 7.2 under fed-batch operating conditions (intermittent fructose addition). The final concentration of 2-HIBA was 7.4 g L(-1) on a milliliter scale. Best reaction conditions identified on the milliliter scale were transferred to a laboratory-scale fed-batch process in a stirred tank bioreactor (V = 2 L). Two different process modes for the production of 2-HIBA, a single-phase and a dual-phase fermentation procedure, were evaluated and compared on a liter scale. The final concentration of 2-HIBA was 6.4 g L(-1) on a liter scale after 2 days of cultivation.
authors.affiliation: Technische Universität München, Garching, Germany.
authors.forename: Torben
authors.initials: T
authors.lastname: Hoefel
authors.forename: Eva
authors.initials: E
authors.lastname: Wittmann
authors.forename: Liv
authors.initials: L
authors.lastname: Reinecke
authors.forename: Dirk
authors.initials: D
authors.lastname: Weuster-Botz
mesh_terms: D000217:Acyltransferases / Q000235:genetics; D019149:Bioreactors; D003470:Culture Media; D020118:Cupriavidus necator / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005285:Fermentation; D017353:Gene Deletion; D005818:Genetic Engineering; D006885:Hydroxybutyrates / Q000378:metabolism*; D007218:Industrial Microbiology / Q000379:methods*; D019751:Intramolecular Transferases / Q000235:genetics / Q000378:metabolism; D014805:Vitamin B 12 / Q000378:metabolism
chemical_list: D003470:Culture Media; D006885:Hydroxybutyrates; C008039:2-hydroxyisobutyric acid; D000217:Acyltransferases; C060970:poly-beta-hydroxybutyrate polymerase; D019751:Intramolecular Transferases; D014805:Vitamin B 12