title: Process control for enhanced L-phenylalanine production using different recombinant Escherichia coli strains.
abstract: A novel fed-batch approach for the production of L-phenylalanine (L-Phe) with recombinant E. coli is presented concerning the on-line control of the key fermentation parameters glucose and tyrosine. Two different production strains possessing either the tyrosine feedback resistant aroF(fbr) (encoding tyrosine feedback resistant DAHP-synthase (3-desoxy-D-arabino-heptusonate-7-phosphate)) or the wild-type aroF(wt) were used as model systems to elucidate the necessity of finding an individual process optimum for each genotype. With the aid of tyrosine control, wild-type aroF(wt) could be used for L-Phe production achieving higher final L-Phe titers (34 g/L) than the aroF(fbr) strain (28 g/L) and providing higher DAHP-synthase activities. With on-line glucose control, an optimum glucose concentration of 5 g/L could be identified that allowed a sufficient carbon supply for L-Phe production while at the same time an overflow metabolism leading to acetate by-product formation was avoided. The process approach is suitable for other production strains not only in lab-scale but also in pilot-scale bioreactors.
authors.affiliation: Institute of Biotechnology (2), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Gerigk
authors.forename: R
authors.initials: R
authors.lastname: Bujnicki
authors.forename: E
authors.initials: E
authors.lastname: Ganpo-Nkwenkwa
authors.forename: J
authors.initials: J
authors.lastname: Bongaerts
authors.forename: G
authors.initials: G
authors.lastname: Sprenger
authors.forename: R
authors.initials: R
authors.lastname: Takors
mesh_terms: D019149:Bioreactors; D002478:Cells, Cultured; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D005246:Feedback; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D010649:Phenylalanine / Q000096:biosynthesis*; D010865:Pilot Projects; D011786:Quality Control; D011994:Recombinant Proteins / Q000096:biosynthesis; D011995:Recombination, Genetic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013045:Species Specificity; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D014443:Tyrosine; D010649:Phenylalanine; D005947:Glucose