title: Framework for online optimization of recombinant protein expression in high-cell-density Escherichia coli cultures using GFP-fusion monitoring.
abstract: A framework for the online optimization of protein induction using green fluorescent protein (GFP)-monitoring technology was developed for high-cell-density cultivation of Escherichia coli. A simple and unstructured mathematical model was developed that described well the dynamics of cloned chloramphenicol acetyltransferase (CAT) production in E. coli JM105 was developed. A sequential quadratic programming (SQP) optimization algorithm was used to estimate model parameter values and to solve optimal open-loop control problems for piecewise control of inducer feed rates that maximize productivity. The optimal inducer feeding profile for an arabinose induction system was different from that of an isopropyl-beta-D-thiogalactopyranoside (IPTG) induction system. Also, model-based online parameter estimation and online optimization algorithms were developed to determine optimal inducer feeding rates for eventual use of a feedback signal from a GFP fluorescence probe (direct product monitoring with 95-minute time delay). Because the numerical algorithms required minimal processing time, the potential for product-based and model-based online optimal control methodology can be realized.
authors.affiliation: Center for Agricultural Biotechnology, University of Maryland Biotechnology Institute, College Park 20742, USA.
authors.forename: H J
authors.initials: HJ
authors.lastname: Chae
authors.forename: M P
authors.initials: MP
authors.lastname: Delisa
authors.forename: H J
authors.initials: HJ
authors.lastname: Cha
authors.forename: W A
authors.initials: WA
authors.lastname: Weigand
authors.forename: G
authors.initials: G
authors.lastname: Rao
authors.forename: W E
authors.initials: WE
authors.lastname: Bentley
mesh_terms: D000465:Algorithms; D001089:Arabinose / Q000494:pharmacology; D018533:Biomass; D002455:Cell Division / Q000187:drug effects; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D003198:Computer Simulation; D004926:Escherichia coli / Q000166:cytology* / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D005246:Feedback; D005456:Fluorescent Dyes / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D017930:Genes, Reporter / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D007700:Kinetics; D008164:Luminescent Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D007544:Isopropyl Thiogalactoside; D001089:Arabinose; D015500:Chloramphenicol O-Acetyltransferase; D005947:Glucose