title: On-line control of an immobilized hybridoma culture with multi-channel flow injection analysis.
abstract: An immobilized hybridoma cell line was cultivated at controlled glucose and glutamine concentrations. On-line analysis of the substrates was carried out with a multi-channel flow injection analysis system. The analysis system also determined on-line the lactate and ammonium concentration. The substrate concentrations were controlled using an adaptive-control strategy. This strategy consisted of the estimation of the real-time concentrations and volumetric substrate consumption rates by an Extended Kalman Filter, and a minimum variance controller, which used the estimated parameters to set the feed rates of the substrates. The closed-loop control was used to start-up two cultures with either glucose or glutamine as control-substrate for the medium feed rate. The controller kept the concentration of the control-substrate constant by enhancing the medium feed rate simultaneously to the increasing volumetric consumption rate of the substrate. When glutamine was used as control-substrate, the glucose concentration remained relatively constant, whereas the glutamine concentration decreased during the start-up at a constant glucose concentration. This indicates that glutamine is consumed faster than glucose and will be a better control-substrate to avoid limitation during the start-up of a culture with the applied hybridoma cell line. During the colonization of the microcarriers, the yield of ammonium on glutamine decreased from 0.80 to 0.55 (mol mol-1), indicating a change in the glutamine metabolism. The yield of lactate on glucose stayed constant for both experiments. During long-term culture of more than 800 h, the controller kept both the glucose and glutamine concentrations constant at perfusion rates between 0.50 h-1 and 0.15 h-1. The medium, glucose and glutamine feed rate were independently controlled. Both the specific glutamine and glucose consumption rates remained constant for all perfusion rates, which was probably as a result of the constant concentrations. The specific monoclonal antibody production rate decreased with the perfusion rate decreasing from 0.40 h-1 to 0.20 h-1. The immobilized-cell concentration decreased only at the lowest perfusion rate. Both effects could not be explained directly by the increasing ammonium and lactate concentrations nor by the decreasing amino-acid concentrations.
authors.affiliation: Institute of Biotechnology, Forschungszentrum Jülich GmbH, Germany.
authors.forename: J J
authors.initials: JJ
authors.lastname: van der Pol
authors.forename: B
authors.initials: B
authors.lastname: Joksch
authors.forename: J
authors.initials: J
authors.lastname: Gätgens
authors.forename: M
authors.initials: M
authors.lastname: Biselli
authors.forename: C D
authors.initials: CD
authors.lastname: de Gooijer
authors.forename: J
authors.initials: J
authors.lastname: Tramper
authors.forename: C
authors.initials: C
authors.lastname: Wandrey
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis; D001709:Biotechnology / Q000295:instrumentation*; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D005973:Glutamine / Q000008:administration & dosage / Q000378:metabolism; D006825:Hybridomas / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008954:Models, Biological; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D007773:Lactates; D000644:Quaternary Ammonium Compounds; D005973:Glutamine; D019344:Lactic Acid; D005947:Glucose