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A simple structured model for maintenance, biomass formation, and ajmalicine production by nondividing Catharanthus roseus cells
Author(s) -
Schlatmann J. E.,
ten Hoopen H. J. G.,
Heijnen J. J.
Publication year - 1999
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(1999)66:3<147::aid-bit2>3.0.co;2-n
Subject(s) - biomass (ecology) , catharanthus roseus , yield (engineering) , chemistry , stoichiometry , nitrogen , carbohydrate , chromatography , biochemistry , biology , thermodynamics , organic chemistry , agronomy , physics
The stoichiometry of maintenance and carbohydrate storage as well as ajmalicine production kinetics of non‐dividing Catharanthus roseus cells in the second stage of a two‐stage batch process were investigated. For the mathematical description of these processes, a simple structured model with 5 parameters is proposed. In the model the biomass is divided in two compartments: active biomass and storage carbohydrates. In induction medium (standard medium without phosphate, nitrogen and hormones), biomass formation, glucose consumption, and CO 2 production appeared to be constant in time. Therefore, it is assumed that the active biomass level is constant. The maintenance coefficient m S , and the yield of storage carbohydrates on glucose Y SC were optimized by fitting the model on experimental data: 0.003 C‐mol/C‐mol/h and 0.82 C‐mol/C‐mol, respectively. Production kinetics were incorporated in this model and related to the active biomass fraction. The maximum specific ajmalicine production rate q p max was fitted on the data: 7.5 μmol/C‐mol/h. The model was tested at several different experimental conditions, and proved to describe the experimental results adequately. An independent experiment at a very high cell density in order to obtain maximum product formation was used to validate the model. It provided a satisfactory description of the results, but the final ajmalicine concentration (198 μmol/L after 18 days) was lower than the calculated maximum, due to accumulation of inhibiting gaseous metabolites. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 66: 147–157, 1999.