Control of Biotechnology Processes

Researchers: Lena de Maré, Stéphane Velut, and Per Hagander in cooperation with Jan Peter Axelsson, Pfizer AB, Christian Cimander Novozymes Biopharma AB, Eva Nordberg Karlsson and Olle Holst, Department of Biotechnology, Lund University.

NovoEnzyme Large-scale production of many enzymes and pharmaceuticals can today be made using genetically modified microorganisms. In so called bioreactors, living cells are grown to large numbers and then made to produce the desired substance. Fed-batch operation, where additional substrate is fed to the culture, is often the preferred way of production. To achieve reproducible cultivations with high cell densities and high productivity, it is important to design good strategies for the substrate-dosage control. A characteristic feature of biological processes is that many important process variables are not easily measured on-line, which complicates the design and realization of feedback strategies.

A project on substrate-dosage control of fed-batch units with genetically modified E. coli is performed together with Pfizer. Information of how to change the substrate feed rate is obtained from standard dissolved oxygen measurements by introducing controlled process perturbations. Tuning rules are derived for the control strategy that assume a minimum of process specific information, and the system is analysed for stability using the theory for piecewise linear systems.

The strategy is implemented at many industries and research laboratories, and it is tested with different E. coli strains and also other organisms like bakers yeast and cholera bacteria. Good cultivation conditions and high production levels are in general obtained from the first experiments.

For the case when the oxygen transfer capacity of the reactor is reached, we have designed a method that combines the use of stirrer speed and temperature in a mid-ranging fashion instead of feed reduction to maintain the oxygen concentration at desired levels also during the production phase.

Sometimes it is not enough to add a carbon nutrient feed in order to obtain a satisfactory growth and production, e.g. due to auxotrophic production strains. In some cases additions of supplementary amino acids or complex media containing for example yeast extract are needed. We have investigated how the pulsing technique can be used to control two feeds simultaneously. The strategies work well, and as almost no process knowledge is required they can be used to shorten the process development phase considerably.

In large scale it is hard to obtain well-mixed conditions, and we have together with Pfizer investigated if gradients might influence the applicability of the probing controllers. There was also a time-varying demand in glucose related to the consumption of complex components present in the broth. It required some more care and experience, but we obtained remarkable results that indicate that the process development phase can be reduced considerably. Even though the performance of the probing strategy was affected by scale and complex media, the methodology rapidly identified a glucose feed protocol similar to an experimentally derived feed regime.

Publications

Stéphane Velut, Andreas Castan, Kevin A. Short, Jan Peter Axelsson, Per Hagander, Barry A. Zditosky, Christopher W. Rysenga, Lena de Maré, Jan Haglund: "Influence of bioreactor scale and complex medium on probing control of glucose feeding in cultivations of recombinant strains of Escherichia coli". Biotechnology and Bioengineering, 97:4, pp. 816-824, July 2007. http://dx.doi.org/10.1002/bit.21294

Stéphane Velut, Lena de Maré, Per Hagander: "Bioreactor Control Using a Probing Feeding Strategy and Mid-Ranging Control". Control Engineering Practice, 15:2, pp. 135-147, February 2007. http://dx.doi.org/10.1016/j.conengprac.2006.05.009

Lena de Maré, Christian Cimander, Anders Elfwing, Per Hagander: "Feeding Strategies for E. coli Cultivations Demanding an Enriched Environment". Bioprocess and Biosystems Engineering, 30:1, pp. 13-25, January 2007. Published online: November 2006, \url{http://dx.doi.org/10.1007/s00449-006-0090-z}

Lena de Maré: "Feeding Strategies Based on Probing Control for E. coli and V. cholerae Cultivations". PhD thesis ISRN LUTFD2/TFRT--1076--SE, Department of Automatic Control, Lund University, Sweden, June 2006.

Lena de Maré, Per Hagander: "Parameter Estimation of a Model Describing the Oxygen Dynamics in a fed-batch E. coli Cultivation". In Reglermöte 2006, Stockholm, Sweden, May 2006.

Stéphane Velut, Per Hagander: "Control of Fed-Batch Bioreactors. Part II". In Alessandro Astolfi (Eds.): Nonlinear and adaptive control: theory and applications for the users, Imperial College Press, London, 2006.

Staffan Haugwitz, Maria Karlsson, Stéphane Velut, Per Hagander: "Anti-Windup in Mid-Ranging Control". In Proceedings of the 44th IEEE Conference on Decision and Control and European Control Conference ECC 2005, Seville, Spain, December 2005.

Lena de Maré, Stéphane Velut, Erika Ledung, Christian Cimander, Bo Norrman, Eva Nordberg Karlsson, Olle Holst, Per Hagander: "A Cultivation Technique for E. coli Fed-Batch Cultivations Operating Close to the Maximum Oxygen Transfer Capacity of the Reactor". Biotechnology Letters, 27:14, pp. 983--990, July 2005.

Stéphane Velut: "Probing Control. Analysis and Design with Application to Fed-Batch Bioreactors". PhD thesis ISRN LUTFD2/TFRT--1072--SE, Department of Automatic Control, Lund University, Sweden, June 2005.

Stéphane Velut, Per Hagander: "A Probing Control Strategy: Stability and Performance". In Proceedings of the 43rd IEEE Conference on Decision and Control, Paradise Island, Bahamas, December 2004.

Stéphane Velut, Lena de Maré, Per Hagander: "A modified probing feeding strategy: control aspects". In Reglermöte 2004, May 2004.

Lena de Maré, Stéphane Velut, Sebastian Briechle, Christina Wennerberg, Christian Cimander, Santosh Ramchuran, Pernilla Tunert, Gustav Silfversparre, Olle Holst, Per Hagander: "Temperature Limited Fed-batch Cultivation with a Probing Feeding Strategy for Escherichia coli". In Computer Applications in Biotechnology 2004, International Federation of Automatic Control, Elsevier Limited, March 2004. A proceedings volume from the 9th IFAC International Symposium, Nancy, France, 28-31 March 2004, ISBN: 0 08 044251 X

Stéphane Velut, Per Hagander: "Analysis of a probing control strategy". In Proc. of the American Control Conference, Denver, Colorado, volume 1, IEEE, June 2003.

Lena de Maré, Lena Andersson, Per Hagander: "Probing control of glucose feeding in Vibrio cholerae cultivations". Bioprocess and Biosystems Engineering, 25, pp. 221--228, January 2003.

Santosh Ramchuran, Eva Nordberg Karlsson, Stéphane Velut, Lena de Maré, Per Hagander, Olle Holst: "Production of heterologous thermostable glycoside hydrolases and the presence of host-cell proteases in substrate limited fed-batch cultures of Escherichia coli BL21(DE3)". Applied Microbiology and Biotechnology, 60:4, pp. 408--416, December 2002.

Stéphane Velut, Per Hagander: "Analysis of a Probing Control Strategy". Technical report ISRN LUTFD2/TFRT--7602--SE, Department of Automatic Control, Lund Institute of Technology, Sweden, November 2002. Accepted for American Control Conference 2003

Lena de Maré, Lena Andersson, Per Hagander: "Cultivations of Vibrio cholerae using probing control of glucose feeding". In International conference on Trends in Monitoring and Control of Life Science Applications, pp. 62, Section on Biochemical Engineering Science European Federation of Biotechnology, October 2002. Poster presentation

Stéphane Velut, Lena de Maré, Jan Peter Axelsson, Per Hagander: "Evaluation of a probing feeding strategy in large scale cultivations". Technical report ISRN LUTFD2/TFRT--7601--SE, Department of Automatic Control, Lund Institute of Technology, Sweden, April 2002.

Lena de Maré, Per Hagander: "Simuleringar och analys av V. cholerae odling där feeden styrs genom återkoppling från ättiksyramätningar". Technical report ISRN LUTFD2/TFRT--7600--SE, Department of Automatic Control, Lund Institute of Technology, Sweden, March 2002.

Lena de Maré, Stéphane Velut, Per Hagander, Mats Åkesson: "Feedback control of flow rate from a peristaltic pump using balance measurements". In European Control Conference, September 2001.

Mats Åkesson, Per Hagander, Jan Peter Axelsson: "Probing Control of Fed-batch Cultivations: Analysis and Tuning". Control Engineering Practice, 9:7, pp. 709--723, January 2001.

Mats Åkesson, Per Hagander, Jan Peter Axelsson: "An improved probing controller for substrate feeding in fed-batch culteres of E. coli: simulations and experiments". In Proceedings of the 8th International Conference on Computer Applications in Biotechnology June 24–27, 2001, Quebec City, Canada, January 2001. CAB8, Montreal, June 2001

Mats Åkesson, Per Hagander, Jan Peter Axelsson: "Avoiding Acetate Accumulation in Escherichia coli Cultures Using Feedback Control of Glucose Feeding". Biotechnology and Bioengineering, 73:3, pp. 223--230, January 2001.

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Last modified: 2006-12-04