Specific Growth Rate

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Jingqi Yuan - One of the best experts on this subject based on the ideXlab platform.

  • Model‐based Specific Growth Rate control for Pichia pastoris to improve recombinant protein production
    Journal of Chemical Technology & Biotechnology, 2020
    Co-Authors: Jingqi Yuan
    Abstract:

    Constant Specific Growth Rate control in the methanol Growth phase was investigated for the fed-batch cultivation of Pichia pastoris expressing recombinant human serum albumin (rHSA). The methanol feeding stRategy was determined based on an earlier proposed macrokinetic model to maintain the Specific Growth Rate at preset levels. The experimental results demonstRate that the control stRategy of constant Specific Growth Rate is more effective than that of constant feeding Rate to maximize production. Furthermore, the most productive setpoint of the Specific Growth Rate is found between 0.005 and 0.006 h−1, which yields protein concentrations higher than 5 g l−1 at 160 h. In addition, a setpoint of 0.008 h−1 is suggested as the upper limit for Specific Growth Rate control for the given expression system. Copyright © 2005 Society of Chemical Industry

  • model based Specific Growth Rate control for pichia pastoris to improve recombinant protein production
    Journal of Chemical Technology & Biotechnology, 2005
    Co-Authors: Jingqi Yuan
    Abstract:

    Constant Specific Growth Rate control in the methanol Growth phase was investigated for the fed-batch cultivation of Pichia pastoris expressing recombinant human serum albumin (rHSA). The methanol feeding stRategy was determined based on an earlier proposed macrokinetic model to maintain the Specific Growth Rate at preset levels. The experimental results demonstRate that the control stRategy of constant Specific Growth Rate is more effective than that of constant feeding Rate to maximize production. Furthermore, the most productive setpoint of the Specific Growth Rate is found between 0.005 and 0.006 h−1, which yields protein concentrations higher than 5 g l−1 at 160 h. In addition, a setpoint of 0.008 h−1 is suggested as the upper limit for Specific Growth Rate control for the given expression system. Copyright © 2005 Society of Chemical Industry

Tai Hyun Park - One of the best experts on this subject based on the ideXlab platform.

  • Importance of Specific Growth Rate for subtilisin expression in fed-batch cultivation of Bacillus subtilis spoIIG mutant
    Enzyme and Microbial Technology, 2002
    Co-Authors: Jeong Seok Oh, Tai Hyun Park
    Abstract:

    Abstract A feeding stRategy was developed for controlling the Specific Growth Rate in a Bacillus subtilis fed-batch operation, and the importance of the Specific Growth Rate was investigated for subtilisin expression. The ratio of the glucose and peptone concentrations in the feeding medium was critical in controlling the Specific Growth Rate, and the appropriate ratio was found to be 1:2. The Specific Growth Rate was well controlled in fed-batch operations including an exponential feeding of a 200 g/liter glucose and 400 g/liter peptone solution. Controlling the value of the Specific Growth Rate had a significant effect on the subtilisin expression, even though the subtilisin expression was only enhanced after the feeding ended. This would appear to be due to cell components, such as sigma factors, produced in the Growth phase that influenced the aprE gene expression. The optimal Specific Growth Rate for the maximum expression Rate and longest production period was 0.35 h−1.

  • Effect of incorrectly estimated parameters on the control of Specific Growth Rate inE. coli fed-batch fermentation
    Biotechnology and Bioprocess Engineering, 1996
    Co-Authors: Tai Hyun Park, Sung Kwan Yoon, Whan Koo Kang
    Abstract:

    An exponential feeding stRategy has been frequently used in fed-batch fermentation of recombinantE. coli. In this feeding scheme, Growth yield and initial cell concentration, which can be erroneously determined, are needed to calculate the feed Rate for controlling Specific Growth Rate at the set point. The effect of the incorrect Growth yield and initial cell concentration on the control of the Specific Growth Rate was theoretically analyzed. Insignificance of the correctness of those parameters for the control of the Specific Growth Rate was shown theoretically and experimentally.

  • fed batch operation of recombinant escherichia coli containing trp promoter with controlled Specific Growth Rate
    Biotechnology and Bioengineering, 1994
    Co-Authors: Sung Kwan Yoon, Whan Koo Kang, Tai Hyun Park
    Abstract:

    A feb-batch operation for the production of bovine somatotropin (bST) under the control of tryptophan promoter in Escherichia coli was investigated. The plasmid used contains a two-cistron system and altered codon usage for higher expression of bST. Specific Growth Rate is an important parameter in the fermentation, because it affects the production of Growth-inhibitory organic acids and the expression of recombinant protein. The feeding Rate was adjusted to keep the Specific Growth Rate constant in this study. The variable Growth yield expressed as a function of time was used for the calculation of the feeding Rate. The Growth yield decreases during the fermentation as product expression is induced. The Specific Growth Rate was well controlled; however, intracellular bST concentration decreased at high cell concentrations. This is considered to be due to degradation by proteases. The decrease was prevented by an exponential feeding of the yeast extract as an organic nitrogen source. © 1994 John Wiley & Sons, Inc.

Fabricio Garelli - One of the best experts on this subject based on the ideXlab platform.

  • Specific Growth Rate observer for the growing phase of a polyhydroxybutyRate production process
    Bioprocess and Biosystems Engineering, 2015
    Co-Authors: Martin Jamilis, Fabricio Garelli, Md Salatul Islam Mozumder, Eveline Volcke, Hernan De Battista
    Abstract:

    This paper focuses on the Specific Growth Rate estimation problem in a PolyhydroxybutyRate bioplastic production process by industrial fermentation. The kinetics of the process are unknown and there are uncertainties in the model parameters and inputs. During the first hours of the Growth phase of the process, biomass concentration can be measured online by an optical density sensor, but as cell density increases this method becomes ineffective and biomass measurement is lost. An asymptotic observer is developed to estimate the Growth Rate for the case without biomass measurement based on corrections made by a pH control loop. Furthermore, an exponential observer based on the biomass measurement is developed to estimate the Growth Rate during the first hours, which gives the initial condition to the asymptotic observer. Error bounds and robustness to uncertainties in the models and in the inputs are found. The estimation is independent of the kinetic models of the microorganism. The characteristic features of the observer are illustRated by numerical simulations and validated by experimental results.

  • Specific Growth Rate estimation in fed batch bioreactors using second order sliding observers
    Journal of Process Control, 2011
    Co-Authors: Hernan De Battista, Jesús Picó, Fabricio Garelli, Alejandro Vignoni
    Abstract:

    Abstract This paper addresses the estimation of Specific Growth Rate of microorganisms in bioreactors using sliding observers. In particular, a second-order sliding observer based on biomass concentration measurement is proposed. Differing from other proposals that only guarantee bounded errors, the proposed observer provides a smooth estimate that converges in finite time to the time-varying parameter. Stability is proved using a Lyapunov approach. The observer exhibits also robustness to process uncertainties since no model of the reaction is used for its design. In addition, the off-surface coordinate of the sliding observer is useful to determine the convergence time as well as to identify sensor faults and unexpected behaviors. Because of the structure of the output error injection, chattering phenomena of conventional sliding mode algorithms are substantially reduced. The features of the proposed observer are assessed by numerical and experimental data.

  • smooth sliding mode observers for Specific Growth Rate and substRate from biomass measurement
    Journal of Process Control, 2009
    Co-Authors: Jesús Picó, Hernan De Battista, Fabricio Garelli
    Abstract:

    Abstract This paper addresses the estimation of Specific Growth Rate and substRate concentration from biomass measurements in fermentation processes. Specifically, sliding-mode observers are proposed, for which finite-time global convergence is demonstRated using Lyapunov stability theory and concepts of variable structure systems. Two observers are developed for Specific Growth Rate estimation, one producing a discontinuous estimation which is used afterwards for substRate estimation, and the other one – based on high-gain observers – that geneRates a smooth estimation with first-order dynamics and finite-time bounded convergence error. In the case of substRate estimation, an observer that increases the convergence Rate to a vicinity of the real substRate concentration while achieving asymptotic convergence despite kinetic model uncertainties in properly excited processes is designed. This observer also exhibits first-order dynamics.

Hernan De Battista - One of the best experts on this subject based on the ideXlab platform.

  • Specific Growth Rate observer for the growing phase of a polyhydroxybutyRate production process
    Bioprocess and Biosystems Engineering, 2015
    Co-Authors: Martin Jamilis, Fabricio Garelli, Md Salatul Islam Mozumder, Eveline Volcke, Hernan De Battista
    Abstract:

    This paper focuses on the Specific Growth Rate estimation problem in a PolyhydroxybutyRate bioplastic production process by industrial fermentation. The kinetics of the process are unknown and there are uncertainties in the model parameters and inputs. During the first hours of the Growth phase of the process, biomass concentration can be measured online by an optical density sensor, but as cell density increases this method becomes ineffective and biomass measurement is lost. An asymptotic observer is developed to estimate the Growth Rate for the case without biomass measurement based on corrections made by a pH control loop. Furthermore, an exponential observer based on the biomass measurement is developed to estimate the Growth Rate during the first hours, which gives the initial condition to the asymptotic observer. Error bounds and robustness to uncertainties in the models and in the inputs are found. The estimation is independent of the kinetic models of the microorganism. The characteristic features of the observer are illustRated by numerical simulations and validated by experimental results.

  • Specific Growth Rate estimation in fed batch bioreactors using second order sliding observers
    Journal of Process Control, 2011
    Co-Authors: Hernan De Battista, Jesús Picó, Fabricio Garelli, Alejandro Vignoni
    Abstract:

    Abstract This paper addresses the estimation of Specific Growth Rate of microorganisms in bioreactors using sliding observers. In particular, a second-order sliding observer based on biomass concentration measurement is proposed. Differing from other proposals that only guarantee bounded errors, the proposed observer provides a smooth estimate that converges in finite time to the time-varying parameter. Stability is proved using a Lyapunov approach. The observer exhibits also robustness to process uncertainties since no model of the reaction is used for its design. In addition, the off-surface coordinate of the sliding observer is useful to determine the convergence time as well as to identify sensor faults and unexpected behaviors. Because of the structure of the output error injection, chattering phenomena of conventional sliding mode algorithms are substantially reduced. The features of the proposed observer are assessed by numerical and experimental data.

  • smooth sliding mode observers for Specific Growth Rate and substRate from biomass measurement
    Journal of Process Control, 2009
    Co-Authors: Jesús Picó, Hernan De Battista, Fabricio Garelli
    Abstract:

    Abstract This paper addresses the estimation of Specific Growth Rate and substRate concentration from biomass measurements in fermentation processes. Specifically, sliding-mode observers are proposed, for which finite-time global convergence is demonstRated using Lyapunov stability theory and concepts of variable structure systems. Two observers are developed for Specific Growth Rate estimation, one producing a discontinuous estimation which is used afterwards for substRate estimation, and the other one – based on high-gain observers – that geneRates a smooth estimation with first-order dynamics and finite-time bounded convergence error. In the case of substRate estimation, an observer that increases the convergence Rate to a vicinity of the real substRate concentration while achieving asymptotic convergence despite kinetic model uncertainties in properly excited processes is designed. This observer also exhibits first-order dynamics.

Jesús Picó - One of the best experts on this subject based on the ideXlab platform.

  • Specific Growth Rate estimation in fed batch bioreactors using second order sliding observers
    Journal of Process Control, 2011
    Co-Authors: Hernan De Battista, Jesús Picó, Fabricio Garelli, Alejandro Vignoni
    Abstract:

    Abstract This paper addresses the estimation of Specific Growth Rate of microorganisms in bioreactors using sliding observers. In particular, a second-order sliding observer based on biomass concentration measurement is proposed. Differing from other proposals that only guarantee bounded errors, the proposed observer provides a smooth estimate that converges in finite time to the time-varying parameter. Stability is proved using a Lyapunov approach. The observer exhibits also robustness to process uncertainties since no model of the reaction is used for its design. In addition, the off-surface coordinate of the sliding observer is useful to determine the convergence time as well as to identify sensor faults and unexpected behaviors. Because of the structure of the output error injection, chattering phenomena of conventional sliding mode algorithms are substantially reduced. The features of the proposed observer are assessed by numerical and experimental data.

  • smooth sliding mode observers for Specific Growth Rate and substRate from biomass measurement
    Journal of Process Control, 2009
    Co-Authors: Jesús Picó, Hernan De Battista, Fabricio Garelli
    Abstract:

    Abstract This paper addresses the estimation of Specific Growth Rate and substRate concentration from biomass measurements in fermentation processes. Specifically, sliding-mode observers are proposed, for which finite-time global convergence is demonstRated using Lyapunov stability theory and concepts of variable structure systems. Two observers are developed for Specific Growth Rate estimation, one producing a discontinuous estimation which is used afterwards for substRate estimation, and the other one – based on high-gain observers – that geneRates a smooth estimation with first-order dynamics and finite-time bounded convergence error. In the case of substRate estimation, an observer that increases the convergence Rate to a vicinity of the real substRate concentration while achieving asymptotic convergence despite kinetic model uncertainties in properly excited processes is designed. This observer also exhibits first-order dynamics.

  • Robust Adaptive Specific Growth Rate Control in Biotechnological Fed-Batch Processes
    IFAC Proceedings Volumes, 2004
    Co-Authors: E. Picó-marco, Jesús Picó, H. Debattista, J.l. Navarro
    Abstract:

    Abstract In this paper, the problem of robust Specific Growth Rate control in biological reactions in fed-batch mode is dealt with. It is assumed that only part of the state is measurable on-line, namely biomass and volume. Moreover, no estimation of the Specific Growth Rate is used, and the only required knowledge about the process is an upper bound of the kinetic functions, and whether it is monotonous or not.

  • Partial stability for Specific Growth Rate control biotechnological fed-batch processes
    Proceedings of 2003 IEEE Conference on Control Applications 2003. CCA 2003., 2003
    Co-Authors: E. Picó-marco, Jesús Picó
    Abstract:

    In this paper, the problem of the Specific Growth Rate control in biological reactions in fed-batch mode is dealt with. It is assumed that only part of the state is measurable on-line, namely biomass and volume. Moreover, no estimation of the Specific Growth Rate is used. An unbounded manifold is tracked using a partial state feedback. Then, techniques for partial stability, i.e., only with respect to part of the variables, are used in order to analyze the problem.