Abstract:An extended dynamical model for growth and sporulation of Bacillus thuringiensis subsp. kurstaki in an intermittent fed-batch culture with total cell retention is proposed. This model differs from reported models, by including dynamics for natural death of cells and substrate consumption for cell maintenance. The proposed model uses sigmoid functions to describe these kinetic parameters. Equations for time evolution of substrate, vegetative, sporulated and total cell concentration were taken from previous work… Show more
“…This research has been done with the same process and fermentation conditions used in Atehortúa et al (2007). The microorganism used in this work was Bacillus thuringiensis serovar.…”
Section: Microorganism and Bioprocess Characteristicsmentioning
confidence: 99%
“…The duration of the batch fermentation is limited and depends on the initial conditions of the microorganism culture. All the fermentations were initialized with the same inocula and different substrate concentration conditions (Atehortúa et al, 2007). When the medium is inoculated, the biomass concentration increases at the expense of reducing the nutrients.…”
Section: [L Min ]mentioning
confidence: 99%
“…This is done with the aim of performing a later on-line biomass estimation and designing an adequate process controller. The extended batch model for growth and sporulation of Bacillus thuringiensies on which this work is based is described in Atehortúa et al (2007). Equations for the model are:…”
Section: [L Min ]mentioning
confidence: 99%
“…These works, nevertheless, point out the need of considering in future research the oxygen dynamics and its limiting effect on cell growth. In the present study, the oxygen concentration is assumed to be in excess, but it decreases to values that are even smaller than the critical one (10%) (Atehortúa et al, 2007). In some fermentations, DO can also be used for estimating the microorganism concentration in the medium if the O 2 consumption is known (Amicarelli et al, 2006;di Sciascio and Amicarelli, 2008).…”
Section: Introductionmentioning
confidence: 99%
“…The paper is organized as follows: next Section presents the microorganism's characteristics and the model based on first principles, with the dynamics as it actually appears in the model of Rivera et al (1999) and Atehortúa et al (2006Atehortúa et al ( , 2007. In the same Section, the DO dynamics for δ-endotoxins from the Bacillus thuringiensis production process are modeled and the parameters estimation is described.…”
-This paper proposes a model to characterize the Dissolved Oxygen Dynamics (DO) for the Bacillus thuringiensis (Bt) δ-endotoxins production process. The objective of this work is to include this dynamics into a phenomenological model of the process in order to facilitate the biomass estimation from the knowledge of oxygen consumption; and for control purposes, by allowing the addition of a new control variable in order to favorably influence the bioprocess evolution. The mentioned DO model is based on first principles and parameter estimation and model verification are supported by real experimental data. Finally, a control strategy is designed based on this model with its corresponding asymptotic stability and robustness analysis.
“…This research has been done with the same process and fermentation conditions used in Atehortúa et al (2007). The microorganism used in this work was Bacillus thuringiensis serovar.…”
Section: Microorganism and Bioprocess Characteristicsmentioning
confidence: 99%
“…The duration of the batch fermentation is limited and depends on the initial conditions of the microorganism culture. All the fermentations were initialized with the same inocula and different substrate concentration conditions (Atehortúa et al, 2007). When the medium is inoculated, the biomass concentration increases at the expense of reducing the nutrients.…”
Section: [L Min ]mentioning
confidence: 99%
“…This is done with the aim of performing a later on-line biomass estimation and designing an adequate process controller. The extended batch model for growth and sporulation of Bacillus thuringiensies on which this work is based is described in Atehortúa et al (2007). Equations for the model are:…”
Section: [L Min ]mentioning
confidence: 99%
“…These works, nevertheless, point out the need of considering in future research the oxygen dynamics and its limiting effect on cell growth. In the present study, the oxygen concentration is assumed to be in excess, but it decreases to values that are even smaller than the critical one (10%) (Atehortúa et al, 2007). In some fermentations, DO can also be used for estimating the microorganism concentration in the medium if the O 2 consumption is known (Amicarelli et al, 2006;di Sciascio and Amicarelli, 2008).…”
Section: Introductionmentioning
confidence: 99%
“…The paper is organized as follows: next Section presents the microorganism's characteristics and the model based on first principles, with the dynamics as it actually appears in the model of Rivera et al (1999) and Atehortúa et al (2006Atehortúa et al ( , 2007. In the same Section, the DO dynamics for δ-endotoxins from the Bacillus thuringiensis production process are modeled and the parameters estimation is described.…”
-This paper proposes a model to characterize the Dissolved Oxygen Dynamics (DO) for the Bacillus thuringiensis (Bt) δ-endotoxins production process. The objective of this work is to include this dynamics into a phenomenological model of the process in order to facilitate the biomass estimation from the knowledge of oxygen consumption; and for control purposes, by allowing the addition of a new control variable in order to favorably influence the bioprocess evolution. The mentioned DO model is based on first principles and parameter estimation and model verification are supported by real experimental data. Finally, a control strategy is designed based on this model with its corresponding asymptotic stability and robustness analysis.
We develop a mechanistic life-cycle model for endospore-forming bacteria (EFB) and test the model with experiments with a Bacillus mixed culture. The model integrates and quantifies how sporulation and germination are triggered by depletion or presence of a limiting substrate, while both substrates affect the rate of vegetative growth by a multiplicative model. Kinetic experiments show the accumulation of small spherical spores after the triggering substrate is depleted, substantially more rapid decay during sporulation than for normal decay of vegetative cells, and a higher specific substrate utilization rate for the germinating cells than that for growth of vegetative cells. Model simulations capture all of these experimental trends. According to model predictions, when a batch reactor is started, seeding with EFB spores instead of active EFB delays the onset of rapid chemical oxygen demand (COD) utilization and biomass growth, but the end points are the same. Simulated results with low aeration intensity show that germination can consume some substrate without dissolved oxygen (DO) depletion.
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