Including dissolved oxygen dynamics into the Bt δ-endotoxins production process model and its application to process control

Amicarelli, Adriana; Sciascio, Fernando di; Toibero, Juan Marcos; Álvarez, Hernán

doi:10.1590/s0104-66322010000100004

Cited by 26 publications

(22 citation statements)

References 44 publications

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“…For K L a equal to 13.3 h -1 , growth continued after the dissolved oxygen concentration reached a value of 0 % (Figure 2). It is well known that the oxygen demand of Bacillus thuringiensis decreases during sporulation (Amicarelli et al, 2010) but in these aeration conditions, the oxygen uptake rate (OUR) reached a maximum value of 3.2 mmol/L.h after 8 h of fermentation ( Figure 1d) and the microscopic observation showed that there was no notable fall of the OUR until maturation of most of the spores. This suggests that an oxygen transfer rate of 3.2 mmol/L/h is critical for the sporulation of "Lip" in the process conditions employed, and could explain the defective sporulation for K L a of 7.2 h -1 where the maximal oxygen transfer rate is 1.7 mmol/L/h.…”

Section: Resultsmentioning

confidence: 97%

The effect of aeration conditions, characterized by the volumetric mass transfer coefficient KLa, on the fermentation kinetics of Bacillus thuringiensis kurstaki

Mounsef

Salameh

Louka

et al. 2015

Journal of Biotechnology

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The aeration is a key factor for Bacillus thuringiensis growth, sporulation and δ-endotoxins production. The objective of our work was to study the effect of aeration on the fermentation kinetics of Bacillus thuringiensis kurstaki (Btk), cultivated in a cereal milling byproduct (CMB) mono-component medium, in order to improve the δ-endotoxins productivity. Aeration conditions were systematically characterized by the volumetric mass transfer coefficient KLa. In the 6% CMB culture medium, different values of the maximal specific oxygen uptake rate were obtained at different values of KLa. For KLa of 7.2 h(-1), the growth was inhibited and the sporulation was defective. There was a linear increase of the average specific growth rate and faster sporulation and liberation of spores and δ-endotoxins crystals when KLa was increased between 13.3 h(-1) and 65.5 h(-1). Similar kinetic was observed in cultures performed at KLa equal to 65.5 h(-1) and 106.2 h(-1). The highest toxins productivity of 96.1 mg L(-1) (h)-1 was obtained in the 9% CMB culture medium for KLa of 102 h(-1). It was possible to track the evolution of the bacterial cells between vegetative growth, sporulation and liberation of mature spores by following the variation of the CO2 percent in the effluent gas.

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Section: Resultsmentioning

confidence: 97%

The effect of aeration conditions, characterized by the volumetric mass transfer coefficient KLa, on the fermentation kinetics of Bacillus thuringiensis kurstaki

Mounsef

Salameh

Louka

et al. 2015

Journal of Biotechnology

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“…Earlier works demonstrated that in Bt cultures oxygen uptake rates are very high during the vegetative growth, falling drastically after the beginning of the transition phase and maintaining a decreasing profile until the end (Rowe et al 2003;Yezza et al 2005;Berbert-Molina et al 2008;Amicarelli et al 2010). Indeed, some authors verified that lower aeration rates in the sporulation phase, in relation to those employed in the earlier stages of growth, led to a greater toxicity in Btk cultures (Ghribi et al 2007a).…”

Section: Resultsmentioning

confidence: 98%

Oxygen supply in Bacillus thuringiensis fermentations: bringing new insights on their impact on sporulation and δ-endotoxin production

Boniolo

Rodrigues

Prata

et al. 2012

Appl Microbiol Biotechnol

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The growth kinetics, sporulation, and toxicity of Bacillus thuringiensis var. israelensis were evaluated through the analysis of batch cultures with different dissolved oxygen (DO) profiles. Firstly, DO was maintained constant at 5%, 20%, or 50% throughout fermentation in order to identify the most suitable one to improve the main process parameters. Higher biomass concentration, cell productivity, and cell yield based on glucose were obtained with 50% DO. The higher aeration level also resulted in higher spore counts and markedly improved the toxic activity of the fermentation broth, which was 9-fold greater than that obtained with 5% DO (LC 50 of 39 and 329 mg/L, respectively). Subsequently, using a two-stage oxygen supply strategy, DO was kept at 50% during the vegetative and transition phases until the maximum cell concentration was achieved. Then, DO was changed to 0%, 5%, 20%, or 100% throughout sporulation and cell lysis phases. The interruption of oxygen supply strongly reduced the spore production and thoroughly repressed the toxin synthesis. On the contrary, when DO was raised to 100% of saturation, toxic activity increased approximately four times (LC 50 of 8.2 mg/L) in comparison with the mean values reached with lower DO levels, even though spore counts were lower than that from the 50% DO assay. When pure oxygen was used instead of normal air, it was possible to obtain 70% of the total biomass concentration achieved in the air assays; however, cultures did not sporulate and the toxin synthesis was consequently suppressed.

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“…Afterward, Amicarelli et al . improved the model process by adding the DO dynamics due to its importance in the biomass estimation problem and the posterior process control. The DO dynamic model is based on unstructured and unsegregated descriptions of the cell population.…”

Section: Bacillus Thuringiensis δ‐Endotoxins Production Processmentioning

confidence: 99%

“…The following state‐space model is the discrete time version of the continuous‐time counterpart developed by Amicarelli et al

[\begin{matrix} center \\ center {normalX}_{normalv} (k + 1) \\ center X_{s} (k + 1) \\ center S (k + 1) \\ center DO (k + 1) \end{matrix}] = [\begin{matrix} center \\ center ((μ (k) ‐ k_{s} (k) ‐ k_{e} (k)) Ts + 1) X_{v} (k) \\ center k_{s} (k) X_{v} (k) Ts + X_{s} (k) \\ center ‐ (\frac{μ (k)}{Y_{x true/ s}} + m_{s}) X_{v} (k) Ts + S (k) \\ center (K_{1} ‐ K_{2} Ts) X (k) ‐ K_{1} X (k + 1) + DO (k) + K_{3} Q_{A} Ts (D O^{*} ‐ DO (k)) \end{matrix}]

where X v is the vegetative cell concentration, X S the sporulated cell concentration, X = X v + X S is the total cell concentration ( X (k + 1) =(μ(k) ‐ k e (k))TsX v (k) + X(k)), S is the limiting substrate concentration, and DO is the DO concentration.…”

Section: Bacillus Thuringiensis δ‐Endotoxins Production Processmentioning

confidence: 99%

Behavior comparison for biomass observers in batch processes

Amicarelli

Quintero

Sciascio

2013

Asia-Pacific J Chem Eng

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On‐line estimation of biomass concentration in batch biotechnological processes is an active area of research because normally, the biomass is the desired process product output, and also because it is necessary for control purposes to replace the unavailable biomass concentration measurements with reliable and robust on‐line estimations. This work presents five different alternatives to face the problem of biomass estimation in a particular batch bioprocess (δ‐endotoxins production of Bacillus thuringiensis), namely: a phenomenological estimator based on dissolved oxygen balance, an extended Kalman filter estimator, a Gaussian process regression‐based estimator, an artificial neural networks‐based estimator, and finally, an estimator based on information fusion by a decentralized Kalman filter. Each proposed biomass estimation method has its own advantages and drawbacks according to their ability to take into account the model uncertainties and the measurement errors. First, the design techniques of these five biomass estimators are exposed, and finally, the behavior of each estimation method is compared. The availability of efficient biomass estimators is of great importance for engineers because, on the one hand, it allows developing new control strategies for other bioprocess variables such as for instance: the growth rate of the microorganism, the dissolved oxygen concentration, and so on. On the other hand, it is also important to improve the performance of the bioprocess optimization procedure. This work also aims to show the evolution on biomass estimation techniques from classical to more contemporary approaches, such as the design based on neural networks and Gaussian processes regression. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

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Including dissolved oxygen dynamics into the Bt δ-endotoxins production process model and its application to process control

Cited by 26 publications

References 44 publications

The effect of aeration conditions, characterized by the volumetric mass transfer coefficient KLa, on the fermentation kinetics of Bacillus thuringiensis kurstaki

The effect of aeration conditions, characterized by the volumetric mass transfer coefficient KLa, on the fermentation kinetics of Bacillus thuringiensis kurstaki

Oxygen supply in Bacillus thuringiensis fermentations: bringing new insights on their impact on sporulation and δ-endotoxin production

Behavior comparison for biomass observers in batch processes

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