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Vallejo, F.; González, Ainhoa; Posada, Aguilar; Restrepo, A.; Ordúz, Sergio

doi:10.1023/a:1008974819161

Cited by 15 publications

(3 citation statements)

References 6 publications

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“…After the sporulation, the process is completed with the cellular wall rupture (cellular lysis), and the consequent liberation of spores and crystals to the culture medium . The microorganisms used in this work were Bt serovar kurstaki strain 172–0451 isolated in Colombia and stored in the culture collection of Biotechnology and Biological Control Unit (CIB) . Growth experiments of the fermentation process were performed in a reactor with a nominal volume of 20 L (Fig.…”

Section: Bacillus Thuringiensis δ‐Endotoxins Production Processmentioning

confidence: 99%

“…[9][10][11] The microorganisms used in this work were Bt serovar kurstaki strain 172-0451 isolated in Colombia and stored in the culture collection of Biotechnology and Biological Control Unit (CIB). [12] Growth experiments of the fermentation process were performed in a reactor with a nominal volume of 20 L (Fig. 1).…”

Section: The Bioprocessmentioning

confidence: 99%

“…Furthermore, by (12), the biomass concentration X Ã ¼X t Ã ð Þ and the variance sX 2 Ã are estimated for a set of different times {t *}, < t * < 16 hours.…”

Section: Estimator Based On Bayesian Gaussian Process Regressionmentioning

confidence: 99%

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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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Section: Bacillus Thuringiensis δ‐Endotoxins Production Processmentioning

confidence: 99%

Section: The Bioprocessmentioning

confidence: 99%

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Behavior comparison for biomass observers in batch processes

Amicarelli

Quintero

Sciascio

2013

Asia-Pacific J Chem Eng

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Production of Bacillus thuringiensis‐based biopesticides in batch and fed batch cultures using wastewater sludge as a raw material

Yezza

Tyagi

Valero

et al. 2005

J of Chemical Tech & Biotech

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Bacillus thuringiensis subsp kurstaki was grown in batch and fed batch cultures using wastewater sludge as a raw material. A simple fed batch strategy based on dissolved oxygen measurement during the fermentation cycle was developed in this work. It was established that while shifting the process strategy from batch to fed batch, the maximum spore concentration was increased from 5.62 × 10 8 to 8.6 × 10 8 colony forming units per cm 3 and resulted in an increase of entomocidal activity from 13 × 10 9 to 18 × 10 9 spruce budworm potency units per dm 3 . Higher entomotoxicity was recorded at low spore concentration using wastewater sludge as a raw material whereas low entomotoxicity was reported at high spore concentration in synthetic medium.

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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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Untitled

Cited by 15 publications

References 6 publications

Behavior comparison for biomass observers in batch processes

Behavior comparison for biomass observers in batch processes

Production of Bacillus thuringiensis‐based biopesticides in batch and fed batch cultures using wastewater sludge as a raw material

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

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