Experimental study of substrate limitation and light acclimation in cultures of the microalgae Scenedesmus obliquus—Parameter identification and model predictive control

In this study, the parameters of a dynamic model of cultures of the microalgae Scenedesmus obliquus are estimated from datasets collected in batch photobioreactors operated with various initial conditions and light illumination conditions. Measurements of biomass, nitrogen quota, bulk substrate concentration, as well as chlorophyll concentration are achieved, which allow the determination of parameters with satisfactory confidence intervals and model cross-validation against independent data. The dynamic model is then used as a predictor in a nonlinear model predictive control strategy where the dilution rate and the incident light intensity are simultaneously manipulated in order to optimize the cumulated algal biomass production.Fil: Gorrini, Federico Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Lara, Jesús Miguel Zamudio. Université de Mons; Bélgica. Universidad de Guanajuato; MéxicoFil: Biagiola, Silvina Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Figueroa, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Escoto, Héctor Hernández. Universidad de Guanajuato; MéxicoFil: Hantson, Anne Lise. Université de Mons; BélgicaFil: Wouwer, Alain Vande. Université de Mons; Bélgic

Microbial co-culturing strategies for fructo-oligosaccharide production

Fructo-oligosaccharide (FOS) mixtures produced by fermentation contain large amounts of non-prebiotic sugars. Here we propose a mixed culture of Aureobasidium pullulans and Saccharomyces cerevisiae cells to produce FOS and consume the small saccharides simultaneously, thereby increasing FOS purity in the mixture. The use of immobilised A. pullulans in co-culture with encapsulated S. cerevisiae, inoculated after 10h fermentation, enhanced FOS production in a 5L bioreactor. Using this strategy, a maximal FOS concentration of 119g L1, and yield of 0.59gFOS gsucrose1, were obtained after 20h fermentation, increasing FOS productivity from about 4.9 to 5.9gFOS L1h1 compared to a control fermentation of immobilized A. pullulans in monoculture. In addition, the encapsulated S. cerevisiae cells were able to decrease the glucose in the medium to about 7.6% (w/w) after 63h fermentation. This provided a final fermentation mixture with 2.0% (w/w) sucrose and a FOS purity of over 67.0% (w/w). Moreover, a concentration of up to 58.0g L1 of ethanol was obtained through the enzymatic transformation of glucose. The resulting pre-purified FOS mixture could improve the separation and purification of FOS in downstream treatments, such as simulated moving bed chromatography.Cristiana C. Castro gratefully acknowledges the financial support from the F.R.S.-FNRS, the Belgium National Fund for Scientific Research (PDR: T.0196.13). Clarisse Nobre acknowledges the Portuguese Foundation for Science and Technology (FCT) for the postdoctoral grant (reference SFRH/BPD/87498/2012) and the strategic funding of the UID/BIO/04469/2013 unit, Project ColOsH 02/SAICT/ 2017 (POCI-01-0145-FEDER-030071), COMPETE 2020 (POCI-01-0145FEDER-006684), and BioTecNorte operation (NORTE-01-0145-FEDER000004), funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Parameter identification of Droop model: an experimental case study

Mathematical modeling and the development of predictive dynamic models are of paramount importance for the optimization, state estimation, and control of bioprocesses. This study is dedicated to the identification of a simple model of microalgae growth under substrate limitation, i.e., Droop model, and describes the design and instrumentation of a lab-scale flat-plate photobioreactor, the associated on-line and off-line instrumentation, the collection of experimental data, and the parameter identification procedure. In particular, a dedicated methodology for parameter identification is discussed, including the determination of an initial parameter set using an analytical procedure, the selection of a cost function, the evaluation of confidence intervals as well as direct and cross-validation tests.status: publishe

Macroscopic Dynamic Modeling of Sequential Batch Cultures of Hybridoma Cells: An Experimental Validation

Hybridoma cells are commonly grown for the production of monoclonal antibodies (MAb). For monitoring and control purposes of the bioreactors, dynamic models of the cultures are required. However these models are difficult to infer from the usually limited amount of available experimental data and do not focus on target protein production optimization. This paper explores an experimental case study where hybridoma cells are grown in a sequential batch reactor. The simplest macroscopic reaction scheme translating the data is first derived using a maximum likelihood principal component analysis. Subsequently, nonlinear least-squares estimation is used to determine the kinetic laws. The resulting dynamic model reproduces quite satisfactorily the experimental data, as evidenced in direct and cross-validation tests. Furthermore, model predictions can also be used to predict optimal medium renewal time and composition

Experimental validation of a simple dynamic model of a laboratory scale recirculating aquaculture system fitted with submerged membrane bioreactor

in pressInternational audienceSubmerged membrane bioreactors (sMBR's) are a promising technology for nitrogen removal in recirculating aquaculture systems (RAS's). However, there are still relatively few reports on the experimental application of this strategy. In this study, a laboratory-scale system, mimicking a RAS fitted with a sMBR, \rouge{was} designed and automated, and a simple dynamic sMBR model including biological and physical phenomena \rouge{was} validated. The system \blue{was} analyzed based on measurements collected by a data logging structure involving a programmable logic controller (PLC), an \rouge{industrial network protocol} and a LabView application software. This study confirms the \rouge{suitability} of sMBR systems \blue{within} aquaculture applications. The dynamic model has good predictive capabilities and could be used for the design of advanced control structures, such as model predictive control

Encapsulation de micro-algues dans un matériaux hybride alginate-silice et production de molécules à hautes valeur ajoutée

Les micro-algues sont des micro-organismes photosynthétiques. Leur croissance en milieu aqueux nécessite un apport lumineux (l = 400 à 700 nm) ainsi qu’un apport en carbone et en nutriments (N, P, S, etc.). Certaines souches, Dunaliella sp. par exemple, sont couramment utilisées dans le cadre de la biosynthèse de caroténoïdes[1] (b-carotène, lutéine entre autres). Quelques recherches ont montré qu’il était possible de réaliser l’extraction in situ des métabolites produits dans un réacteur biphasique (le b-carotène hydrophobe est extrait dans une phase organique biocompatible telle que le décane ou le dodécane) [2,3,4,5]. Le projet FOTOBIOMAT (subsidié par le programme Greenomat de la Région Wallonne – Belgique) a pour but de développer un nouveau type de photobioréacteur dans lequel sont mises en oeuvre les micro-algues encapsulées dans des billes constituées d’un matériau hybride. Le processus de photosynthèse est ainsi utilisé afin de convertir du CO2 en composés à haute valeur ajoutée (b-carotène p. ex.). La viabilité des micro-algues encapsulées doit être très importante (min. 6 mois). Idéalement, le b-carotène produit devrait être récupéré par une voie “propre” et ce, quasi en continu.FOTOBIOMA

Hybridoma cell culture optimization using nonlinear model predictive control

This work addresses the application of control systems to the optimization of a monoclonal antibodies (MAb) production chain. The attention is focused on the maximization of hybridoma fed-batch culture productivity. The proposed model presents kinetics showing strong nonlinearities through min-max functions expressing overflow metabolism. A nonlinear model predictive control (NMPC) algorithm, choosing the best trajectory over a moving finite horizon among different sequences of inputs, is suggested in order to optimize productivity. Sensitivities of selected objective functions are considered in a minimax robust version of the NMPC in order to choose the best configuration with respect to practical operating conditions. © IFAC.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Contribution à l'amélioration de l'accès à une eau potable de qualité pour les populations de la région nord du Burkina Faso

Contribution à l'amélioration de l'accès à une eau potable de qualité pour les populations de la région du nord du Burkina Fas

Investigation of the effect of a genetic manipulation through macroscopic dynamic modeling

Genetic manipulation has allowed the development of a strain of Escherichia coli with a higher biomass yield. The objective of this work is to understand the effect of the genetic manipulation at a macroscopic level, i.e. to derive a dynamic model of the evolution of the main macroscopic components of interest (substrate, biomass and products), and to compare it with a model of the wild type strain. After parameter estimation based on extensive experimental data from cultivation in batch and fed-batch, pseudo-stoichiometric coefficients and kinetic terms show that the mutant strain produces more biomass in the oxidative phase and produces less acetate per substrate consumed than the wild type strain. On the other hand, no significant difference in the maximal glucose consumption rate and the maximal critical consumption rate are found. © 2012 IFAC.SCOPUS: cp.pinfo:eu-repo/semantics/publishe