Setting up and modelling of overflowing fed-batch cultures of Bacillus subtilis for the production and continuous removal of lipopeptides

This work is related to the setup of overflowing exponential fed-batch cultures (O-EFBC) derived from carbon limited EFBC dedicated to the production of mycosubtilin, an antifungal lipopeptide belonging to the iturin family. O-EFBC permits the continuous removal of the product from the bioreactor achieving a complete extraction of mycosubtilin. This paper also provides a dynamical Monod-based growth model of this process that is accurate enough to simulate the evolution of the specific growth rate and to correlate it to the mycosubtilin specific productivity. Two particular and dependant phenomena related to the foam overflow are taken into account by the model: the outgoing flow rate of a broth volume and the loss of biomass. Interestingly, the biomass concentration in the foam was found to be lower than the biomass concentration in the bioreactor relating this process to a recycling one. Parameters of this model are the growth yield on substrate and the maximal specific growth rate estimated from experiments led at feed rates of 0.062, 0.071 and 0.086 h --1. The model was extrapolated to five additional experiments carried out at feed rates of 0.008, 0.022, 0.040, 0.042 and 0.062 h --1 enabling the correlation of the mean specific growth rates with productivity results. Finally, a feed rate of 0.086 h --1 corresponding to a mean specific growth rate of 0.070 h --1 allowed a specific productivity of 1.27 mg of mycosubtilin g --1 of dried biomass h --1

Real time in situ microscopy for animal cell-concentration monitoring during high density culture in bioreactor

International audienceAn in situ microscope (ISM) device is utilised in this study to monitor hybridoma cells concentration in a stirred bioreactor. It generates images by using pulsed illumination of the liquid broth synchronised with the camera frame generation to avoid blur from the cell's motion. An appropriate image processing isolates the sharp objects from the blurred ones that are far from the focal plane. As image processing involves several parameters, this paper focuses on the robustness of the results of the cells counting. This stage determines the applicability of the measuring device and has seldom been tackled in the presentations of ISM devices. Calibration is secondly performed for assessing the cell-concentration from the cell automated numeration provided by the ISM. Flow cytometry and hemacytometer chamber were used as reference analytical methods. These measures and the output of the image processing allow estimating a single calibration parameter: the reference volume per image equal to 1.08 × 10 −6 mL. In these conditions, the correlation coefficient between both reference and ISM data sets becomes equal to 0.99. A saturation of this system during an ultrasonic wave perfusion phase that deeply changes the culture conditions is observed and discussed. Principal component analysis (PCA) is used to undergo the robustness study and the ISM calibration step

Integrated extraction-adsorption process for selective recovery of antioxidant phenolics from food industry by-product

International audienceThis work aimed at proposing a green process for selective recovery of antioxidant polyphenols, in order to propose a sustainable valorisation of chicory grounds, a food-industry by-product. An integrated extraction-adsorption process was performed, enabling simultaneous extraction of phenolics and their purification in a single operation. After selecting the most efficient adsorbent among tested and experimental conditions for adsorption and desorption of antioxidant polyphenols, the integrated process was studied, using a central composite design, considering total polyphenols yield, antioxidant activity and energy consumption of the equipment. Influence of processing time (2, 4 or 6 h), processing flow rate (1, 3 or 5 L.h(-1)) and resin/chicory grounds ratio (1/10, 2/10 or 3/10, d.w./d.w.) were investigated. A mathematical model for multi-criteria optimisation was proposed. The integrated process enabled to improve polyphenols recovery efficiency by 63% and to reduce energy consumption by 2.8 times, compared to conventional process, where extraction and adsorption were performed successively

An original use of size exclusion-HPLC for predicting the performances of batch ultrafiltration implemented to enrich a complex protein hydrolysate in a targeted bioactive peptide

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The viability of animal cell cultures in bioreactors: Can it be estimated online by using in situ microscopy?

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