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Extractive bioconversion of 3-hydroxypropionic acid : limiting mechanisms and integrated process optimisation

Abstract : The increasing awareness on climate change has raised the concern of industries to reduce their dependency on fossil feedstocks. In the case of chemical industry, this has increased the demand for bio-based chemicals which has triggered the development of new and more efficient biotechnological processes. 3-hydroxypropionic acid (3-HP) is a platform molecule that can be produced from biomass and can be converted into a wide range of commercially valuable chemicals such as poly(3-hydroxypropionate) and acrylic acid. 3-HP production by microbial processes has made remarkable advances, but its industrial commercialization is still limited by low productivities caused by product inhibition and challenging recovery and purification. Reactive extraction, assisted by a hollow fibres membrane contactor (HFMC), also known as reactive pertraction, is a promising strategy to intensify 3-HP bioconversion and reduce downstream process costs. Several points remain to be better understood, however, to develop a continuous extraction system coupled to bioconversion and maintain a low acid concentration in the medium. This work aims to elucidate some key aspects for the proper design of such an integrated process. First, the reactive extraction of 3-HP was studied at the liquid-liquid interface scale through observation of the dynamic interfacial tension (IFT), in order to better understand the limiting mechanisms. It was found that mass transfer near the interface was not governed by diffusion only, suggesting that phenomena such as concentration-induced density gradients and associated buoyancy forces, or concentration-induced interfacial tension gradients and associated Marangoni convection can also play an important role. A comprehensive methodology for the selection of an organic phase composition, based on both extraction performance and biocompatibility with a 3-HP producing strain, Lactobacillus reuteri DSM 17938, was also developed. The effect of the composition of the selected organic phases was evaluated, highlighting the importance of finding a compromise between extraction yield, biocompatibility and viscosity, adapted to the microbial strain used. Finally, the integration of reactive pertraction with bioconversion was performed. Two different 3-HP producing strains, L. reuteri DSM 17938 and Acetobacter sp. CIP 58.66, were studied. It was observed that L. reuteri was very sensitive to reactive pertraction conditions. Moreover, bioconversion pH was not optimal for 3-HP extraction. Overall, 3-HP production and extraction were very limited in this integration attempt. In contrast, extractive bioconversion with Acetobacter sp. resulted in better performances. The integrated approach was did not significantly reduce the high 3-HP production capacities of the strain that showed a good resistance to the cumulative stresses, making it a promising candidate for extractive bioconversion. A significant imbalance between production and extraction rates was observed, however, leading to pH decrease during 3-HP production but this had a limited impact on Acetobacter sp. bioconversion ability. Further optimisation strategies where explored using a mathematical model as a simulation tool. The information obtained throughout this work paves the route to the design of an integrated and intensified bio-based 3-HP production process.
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Submitted on : Monday, July 25, 2022 - 4:54:13 PM
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  • HAL Id : tel-03738028, version 1

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Ana Karen Sanchez Castañeda. Extractive bioconversion of 3-hydroxypropionic acid : limiting mechanisms and integrated process optimisation. Génie des procédés. Université Paris-Saclay, 2020. Français. ⟨NNT : 2020UPASA006⟩. ⟨tel-03738028⟩

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