Development of a cascading strategy to fully harness the functional potential of lignins In a zero-waste lignocellulosic biorefinery approach, Zelcor project proposed a cascading scheme to harness the molecular heterogeneity of technical lignins recovered from lignocellulose fractionation. A first solvent-extraction step yields 30% of a lignin fraction composed of monomers and oligomers of interest as active ingredients for insect-repellent packaging (Vachon et al., 2020; 2023; coll. WFBR and Sabic, NL). The absence of these compounds in the solid residue improves its depolymerization by a methyl imidazolium bromide treatment previously developed on model lignins with 2 CNRS teams (Thierry et al., 2018). The ether bond cleavages within lignin releases demethylated compounds with enhanced antioxidant properties (Majira et al., 2019; coll. WFBR and Ineris). This demethylation strategy was useful to provide model lignin fractions for the investigation of relationships between lignin molecular and supramolecular structures and their properties within cellulose matrix (Gerbin et al., 2021; coll. Aalto Univ. and INRAE FARE). Targeting highly recalcitrant biorefinery products like humins, another depolymerization strategy based on polyoxometalates based ionic liquids was settled in coll. with CNRS Institut Lavoisier de Versailles (ILV) (Y. Martinetto’s then N. Zeaiter PhD theses; Martinetto et al., 2020; 2021). Coll. with Univ. Paris-Est Créteil (UPEC) and Ynsect showed the possibility to convert the final residue of the cascading process by selected termite species, the ingestion by the insects being proved thanks to Apsynth’s pyrolysis GC-MS expertise (Jusselme et al. 2020). Between 2018 and 2023, Zelcor has produced 20 original scientific papers, half of them involving Apsynth. This project was awarded the prize "Les étoiles de l'Europe" 2021.
Biocatalytic selective acylation of technical lignins The first challenge of this study was to develop a two-step process for the functionalization of a model technical lignin to make its solubility properties more appropriate for incorporation in polyolefinic and polyester polymers and cosmetic emulsion formulation. The first stage of the process exploited the fractionation strategy developed in Zelcor to recover a butanone soluble fraction that was homogeneous in terms of physicochemical properties and was then subjected to enzymatic esterification using an easily recyclable supported enzyme and aliphatic acids of variable chain length (Sarieddine et al., 2023). An exhaustive study of the reaction conditions was carried out to optimize the process, and a major investment in analytical chemistry, combining methods used in fatty acid ester chemistry and those dedicated to lignins, enabled to assess the structural impact of the process on the starting lignin. The grafted lignins were then incorporated in various proportions into synthetic polymers using different formulation methods. The advantage of using these grafted lignins over the starting lignin was demonstrated through the rheological, thermomechanical and oxidation resistance properties of these composite material (coll. UMR FARE, A. Sarieddine’s thesis). Moreover, these same lignins were used as cosmetic emulsifiers, improving the stability and sensory properties of these water-in-oil self-emulsions (coll. URCOM and IFF-Lucas Meyer Cosmetics, C. Hadjiefstathiou's thesis) (Hadjiefstathiou et al., 2023, 2024a, 2024b). This work was valorized through 4 scientific papers and a European patent deposited by IFF.
Implementation and elucidation of the action mechanisms of oxido-reductases on lignins The main challenges addressed by Apsynth in coll. with enzymologists and synthetic biologists was to use microorganisms oxido-reductases to improve the functionalities of technical lignins. In parallel, the potential of different anaerobic bacteria for lignocellulosic biomasses deconstruction has been investigated (ANR Expande, INRAE BBF and CNRS LCB units). Each study required specific analytical strategies to decipher polymerization/depolymerization processes, as developed by Rouches et al. (2021) (Ligbio project). Coll. with Univ. of Warwick (Ligbio, Milimo and Zelcor projects) focused on the potential of bacterial oxido-reductases to convert recalcitrant biorefinery residues into high value-added building blocks for polymers, as product of bacterial metabolism. A major result is the evidence that a Manganese Superoxide Dismutase (Sphingobacterium sp. T2) catalyzes the oxidative demethylation of polymeric lignin (Rashid et al., 2018). Complementary, coll. with INRAE BFF (Zelcor and ANR Funclipro projects) explored fungal enzymes. Trichoderma reesei, a fungus widely used commercially, was able to grow on technical lignins alone and to produce a copper oxidase preferentially oxidizing alcohols (over aldehydes) and leading to lignin-dimer polymerization depending on the dimer structure (Daou et al., 2021b, Zelcor). In Funclipro (coll. INRAE BBF and FARE units, FCBA, Univ. of Clermont Ferrand) Apsynth investigated the capacity of a Pycnoporus cinnabarinus laccase to functionalize a pine Kraft lignin sample and settled a set of analytical methods for screening enzymatic treatment conditions (Garajova et al., 2023). These results not only bring useful knowledge on how oxido-reductase-based processes could be developed, but also on novel biocatalysts of industrial interest.
Biocatalytic selective acylation of technical lignins The first challenge of this study was to develop a two-step process for the functionalization of a model technical lignin to make its solubility properties more appropriate for incorporation in polyolefinic and polyester polymers and cosmetic emulsion formulation. The first stage of the process exploited the fractionation strategy developed in Zelcor to recover a butanone soluble fraction that was homogeneous in terms of physicochemical properties and was then subjected to enzymatic esterification using an easily recyclable supported enzyme and aliphatic acids of variable chain length (Sarieddine et al., 2023). An exhaustive study of the reaction conditions was carried out to optimize the process, and a major investment in analytical chemistry, combining methods used in fatty acid ester chemistry and those dedicated to lignins, enabled to assess the structural impact of the process on the starting lignin. The grafted lignins were then incorporated in various proportions into synthetic polymers using different formulation methods. The advantage of using these grafted lignins over the starting lignin was demonstrated through the rheological, thermomechanical and oxidation resistance properties of these composite material (coll. UMR FARE, A. Sarieddine’s thesis). Moreover, these same lignins were used as cosmetic emulsifiers, improving the stability and sensory properties of these water-in-oil self-emulsions (coll. URCOM and IFF-Lucas Meyer Cosmetics, C. Hadjiefstathiou's thesis) (Hadjiefstathiou et al., 2023, 2024a, 2024b). This work was valorized through 4 scientific papers and a European patent deposited by IFF.
Implementation and elucidation of the action mechanisms of oxido-reductases on lignins The main challenges addressed by Apsynth in coll. with enzymologists and synthetic biologists was to use microorganisms oxido-reductases to improve the functionalities of technical lignins. In parallel, the potential of different anaerobic bacteria for lignocellulosic biomasses deconstruction has been investigated (ANR Expande, INRAE BBF and CNRS LCB units). Each study required specific analytical strategies to decipher polymerization/depolymerization processes, as developed by Rouches et al. (2021) (Ligbio project). Coll. with Univ. of Warwick (Ligbio, Milimo and Zelcor projects) focused on the potential of bacterial oxido-reductases to convert recalcitrant biorefinery residues into high value-added building blocks for polymers, as product of bacterial metabolism. A major result is the evidence that a Manganese Superoxide Dismutase (Sphingobacterium sp. T2) catalyzes the oxidative demethylation of polymeric lignin (Rashid et al., 2018). Complementary, coll. with INRAE BFF (Zelcor and ANR Funclipro projects) explored fungal enzymes. Trichoderma reesei, a fungus widely used commercially, was able to grow on technical lignins alone and to produce a copper oxidase preferentially oxidizing alcohols (over aldehydes) and leading to lignin-dimer polymerization depending on the dimer structure (Daou et al., 2021b, Zelcor). In Funclipro (coll. INRAE BBF and FARE units, FCBA, Univ. of Clermont Ferrand) Apsynth investigated the capacity of a Pycnoporus cinnabarinus laccase to functionalize a pine Kraft lignin sample and settled a set of analytical methods for screening enzymatic treatment conditions (Garajova et al., 2023). These results not only bring useful knowledge on how oxido-reductase-based processes could be developed, but also on novel biocatalysts of industrial interest.
Leader:
Stéphanie Baumberger