Lignin is a complex heterogeneous aromatic polymer consisting of up to 30 % of plant material. It... more Lignin is a complex heterogeneous aromatic polymer consisting of up to 30 % of plant material. Its aromatic structure suggests that it is a possible renewable source for aromatic chemicals. However, the natural complexity and high stability of lignin makes its depolymerization a highly challenging task. Many efforts have been directed toward a better understanding of the structure and composition of lignin in order to design more efficient and greener deconstruction paths. This chapter aims at providing an overview of key advances in the field of lignin depolymerization, with special emphasis on chemical catalysis, ionic liquids, and biocatalysis. The various technologies are discussed and critically evaluated in terms of potential for further industrial implementation. Research gaps that still need to be addressed and the most promising approaches are highlighted.
Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin,... more Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin, Indulin AT. Lignin was depolymerised in an aqueous alkaline solution using a continuous flow reactor generating four fractions. First is the gas fraction (mainly CO(2)), the second includes methanol, acetic acid and formic acid, thus defined as small organic compounds and third one (up to 19.1 wt.% of lignin) is mostly composed of aromatic monomers. The fourth fraction (45-70 wt.%) contains oligomers (polyaromatic molecules) and modified lignin. Pyrocatechol was the most abundant product at high severities (315°C) with selectivity up to 25.8%. (31)P NMR showed the loss of almost all aliphatic OH groups and apparition of catechol groups during depolymerisation.
For almost a century, the wheat Lr34 gene has conferred durable resistance against fungal rust di... more For almost a century, the wheat Lr34 gene has conferred durable resistance against fungal rust diseases. While sequence homology predicts a putative ATP binding cassette transporter, the molecules that are transported (allocrites) by the encoded LR34 variants, and any associated mechanism of resistance, remain enigmatic. Here, the in vitro transport characteristics of 2 naturally occurring Lr34 variants (that differ in their ability to mediate disease resistance; Lr34sus and Lr34res) are investigated. Initially, a method to express and purify recombinant LR34Sus and LR34Res pseudo half-molecules from Saccharomyces cerevisiae, is described. Subsequently, a semi-targeted chlorophyll catabolite (CC) extraction from Lr34res-expressing wheat plants was performed based on previous reports highlighting increased accumulation of CCs in Lr34res-expressing flag leaves. Following partial biochemical characterization, this extract was applied to an LR34 in vitro proteoliposome transport assay. Mass spectroscopic analyses of transported metabolites revealed that LR34Sus imported a wheat metabolite of 618 Da and that the LR34Res transporter did not. While the identity of the LR34Sus transported metabolite remains to be confirmed and any allocrites of LR34Res remain to be detected, this work demonstrates that these variants have different allocrite preferences, a finding that may be relevant to the mechanism of disease resistance.
... Fe was minimised. The residue was extensively washed with deionised water to remove all chlor... more ... Fe was minimised. The residue was extensively washed with deionised water to remove all chloride ions, and gently dried at 40°C. The purified humic acid presents a very low ash content (<0.1%). The elemental composition ...
ABSTRACT Valorization of lignin into biomaterials requires its good compatibility with the polyme... more ABSTRACT Valorization of lignin into biomaterials requires its good compatibility with the polymeric matrix it is incorporated into. Softwood Kraft lignin was esterified with various anhydrides (acetic, propionic, butyric, methacrylic, maleic) using a solvent-free, catalyst-free, microwave-assisted method. The esterification was fast and efficient (degrees of substitution >90% after 10 min). The reaction was worked up using water or ethanol as purification agent. Esterified lignins were characterized by FT-IR, GPC, quantitative 31P NMR and TGA/DSC. NMR analyses indicated that non-cyclic anhydrides reacted with both aliphatic and phenolic OH groups, while maleic anhydride reacted exclusively with aliphatic OH groups. All acylated lignins except the maleated one showed higher thermal stability than the unmodified lignin. Lignins acylated with non-cyclic anhydrides can be applied as green fillers in apolar polyolefins while maleated lignin can serve as metal adsorbent or macroreagent for the synthesis of polyesters or polyamides. We showed in this study that lignin can be modified in a fast and easy way.
Lignin is a complex heterogeneous aromatic polymer consisting of up to 30 % of plant material. It... more Lignin is a complex heterogeneous aromatic polymer consisting of up to 30 % of plant material. Its aromatic structure suggests that it is a possible renewable source for aromatic chemicals. However, the natural complexity and high stability of lignin makes its depolymerization a highly challenging task. Many efforts have been directed toward a better understanding of the structure and composition of lignin in order to design more efficient and greener deconstruction paths. This chapter aims at providing an overview of key advances in the field of lignin depolymerization, with special emphasis on chemical catalysis, ionic liquids, and biocatalysis. The various technologies are discussed and critically evaluated in terms of potential for further industrial implementation. Research gaps that still need to be addressed and the most promising approaches are highlighted.
Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin,... more Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin, Indulin AT. Lignin was depolymerised in an aqueous alkaline solution using a continuous flow reactor generating four fractions. First is the gas fraction (mainly CO(2)), the second includes methanol, acetic acid and formic acid, thus defined as small organic compounds and third one (up to 19.1 wt.% of lignin) is mostly composed of aromatic monomers. The fourth fraction (45-70 wt.%) contains oligomers (polyaromatic molecules) and modified lignin. Pyrocatechol was the most abundant product at high severities (315°C) with selectivity up to 25.8%. (31)P NMR showed the loss of almost all aliphatic OH groups and apparition of catechol groups during depolymerisation.
For almost a century, the wheat Lr34 gene has conferred durable resistance against fungal rust di... more For almost a century, the wheat Lr34 gene has conferred durable resistance against fungal rust diseases. While sequence homology predicts a putative ATP binding cassette transporter, the molecules that are transported (allocrites) by the encoded LR34 variants, and any associated mechanism of resistance, remain enigmatic. Here, the in vitro transport characteristics of 2 naturally occurring Lr34 variants (that differ in their ability to mediate disease resistance; Lr34sus and Lr34res) are investigated. Initially, a method to express and purify recombinant LR34Sus and LR34Res pseudo half-molecules from Saccharomyces cerevisiae, is described. Subsequently, a semi-targeted chlorophyll catabolite (CC) extraction from Lr34res-expressing wheat plants was performed based on previous reports highlighting increased accumulation of CCs in Lr34res-expressing flag leaves. Following partial biochemical characterization, this extract was applied to an LR34 in vitro proteoliposome transport assay. Mass spectroscopic analyses of transported metabolites revealed that LR34Sus imported a wheat metabolite of 618 Da and that the LR34Res transporter did not. While the identity of the LR34Sus transported metabolite remains to be confirmed and any allocrites of LR34Res remain to be detected, this work demonstrates that these variants have different allocrite preferences, a finding that may be relevant to the mechanism of disease resistance.
... Fe was minimised. The residue was extensively washed with deionised water to remove all chlor... more ... Fe was minimised. The residue was extensively washed with deionised water to remove all chloride ions, and gently dried at 40°C. The purified humic acid presents a very low ash content (<0.1%). The elemental composition ...
ABSTRACT Valorization of lignin into biomaterials requires its good compatibility with the polyme... more ABSTRACT Valorization of lignin into biomaterials requires its good compatibility with the polymeric matrix it is incorporated into. Softwood Kraft lignin was esterified with various anhydrides (acetic, propionic, butyric, methacrylic, maleic) using a solvent-free, catalyst-free, microwave-assisted method. The esterification was fast and efficient (degrees of substitution >90% after 10 min). The reaction was worked up using water or ethanol as purification agent. Esterified lignins were characterized by FT-IR, GPC, quantitative 31P NMR and TGA/DSC. NMR analyses indicated that non-cyclic anhydrides reacted with both aliphatic and phenolic OH groups, while maleic anhydride reacted exclusively with aliphatic OH groups. All acylated lignins except the maleated one showed higher thermal stability than the unmodified lignin. Lignins acylated with non-cyclic anhydrides can be applied as green fillers in apolar polyolefins while maleated lignin can serve as metal adsorbent or macroreagent for the synthesis of polyesters or polyamides. We showed in this study that lignin can be modified in a fast and easy way.
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Papers by Fanny Monteil-Rivera