The thesis was successfully defended with the following jury:

Ms Dorothée LAURENTI, Director of Research, CNRS, Lyon, Rapporteur
Ms Christine Gérardin, Professor, University of Lorraine, Nancy, Rapporteur
Ms Annabelle DEJARDIN, Research Director, INRAE, Orléans, Examiner
Mr Frédéric MARTEL, R&D Director, Européenne de Biomasse, Pomacle, Examiner

Thesis abstract

The production of chemicals, materials and biofuels from lignocellulosic biomass (LB) is in full development to limit the use of fossil resources. However, the conversion process in biorefineries is limited by one of its steps, still too costly: the LB pretreatment. In order to optimize this stage, it is essential to understand and predict the changes it causes in the LB at different scales, both chemically and structurally.
To address this issue, one of the most comprehensive data sets to date on the chemical evolution of poplar wood polysaccharides and their degradation products during dilute acid pretreatment has been compiled and made available in a public database. No less than 38 pretreatment conditions covering a wide range of parameters (2-60 min, 120-190°C, 0-4 %wt H₂SO₄) have been defined, together with the characterization of twelve chemical compounds.
This data set was explored using polynomial models to define trade-offs between cellulose integrity and hemicellulose degradation, while limiting the production of inhibitors. The links between evolutionary kinetics were also illustrated using two main degradation pathways derived from C5 and C6 sugars. Finally, these results were used to highlight the differences in chemical, structural and enzymatic degradation between raw and genetically modified poplar wood for CAD gene (Cinnamyl Alcohol Dehydrogenase) involved in lignin synthesis.

Well done Julien and all the best!