Pretreatments and enzymatic hydrolysis of Miscanthus x giganteus for oligosaccharides production: delignification degree and characterisation of the hydrolysis products

Poster (2010, February 04)

The aim of the present study is to compare two delignification methods (formic/acetic acid1 and soaking in aqueous ammonia) on Miscanthus x giganteus and to assess the suitability to produce cellobiose ... [more ▼]

The aim of the present study is to compare two delignification methods (formic/acetic acid1 and soaking in aqueous ammonia) on Miscanthus x giganteus and to assess the suitability to produce cellobiose and other oligosaccharides after enzymatic hydrolysis. Oligosaccharides have recently gotten attention for their health benefits. Two methods were compared in order to quantify lignin: the acid detergent lignin method (procedure of Van Soest most commonly employed by animal scientist and agronomists for analysis of forages) and the Klason lignin procedure. Lignin concentrations in raw material determined by both methods were different; Klason lignin value (23.5%) was greater than the acid detergent lignin concentration (12.9%). Possible reasons of these results will be discussed. Pretreatment by the formic/acid mixture showed a better deliginification rate compared to the soaking in aqueous ammonia method. Results were based on Klason lignin. Analysis of the structural carbohydrates revealed that untreated miscanthus was mainly composed of glucose and xylose. Extracted pulps by both delignification methods were hydrolysed by commercial cellulases and hemicellulases. A major challenge is the characterisation of complex mixtures of lignocellulosic hydrolysates. In this study, the hydrolysis products were separated and quantified by highperformance anion exchange chromatography with pulsed amperometric detection (HPAECPAD). This method was successfully applied to the quantitative analysis of monosaccharides (glucose and xylose) and disaccharides (cellobiose and xylobiose) formed by the enzymatic hydrolysis of pretreated miscanthus. The influence of the pretreatments on the oligosaccharides yields will be presented. [less ▲]

Influence of homogenization and drying on the thermal stability of microfibrillated cellulose

in Polymer Degradation and Stability (2010), 95

La steam explosion : application en tant que prétraitement de la matière cellulosique

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(Spécial N°2),

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the ... [more ▼]

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose cristallinity rate,…), hydrolysis of hemicellulosic components (mono and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels or high value-added molecules process. [less ▲]

Activités de l'unité de Chimie Biologique Industrielle

Speech (2009)

Vapocraquage et Steam Explosion

Conference (2009, October 21)

Les produits lignocellulosiques comme source de biocarburants de deuxième génération dans un concept de bioraffinage

Conference given outside the academic context (2008)

STUDY OF THE POSSIBILITY TO PRODUCE CELLULOSE MICROFIBRILS BY APPLYING SHEARING TREATMENTS TO CELLULOSE FIBERS

Poster (2007, June 04)

Cellulose is a linear biopolymer composed of glucose residues linked by β 1-4 glucosidics bonds. These characteristics enable cellulose molecules to adopt an extended rod-like configuration. In the ... [more ▼]

Cellulose is a linear biopolymer composed of glucose residues linked by β 1-4 glucosidics bonds. These characteristics enable cellulose molecules to adopt an extended rod-like configuration. In the microfibrils, the multiple hydroxyl groups on the glucose residues hydrogen bond with each other, holding the chains firmly together and contributing to their high tensile strength. This study has shown the possibility to produce cellulose microfibrils by applying shearing treatment. Homogenisation and microfluidisation treatments permit to obtain microfibrils with 5 to 20 μm length and a 20 to 50 nm diameter. This study also shows that a tridimensional network, typical of a gel, appears in the treated samples [less ▲]

Organ donors with primary central nervous system tumor

in Transplantation (2000), 70(1), 244-8251-2

Patients with primary central nervous system (CNS) tumor have been accepted for organ donation because these tumors very rarely spread outside the CNS. However several case reports of CNS tumor ... [more ▼]

Patients with primary central nervous system (CNS) tumor have been accepted for organ donation because these tumors very rarely spread outside the CNS. However several case reports of CNS tumor transferral with organ transplantation recently challenged this attitude. Some risk factors for extraneural spread of CNS tumors have been determined, but the absence of risk factors does not exclude the possibility of metastases. To our knowledge, 13 cases of CNS tumor transferral with organ transplantation (one heart, three livers, eight kidneys, one kidney/pancreas) have been reported in the literature. Even if no prospective evaluation of the CNS tumor transmission risk with transplantation has been undergone, this risk may be estimated between a little more than 0% and 3% from retrospective series. The authors consider that patients with CNS tumor should be accepted as donors as long as the risk of dying on the waiting lists is significantly higher than the tumor transferral risk. Therefore the authors would have no restriction for transplanting organs from donors with benign or low-grade CNS tumor. For high-grade tumors, the authors would consider these donors as "marginal donors," and balance the risk of tumor transmission with the medical condition of the recipient. [less ▲]