Application of soluble and immobilized xylanases to produce xylooligosaccharides from sugar cane bagasse

Abstract

Large amounts of sugar cane bagasse are available in Brazil. It contains circa 30% of hemicelluloses (w/w), composed by several heteropolymers, mainly xylan, a xylose polymer. Xylitol, ethanol and xylooligosaccharides (XOS), small oligomers of xylose (2-5 xylose-units), are possible products of xylose. The production of XOS from lignocellulosic material requires soft extraction of hemicellulose, in order to obtain oligomeric xylan. These oligomers must be further hydrolyzed by endo xylanases under very controlled conditions, in order to produce XOS. Generation of xylose must be avoided, in the both steps extraction and hydrolysis, since its separation from XOS is expensive. Enzymes are potent and specific catalysts, but also are expensive and fragile. Their immobilization and stabilization may reduce the hydrolysis costs. In this project, it will be studied organossolve (ethanol) and alkaline pre-treatment (NaOH) of the sugar-cane bagasse, under different operational conditions, in order to define the more adequate pre-treatment for oligomers xylan production. Different xylanases will be tested in order to select the one that will lead to the less production of xylose. The selected xylanase (s) will be immobilized. The selected enzyme(s), soluble and immobilized, will be tested in the hydrolysis of the xylan oligomers extract from sugar cane bagasse. Kinetic studies with the selected enzymes will be performed in order to define optimal operational conditions for obtaining xylooligossaccharides. (AU)