ABSTRACT
Cello-oligosaccharides (COS) are oligomers with 2 to 6 ß-1,4-linked glucose units, with potential applications in the food/feed and bioenergy industrial sectors. In this study, the combination of five heterologous expressed endoglucanases varying the temperature and pH conditions were evaluated by design of experiments for COS production. Afterwards, the best combination was tested to produce COS from different pretreated sugarcane straws: ionic liquid, diluted acid, hydrothermal and steam-explosion. The results showed that steam explosion pretreated sugarcane straw treated with CtCel9R enzyme at 50 °C and pH 5.0 yielded 13.4 mg COS g biomass-1, 5-18-fold higher compared to the other pretreated straws. Under the conditions evaluated, the removal of hemicellulose and decrease in the cellulose crystallinity can benefits the enzymatic hydrolysis. This is the first study that combined the evaluation of different enzymes, conditions, and sugarcane straw pretreatments to optimize COS production in a single step without glucose formation.
Subject(s)
Cellulase , Saccharum , Cellulose , Hydrolysis , OligosaccharidesABSTRACT
Second-generation bioethanol is a sustainable energy source that can be produced from different renewable materials. However, there is a challenge we must overcome to significantly enhance bioethanol production: the hydrolysis of lignocellulosic biomass to fermentable sugars. Synergistic enzymes, such as endoglucanases, ß-glucosidases, cellobiohydrolases, and, more recently, lytic polysaccharide monooxygenases and cellobiose dehydrogenases have been used with great success to hydrolyze pretreated biomass. Further advances in the field of second-generation bioethanol production will likely depend on an increased understanding of the interactions between enzymes and lignocellulosic substrates, the development of enzyme engineering, and the optimization of enzyme mixtures to enhance cellulose hydrolysis.
