Sequential and simultaneous strategies for biorefining of wheat straw using room temperature ionic liquids, xylanases and cellulases

Abstract Sequential and simultaneous strategies for fractioning wheat straw were developed in combining 1-ethyl-3-methyl imidazolium acetate [C2mim][OAc], endo -xylanases from Thermobacillus xylanilyticus and commercial cellulases. After [C2mim][OAc]-pretreatment, hydrolysis catalyzed by endo -xylanases of wheat straw led to efficient xylose production with very competitive yield (97.6 ± 1.3%). Subsequent enzymatic saccharification allowed achieving a total degradation of cellulosic fraction (>99%). These high performances revealed an interesting complementarity of [C2mim][OAc]- and xylanase-pretreatments for increasing enzymatic digestibility of cellulosic fraction in agreement with the structural and morphological changes of wheat straw induced by each of these pretreatment steps. In addition a higher tolerance of endo -xylanases from T. xylaniliticus to [C2mim][AcO] until 30% v/v than cellulases from T. reesei was observed. Based on this property, a simultaneous strategy combining [C2mim][OAc]- and endo -xylanases as pretreatment in a one-batch produced xylose with similar yield than those obtained by the sequential strategy.