Agradecimentos: This work was financially supported by São Paulo Research Foundation (FAPESP), grants #2014/18714-2, #2014/06923-6, #2017/00525-0, #2017/22669-0, and by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), grants 443916/2014-4, 304816/2017, 404654/2018-5 and 302627/2018-9. This study was also financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001. The Egyptian Cultural Educational Bureau, the University of Nebraska Agricultural Research Division/FAPESP SPRINT program, the Nebraska Corn Checkoff Presidential Chair Endowment and São Carlos Institute of Physics Ver menos

Abstract: Xylanases decrease the xylan content in pretreated biomass releasing it from hemicellulose, thus improving the accessibility of cellulose for cellulases. In this work, an endo-ß-1,4-xylanase from Aspergillus fumigatus var. niveus (AFUMN-GH10) was successfully expressed. The structural analysis and biochemical characterization showed this AFUMN-GH10 does not contain a carbohydrate-binding module. The enzyme retained its activity in a pH range from 4.5 to 7.0, with an optimal temperature at 60?°C. AFUMN-GH10 showed the highest activity in beechwood xylan. The mode of action of AFUMN-GH10 was investigated by hydrolysis of APTS-labeled xylohexaose, which resulted in xylotriose and xylobiose as the main products. AFUMN-GH10 released 27% of residual xylan from hydrothermally-pretreated corn stover and 14% of residual xylan from hydrothermally-pretreated sugarcane bagasse. The results showed that environmentally friendly pretreatment followed by enzymatic hydrolysis with AFUMN-GH10 in low concentration is a suitable method to remove part of residual and recalcitrant hemicellulose from biomass Ver menos