Aqueous solutions of deep eutectic systems as reaction media for the saccharification and fermentation of hardwood xylan into xylitol


The aim of this study was to evaluate the effect of aqueous solutions of deep eutectic solvent, Cholinium Chloride:Urea ([Ch]Cl:U) at 50 wt% and 20 wt%, using different molar ratios (1:1, 2:1 and 1:2) on the enzymatic hydrolysis of xylan for xylose production and its subsequent bioconversion into xylitol using a recombinant yeast strain. The lowest xylan conversion into xylose (45%) was obtained using 1:2 [Ch]Cl:U molar ratio. On the other hand, the 1:1 [Ch]Cl:U molar ratio, at 20 wt% in water, improved this conversion, achieving the highest xylose yield (81.4%). The xylitol production was then optimized with [Ch]Cl:U (1:1) at 20 wt% by simultaneous saccharification and fermentation process, attaining 23.67 g/L, corresponding to 66.04% of xylitol yield. This study reveals the possibility of using xylan solubilized in DES aqueous solutions directly for xylitol production, thus assembling a one-step process.



subject category

Agriculture; Biotechnology & Applied Microbiology; Energy & Fuels


Romani, A; Morais, ES; Soares, PO; Freire, MG; Freire, CSR; Silvestre, AJD; Domingues, L

our authors


This study was supported by BIOVINO project (0688_BIOVINO_6_E) funded by INTERREG Espana - Portugal and European Regional Development Fund (ERDF), carried out at the Biomass and Bioenergy Research Infrastructure (BBRI) - LISBOA-01-0145-FEDER-022059, supported by Operational Programme for Competitiveness and Internationalization (PORTUGAL2020), by Lisbon Portugal Regional Operational Programme (Lisboa 2020) and by North Portugal Regional Operational Programme (Norte 2020) under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit, BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte and within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MCTES. The research leading to reported results has received funding from FCT through the projects DeepBiorefinery (PTDC/AGR-TEC/1191/2014) and MultiBiorefinery (POCI-01-0145FEDER-016403), EcoTech project (POCI-01-0145-FEDER-032206), through C. Freire Researcher contract (CEECIND/00464/2017) and E. S. Morais PhD grant (SFRH/BD/129341/2017).

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