Biobutanol production from apple pomace: The importance of pretreatment methods on the fermentability of lignocellulosic agro-food wastes

Apple pomace was studied as a possible raw material for biobutanol production. Five different soft physicochemical pretreatments (autohydrolysis, acids, alkalis, organic solvents and surfactants) were compared. The pretreated biomass was subsequently subjected to a conventional enzymatic treatment to complete the hydrolysis. One of the hydrolysates was readily fermented by Clostridium beijerinckii CECT 508 in 96 h (3.55 g/L acetone, 9.11 g/L butanol, 0.26 g/L ethanol; 0.276 gB/gS yield; 91% sugar consumption). Therefore, it is possible to optimise pretreatment conditions of lignocellulosic apple pomace to reduce inhibitor concentrations in the final hydrolysate and perform successful ABE fermentations without the need of a detoxification stage.This document is a pre-print version of the manuscript that was subsequently peer-reviewed and accepted for publication by the journal Applied Microbiology and Biotechnology (Vol. 101, pages 8041-8052, year 2017). The final publication is available at Springer via http://dx.doi.org/10.1007/s00253-017-8522-z. The present work has been performed as part of the H2020-LCE-2015 Waste2Fuels project (Sustainable production of next generation biofuels from waste streams - Waste2Fuels; GA - 654623), funded by the European Union's Horizon 2020 Research and Innovation Programme. MH-V is supported by a postdoctoral contract (DOC-INIA, grant number DOC 2013-010) funded by the Spanish Agricultural and Agrifood Research Institute (INIA) and the European Social Fund. The authors thank Novozymes for kindly providing samples of their enzymes. Authors thank R. Antón del Río, N. del Castillo Ferreras and G. Sarmiento Martínez for their technical help