Potential use of Sotol bagasse (Dasylirion spp.) as a new biomass source for liquid biofuels production: Comprehensive characterization and ABE fermentation

This study presents a physico-chemical characterization of bagasse obtained from the artisanal and industrial production of Sotol. The last was employed as feedstock for acetone-butanol-ethanol (ABE) fermentation using Clostridium beijerinckii. Chemical analyses revealed a significant presence of CaC₂O₄, and levels of inorganic elements close to or above the limits established in ISO 16968:2015. These, together with their calorific values that are below other lignocellulosic materials, limit the use of sotol bagasse as solid biofuel. Structural characterization exhibited that the industrial sotol bagasse contained cellulose with lower crystallinity, thus easing its bioavailability for microorganisms to perform ABE fermentation. It was possible to obtain acetone, butanol, and ethanol (0.94 ± 0.05 g/L, 1.97 ± 0.52 g/L and 1.90 ± 0.40 g/L, respectively) using industrial sotol bagasse as substrate for C. beijerinckii. Then a scale-up of ABE fermentation was carried out to obtain information on ABE yield and Clostridium growth kinetics at different working volumes. ABE yield was lower the scale-up experiment (0.31 ± 0.02 g/g) compared to the obtained with smaller working volume (0.48 ± 0.07 g/g). These results offer crucial insights into the potential use of industrial sotol bagasse as a novel renewable feedstock to obtain biofuels throughout ABE fermentation.