Sotol bagasse (Dasylirion sp.) as a novel feedstock to produce bioethanol 2G: Bioprocess design and biomass characterization

Sotol (Dasylirion spp.) is a plant endemic to northern Mexico used since ancient times by North American Indians. In the present research, we studied the transformation of lignocellulosic Sotol Bagasse (SB) components as a feedstock for bioethanol 2G production. For this purpose, SB was pretreated with diluted acid (AP) and alkali (BP). In AP, biomass was exposed to different acid concentrations and reactions proceeded at different times according to a 32 experimental design. BP was performed by stirring SB with a 3 M NaOH solution at 30 °C and 120 rpm for 6 h. Pretreated samples were hydrolyzed using the Cellic CTec2® enzyme complex. These experiments were performed at the micro-level. Two conditions presented the best performance: AP1 (0.5% v/v acid; 15 min; 121 °C) and AP2 (1% v/v acid; 30 min; 121 °C). Then, AP1 and AP2 were selected for process scale-up, resulting in RS yields of 22.4% and 19.46%, respectively. The sugars produced were fermented in presence of Kluyveromyces marxianus producing an 81.85% ethanol yield. Data indicated that fermentation of SB treated with AP1 produced ethanol. In addition, fermentation of SB pretreated with AP2 generated ethanol and low concentrations of iso-butanol, acetaldehyde, and isoamyl alcohol. Ethanol and energy yield of AP1 treated biomass were 0.19 L bioethanol and 4.09 MJ per kg SB. These results proved that the proposed process is sustainable and can potentially be used for bioethanol 2G production using SB. As a result, circular bioeconomy will be stimulated.