Bioethanol production from agave lechuguilla biomass pretreated by autohydrolysis

Agave lechuguilla cogollos (heart or pulpy central stem with attached leaf bases) were used as feedstock for production of second generation bioethanol following a scheme based on pretreatment by autohydrolysis, enzymatic saccharification and fermentation of hydrolysates. Autohydrolysis was carried out in a Parr reactor at different severity factors with a solid/liquid ratio of 1/6 (w/v) and 200 rpm. Solid fraction obtained was hydrolyzed using the commercial cellulase Accellerase 1500 (Genencor®). Hydrolysate was fermented with the Saccharomyces cerevisiae ATCC 4126 yeast. Using a severity factor of 4.127 (190 °C during 30 min) it was possible to preserve most of the glucans while increasing its enzymatic digestibility. Enzymatic hydrolysis of the solid fraction showed a maximum yield of 60.85%, with a final glucose concentration of 59 g/L. Ethanol concentration at the end of the fermentation was 25.4 g/L (91% of the theoretical ethanol yield).