Fungal pretreatment of Agave lechuguilla Torr. biomass to produce ethanol

Abstract

Recently, the biomass of Agave lechuguilla has been reported as a raw material with potential for the production of ethanol. However, the high energy expenditure in the pretreatment used, requires the search for methods that minimize this parameter and favor an improvement in the economic feasibility of the process. Compared to traditional pretreatment technologies, biological pretreatment offers an alternative in which lignin removal enzymes are able to unfold the complex structures of lignin, without the use of chemicals and with lower energy expenditure. In this work the biological pretreatment of biomass of Agave lechuguilla with Phanerochaete chrysosporium H-298 was evaluated. The two factors assessed for the optimization of the process were: the incubation time and the concentration of the nitrogen source. The results showed a maximum delignification (36.15 %), preserving cellulose without significant changes. The optimal pretreatment conditions were: 60 days of incubation and a nitrogen concentration of 1 M. The enzymatic hydrolysis of the pretreated material using the Cellic^® CTec3 enzymatic complex showed a maximum glucose release of 44.9 g L^-1 at 92 hours, corresponding to hydrolysis yield of 93.09 %, higher than that obtained in the hydrolysis of the biomass without pretreatment (37.92 %). The concentration of ethanol at 10 h of fermentation was 16.53 g L^-1 (equivalent to an ethanol concentration >2 v/v), observing 5.7 g L^-1 of glucose remainder at this incubation time.