SEMI-SIMULTANOUS SACCHARIFICATION AND FERMENTATION OF OPUNTIA FICUS-INDICA CLADODE FOR BIOETHANOL PRODUCTION USING WILD STRAIN

Semi-simultaneous saccharification and fermentation processes (SSSF) are capable of improving ethanol production compared with separate hydrolysis and fermentation (SHF) systems because there are reduce of enzymes inhibition due conversion of sugars by yeasts immediately after saccharification. In this work a wild Acinetobacter pittii bacterium and a wild Kluyveromyces marxianus yeast were used for SSSF process. The bacterium, isolated from decayed cladodes, had capacity of produce cellulases enzymes, while the yeast, isolated from termite stomach, had fermentative capacity. The SSSF was tested on Opuntia ficus-indica cladode flour medium (CFM) with and without agitation (0 and 200 rpm). Ethanol yields (Yp/s) obtained with CFM were 0.43?0.01 and 0.18?0.01 for 0 and 200 rpm, respectively, that represents 84% and 35% of efficiency of SSSF. Ethanol final concentrations reached 11.7?0.02 g/L and 5.80?0.02 g/L for 0 and 200 rpm, respectively. The ability of A. pittii for cellulases production combined with K. marxianus fermentation capacity in their bests conditions, represented in higher bioethanol production during SSSF.