Simultaneous saccharification isomerization and Co-fermentation – SSICF: A new process concept for second-generation ethanol biorefineries combining immobilized recombinant enzymes and non-GMO Saccharomyces

Abstract

Integrated bioprocess strategies may facilitate ethanol production from both C6 and C5 fractions of lignocellulosic feedstocks. We propose a new process concept, SSICF, where sugarcane bagasse is hydrolyzed simultaneously with xylose isomerization and the co-fermentation of C6 and C5 sugars. A commercial cocktail was supplemented with our multi-enzymatic system composed of three recombinant enzymes immobilized in Feroxyhyte magnetic nanoparticles: β-glucosidase, β-xylosidase and xylose isomerase. SSICF was performed using non-GMO Saccharomyces at pH 6.0 and 35 °C for 72 h in a synthetic medium containing cellobiose and xylose, and another medium containing pretreated sugarcane bagasse (PSB). The results of ethanol global yields in SSICF were 77.67% and 73.24% for the synthetic medium and PSB, respectively. In a nutshell, this is the first report of a successful proof-of-concept of SSICF with four rounds of enzyme recycling and a non-GMO yeast, an innovative process with high potential for industrial use.