Intensification of corn fiber saccharification using a tailor made enzymatic cocktail

Abstract

The transition from an economic model based on resource extraction to a more sustainable and circular economy requires the development of innovative methods to unlock the potential of raw materials such as lignocellulosic biomasses. Corn fiber differs from more traditional lignocellulosic biomasses due to its high starch content, which provides additional carbohydrates for fermentation-based biomanufacturing processes. Due to its unique chemical composition, this study focused on the development of a tailor made enzymatic cocktail for corn fiber saccharification into monosaccharides. Three commercially available hydrolytic enzymes (Cellic® CTec2, Pentopan® Mono BG, and Termamyl® 300 L) were combined to hydrolyze the polysaccharide structure of the three main carbohydrate fractions of corn fiber (cellulose, hemicellulose and starch, respectively). Prior to saccharification, corn fiber was submitted to a mild hydrothermal pretreatment (30 min at 100 °C). Then, two experimental designs were used to render an enzymatic cocktail capable of providing efficient release of monosaccharides. Using 60 FPU/g DM of Cellic® CTec2 and 4.62 U/g DM of Termamyl® 300 L, without addition of Pentopan® Mono BG, resulted in the highest efficiencies for glucose and xylose release (66% and 30%, respectively). While higher enzyme dosages could enhance the saccharification efficiency, adding more enzymes would have a more pronounced effect on the overall process costs rather than in increasing the efficiency for monosaccharides release. The results revealed that the recalcitrance of corn fiber poses a problem for its full enzymatic degradation. This fact combined with the unique chemical composition of this material, justify the need for developing a tailor made enzymatic cocktail for its degradation. However, attention should also be given to the pretreatment step to reduce even more the recalcitrance of corn fiber and improve the performance of the tailored cocktail, as a consequence.

Keywords: Cellulases; Corn fiber; Design of experiments; Enzymatic saccharification; Hemicellulases.