Enzymatic Hydrolysis and Fermentation of Sugar Beet Pulp

Abstract

Pressed sugar beet pulp, a byproduct of the table sugar industry, has potential as a biofuel feedstock that will benefit producers and processors in North Dakota and Minnesota. The goal of this research is to maximize ethanol titers and yields through enzymatic hydrolysis of sugar beet pulp and fermentation of the five- and six- carbon sugars. Hemicellulose and pectin were hydrolyzed and fermented separately from cellulose in order to increase ethanol titers and yields. A commercial pectinase was used to hydrolyze hemicellulose and pectin in the pulp. The resulting solid and liquid streams were either processed sequentially in a serial fermentation or separated and fermented in parallel. The first hydrolyzate stream, containing high concentrations of glucose, arabinose, and galacturonic acid, was fermented using Escherichia coli KO11. The remaining solids had a high cellulose content and were processed via simultaneous saccharification and fermentation using commercial cellulases and Saccharomyces cerevisiae.