(623b) Enzymatic Processing of Corn Fibers for a Complete Recovery of Ferulic Acid and Fermentable Sugars

Corn fibers from wet milling processes are a rich source for ferulic acid and fermentable sugars. Compared to other grain fibers, corn fibers are particularly recalcitrant, resisting enzymatic hydrolysis. Without pretreatment using harsh conditions, only a small percentage of ferulic acid and fermentable sugars could be released. Pretreatment not only represents extra steps in biorefinery but also renders the recovered sugars and ferulic acid unsuitable for some applications such as natural vanillin synthesis. The inhibitors generated from the pretreatment often lower the productivity and complicate the subsequent steps of bioprocessing. Neosartorya spinosa NRRL185 was discovered in our previous research as a microbe capable of producing and secreting useful cellulases and hemicellulases for processing various biomass feedstock. In this study, crude enzymes harvested at an appropriate time of cultivation were used to release ferulic acid and fermentable sugars from corn fibers. A complete recovery of ferulic acid and a complete hydrolysis of corn fiber polysaccharides were achieved without any pretreatment. Ferulic acid recovered from corn fiber was extracted with organic solvent and was then tested as a potential starting material for vanillin production. Using Streptomyces setonii ATCC391161, a known microbe capable of conversing ferulic acid to vanillin, ferulic acid was converted to vanillin, indicating that corn fiber is a suitable source of ferulic acid in the synthesis of vanillin. The crude enzymes were also used to convert corn fiber and xylan-containing substrates to synthesize xylo-oligosaccharides. Xylo-oligosaccharides rich in 10-mers or higher were obtained. Fermentable sugars from corn fibers could be used for biofuels and other useful products. This work demonstrates the feasibility to build a biorefinery platform with multiple co-products from a single biomass feedstock.