|Gupta, Subhash - USDA/APHIS|
Submitted to: Applied Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 1995
Publication Date: N/A
Interpretive Summary: Corn fiber is an abundant byproduct of wet-milled corn, including much of the corn used in fuel ethanol production. Corn fiber is currently used as a low-value component of animal feeds. Sugars that make up the carbohydrate fractions of corn fiber might be upgraded by bioconversions to value-added products, including specialty chemicals and ethanol. However, available processes to release these sugars have proven unsatisfactory. Enzymes from the yeastlike fungus Aureobasidium were tested for the ability to break down corn fiber to sugars. Using these enzymes, up to 70% of the sugar xylose and 100% of arabinose were liberated from corn fiber, along with a substantial quantity of glucose. This work should be useful to those involved in the development of new, value-added coproducts from corn. New and expanded markets for corn products will benefit agricultural producers and processors.
Technical Abstract: Crude enzyme preparations from Aureobasidium sp. strain NRRL Y-2311-1 were characterized and tested for the capacity to saccharify corn fiber. Cultures grown on xylan, corn fiber and alkaline hydrogen peroxide (AHP)-pretreated corn fiber produced specific levels of endoxylanase, amylase, protease, cellulase and other activities. Using equal units of endoxylanase activity, crude enzymes from AHP-pretreated corn fiber cultures were most effective in saccharification. Multiple enzyme activities were implicated in this process. Pretreatment of corn fiber with AHP appeared to expose cellulose to enzymatic digestion, and nearly doubled the susceptibility of hemicellulose. Up to 138 mg xylose, 125 mg arabinose and 490 mg glucose were obtained per g corn fiber under conditions tested.