|DE LEON, NATALIA|
Submitted to: Biotechnology for Biofuels and Bioproducts
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2009
Publication Date: 3/9/2009
Citation: Lorenz, A.A., Anex, R.P., Isci, A., Coors, J.G., deLeon, N., Weimer, P.J., Wolfrum, E.J. 2009. Forage Quality and Composition Measurements as Predictors of Ethanol Yield from Maize (Zea mays L.) Stover. Biotechnology for Biofuels. 2:5.
Interpretive Summary: In the search for cellulosic feedstocks that will most efficiently be fermented to ethanol, inexpensive, accurate, and rapid methods of feedstock evaluation would greatly facilitate scientists. Conventional methods for predicting ethanol yield from fermentation of cellulosic biomass are based primarily on the glucan content (a component of the plant’s sugar) of the biomass and do not take into account how readily enzymes and microorganisms can access and break down this glucan. We conducted a study to determine if forage evaluation methods already employed in the field of ruminant nutrition (and that already take into account glucan convertability, not just content) would be a more accurate predictor of ethanol yield. We determined the ethanol yield from fermentation of corn stover and related this fermentability to glucan content and to several other measures of fermentability and of forage composition used in ruminant nutrition (such as content of neutral detergent fiber, NDF). Variation in ethanol yield was driven by glucan convertibility rather than by glucan content. Our data indicate that forage quality and composition measurements may be used to predict cellulosic ethanol yield. These results provide a method for easily predicting ethanol yield that is less expensive, more accurate, and more rapid, and can be used to guide biofeedstock improvement through agronomic research and plant breeding.
Technical Abstract: Improvement of biofeedstock quality for cellulosic ethanol production will be facilitated by inexpensive and rapid methods of evaluation, such as those already employed in the field of ruminant nutrition. Our objective was to evaluate whether forage quality and compositional measurements could be used to estimate ethanol yield of corn stover, as measured by a simplified pretreatment and simultaneous saccharification and fermentation (SSF) assay. Twelve maize varieties selected to be diverse for stover digestibility and composition were evaluated. Variation in ethanol yield was driven by glucan convertibility rather than by glucan content. Convertibility was highly correlated with ruminal digestibility and lignin content. There was no relationship between structural carbohydrate content (glucan and neutral detergent fiber [NDF]) and ethanol yield. However, when these variables were included in multiple regression equations including convertibility or NDF digestibility (NDFD), their partial regression coefficients were significant and positive. A regression model including NDF and NDFD explained 95% of the variation in ethanol yield. Forage quality and composition measurements may be used to predict cellulosic ethanol yield to guide biofeedstock improvement through agronomic research and plant breeding.