Breeding Of High-Yielding Grasses For Bioethanol Production

With a promising suit of environmental benefits and economic opportunities, the conversion of cellulosic biomass into ethanol is highly regarded as a technologically-mature alternative to fossil-based transportation fuels. Despite extensive revamps in public and private funding, and unrelenting legislative support, cellulosic ethanol is yet to transcend the “pilot” biorefinery and achieve wide-scale commercialization. Innovations leading to reductions in the chemical and energetic stringency of pretreatments, and increases in yields of enzymatic hydrolysis and fermentation processing steps are at the core of biofuel research and are expected to yield the greatest economic leverage. Remarkably, much less recognition has been given to the influence biomass feedstocks could exert on the processing efficiency and overall economics of cellulosic ethanol platforms. In fact, most assessments of the technical and economic feasibility of bioconversion systems have minimized the role of lignocellulosic feedstocks to cost and availability considerations. The main objective of this study was to uncover the effect of biomass chemical composition on bioconversion efficiency, with the aim of demonstrating that feedstock quality can influence the intensity and extensiveness of processing conditions used. Genetically divergent lines of high-yielding grasses, including maize and Miscanthus sinensis, were subjected to a series of thermal dilute-acid pretreatments of increasing severity and were evaluated for carbohydrate recovery and fermentation-inhibitor production upon enzymatic saccharification. The relations between feedstock differences in fermentable monosaccharide yields and the different components of the plant cell wall will be discussed in detail.