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Crop Biotech Update

Chemical Characteristics and Enzyme Digestibilities of Low-Lignin Sugarcane Hybrid Plants

December 16, 2011

In order to reduce the pretreatment cost of lignocellulosic biomass for biofuel ethanol production, the use of low-lignin feedstocks is one of the strategies being considered. Pretreatment is usually the first step in the bioethanol conversion process, which essentially deconstructs the plant cell biomass, prior to ethanol production. It is often an energy intensive step,contributing significantly to the cost of production.

Brazil is one of the leaders in biofuel ethanol production from sugarcane juice. It has initiated its own plant breeding programs for the development of low-lignin sugarcane, in an effort to utilize the sugarcane bagasse residues as a secondary bioenergy feedstock after the ethanol-processing of the juice. Low-lignin sugarcane bagasse residues are seen to lower the cost of pretreatment. Researchers from the Universidade de São Paulo and the Universidade Federal de Viçosa (Brazil) report the characteristics of 11 experimental, low-lignin sugarcane hybrids (and two reference samples), in terms of chemical composition, agronomic characteristics and enzyme digestibility.

The lignin contents of the hybrids and reference samples ranged from 17% to 24%, corresponding to glucan(glucose-based carbohydrate) content between 38% and 43%. Some experimental sugarcane hybrids possessed high biomass and high sucrose contents with low lignin, but samples with the smallest amounts of lignin did not necessarily produce the largest amounts of total polysaccharides. "A variable increase in the mass of a number of components, including extractives, seemed to compensate for the reduction in lignin content". The plants with lower lignin content were found to require less delignification inputs to achieve higher conversion of cellulose to simple sugars during enzymatic treatment. The full study is published in the open access journal, Biotechnology for Biofuels (URL above).