Plant cell wall reconstruction toward improved lignocellulosic production and processability

Natural resources and environmental quality are in constant decline in parallel with the rapid growth of the world population. Current methods of energy consumption are considered environmentally hazardous and contribute to global warming. To address this rapidly growing concern, development of improved extraction techniques for renewable fuel alternatives is underway. To date, most bioethanol is derived from conventional food and animal feed crops such as corn and sugarcane. A mass shift towards second generation lignocellulosic biomass-derived biofuels will rely on techniques that will enable easy access to plant cell wall components. Lignocellulosic conversion to biofuel requires pretreatment with heat and acid to break the cell wall for effective lignin release. Transgenic plants have been designed for such processes to express reduced or modified lignin for facilitation of saccharification. Plants have been successfully engineered to express enhanced levels of glycoside hydrolases to enable efficient and cost-effective polysaccharicle hydrolysis. Furthermore, strategies focusing on increased accessibility of cellulose-degrading enzymes to their substrate have been developed, and rely on cell wall-targeted expression of glycoside hydrolases, cellulose binding modules (CBMs) or other cell wall modifying proteins. A novel approach to cell wall modification comprising the introduction of non-crystalline, soluble polysaccharides to cell walls is discussed. Such approaches will further advance efforts toward establishment of applicable and effective biofuel production methods. (C) 2009 Elsevier Ireland Ltd. All rights reserved.