Energy Feedstocks: Understanding Recalcitrant Biomass
Atmospheric carbon dioxide is fixed by plants into carbohydrates. Sugar cane and beet roots store large amounts of simple sugars, corn grain and wheat kernels store carbon as starch, and cellulose and hemicellulose are found in the leaves of all agricultural crops as well as in the leaves and wood of trees. Most ethanol for fuel use today is produced from corn grain, and the technology for breaking down starch into simple sugars is well developed. Cellulosic biomass, such as wood, forest product residues, grasses, agricultural residues and specialty energy crops, can provide much larger amounts of biomass for production of transportation fuels. However, cellulosic biomass is resistant to breakdown; plants have evolved complex means to employ cellulose and hemicellulose as structural materials that are very resistant to microbial attack. Lignin, a polyphenolic material, serves to strengthen the cellulosic material to form the plant cell wall, which provides resistance to pests and pathogens. The crystalline cellulose core of cell walls is very resistant to chemical and biological breakdown, and the complex structures of the cell wall also contribute to its recalcitrance. Research in JBEI’s Feedstock Division is directed at overcoming the recalcitrance of lignocellulosic plant matter so that it can be more easily deconstructed by enzymes. The main objectives of the Feedstocks Division are to elucidate the function of genes involved in synthesis of plant cell wall constituents using high-throughput functional genomics and glycomics and to expand knowledge of lignin polymerization to allow the development of plants with novel types of lignin with equivalent biological function but with improved susceptibility to enzymatic and chemical depolymerization.
