The Genomic Science program of the Office of Biological and Environmental Research (BER) within the U.S. Department of Energy (DOE) Office of Science focuses on understanding microbes, microbial communities, and plants as integrated systems of relevance to DOE?s energy and environmental missions. One aspect of this program seeks to develop the fundamental science, research technologies, and knowledgebase necessary to enable the costeffective, sustainable production of advanced biofuels and bioproducts from plant biomass. Lignocellulosic materials from plants provide the largest reservoir of raw materials for biofuels and biobased products, yet cost-effective use of these materials is hampered by their complexity and resistance to breakdown. Cellulose is contained within plant cell walls in the form of long, tightly bound chains of sugars (polysaccharides) that can be converted into biofuels and bioproducts by microbes and enzymes. Physically accessing these sugars, however, is difficult because the cellulose is embedded within a matrix of other polymers including hemicellulose and lignin, making it resistant to degradation (see Fig. 1. Three-Dimensional Illustration of Lignocellulose Meshwork, this page). This resistance, called recalcitrance, and a lack of efficient methods to convert lignocellulose to useful products are major impediments to the cost-effective production of biofuels and bioproducts from plant biomass.