REVIEWS
Genomics of cellulosic biofuels
Edward M. Rubin1,2
The development of alternatives to fossil fuels as an energy source is an urgent global priority. Cellulosic biomass has the potential to contribute to meeting the demand for liquid fuel, but land-use requirements and process inefficiencies represent hurdles for large-scale deployment of biomass-to-biofuel technologies. Genomic information gathered from across the biosphere, including potential energy crops and microorganisms able to break down biomass, will be vital for improving the prospects of significant cellulosic biofuel production. he capture of solar energy through photosynthesis is a process that enables the storage of energy in the form of cell wall polymers (that is, cellulose, hemicellulose and lignin). The energy stored in these polymers can be accessed in a variety of ways, ranging from simple burning to complex bioconversion processes. The high energy content and portability of biologically derived fuels, and their significant compatibility with existing petroleum-based transportation infrastructure, helps to explain their attractiveness as a fuel source. Despite the increasing use of biofuels such as biodiesel and sugar- or starch-based ethanol, evidence suggests that transportation fuels based on lignocellulosic biomass represent the most scalable alternative fuel source1. Lignocellulosic biomass in the form of plant materials (for example, grasses, wood and crop residues) offers the possibility of a renewable, geographically distributed and relatively greenhouse-gas-favourable source of sugars that can be converted to ethanol and other liquid fuels. Calculations of the productivity of lignocellulosic feedstocks, in part based on their ability to grow on marginal agricultural land, indicates that they can probably have a large impact on transportation needs without significantly compromising the land needed for food crop production2.