3-39: Biofuel Production from Multiple Agave Species

Biomass production is currently limited to areas of the US that have significant rainfall. If the semi-arid portions in the western half of the US could be used to grow biomass, additional biofuels could be produced from these otherwise unproductive lands. Agave is one of the most water-use efficient plants in the world due to its crassulacean acid metabolism (CAM). The fermentation of five Agave species has been investigated: Agave americana. 'Big Blue', Agave americana marginata, Agave americana 'Gainesville', Agave salmiana 'ferox', and Agave tequilana. Simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) tests were conducted on the whole above ground plant using 2-3 year old plants, and not the core piñas found in 10+ year old plants. Surprisingly, initial testing of the leaves of five Agave species has determined only one species can support fermentation to biofuel: Agave tequilana, a species restricted by the Mexican government due to its value as a tequila and mescal source. Use of classical detoxification methods such as overliming, removal of potential inhibitory constituents by granular activated carbon, anion and cation exchange resins, and hydrophobic membrane treatment proved to have some potential value. In addition, we have investigated the use of different enzymes for the breakdown of the complex carbohydrates, such as cellulases, hemicellulases, pectinases, beta-glucosidases and other similar enzymes. We will present the approaches that have made the whole plant complex carbohydrates from otherwise recalcitrant Agave species fermentable to biofuels.