Tissue Composition of Agave americana L. Yields Greater Carbohydrates From Enzymatic Hydrolysis Than Advanced Bioenergy Crops.

Agave americanaL. is a highly productive, drought-tolerant species being investigated as a feedstock for biofuel production. SomeAgavespp. yield crop biomass in semi-arid conditions that are comparable to C(3)and C(4)crops grown in areas with high rainfall. This study evaluates the bioethanol yield potential ofA. americanaby (1) examining the relationship between water use efficiency (WUE) and plant carbohydrates, (2) quantifying the carbohydrate and energy content of the plant tissue, and (3) comparing the products of enzymatic hydrolysis to that of other candidate feedstocks (Miscanthus x giganteusGreef et Deuter,Sorghum bicolor(L.) Moench, andPanicum virgatumL.). Results indicate that (1) WUE does not significantly affect soluble and insoluble (i.e., structural) carbohydrate composition per unit mass inA. americana; (2) without pretreatment,A. americanabiomass had the lowest gross heat of combustion, or higher heating/calorific value, compared to high yielding C(4)crops; and (3) after separation of soluble carbohydrates,A. americanacellulosic biomass was most easily hydrolyzed by enzymes with greater sugar yield per unit mass compared to the other biomass feedstocks. These results indicate thatA. americanacan produce substantial yields of soluble carbohydrates with minimal water inputs required for cultivation, and fiber portions of the crop can be readily deconstructed by cellulolytic enzymes for subsequent biochemical fermentation.