title: Prospecting for Energy-Rich Renewable Raw Materials: Agave Leaf Case Study.
abstract: Plant biomass from different species is heterogeneous, and this diversity in composition can be mined to identify materials of value to fuel and chemical industries. Agave produces high yields of energy-rich biomass, and the sugar-rich stem tissue has traditionally been used to make alcoholic beverages. Here, the compositions of Agave americana and Agave tequilana leaves are determined, particularly in the context of bioethanol production. Agave leaf cell wall polysaccharide content was characterized by linkage analysis, non-cellulosic polysaccharides such as pectins were observed by immuno-microscopy, and leaf juice composition was determined by liquid chromatography. Agave leaves are fruit-like--rich in moisture, soluble sugars and pectin. The dry leaf fiber was composed of crystalline cellulose (47-50% w/w) and non-cellulosic polysaccharides (16-22% w/w), and whole leaves were low in lignin (9-13% w/w). Of the dry mass of whole Agave leaves, 85-95% consisted of soluble sugars, cellulose, non-cellulosic polysaccharides, lignin, acetate, protein and minerals. Juice pressed from the Agave leaves accounted for 69% of the fresh weight and was rich in glucose and fructose. Hydrolysis of the fructan oligosaccharides doubled the amount of fermentable fructose in A. tequilana leaf juice samples and the concentration of fermentable hexose sugars was 41-48 g/L. In agricultural production systems such as the tequila making, Agave leaves are discarded as waste. Theoretically, up to 4000 L/ha/yr of bioethanol could be produced from juice extracted from waste Agave leaves. Using standard Saccharomyces cerevisiae strains to ferment Agave juice, we observed ethanol yields that were 66% of the theoretical yields. These data indicate that Agave could rival currently used bioethanol feedstocks, particularly if the fermentation organisms and conditions were adapted to suit Agave leaf composition.
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Kendall R
authors: KR
authors: Corbin
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Caitlin S
authors: CS
authors: Byrt
authors: Energy Biosciences Institute, University of California, Berkeley, California, United States of America.
authors: Stefan
authors: S
authors: Bauer
authors: Department of Horticulture, University of Kentucky, Lexington, Kentucky, United States of America.
authors: Seth
authors: S
authors: DeBolt
authors: AUSAGAVE, Aldgate, South Australia, Australia.
authors: Don
authors: D
authors: Chambers
authors: School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia.
authors: Joseph A M
authors: JA
authors: Holtum
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Ghazwan
authors: G
authors: Karem
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Marilyn
authors: M
authors: Henderson
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Jelle
authors: J
authors: Lahnstein
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Melbourne, Victoria, Australia.
authors: Cherie T
authors: CT
authors: Beahan
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Melbourne, Victoria, Australia.
authors: Antony
authors: A
authors: Bacic
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Geoffrey B
authors: GB
authors: Fincher
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Natalie S
authors: NS
authors: Betts
authors: The Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, South Australia, Australia.
authors: Rachel A
authors: RA
authors: Burton
mesh_terms: D027882:Agave / Q000737:chemistry* / Q000378:metabolism; D018533:Biomass; D002482:Cellulose / Q000737:chemistry*; D005285:Fermentation; D006868:Hydrolysis; D008031:Lignin / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry* / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry; D059205:Renewable Energy
chemical_list: D011134:Polysaccharides; D002482:Cellulose; D008031:Lignin