Prospecting for Energy-Rich Renewable Raw Materials: Agave Leaf Case Study

Authors

Kendall R. Corbin, University of Adelaide, Australia
Caitlin S. Byrt, University of Adelaide, Australia
Stefan Bauer, University of California - Berkeley
Seth DeBolt, University of KentuckyFollow
Don Chambers, AUSAGAVE, Australia
Joseph A. M. Holtum, James Cook University, Australia
Ghazwan Karem, University of Adelaide, Australia
Marilyn Henderson, University of Adelaide, Australia
Jelle Lahnstein, University of Adelaide, Australia
Cherie T. Beahan, University of Adelaide, Australia
Antony Bacic, University of Adelaide, Australia
Geoffrey B. Fincher, University of Adelaide, Australia
Natalie S. Betts, University of Adelaide, Australia
Rachel A. Burton, University of Adelaide, Australia

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.

Document Type

Article

Publication Date

8-25-2015

Notes/Citation Information

Published in PLOS One, v. 10, no. 8, article e0135382, p. 1-23.

© 2015 Corbin et al.

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Digital Object Identifier (DOI)

http://dx.doi.org/10.1371/journal.pone.0135382

Funding Information

This work was supported by Australian Research Council Centre of Excellence in Plant Cell Walls CE110001007 (GF and RB) (http://www.arc.gov.au/), and National Science Foundation 135488 (SD) (http://www.nsf.gov/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Repository Citation

Corbin, Kendall R.; Byrt, Caitlin S.; Bauer, Stefan; DeBolt, Seth; Chambers, Don; Holtum, Joseph A. M.; Karem, Ghazwan; Henderson, Marilyn; Lahnstein, Jelle; Beahan, Cherie T.; Bacic, Antony; Fincher, Geoffrey B.; Betts, Natalie S.; and Burton, Rachel A., "Prospecting for Energy-Rich Renewable Raw Materials: Agave Leaf Case Study" (2015). Horticulture Faculty Publications. 25.
https://uknowledge.uky.edu/horticulture_facpub/25