Development of Agave as a dedicated biomass source: production of biofuels from whole plants

Abstract

BackgroundAgave species can grow well in semi-arid marginal agricultural lands around the world. Selected Agave species are used largely for alcoholic beverage production in Mexico. There are expanding research efforts to use the plentiful residues (bagasse) for ethanol production as the beverage manufacturing process only uses the juice from the central core of mature plants. Here, we investigate the potential of over a dozen Agave species, including three from cold semi-arid regions of the United States, to produce biofuels using the whole plant.ResultsEthanol was readily produced by Saccharomyces cerevisiae from hydrolysate of ten whole Agaves with the use of a proper blend of biomass degrading enzymes including inulinase that overcomes inhibition of most of the species tested. As an example, US grown Agave neomexicana produced 119 ± 11 mg ethanol/g biomass. Unlike yeast fermentations, Clostridium beijerinckii produced n-butanol plus acetone from all species tested. Butyric acid, a precursor of n-butanol, was also present due to incomplete conversion during the screening process. Since Agave contains high levels of free and polyfructose which are readily destroyed by acidic pretreatment, a two-step procedure was developed to depolymerize polyfructose while maintaining its fermentability. The hydrolysate from before and after dilute acid processing was used in C. beijerinckii fermentations with selected Agave species with A. neomexicana producing 144 ± 4 mg fermentation products/g biomass.ConclusionsResults showed Agave’s potential to be a source of fermentable sugars beyond the existing beverage species to now include many species previously unfermentable by yeast, including cold-tolerant lines. This development should stimulate development of Agave as a dedicated feedstock for biofuels in semi-arid regions throughout the globe.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0261-8) contains supplementary material, which is available to authorized users.

Recent developments in Agave performance as a drought‐tolerant biofuel feedstock: agronomics, characterization, and biorefining

“…Figure shows a general scheme of a biochemical platform biorefinery based on Agave where a sustainable processing of biomass into liquid biofuels (ethanol or n‐butanol), gaseous biofuels (hydrogen and methane), and value‐added products (such as spirits, succinic acid, or lactic acid) occurred via biological conversion . This included different stages after harvesting, where the stems are removed and the leaves are cut (which can be left in the field to recycle nutrients) and cooked in autoclaves or diffusers.…”

Direct Conversion of Carbohydrates into Ethyl Levulinate with Potassium Phosphotungstate as an Efficient Catalyst

“…Carbohydrates derived from biomass are one of the most abundant renewable resources and possess a great potential as raw materials to product fuels and bulk chemicals [1,2]. Among those bio-based products, levulinic acid has been listed as one of the 12 most important building blocks, which can be used for the production of various high-value organic chemicals, such as resin, polymers, pharmaceutical compounds, and flavor substances [3][4][5].…”

Review and in silico analysis of fermentation, bioenergy, fiber, and biopolymer genes of biotechnological interest inAgaveL. for genetic improvement and biocatalysis

“…In the Yucatan Peninsula of Mexico with precipitation of 981 mm yr −1 , A. fourcroydes has reached yields of 15 Mg ha −1 yr −1 . CAM photosynthesis and low contents of lignin are also advantageous for using Agave plants as energy crops for production of second‐generation biofuels by enzymatic digestion of lignocellulosic plant material . Finally, residues from the tequila industry might be a source of fuel and for generating electricity …”

“…[124][125][126][127] At present, the need for bioenergy feedstock production from marginal lands such as in the western United States and North/Northeast China is a reality; hence, Agave L. as a source of readily fermentable simple sugars is a subject of high interest for its application in bioenergy. 128,129 Fructosyltransferases gene modification for improving fructans quality and desired DF values to increase the yields of fermentable simple sugars and its application in biofuels and distilled beverages, is an important biotechnological application of these enzymes.…”

“…CAM photosynthesis and low contents of lignin are also advantageous for using Agave plants as energy crops for production of second-generation biofuels by enzymatic digestion of lignocellulosic plant material. 129,140 Finally, residues from the tequila industry might be a source of fuel and for generating electricity. 6,19,141,142 Despite the advantages of this CAM crop for biotechnological applications, Agave crops require long growth periods (ca.…”