Structural Analysis of Fructans from Agave americana Grown in South Africa for Spirit Production

Abstract

Fructans isolated from Agave americana grown in South Africa are currently used for spirit production. Structural studies on water-soluble fructans were performed to facilitate the development of other applications including its use as a prebiotic. Acid hydrolysis followed by HPAEC-PAD analysis confirmed that the fructan was composed of glucose and fructose, and size analysis by HPAEC-PAD and size exclusion chromatography indicated that the saccharides have a DP range from 6 to 50. An average DP of 14 was estimated by (1)H NMR analysis. Linkage analysis and ESI-MS studies suggest that A. americana has a neofructan structure consisting of a central sucrose to which (2 → 1)- and (2 → 6)-linked β-D-Fruf chains are attached. The (2 → 1)-linked units extend from C-1 of Fru and C-6 of glucose, whereas the (2 → 6)-linked β-D-Fruf units are attached to C-6 of the central Fru. This structure accounts for the presence of equimolar amounts of 1,6-linked Glu and 1,2,6-linked Fru found in linkage analysis and the multiplicity of the NMR signals observed. Detailed ESI-MS studies were performed on fructan fractions: native, periodate oxidized/reduced, and permethylated oligomers. These derivatizations introduced mass differences between Glc and Fru following oxidation and between 1,2-, 1,6-, 2,6-, and 1,2,6-linked units after methylation. Thus, ESI-MS showed the presence of a single Glc per fructan chain and that it is predominantly internal, rather than terminal as found in inulin. These structural features were confirmed by the use of 1D and 2D NMR experiments.

Diazotrophic potential among bacterial communities associated with wild and cultivatedAgavespecies

“…Bacterial colonies growing on these petri dishes were further diluted and inoculated in solid media until axenic cultures were obtained. Bacteria that were positive in the acetylene reduction assay were also tested for their ability to use fructans, the complex carbon polymers presented in Agave species, as the only carbon source (Mancilla-Margalli & Lopez, 2006;Ravenscroft et al, 2009;Mellado-Mojica & Lopez, 2012). ), 18 strains were identified as distinct.…”

“…Further confirmation of possible nitrogenase activity was pursued by performing the acetylene reduction assay as described elsewhere (Hardy et al, 1968). Bacteria that were positive in the acetylene reduction assay were also tested for their ability to use fructans, the complex carbon polymers presented in Agave species, as the only carbon source (Mancilla-Margalli & Lopez, 2006;Ravenscroft et al, 2009;Mellado-Mojica & Lopez, 2012). The 18 bacterial strains were subsequently identified by amplifying and sequencing the complete 16S rRNA gene using the procedures described above.…”

Genomic resources and transcriptome mining in Agave tequilana

“…These examples underline the need to seek alternatives for the exploitation of agaves in Mexico and several areas such as the use of agave sugars as dietary supplements and substitutes for sugar and fats (Lopez et al, 2003;Ortiz-Basurto et al, 2008;Urias-Silvas et al, 2008;Gomez et al, 2009;Ravenscroft et al, 2009;Leach & Sobolik, 2010) or for the production of paper (Idarraga et al, 1999) have been explored. Recently however, attention has focused on the potential of agave species as bioenergy crops (Borland et al, 2009;Somerville et al, 2010).…”

Prebiotic Agave Fructans and Immune Aspects

“…A DP ranging from 3 to 37 has been observed in different species, and DP increases throughout plant development (Lopez et al, 2003;Mancilla-Margalli and López, 2006;Ravenscroft et al, 2009;Michel-Cuello et al, 2012). A DP ranging from 3 to 37 has been observed in different species, and DP increases throughout plant development (Lopez et al, 2003;Mancilla-Margalli and López, 2006;Ravenscroft et al, 2009;Michel-Cuello et al, 2012).…”