Comparative Analysis of End Point Enzymatic Digests of Arabino-Xylan Isolated from Switchgrass (Panicum virgatum L) of Varying Maturities using LC-MSn †

Metabolites

Michael J. Bowman¹  Bruce S. Dien¹  Patricia J. O𠆛ryan¹  Gautam Sarath² 

[1] U.S. Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, Bioenergy Research Unit, 1815 N. University Street, Peoria, IL 61604, USA;U.S. Department of Agriculture, Agricultural Research Service, Central-East Regional Biomass Center, 137 Keim Hall, East Campus, UNL, Lincoln, NE 68583, USA;

关键词: switchgrass;    xylan;    xylooligosaccharides;    LC-MSⁿ;    biofuel;   

DOI  :  10.3390/metabo2040959

来源: mdpi

【 摘 要 】

Switchgrass (Panicum virgatum L., SG) is a perennial grass presently used for forage and being developed as a bioenergy crop for conversion of cell wall carbohydrates to biofuels. Up to 50% of the cell wall associated carbohydrates are xylan. SG was analyzed for xylan structural features at variable harvest maturities. Xylan from each of three maturities was isolated using classical alkaline extraction to yield fractions (Xyl A and B) with varying compositional ratios. The Xyl B fraction was observed to decrease with plant age. Xylan samples were subsequently prepared for structure analysis by digesting with pure endo-xylanase, which preserved side-groups, or a commercial carbohydrase preparation favored for biomass conversion work. Enzymatic digestion products were successfully permethylated and analyzed by reverse-phase liquid chromatography with mass spectrometric detection (RP-HPLC-MSⁿ). This method is advantageous compared to prior work on plant biomass because it avoids isolation of individual arabinoxylan oligomers. The use of RP-HPLC- MSⁿ differentiated 14 structural oligosaccharides (d.p. 3–9) from the monocomponent enzyme digestion and nine oligosaccharide structures (d.p. 3–9) from hydrolysis with a cellulase enzyme cocktail. The distribution of arabinoxylan oligomers varied depending upon the enzyme(s) applied but did not vary with harvest maturity.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.