Compositional Analysis of Water-Soluble Materials in Switchgrass

Abstract

Any valuation of a potential feedstock for bioprocessing is inherently dependent upon detailed knowledge of its chemical composition. Accepted analytical procedures for compositional analysis of biomass water-soluble extracts currently enable near-quantitative mass closure on a dry weight basis. Techniques developed in conjunction with a previous analytical assessment of corn stover have been applied to assess the composition of water-soluble materials in four representative switchgrass samples. To date, analytical characterization of water-soluble material in switchgrass has resulted in >78% mass closures for all four switchgrass samples, three of which have a mass closure of >85%. Over 30 previously unknown constituents in aqueous extracts of switchgrass were identified and quantified using a variety of chromatographic techniques. Carbohydrates (primarily sucrose, glucose, and fructose) were found to be the predominant water-soluble components of switchgrass, accounting for 18-27% of the dry weight of extractives. Total glycans (monomeric and oligomeric sugars) contributed 25-32% to the dry weight of extractives. Additional constituents contributing to the mass balance for extractives included various alditols (2-3%), organic acids (10-13%), inorganic ions (11-13%), and a distribution of oligomers presumed to represent a diverse mixture of lignin-carbohydrate complexes (30-35%). Switchgrass results are compared with previous analyses of corn stover extracts and presented in the context of their potential impact on biomass processing, feedstock storage, and future analyses of feedstock composition.

Comparative Analysis of Extremely Thermophilic Caldicellulosiruptor Species Reveals Common and Unique Cellular Strategies for Plant Biomass Utilization

“…Initially, cell density increased rapidly to ϳ2 ϫ 10 7 cells per ml, with doubling times under 3 h, likely supported by readily solubilized sugars released by abiotic thermal factors. Switchgrass typically contains approximately 15% water-soluble material, 25 to 50% of which is carbohydrate (27,28). After approximately 24 h, as the readily solubilized sugars were utilized by the bacteria, planktonic cells entered a second, slower growth phase, which was tracked over the next 200 h. During the slower growth phase, the Caldicellulosiruptor species can recruit carbohydrates by deploying extracellular, multidomain glycoside hydrolases (GHs), both free (29,30) and attached to the cell surface via the S-layer (15).…”

Rapid analysis of carbohydrates in aqueous extracts and hydrolysates of biomass using a carbonate-modified anion-exchange column

“…For biofuel research, determining the concentrations of sugars present in aqueous hydrolysates resulting from quantitative saccharification [1] or chemical pretreatment [2][3][4][5] of biomass is paramount to reliable technical or economic valuations of a given feedstock or conversion process. It has recently been demonstrated that knowledge of the water-soluble sugar content of biofuel feedstocks may also be important in such valuations [6][7][8]. Analytes of interest in biofuel research typically include the monomeric sugars glucose, xylose, arabinose, galactose, mannose, and fructose, as well as sucrose, maltose, and cellobiose dimers.…”

Dry anaerobic digestion of lignocellulosic and protein residues

“…2C). Since the extractives include compounds, such as free sugars, oligomers, and organic acids (Chen et al, 2007;Chen et al, 2010), these compounds can be easily degraded and can potentially contribute to biogas production (Tong et al, 1990). The composition of the extractives was not analysed in this study; however, further research on the degradation of extractive compounds and their contributions to the AD process would be interesting.…”