Carbohydrates of the inner bark of Pseudotsuga menziesii

A holocellulose fraction was isolated from the inner bark of Psedotsuga menziesii and analyzed. It was composed of acid-insoluble lignin (3·1 acid-soluble lignin (4·1%), l-arabinose (2·6%), d-xylose (6.3%). d-mannose(9·5%), d-galactose (2·3%), and d-glcose (61·1%). The presence of these sugars and their configurations were positively established by the preparation of crystalline derivatives. The holocellulose was fractionated into its component polysaccharides, a xylan, a galactoglucomannan, a glucomannan, and a glucan-rich residue.     

A galactoglucomannan from extracellular polysaccharides of suspension-cultured cells of Nicotiana tabacum

A polysaccharide containing d-xylose, l-arabinose, d-mannose, d-galactose and d-glucose residues in the molar ratio of 0.07:0.16:1.     

Galactomannans and a galactoglucomannan in legume seed endosperms: Structural requirements for β-mannanase hydrolysis

A series of galactomannans with varying degrees of galactose substitution have been extracted from the endosperms of legume seeds with water and alkali and the amount of substitution required for water solubility has been determined. Some were heterogeneous with respect to the degree of galactose substitution. The structural requirements for hydrolysis by plant β-mannanase have been studied using the relative rates and extents of hydrolysis of these galactomannans. A more detailed examination of the products of hydrolysis of carob galactomannan has been made. At least two contiguous anhydromannose units appear to be needed for scission. This is similar to the requirement for hydrolysis by microbial enzymes. Judas tree (Cercis siliquastrum) endosperm contained a polysaccharide with a unique composition for a legume seed reserve. Gel chromatography and electrophoresis on cellulose acetate indicated homogeneity. Hydrolysis with a mixture of β-mannanase and α-galactosidase gave a glucose-mannose disaccharide and acetolysis gave a galactose-mannose. These results, as well as the pattern of hydrolysis by β-mannanase were consistent with a galactoglucomannan structure.     

Influence of aromatic compounds on biodegradation of [14C]-labeled xylan and mannan by the white-rot fungus Phlebia radiata

Radiolabeled [¹⁴C]arabinoxylan from wheat meal and [¹⁴C]galactoglucomannan from red clover meal were prepared by using ¹⁴CO₂ as a precursor. Twice as much mannan was mineralized than xylan after 14 days of incubation with Phlebia radiata. Low-molecular-weight phenolic compounds structurally related to lignin increased during mineralization of both hemicellulose fractions. Veratryl alcohol increased degradation of arabinoxylan by approximately 28.5%, whereas veratric acid increased it by only 9.0%. Vanillic acid and ferulic acid also stimulated degradation by 16.6% and 34.7%, respectively. Veratryl alcohol and ferulic acid increased degradation of galactoglucomannan by approximately 75%. Veratraldehyde in both cases repressed the degradation process (23.6% arabinoxylan, 43.8% galactoglucomannan). These results indicate that the degradation of hemicelluloses, e.g., xylan and mannan, by P. radiata is enhanced by addition of aromatic compounds. Journal of Industrial Microbiology & Biotechnology (2002) 28, 168–172 DOI: 10.1038/sj/jim/7000221 Received 25 July 2001/ Accepted in revised form 23 October 2001