Presence of soluble lignin-carbohydrate complexes in the bovine rumen.
The cell-free rumen liquor of a steer on a diet of spear grass has been shown to contain macromolecular substances in which carbohydrates and lignin-derived compounds are covalently bound to each other. The lignin-carbohydrate complexes are soluble at pH 7 or higher, but precipitate at pH 3. At the latter pH, small amounts of a polymer, assumed to be glycoprotein, remain in solution. Some of the lignin-carbohydrate linkages are broken by treatment with alkali. Treatment with 50mM sulphuric acid for a few minutes at room temperature converts part of the complex into an acetone-soluble product, which still contains both carbohydrate and lignin-derived compounds. The formation of soluble lignin-carbohydrate complexes by the action of rumen micro-organisms on the grass may account for the dissolution (and hence the apparent digestion) of about half of the total lignin-intake.
D000096:Acetone; D000818:Animals; D002241:Carbohydrates / Q000032:analysis* / Q000302:isolation & purification; D002417:Cattle; D011232:Chemical Precipitation; D002850:Chromatography, Gel; D003956:Dialysis; D008031:Lignin / Q000032:analysis* / Q000302:isolation & purification; D012417:Rumen / Q000032:analysis*; D012972:Sodium Hydroxide; D012995:Solubility; D013464:Sulfuric Acids
D002241:Carbohydrates; D013464:Sulfuric Acids; D000096:Acetone; D012972:Sodium Hydroxide; D008031:Lignin