Properties of Powdered Wood and Isolation of Lignin by Cellu[lo]lytic Enzymes

Abstract

Spruce and aspenwood were ground in a vibratory ball mill for 5 hr., and the powdered wood was then subjected to the action of enzymes. The objective was to separate the lignin with a minimum of alteration and to discover something of the nature of the association between the lignin and carbohydrate. This powdered wood is entirely soluble in 2 N NaOH, in strong aqueous solutions of such highly soluble salts as sodium thiocyanate, and in formic acid. It is partially soluble in a variety of organic solvents. Cellulases readily digest about 95per thousand of the carbohydrate from the powdered wood, leaving a lignin residue with a carbohydrate content of 12 to 14per thousand. This residue, on hydrolysis with strong acid, gives all five sugars present in the original wood. The residual carbohydrate appears to be quite firmly attached to the lignin and is polymeric in nature. In spite of much effort, no method has been found to remove the bulk of it without simultaneously removing a part of the lignin. The impure spruce lignin is completely soluble in many solvents, among them dilute aqueous sodium hydroxide, methyl cellosolve, pyridine, benzyl alcohol, dimethyl sulphoxide, formic acid, formamide, and phenol. It is largely insoluble in ethanol, acetone, dioxane, and acetic acid, but the addition of 20per thousand of water causes solution in all but ethanol. For comparison, a few experiments were made on lignins isolated with brown rot organisms. Isolated lignins were also ground in the mill. Periodate lignin and sulphuric acid lignin, which are insoluble in dilute alkali and in methyl cellosolve, become soluble in these solvents after they are ground for 5 hr. Ultraviolet spectra were run on solutions of the powdered wood and lignins.

Keywords

Related Publications