A METHOD FOR STUDYING DECOMPOSITION OF ISOLATED LIGNIN, AND THE INFLUENCE OF LIGNIN ON CELLULOSE DECOMPOSITION

Abstract

Lignin dissolved in alcohol is incorporated upon cellulose fibers, and the cellulose-lignin mixture is used as a source of lignin. Lignin thus prepared underwent some decomposition by different organisms, at a much slower rate, however, than the decomposition of cellulose. Lignin admixed with cellulose did not hinder the decomposition of the latter. In natural plant materials, however, especially wood, lignin markedly retards cellulose decomposition. When the lignin is removed, the rate of cellulose decomposition increases; however, 8% of lignin would retard cellulose decomposition by 50%. When the lignin concn. is reduced to 1.5%, the cellulose becomes as readily subject to decomposition by microorganisms as is pure cellulose. The depressing effect of lignin on cellulose decomposition in plant residues cannot, therefore, be considered due to the lignin as such, but must be due to the manner of its binding with the cellulose. Whether this binding is chemical or physical, the fact is that it protects the cellulose from rapid attack by saprophytic microorganisms.