Influence of chemical and biological pretreatments on the degradation of lignocellulosic material by biological systems

A highly lignified lignocellulosic substrate, barley straw, was modified by treatment with a variety of chemical and biological reagents. These reagents had specific effects on different components of the cell wall. The residual materials after the treatments were analysed for their composition and degradability by two biological pretreatments, rumen liquor and pepsin/cellulase. The biological pretreatments (cellulase and hemi-cellulase) gave residues with decreased degradability. Reagents which primarily attack the hemicellulose component gave residues with slightly increased degradabilities. When the treatments primarily hydrolysed the phenolic acid/acetic acid ester bonds, the degradabilities were also slightly increased, but only reagents which primarily attack the core lignin component of the cell wall gave residues with greatly increased degradabililies. Similar results were obtained with both biological systems, but the rumen liquor system was always more efficient than the pepsin/cellulose system.