The effect of fiber characteristics on hydrolysis and cellulase accessibility to softwood substrates

The effect of gross fiber characteristics on enzyme accessibility and hydro lysis of Douglas fir kraft pulp substrates was investigated. The average fi ber size and coarseness of the substrate had a significant effect on the en zyme adsorption capacity. This was primarily due to the increased specific surface area of small fibers and fines. The observed adsorption capacities were in agreement with the hydrolysis rates and yields because the substrat es with the lower average fiber size were hydrolyzed both at a faster rate and more completely. The observed changes in fiber-length distribution and fiber coarseness suggested that the effect of fiber size was most influenti al during the initial stages of hydrolysis. The small fibers and fines pres ent in heterogeneous, lignocellulosic substrates were hydrolyzed rapidly, y ielding a high initial rate of hydrolysis. (C) 1999 Elsevier Science Inc. A ll rights reserved.