Enhancement of cellulose accessibility and enzymatic hydrolysis by simultaneous wet milling

作者：Rick G. Kelsey, Fred Shafizadeh · 发表于：Biotechnology and Bioengineering · 年份：1980 · DOI：10.1002/bit.260220511 · 被引用次数：58 · 研究领域：Biofuel production and bioconversion、Advanced Cellulose Research Studies、Enzyme Production and Characterization

Abstract It has been shown that the rate of enzymatic saccharification of cellulosic materials including “pure” cellulose (Whatman CF−11 cellulose), newsprint, lignocellulose (prehydrolyzed to remove hemicelluloses), and wood can be substantially increased by simultaneous wet milling. An enhanced hydrolysis rate was sustained above that observed for ball milling: providing a more extensive saccharification. The cellulosic substrates were wet milled with a variety of grinding elements, such as sand, glass beads, and stainless‐steel beads, agitated in a shaker bath. Simultaneous hydrolysis was achieved with a 2% substrate slurry in a 0.1M acetate buffer at 45°C and pH 5. The effectiveness of this process was dependent upon the lignified matrix of the cellulose microfibrils, the grinding elements, and the oscillation frequency of the shaker bath. Wet milling “pure” cellulose for 48 hr, with 3.5 mm glass beads and 200 oscillations/min (opm), yielded 1031 mg reducing sugar/g substrates (93% saccharification) as compared to 483 mg (44%) for the ball‐milled sample and 253 mg (23%) for the unmilled material. With the lignified substrates stainless‐steel beads (3.5 mm) were more effective than glass. For lignocellulose 529 mg sugar/g substrate (93% saccharification) could be obtained by wet milling with cellulase for 24 hr. This was about three times greater than that of the ball milled (169 mg, 30%) and 10 times greater than that of the unmilled (52 mg, 9%) substrates. The method was...