Enzymatic Hydrolysis of Bamboo and Larch Alkaline Sulfite Pulps for Glucose Production

Abstract

Application of alkaline sulfite-anthraquinone (AS-AQ) cooking was investigated as a pretreatment for enzymatic saccharification and bioethanol production from Japanese larch (Larix leptolepis) and bamboo (Phyllostachys pubescens) culm. It was found that a 60⁄40 ratio of NaOH⁄Na₂SO₃ in the cooking liquor could produce high-yield pulp with the lowest lignin content. According to a method of filter paper cellulase activity, it was shown that the lignin of pulp inhibited enzymatic saccharification when both AS-AQ and soda-AQ pulps were treated by cellulase. Comparing the pulps at a given lignin content revealed that the enzymatic saccharification ratio of larch AS-AQ pulp was higher than that of soda-AQ pulp. Furthermore, it was found that the saccharification ratio of bamboo culm AS-AQ pulp was higher than that of larch AS-AQ pulp, and that the bamboo pulps with a lignin content of 6.8% were more easily hydrolyzed than filter paper. These results clearly show that the AS-AQ method is more effective than the soda-AQ method as a pretreatment, and that bamboo culm AS-AQ pulp is a promising raw material for bioethanol production.