纖維素及半纖維素分解?的性質及利用稻草進行同時糖化醱酵之初步探討

Abstract

以處理過的稻草?碳源培養Trichoderma reesei QM 9414，誘導其產生纖維素分解?及半纖維素分解?，在第9天可得較高活性之酵素液。其酵素作用之最適pH值及溫度?：β - xylosidase?pH 3.8、55℃；xylanase?pH 4.3、55℃；C1 cellulase?pH 4.3、60℃；FP cellulase?pH 4.8、55℃；Cx cellulase?pH 4.8、60℃；β - glucosidase?pH 4.3，最適作用溫度高於65℃。糖化作用之最適pH值及溫度則?pH 4.3、50℃。各酵素對pH值及溫度之穩定性不盡相同，以xylanase最不穩定，添加1 mg/ml的牛血清蛋白可提高酵素之穩定性。以處理過的稻草?基質進行糖化，其糖化產物含有纖維貳糖、木二糖、大量木糖及葡萄糖和少量阿拉伯糖。 利用糖化液醱酵產物探討其對酵素的影響，發現酒精對酵素稍有抑制作用，檸檬和乳酸則抑制效果較大。 利用Saccharomyces cerevisiae與Trichoderma reesei QM 9414所產生的酵素液進行同時糖化及醱酵，以5％稻草?碳源，於37℃作用24小時後得總還原糖20.75 mg/ml，較單獨利用酵素之糖化所得14.81 mg/ml?高。

The cellulases and hemicellulases of Trichoderma reesei QM9414 induced by pretreated rice straw had the highest activities at the ninth day of incubation. The optimum pH and temperature of these enzymes were: β-xylosidase, pH 3.8, 55℃; xylanase, pH 4.3, 55℃; C1 cellulase, pH 4.3, 60℃; FP cellulase, pH 4.3, 55℃; Cx cellulase, pH 4.8, 60℃; β-glucosidase, pH 4.3, higher than 65℃. The optimum pH and temperature for the saccharification were pH 4.3 and 50℃, respectively. The pH and temperature stability of these enzymes were varied in a great range, xylanase was less stable. However, the stability of these enzymes could be improved by adding 1mg/ml bovin serum albumin. Using pretreated rice straw as substrate, the saccharification products contained: cellobiose, xylobiose, large amount of xylose and glucose and small amount of arabinose. By studying the inhibitory effects of fermentation products, it was found that ethanol inhibited the enzyme activities slightly. But citric acid and lactic acid had strong inhibitory effect. The simultaneous saccharification and fermentation was performed by using Saccharomyces cerevisiae and crude enzyme solution produced by Trichoderma reesei QM9414 at 37℃ using 5% treated rice straw as carbon source. After incubation for 24 hours, the concentration of total reducing sugars produced by simultaneous saccharification and fermentation was 20.75 mg/ml which was higher than that of the simple saccharification, 14.81 mg/ml.