Improving saccharification of ramie stalks by synergistic effect of in-house cellulolytic enzymes consortium.

ABSTRACT

The high cost of cellulase is one of the main obstacles hindering the large-scale biorefining of lignocellulosic biomass. Therefore, developing efficient method for preparation of cellulase is promising. In the present study, the production of cellulase by Trichoderma reesei, Trichoderma harzianum, and Aspergillus niger was optimized, and the synergistic effect of these cellulase on enzymatic hydrolysis of pretreated ramie stalks was also evaluated. The maximum CMCase (Carboxymethyl Cellulase) and filter paper activity (FPA) produced by T. reesei reached to 3.12 IU/mL and 0.13 IU/mL, respectively. The maximum activities of CMCase (3.68 IU/mL), FPA (0.04 IU/mL) and ß-glucosidase (8.44 IU/mL) were obtained from A. niger. The results also showed that under the premise of the same FPA activity, the contribution of ß-glucosidase activity to yield of reducing sugar was greater than that of CMCase. Besides, cellulase produced by T. reesei and A. niger had the best synergistic effect on enzymatic hydrolysis of pretreated ramie stalks. The highest reducing sugars yield (417 mg/g dry substrate) was achieved when enzyme cocktail was prepared at the ratio of 11, which was 1.36-3.35 folds higher than that of different single enzymes. The present research has provided a novel method for efficient preparation of enzymes consortium for enzymatic hydrolysis of ramie stalks.