Abstract: This paper deals with the optimization of fermentation conditions for cellulase production from corn stover treated by alkaline hydrogen peroxide by both Trichoderma reesei and Aspergillus niger. Four fermentation conditions including delay time of Aspergillus niger inoculation, inoculum ratio between Trichoderma reesei and Aspergillus niger, fermentation time and solid-to-liquid ratio were investigated by one-factor-at-a-time experiments and their respective appropriate levels were determined for the optimization of these fermentation conditions using a Box-Behnken design coupled with response surface analysis. The optimal fermentation conditions for cellulase production were as follows: Aspergillus niger was inoculated 36 h later than Trichoderma reesei at a ratio of 1:5 between them; the fermentation medium was at a solid-to-liquid ratio of 2:50 (m/V) and pH was 5.0 and contained 0.4%Tween-80 and its filled quantity was 50 mL in a 250 mL flask; the fermentation period was 7 d. The final products obtained under these conditions showed a filter paper activity of 1.224 IU/mL and a β-glucosidase activity of 0.315 IU /mL. HPLC analysis indicated that more complete cellulase system with enhanced hydrolysis efficiency on lignocellulose for production of fermentable sugars was produced by jointly Trichoderma reesei and Aspergillus niger than either of them.

Key words: Trichoderma ressei, Aspergillus niger, cellulase, mixed fermentation