Research on Conditions of Producing Cellulose by Mixed Fermentation for Bioethanol

The conditions for cellulase production were studied with the mixed germs of Aspergillus niger (A.niger) and Trichoderma viride (R.viride) using straw stalk powder as carbon recourse by solid-state fermentation (SSF). The conditions of the mixed strains SSF were optimized by single factor experiments and orthogonal experiments in four aspects: the inoculation ratio, the bran-straw mass ratio, fermentation time and the filled volume. The optimal SSF conditions of the mixed strains were as follows: inoculation ratio of R.viride to A.niger was 1, the bran-straw mass ratio was 0.3, the time of fermentation was four days and the filled volume is 100 mL /1000 mL. The enzyme activity of FPA, CMC and β-glucosidase are 5.29 IU/mL, 9.33 IU/mL and 49.91 IU/mL in the optimal cultivation condition, which were 2.28~2.47 times, 2.39~2.45 times, 1.38~2.09 times as high as single-germ fermentation, respectively. The enzyme activity of cellulose from the mixed fermentation was higher than that from the fermentation of single bacteria.