Study of a high yield system of cellulase hydrolysis in mutant of Lee Trichoderma induced by heavy ion irradiation in a mixed fermentation culture with Aspergillus niger

S. Wang, B. Jiang, X. Zhou, J. Chen, W. Li, J. Liu, W. Hu, G. Xiao, M. Dong, Y. Wang
Institute of Modern Physics, Chinese Academy of Sciences,
China

Keywords: cellulase hydrolysis, mutant of Lee Trichoderma, heavy ion irradiation, mixed fermentation culture, aspergillus niger

Summary:

The aim of this study was to evaluate and validate the efficiency of carbon ion irradiation to mutagenesis of Trichoderma viride (T. viride) and a novel sequential liquid cultivation method for cellulase production via mixed culture fermentation with Trichoderma reesei (T. reesei) and Aspergillus niger (A. niger). We found that 12C6+ ion irradiation induced the changes in the cellulase biosynthesis of A. niger. The mixed culture system was successfully established with a ratio of T. reesei to A. niger at 5:1 for 96 h with simultaneous inoculation. The β-glucosidase (BG) activity of the mixed culture increased after 72 h. At 96 h, the filter paper activity (FPA) and BG of the mixed culture were 689.00±36.89 and 797.15±11.14 IU/mL, respectively, which are significantly higher than those of the monocultures (408.70±40.85 and 646.98±27.23 IU/mL for T. Reesei, and 447.29±15.13 and 658.89±43.12 IU/mL for A. niger, respectively). The endoglucanase (EG) activity of the mixed culture was 2342.81±36.62 IU/mL, which is significantly higher than those of monocultures (2206.57±27.23 IU/mL for T. reesei and 1727.62±10.59 IU/mL for A. Niger). Taken together, cellulose production and hydrolysis yields were significantly enhanced by combination of the two methods: the first method is to optimize a high yield of a cellulase-producing strain via heavy ion irradiation mutagenesis and high throughput screening. The second method is to mix the culture of organic mutant T. viride and A. niger to effectively obtain the enzymatic hydrolysis of cellulase.