Enhancing saccharification of wheat straw by mixing enzymes from genetically-modified Trichoderma reesei and Aspergillus niger

Abstract

Objectives: To increase the efficiency of enzymatic hydrolysis for plant biomass conversion into renewable biofuel and chemicals. Results: By overexpressing the point mutation A824 V transcriptional activator Xyr1 in Trichoderma reesei, carboxymethyl cellulase, cellobiosidase and β-d-glucosidase activities of the best mutant were increased from 1.8 IU/ml, 0.1 IU/ml and 0.05 IU/ml to 4.8 IU/ml, 0.4 IU/ml and 0.3 IU/ml, respectively. The sugar yield of wheat straw saccharification by combining enzymes from this mutant and the Aspergillus niger genetically modified strain ΔcreA/xlnR<inf>c</inf>/araR<inf>c</inf> was improved up to 7.5 mg/ml, a 229 % increase compared to the combination of wild type strains. Conclusions: Mixing enzymes from T. reesei and A. niger combined with the genetic modification of transcription factors is a promising strategy to increase saccharification efficiency.