Transcriptional Analysis Of Aspergillus Fumigatus Z5 Cellulase Genes And Heterologous Expression Of Cellobiohydrolase And Xylanase Genes

Cellulase has very high biotechnological importance in the lignocelluloses bioconversion to liquid fuels and other useful products. The bottlenecks in the bio-conversion are the low efficiency and high cost of cellulases to hydrolyze the lignocellulose, which could not meet the needs of industrial biomass utilization.Strain Aspergillus fumigatus Z5 had ability to produce various cellulases when using Avicel as the single carbon source, including endo-glucanase, cellobiohydrolase, ?-glucosidase and xylanase. In this study, Real-time PCR was used to detect the transcription of 40 predicted cellulase related genes of Z5. The result showed the high relative expression level of cellobiohydrolase (number 19), but the enzyme assay turned out the low activity of cellobiohydrolase. Xylanase is one component of the hemicellulases expressed by Z5, its activity was also not high enough. These two enzymes play an important role in cellulose hydrolysis. Therefore, it is significant for us to construct engineering strain to express cellobiohydrolase and xylanase gene efficiently by genetic engineering technology.In this study, cellobiohydrolase and xylanase genes were inserted into the expression vector pPICZaA, then the recombinant expression vector pPICZaA-xyn-1 and pPICZaA-cbh-1 were transferred into Pichia pastoris GS115 by electroporation, got the engineering strains. Finally, the cellobiohydrolase gene was successfully expressed, but not the xylanase gene. The maximum activity of recombinant cellobiohydrolase was 2.27U/ml, and it had optimal pH and temperature at 5.0 and 50?. The Km and Vmax were 0.87umol·L-1 and 0.054umol·min-1·mg/1, respectively.