Effects Of Bgl2 Gene And VIB Gene On Cellulase Expression Of Trichoderma Orientalis EU7-22

With the continuous decreases of fossil energy and the increasing severe environmental pollution,the environment friendly renewable energy has become more and more crucial.Biomass energy has been playing an increasingly important role in the energy system.The efficient degradation and utilization of natural cellulose could alleviate energy shortage and environmental problems.Cellulase produced by microorganisms,especially from filamentous fungi,is the most efficient and environmentally friendly way to utilize cellulose.Trichoderma orientalis EU7-22 is a filamentous fungi with high yield of cellulase.Further research on the gene regulation could greatly improve the cellulase expression.In this paper,the gene bgl2 encoding cellulase and the gene VIB encoding a new transcriptional regulatory factor were cloned from Trichoderma orientalis EU7-22.The mutant strains of those genes were constructed to identify its functions.(1)The bgl2 deletion mutant strain-bg12 has been successfully constructed in Trichoderma orientalis EU7-22.Under the condition containing avicel and bran,the FPAase and pNPCase of-bg12 strains increased 17.4%and 12.3%compare to parental strains EU7-22,respectively.And the CMCase,pNPGase and protein secretion of the-bgl2 strain were similar to those of the original strain.Therefore,the knockout of bgl2 gene can improve cellulase expression of Trichoderma orientalis EU7-22.(2)The VIB gene deletion mutant strain-VIB and the VIB gene overexpress mutant strain+VIB were constructed in Trichoderma orientalis EU7-22,respectively.Under the condition containing avicel and bran,the cellulase activity of-VIB strain was hardly detected,however,the cellulase activity of the+VIB strain was greatly improved.The FPAase,CMCase,pNPCase and pNPGase produced by+VIB strain were 1.51 IU mL-1,41.10 IU mL-1,0.86 IU mL-1 and 3.47 IU mL-1,respectively,which increased by 92%,34%,87%and 38%compared with the original strain.(3)On the basis of-bgl2 strain and+VIB strain,the engineering strain BBV-9 which knocked out bgl2 gene and overexpressed VIB gene,was successfully constructed.Under the induction conditions containing avicel and bran,the FPAase,CMCase,pNPCase,pNPGase and protein secretion of strain BBV-9 increased 87%,70%,98%,58%and 37%compare to original strain EU7-22,respectively.The results showed that double mutant of VIB gene and bgl2 gene could significantly improve the cellulase expression of Trichoderma orientalis EU7-22.