Screening Of Strains With High Cellulase Activity And Optimization Of Culture Conditions

Cellulase-producing 3.4261 was chosen as the original strain and treated with UV and DES, two high cellulase-producing mutants,named E20-2 and E40-4 were obtained by screening with transparent zone method and shaking culture method.Preliminary analysis of optimal fermentation conditions of E20-2 showed that the process required ratio of wheat bran and wheat straw was 3 to 7,ratio of solid and liquid was 1/4 to 1/3,Tween80 concentration was 0.1%,temperature 28℃,pH 6.0,cultured for 5 days.The CMCase and FPA of the mutant strain reached 654U/g and 69U/g respectively,which were 230%and 72%higher than the orginal strain.More than sixty strains were obtained by screening with transparent zone method from the Maqu county of China where the climate was special.Then through shaking culture method,five high cellulase-producing stains were obtained,the highest cellulase-producing strain named G7.Preliminary analysis of submerged fermentation conditions showed that the optimal concentration of CMCNa was 0.4%,(NH₄)₂SO₄ 0.15%,pH 6.0,and a temperature range between 28℃and 30℃,cultured for 4 days.The CMCase and FPA of G7 reached 1.767U/mL and 7.524U/mL.Results indicated that E20-2's isolate fermentation was more effective than mixed fermentation.