Screening Of High-efficienct Strain For Degradation Cellulose Material

The search and exploitation of efficient cellulolytic strains is the key step for the exploiture and utilization of cellulose resources. In order to obtain efficient cellulose decomposing microbes, the author isolated 6 cellulose pro- ducing strains from putrid straw, wood, soil, and cattle feces etc. On the basis of these strains, a high cellulase-producing strain was isolated through the experiments of decomposition of filter paper, identifying of cellulose-Congo red medium and liquid fermentation. The strain was identified as Penicillium sp. by its biological property and analysis of 18S rDNA sequences.The liquid fermentation conditions for cellulase-producing were studied extensively. The optimum conditions for cellulase production were abtained as: 3% straw powder as carbon source, 0.25% urea as nitrogen source, fermentation at 30 oC and natural pH for 4d. The maximum activities of CMCase and FPA were obtained as 45.01 IU/mL and 6.89 IU/mL, respectively. The reduce sugar yield of saccharification reached 40.2%(w/w).A mutant strain EZ30 was isolated after several steps of EMS and UV mutagenesis. Its stability of producing cellulase is excellent compared to the original strain under the same culture condition. No difference was observed between the colonies of strain EZ30 and strain Penicillium sp. T24-2 on the plate compared to the original strain, the CMCase produced by mutant strain increased from 158.52 IU/g to 210 IU/g and the reduce sugar yield of saccharification from 33.3% to 40%(w/w). The two cellulases exhibited similar specific acticity(15.85 IU/μg). It hints that the mutant strain could express more enzyme under same culture condition. The research results suggested that mutant strain EZ30 is an effective cellulose-decomposing strain, and it is a potential candidater for the future industrial utilization .