Abstract: In order to improve tobacco taste， decrease the smoking pungent taste， increase the fragrance and improve the smoking quality， a mold strain Aspergillus niger possessing relatively higher cellulase enzymatic activity was isolated from tobacco leaves The PlackettBurman design was used to choose the most important factors， then， these factors were optimized by RSM method， and the purification of enzyme was investigated The results indicated that the optimum carbon source and nitrogen source were 1.4% corn cob and 0.4% NH4NO3， the optimum original pH was 5.6 and the optimum cultural temperature was 30.4℃ Under these conditions， the specific enzyme activity was 40.02 U·mL-1 The crude cellulase was isolated and purified by means of ammonium sulfate precipitation， followed by chromatography on Sephadex G100 The specific activity of the cellulase increased to 3.5 fold of the source enzyme with an activity recovery of 32.6%.

Key words: Aspergillus niger, cellulase, response surface methodology, electrophoresis