Abstract:

Response surface methodology was applied to optimize the fermentation conditions of Bacillus J-5 for the
production of carboxymethyl cellulase (CMCase). Firstly, the effect of medium components and culture conditions such
as nitrogen source, carbon/nitrogen ratio, solid-to-liquid ratio, fermentation temperature, fermentation duration and
supplementary carbon source on CMCase activity was examined by the one-factor-at-a-time method. Secondly, carbon/
nitrogen ratio, solid-to-liquid ratio and initial medium pH were selected for the investigation of their effects on CMCase
activity as well as the interaction among them by response surface analysis (RSA). The optimal conditions for CMCase
production were established as follows: carbon/nitrogen ratio, 25:1 (m/m); initial medium pH, 3.2; solid-to-liquid ratio,
1:3.25 (m/V), fermentation temperature, 38 ℃; fermentation duration, 144 h; and supplementary carbon source concentration,
1 g/100 g. Under these conditions, the predicted value of CMCase activity was 58.15 U/g, agreeing with the experimental
value of 57.996 U/g. The high CMCase activity from Bacillus J-5 could effectively degrade garlic peel.

Key words: garlic peel, carboxymethyl cellulase, response surface analysis