Cellulase and Xylanase Expression in Response to Different pH Levels of Penicillium echinulatum S1M29 Medium

The effect of pH on the production of cellulases and xylanases by Penicillium echinulatum S1M29 was evaluated in a shake flask and in a bioreactor. To control the pH in a shake flask, a buffer made with citric acid and disodium phosphate was used. The buffer was capable of maintaining the culture pH values for the first 48 h. In the bioreactor, the pH was controlled automatically by the addition of NaOH and H2SO4. In the shake flask, the highest activities of xylanases (18.5 IU/mL) and endoglucanases (8.2 IU/mL), as well as the highest filter paper activity (FPA) (0.9 IU/mL), were obtained at initial pH values of between 6.0 and 7.0. In the bioreactor, the highest activities of these enzymes were obtained in a pH range of 5.5 to 6.5. Different isoforms of the endoglucanases were found in the various cultures depending on the pH. More acidic pH ranges favored the production of β-glucosidases in both the shake flask and the bioreactor.