OPTIMIZED CELLULASE PRODUCTION BY PHANEROCHAETE-CHRYSOSPORIUM - CONTROL OF CATABOLITE REPRESSION BY FED-BATCH CULTIVATION

The cellulase system of Phanerochaete chrysosporium is adaptive and th us sensitive to carbon catabolite repression. Our attempts to optimize cellulase production have led to significant improvements. Specific y ields (cellulase produced per carbon source) in batch cultivations on cellulose were of the order of 40-60 mg/g. In fed-batch cultivation, h owever, specific yield was improved to 120 mg/g when cellulose was the substrate. Using cellobiose as the substrate a yield of 100-130 mg/g was routinely obtained. The effectiveness of the technique is clearly shown by the result obtained in a cultivation where cellobiose and glu cose were fed simultaneously. Although the cellobiose added represents about 50% of the glucose added, the specific yield achieved, 70 mg/g, was still higher than in batch cultivations on cellulose. However, th e cellulase production rate in this culture was very sensitive to chan ges in culture conditions. The protein, the avicelase- and the CMCase- activity profiles produced on either pure or mixed carbon sources were very similar.