초록
A novel deep-bed solid-state bioreactor was designed and fabricated for cellulolytic enzymes production using mixed fungal cultures. Better temperature and moisture control was achieved through a unique bioreactor design comprising an outer wire-mesh frame with internal air distribution along with near-saturation conditions within the cabinet. Without airflow through the internal distributors, maximum temperatures of 48<SUP>o</SUP>C and 52<SUP>o</SUP>C were observed during half- and full-capacity operation. These were reduced to 44<SUP>o</SUP>C and 43<SUP>o</SUP>C on resumption of airflow. In terms of cellulolytic enzyme production, no significant differences occurred in filter paper activity with depth in half-capacity operation; however, in full-capacity operation, top-level filter paper activity (5.39FPU/g-solids) was significantly different from middle- and bottom-level activity. Top level beta-glucosidase, endocellulase, and xylanase activities were significantly (P<0.05) different from middle and bottom levels in both half- and full-capacity operation. A two-phase coupled heat and mass transfer model was developed that predicted the experimental trends reasonably well. Model predictions confirmed that cabinet temperature of 30<SUP>o</SUP>C and distributor airflow rate of 3.42kgh<SUP>-1</SUP> during operation enabled effective temperature control.