Degradation of Tough Materials by Cellulase from Corticium rolfsii

Abstract

Corticium rolfsii AHU 9627, which we isolated from a tomato stem, is not only one of the strongest producers of a raw starch saccharifying amylase but also a powerful producer of cellulase. The effects of the cultural conditions and medium components on cellulase production were investigated. The enzyme production was enhanced remarkably by increases in both the concentrations of carbon sources and organic nutrients in the medium. Under the optimum cultural conditions, the enzyme activity of the culture supernatant reached a maximum after 12 days incubation at 27°C, and the activities of filter paper cellulase, avicelase, β-glucosidase and CMCase reached 15.6, 7.2, 9.1 and 460IU/ml, respectively. These productivities were substantially higher than those in the case of Trichoderma reesei QM 9414. In addition, the crude enzyme also contained amylase: 17.3IU/ml as raw starch saccharifying amylase. One of the important features of Corticium cellulase is that it shows maximum activity at low pH, so contamination can be avoided during saccharification. It showed maximum activity in the pH range of 3.5 to 4.5 and was thermostable up to 55-70°C. Analysis of saccharification digests indicated that glucose was the predominant product, with a negligible amount of cellobiose. Moreover, after 24 hr incubation, 20% raw cassava block was completely dissolved by Corticium enzymes.