UBC Theses and Dissertations
The partial characterization of cellulases from Cellulomonas fimi Langsford, Maureen Lynn
The cellulases of C. fimi have been partially characterized. The extracellular CMCase had optimal activity at pH 7.0 and 52°C. However, the enzyme was not stable at high temperatures. Since the enzyme was inactivated more slowly at lower temperatures, subsequent CMCase activity was determined at 37°C. CMCase was inducible by cellulose and appeared to be regulated by catabolite repression. When cultures were grown on glucose or cellobiose in the presence of inducing levels of cellulose, no cellulase was detected. CMC induced lower levels of CMCase and fewer proteins than did avicel. Analysis by non-denaturing PAGE revealed that CMC-induced cellulases had mobilities different from avicel-induced cellulases. CMCase in culture supernatants continued to increase during growth for 9 days on CMC or avicel. In older cultures, the active components had faster mobilities on polyacrylamide gels. The cellulases of C. fimi are probably derived from only 3-4 gene products. The apparent multiplicity of components may be the result of enzymatic modification, stoichiometric differences in complex formation, or variation in enzyme affinity for substrate.
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