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PRODUCTION AND PURIFICATION OF CELLULOSE-DEGRADING ENZYMES FROM A FILAMENTOUS FUNGUS TRICHODERMA HARZIANUM

SIBTAIN AHMED, AMMARA BASHIR, HUMA SALEEM, MUBSHARA SAADIA AND AMER JAMIL^*

Abstract: The major components of plant cell walls are cellulose, hemicellulose and lignin, with cellulose being the most abundant component. Cellulose degrading-enzymes provide a key opportunity for achieving tremendous benefits of biomass utilization. Trichoderma harzianum, a filamentous fungus, produces cellulose degrading enzymes and has been exploited by the industry. In this study, three cellulases, exoglucanase (EXG), endoglucanase (EG) and b-glucosidase (BGL) were partially purified from T. harzianum. The optimal pH, temperature and incubation time for cellulases production was found to be 5.5, 28^oC and 120 h respectively. To promote cellulases production, we evaluated the effects of glucose, carboxymethylcellulose (CMC), corn cobs, birchwood xylan and wheat bran as carbon sources for cellulase production. The results showed that CMC induced cellulases production whereas glucose repressed the synthesis of cellulases. The fungus was cultivated with 1% CMC for 120 h at 28ºC, pH 5.5 and the resulting culture filtrate was used for cellulase purification. EXG, EG and BGL were partially purified from culture filtrate of fungus by Ammonium sulfate precipitation followed by gel filtration chromatography on Sephadex G200 and on Sephadex G50. After final purification step specific activities (IU/mg^-1) of the enzymes were; EXG: 49.22, EG: 0.63 and BGL: 0.35 with 21.87-, 7.15- and 1.74- fold purification, respectively.

Molecular Biochemistry Lab., Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad-38040, Pakistan.
Corresponding author's email: amerjamil@yahoo.com