Characterization of cellulolytic enzymes of Fusarium soil Isolates

Cellulase has tremendous industrial application. Fusarium spp. should be exploited as commercial source of cellulase. Three F. solani, three F. oxysporum and one F. chlamydosporum isolates have been recovered from soil, identified through rDNA sequence analysis and their cellulolytic activities have been characterized based on carboxymethylcellulose assay, filter paper assay and cotton assay. All the isolates grew profusely in CMC containing potato dextrose broth and produced sufficient protein including cellulase. Highest CMCase activity (0.445 IU ml(-1)) by F. oxysporum SF0801, FPase activity (9.25 IFPU ml(-1)) by F. oxysporum SF1905 and cotton degradation activity (0.053 U ml(-1)) by F. solani SF1303 have been observed. Optimum temperature and pH of the enzymes were found to be 50 degrees C and acidic condition in most cases. Enzymes from all the isolates showed stability and increased activity when pre-incubated in temperature (40-80 degrees C), pH (4 - 9), metal salts (CaCl2, CdCl2, CuSO4, FeCl3, HgCl2, KCl, MgCl2, NaCl, NiCl2, ZnSO4), inhibitors (beta-mercaptoethanol, EDTA, urea, IAA), surfactants (Tween 80, SDS) and oxidizing agent (H2O2). Enzyme kinetic analysis revealed low Km value in F. oxysporum SF0801 (0.121 mg ml(-1)) indicating its strongest affinity with the substrate (CMC). Thus the isolates might be utilized as the potential candidates for bioconversion cellulose into fuel and other industrial process.