Application of semi-quantitative and quantitative methods for the selection of cellulolytic filamentous fungi isolated from pulp mill materials

A semi-quantitative method (the enzymatic activity index, EI) and a quantitative method (the amount of reducing sugars, RS) have been used for selecting cellulolytic microorganisms. The analysis was performed with 90 isolates of filamentous fungi selected from pulp mill materials. In both methods 1% low viscosity carboxymethylcellulose (1% CMC l.v.) was used as a substrate. For n = 90, no correlation between the parameters has been found.

A further analysis was carried out for 12 selected isolates: 6 with the highest RS values and 6 with the highest EI values. For the chosen fungi, also cultivated on 1% CMC l.v. medium, the following parameters have been determined: the total cellulase activity (filter paper assay, FPase), endoglucanase (CMCase) activity, β –glucosidase (CBase) activity, and the changes in the culture medium viscosity (DV). The statistical analysis revealed a negative, moderately marked correlation between EI and RS and clearly marked positive correlations for two pairs: RS-FPase and DV-FPase. A high positive correlation between RS and DV has also been observed. Correlations between EI, RS, DV, CMCase, and CBase activities were weak. It was shown that the quantitative parameter RS is more suitable than EI for the evaluation of the total cellulolytic activity of filamentous fungi. The application of CMC as the only source of carbon in the culture media and the subsequent determination of EI or RS has failed to provide the means for selecting fungi with a high endoglucanase (CMCase) activity.