Abstract

The indigenous cellulolytic fungus Trichoderma longibrachiatum (GHL) isolated from soil near an Algerian hot spring was used for the production of cellulases by submerged fermentation on Mandels medium with cellulose Avicel (1%) as the sole carbon source. Endoglucanase and filter paper activities of the wild-type strain ofTrichoderma were compared to the hypercellulolytic mutated Trichoderma reesei Rut C-30, in shake flask cultures at 35°C. After seven days of fermentation, T. longibrachiatum show equivalent activities than T. reesei (10.61 IU/ml of endoglucanase (CMCase) and 2.04 IU/ml of filter paper activity (FPA)). On the other hand, the ß-glucosidase activity of Trichoderma GHL was twice more important than that of T. reseei. The influence of inoculum size on cellulase activities did not prove significant differences in enzymatic activities for spore concentrations between 10⁵and 10⁸ spores/ml. The cellulases produced by the isolated strain were also characterized. The optimum temperatures were 55 and 60°C for endoglucanase and FPA, respectively. The endoglucanase was thermostable at 70°C after 5 h incubation, and it preserved 80% of the original activity. The half-life of the FPA appeared to be 3 h at 60°C. The endoglucanase was optimally active at pH 4.0, and the FPA was optimal at pH 4.0 and 5.0. These activities were stable at 50°C after 5 h incubation in a pH range of 3.0 to 6.0 and 4.0 to 6.0, respectively. These results suggest that the non-mutated strain T. longibrachiatum (GHL) should be an attractive producer for cellulases production.

Key words: Cellulase, Trichoderma reesei, Trichoderma longibrachiatum, submerged fermentation, characterization.

Abbreviation

CMCase, Carboxymethyl cellulase; FPase, filter paper activity; FPA,filter paper activity; T, Trichoderma