Trichoderma atroviride 676 was studied to evaluate its efficiency in the production of some lignocellulolytic enzymes, using lignocellulosic residual biomass. Best results were obtained when 3.0 % (w/v) untreated sugarcane bagasse was used (61.3 U mL(-1) for xylanase, 1.9 U mL(-1) for endoglucanase, 0.25 U mL(-1) for FPase, and 0.17 U mL(-1) for β-glucosidase) after 3-4 days fermentation. The maximal enzymatic activity for endoglucanase, FPase, and xylanase were observed at 50-60 °C and pH 4.0-5.0, whereas thermal stability at 50 °C (CMCase and FPase) or 40 °C (xylanase) was obtained after 8 h. Zymograms have shown two bands of 104 and 200 kDa for endoglucanases and three bands for xylanase (23, 36, and 55.7 kDa). The results obtained with T. atroviride strain 676 were comparable to those obtained with the cellulolytic strain Trichoderma reesei RUT-C30, indicating, in the studied conditions, its great potential for biotechnological application, especially lignocellulose biomass hydrolysis.

Endoxylanases have played an important role in many industrial processes as bleachers to kraft pulp, animal feeds and baked goods. Also, nowadays, a special attention has been devoted to the role of these enzymes in saccharification of lignocellulose biomass for biofuels production. Trichoderma species are among fungi those that have been most extensively studied, due to their efficient production of these enzymes. Among the different strategies for improving the production and biochemical aspects of enzymes of commercial interest, mutations induced using chemical agents and/or physical devices can be cited. In the present strain T. atroviride 102C1 was obtained by using UV light and nitrosoguanidine as mutagenic agents. A factorial design (central composite rotational design, CCRD) was performed to estimate the optimal levels of C (sugarcane bagasse) and N (corn steep liquor) sources for best xylanase production. After the CCRD, the 102C1 mutant strain showed increased activity of 340% for xylanase production when compared to the wild type. The enzyme was partially characterized according to its pH and temperature profile, also using CCRD. The characterization of 102C1 mutant strain as a high endoxylanase producer allows its use in biotechnological applications, particularly in the hydrolysis of lignocellulosic biomass for biorefinary proposes.

Many traditional mutagenic strategies have been used to improve cellulase production by microorganisms, especially fungi species. Trichoderma species are among cellulolytic fungi, those that have been most extensively studied, due to their efficient production of these enzymes. In the present study, N-methyl-N´-nitro-N-nitrosoguanidine (NTG) was used as mutagenic agent to obtain cellulolytic mutant from wild strain T. atroviride 676. After mutagenic procedures, two strains (102C1 and 104C2) were selected as promising cellulase-producing mutant. The effect of the carbon (sugarcane bagasse: SCB) and nitrogen (corn steep liquor: CSL) sources on endoglucanase production by the mutants 102C1 and 104C2 was studied using submerged cultivations at 28°C. Different concentrations of SCB and CSL were used and nine different media were generated. Mutant 102C1 showed the best results when using 2.5% SCB and 0.7% CSL. A central composite rotational design (CCRD) was performed to estimate optimal conditions of pH and temperature for endoglucanase activity of strain 102C1, which were pH 3.6 and temperature 66°C. The characterization of this acidophilic and thermophilic endoglucanase activity produced by the mutant strain 102C1 allows its use in biotechnological applications, particularly in the hydrolysis of agro industrial residues, such as SCB, for bioethanol production.