Production of thermophilic and acidophilic endoglucanases by mutant Trichoderma atroviride 102C1 using agro-industrial by-products
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.
Keywords: Trichoderma atroviride, CMCase, nitrosoguanidine, sugarcane bagasse, corn steep liquor