Abstract: Cellulase producing strain Trichoderma reesei was mutated by low energy N⁺ implantation. When the implantation energy was 10 keV, and the implantation doses were 150×10¹⁴ and 200×10¹⁴ N⁺/cm², three high yield mutant strains were obtained.Their cellulase yield reached 3.300 IU/mL, and improved over 20.0% than that of original strain(2.698 IU/mL). Furthermore, mutant strains had better heredity stability after five passages. Plackett-Burman and central composite rotatable design experiment were applied to optimize the concentration of nutrient factors for cellulase production. The changing patterns of glucose, wheat bran and microcrystalline cellulose were obtained, and the corresponding response surface analysis diagram were also obtained. Experimental results showed that glucose, wheat bran and microcrystalline cellulose had an individual significant influence on cellulose production. The optimum concentration of nutrient factors for cellulase production was 4.9 g/L of glucose, 23.0 g/L of wheat bran, and 7.7 g/L of microcrystalline cellulose. Under the optimized conditions, the cellulase yield of T.reesei 150-1-1 reached 2.439 IU/mL, with a 22% increase than that before optimization.

Key words: N⁺ ion implantation, Trichoderma reesei, cellulase