Optimization of the Medium for the Production of Cellulase by the Mutant Trichoderma reesei WX-112 Using Response Surface Methodology

Optimization of the Medium for the Production of Cellulase by the Mutant Trichoderma reesei WX-112 Using Response Surface Methodology

Xue-Cai Hao¹, Xiao-Bin Yu¹* and Zhong-Li Yan²¹The Key Laboratory of Industrial Biotechnology, Ministry of Education, Southern Yangtze University, Wuxi-214036, Jiangsu Province, PR China
²College of Food Science and Bioenginering, Tianjin University of Science and Technology, Tianjin-300222, PR China

Article history:
Received May 24, 2005
Accepted October 13, 2005

Key words:
cellulase, Trichoderma reesei WX-112, optimization, fractional factorial design (FFD), central composition design (CCD), response surface methodology (RSM)

Summary:
The mutant strain Trichoderma reesei WX-112 with high cellulase activity was isolated by a newly invented plate. The mutant’s ability to produce cellulase increased 1.95 times after the treatment with UV and N-methyl-N’-nitro-N-nitrosoguanidine (MNNG). Also, the medium composition was optimized using response surface methodology (RSM). A fractional factorial design (2^6–2) was applied to elucidate the medium components that significantly affect cellulase production. The concentration of Avicel and soybean cake flour in the medium were significant factors. The steepest ascent method was used to locate the optimal domain and a central composite design was used to estimate the quadratic response surface from which the factor levels for maximum production of cellulase were determined. The composition of fermentation medium optimized with response surface methodology was (in g/L): wheat bran 30, Avicel 36.4, soybean cake flour 24.7, KH₂PO₄ 4 and corn steep flour 5. Compared to the original medium, the cellulase activity increased from 7.2 to 10.6 IU/mL.

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