Abstract:

Components of cellulase produced by Leptographium qinlingensis and the optimum conditions for biosyntheses of the enzymes were studied by single factor and orthogonal experiment in this paper. The result showed that Leptographium qinlingensis had a complete cellulase system which was composed of endo-β-1, 4-glucanases (C_X), exo-β-1, 4-glucanases (C₁) and β-1, 4-glucosidase (BG). Furthermore, it was also showed that the enzyme C_X was the major component of the cellulase whose optimum activity (35.215 U) was 13.662 times higher than enzyme C₁ and 8.780 higher times than enzyme BG respectively. A orthogonal experiment indicated that the optimum conditions of enzyme C_X, enzyme C₁ and enzyme BG were different. The optimum conditions to produce enzyme C_X were at 29 ℃ with six-day cultivating time, pH value 4.0 and 150 r·min^-1 rotating speed. Among the four factors (temperature, cultivating time, pH value and rotating speed)， temperature, had the largest impact on producing cellulase by Leptographium qinlingensis，followed by cultivation time and rotating speed.

Key words: Dendroctonus armandi, Leptographium qinlingensis, cellulase, orthogonal experiment