Abstract: We optimized the liquid medium components to produce the laccase activity of Panus rudis FG-35 by using Plackett-Burman design and response surface methodology. The results of single-factor test showed that soluble starch and peptone were the best sources of carbon and nitrogen. Then the Plackett-Burman design was applied to determine the specific medium components affecting laccase activity and found that soluble starch, Ca²⁺and Tween-40 were the key factors. Based on these results, steepest ascent experiments were applied to find central points of laccase activity. These significant parameters were further optimized using Box-Behnken design, response surface methodology and regression analysis. Finally, the optimal medium was：soluble starch 10.040 4 g/L, peptone 0.2 g/L, K₂HPO₄ 1.00 g/L, ZnSO₄?7H₂O 0.008 g/L, MgSO₄?7H₂O 0.5 g/L, CuSO₄?7H₂O 0.007 g/L, FeSO₄?7H₂O 0.005 g/L, MnSO₄ 0.035 g/L, CaCl₂ 0.081 6 g/L, VB₁ 0.1 g/L, Tween-40 0.428%. Under these optimal conditions, the activity of laccase increased from 263.31 U/mL to 127.194 U/mL(1.0-fold increase in total yield), similar to the predictions. And the results of lignin degradation experiments indicated that the optimal medium made contribution to the degradation rate of lignin which about 14.34% improvement over before.

Key words: Laccase, Plackett-Burman design, Response surface, Degradation