Abstract: In this study,Plackett-Burman design,path of the steepest ascent,and Box-Behnken design were used to optimize the liquid medium composition for laccase production of white rot fungus Porodaedalea laricis with the laccase activity set as a response. The optimal compositions for production of P. laricis laccase was obtained as follows：peeled potato 365.61 g/L,peptone 5.0 g/L,glucose 20.0 g/L,KH₂PO₄ 1.0 g/L,MgSO₄·7H₂O 0.5 g/L,MnSO₄·H₂O 0.15 g/L,CaCl₂·2H₂O 0.03 g/L,ammonium tartrate 6.68 g/L,sodium succinate 1.5 g/L,Tween 80 0.48 mL/L,corncob 46.43 g/L,and vitamin B1 0.01 g/L. Under the optimized conditions,the laccase activity was 3.29 U/mL,which was 2.81-fold of that given in the basal medium,and this yield was very in good agreement with the theoretical result of 3.32 U/mL,indicating the model was accurate and reliable. Moreover,the laccase exerted notably decolorizing capacity for many synthetic dyes including Reactive Brilliant Blue X-BR,Remazol Brilliant Blue R,Acid Black 172,Congo Red,Methylene Blue,Neutral Red,Indigo Blue,Naphthol Green B,and Crystal Violet,with the respective decolorization rate of 95.64%,97.21%,36.11%,91.63%,61.42%,74.65%,48.60%,25.13%,and 68.80% after 168 h.

Key words: Porodaedalea laricis, laccase, liquid cultivation, response surface methodology, dye decolorizing capacity