The results show that the optimum combination was A3B2C3D2, i.e., when 2 mL seed cultures of T. reesei Aq-5b and 1 mL seed cultures of T. viride NSW-XM were transferred into 250 mL Erlenmeyer flasks containing 50 mL fermentation medium (initial pH 5.5) and maintained at 34 °C, 120 rpm for 4 d, the best mixed culture system was constructed (system I)