Abstract:

White rot fungus Trametes gibbosa was statically cultured at 28 ℃ in 4 kinds of different LNAS media. The solutions were sampled at different interval, and the optical density of the solutions, representing oxidized products of 2,6-DMP, ABTS and veratryl alcohol (VA) catalyzed by manganese peroxidase (MnP), laccase and lignin peroxidase (LiP), were measured spectrophotometrically at 470 nm at 420 nm at 310 nm, respectively. Results showed that T. gibbosa could synthesize MnP (only when Mn²⁺is present) and laccase (no matter Mn²⁺is present or absent) simultaneously, but no LiP. Substrates wood sawdust and 2, 6-DMP could significantly enhance MnP and laccase activities. Furthmore, T. gibbosa was statically cultured at 30 ℃ in LNAS medium containing Mn²⁺ and wood sawdust added was as initializing culture condition, and then two times orthogonal and several single-factor tests were conducted to optimize medium compositions and culture conditions of T. gibbosa for producing MnP. Results indicated that the most optimal culture condition within the fixed factors and levels was fructose 5 g ·L^-1,tartaric acid ammonium 15 mmol ·L^-1, Mn²⁺ 200 μmol ·L^-1, Tween -80 0.25 mL ·L^-1, MgSO₄ ·7H₂O 0.35 g ·L^-1, mineralt solution 10 mL ·L^-1, vitamin solution 1 mL ·L^-1 and pH 4.5 in the improved LNAS medium; culture temperature 27 ℃; and 110 mL culture solution volume at 150 r ·min shaking condition, and the produced manganese peroxidase activity could reach to 314.52 U ·L^-1, which was 8.4 times higher than that produced at initializing culture condition. MnP yield produced by T. gibbosa could be enhanced in a great deal in the optimizing culture condition.

Key words: Trametes gibbosa, ligninolytic enzymes, manganese peroxidase, culture condition, orthogonal test