Purification and characterization of laccase produced by Schyzophylum commune IBL-06. in solid state culture of banana stalks

Abstract

Shyzophyllum commune IBL-06 produced 367 IU/mL of laccase in solid state bioprocess of banana stalk under optimum physical and nutritional parameters. The optimum SSF conditions were pH 4.5; temperature, 35°C; inoculum size, 3mL (10 6-10 8 mL -1); moisture content, 60%; C:N ratio in the medium, 15:1 (glucose and ammonium nitrate as additional carbon and nitrogen sources, respectively), ABTS (1mM), 1 mL, and CuSO 4 (1mM), 1mL. Laccase was purified 3.95-fold with specific activity of 158 U/mg by ammonium sulfate precipitation, followed by gel filtration chromatography using Sephadex G-100 column. Molecular weight of the laccase was 63 KDa on SDS-PAGE. Purified laccase had an optimum pH of 6.0 and was stable in the pH range from 6 to 7. The optimum temperature was 40 °C, and it displayed considerable stability within the range 30 to 35 °C with 24 h incubation. Km and V max were 0.025 mM and 80 mM/min, respectively, using ABTS as a substrate. Copper sulfate increased the activity of purified laccase when used at low concentration, but silver nitrate exerted the strongest inhibition.