In vivo and in vitro decolorization of synthetic dyes by laccase from solid state fermentation with Trametes sp. SYBC-L4

Synthetic decolorization of dyes through solid cassava residue substrate fermentation with Trametes sp. SYBC-L4 via in vivo and in vitro processes was investigated in this study. Effects of pH and mediator (1-hydroxybenzotriazole, HBT) concentration on dyes decolorization were evaluated. In vitro, decolorization ratios of dyes differed considerably in pH and increased with the increasing of HBT concentration. Crude laccase (50 U/L) derived from Trametes sp. SYBC-L4 decolorized 67.91 ± 1.25 % Congo red (100 mg/L), 94.58 ± 1.05 % aniline blue (100 mg/L) and 99.02 ± 0.54 % indigo carmine (100 mg/L) with 2.5 mM HBT at pH 4.5 in 36 h of incubation. In vivo, decolorization ratios of dyes were not enhanced by usage of the mediator. After 10 days of fermentation, decolorization ratio of Congo red (1,000 mg/kg), aniline blue (1,000 mg/kg) and indigo carmine (1,000 mg/kg) was 57.82 ± 0.84, 92.53 ± 1.12 and 97.26 ± 1.92 % without the usage of mediator at pH 4.5, respectively. Moreover, there was no obvious difference between the in vivo decolorization of aniline blue and indigo carmine in the pH range of 3.0–9.0. Results showed that Trametes sp. SYBC-L4 had great potential to be used for dyes decolorization via in vivo and in vitro processes. Moreover, in terms of pH range and mediator, in vivo decolorization with Trametes sp. SYBC-L4 was more advantageous since laccase mediator was needless and the applicable range of pH was broader.