P13: Study of the indigo carmine discoloration by the immobilization of extracellular enzymes of Trametes versicolor

The textile industry is considered as a big pollution problem. The World Bank estimates that 17 to 20 percent of industrial water pollution comes from textile dyeing and treatment, effluents contains a lot of chemicals making the treatment hard task..

Residual medium of Trametes versicolorwas ultra filtrated to concentrate the enzymes and it was used for the immobilization process on silica. The process include glutaraldehyde as a crosslinking and 3 amine-propyltrietoxisilane, it was tested three different dissolvent for the silanization reaction: water, ethanol and acetone. In order to evaluate which dissolvent was better, it was measure the protein and activity of the immobilized enzyme and calculated the indigo carmine discoloration kinetic parameters. With the three dissolvent the amount of protein immobilized was similar, nearby 2 mg/g support; the laccase activity was 8020, 9920 and 11830 U/mg protein, using water, ethanol and acetone respectively,

The optimal pH and temperature were pH=3 and 60 ^oC for the system using water, and pH=4 and 60 ^oC for the systems using ethanol or acetone. The kinetic parameters measured using indigo carmine as a substrate was: Vmax 27, 28 and 30 micromole/min and Kg was 15, 11 and 10 micromole, using water, ethanol and acetone respectively. The system using water completed 41 cycles of use, with ethanol 40 cycles and using acetone was completed 45 cycles  in 4 months.

It was possible the enzyme immobilization without purification, the dissolvent used in the silanization reaction had effect over the immobilization method, the best was acetone.