Fungal laccase: copper induction, semi-purification, immobilization, phenolic effluent treatment and electrochemical measurement

Abstract

The laccase activity induced by copper ions in Trametes versicolor by two inducers was studied and the aims were to show that it is possible to obtain a high laccase activity in almost 12 of the enzymes product using a basic culture medium but different copper concentration. Laccase was inducted by 2,5-xylidine and copper sulfate. Semi-purification of the crude laccase was carried out through precipitation and the column separation with NaCl gradient. In order to apply in an effluent treatment, laccase was immobilized on different vitroceramics supports, pyrolytic graphite and also on a carbon fiber electrode as biosensor. The maximum laccase activity was 40,774.0 U L-1 at the 12th day. The best support for immobilization was pyrolytic graphite (glutaraldehyde treated-94% efficiency). Total phenol removal in Kraft E1 effluent was 19% for immobilized pyrolytic graphite with the mediator present. The biosensor prepared with this material showed a good linear response to catechol. The optimization of laccase activity induction through the combination of 2,5-xylidine and cooper sulfate was obtained and led to its use in environmental remediation.   Key words: Trametes versicolor, laccase induction, semi-purification, immobilization, effluent treatment.