Transformation of 2,4,6-trichlorophenol by free and immobilized fungal laccase

Laccase from the white rot fungus Coriolus versicolor was immobilized on Ce lite R-637 by covalent binding with glutaraldehyde. After a sharp primary d ecline in activity (up to 50%), the retained enzyme activity was stable ove r a storage period of 33 days at 4 degreesC. A comparative study of soluble and immobilized laccases revealed the increased resistance of immobilized enzyme to the unfavourable effects of alkaline pH, high temperature and the action of inhibitors. A combination of these properties of immobilized lac case resulted in the ability to oxidize 2,4,6-trichlorophenol (2.4,6-TCP) a t 50 degreesC at pH 7.0. The reactions of soluble and immobilized laccase w ith 2,4,6-TCP were examined in the presence and absence of redox mediators. 3,5-Dichlorocatechol, 2,6-dichloro-1,4-hydroquinone and 2,6-dichloro-1,4-h ydroquinone were found to be the primary products of 2,4,6-TCP oxidation by laccase. oligo- and polymeric compounds were also found.