Immobilization of wood-rotting fungi laccases on modified cellulose and acrylic carriers

Extracellular laccases produced by three different wood-rotting fungi, Cerrena unicolor, Heterobasidion annosum and Trametes versicolor, were immobilized via covalent bonds formation on DEAE-Granocel 500, CM-Granocel 500, and acrylic carriers. Out of the tested carriers, only the DEAE-Granocel 500, which was activated by divinyl sulphone appeared to be a suitable matrix for the expression of enzymic activity. Only one laccase of all the tested enzymes produced by C. unicolor showed the best binding to the carrier and a satisfactory enzymic activity. The immobilized laccase exhibited the highest enzymic activity at pH 5.2 and it was more resistant to thermal denaturation than the native enzyme. At 90 degreesC, it retained 75% activity compared to the free enzyme. It was also more stable during storage at 4 degreesC: after 4 months the immobilized laccase retained 98% of initial activity. Immobilized C. unicolor laccase was active in 10-60% concentration of methanol, acetone, isopropanol or acetonitrile. The best enzymic activity was observed in 20% solution of acetonitrile in buffer. (C) 2002 Elsevier Science Ltd. All rights reserved.