| Summary: | 6 Abstract The aim of this Ph.D. thesis was to characterize ligninolytic activities of two white- rot fungi, Dichomitus squalens and Irpex lacteus, cultivated on various solid supports in their immobilized form and to identify the role of ligninolytic enzymes in the decolorization of synthetic dyes. Significant induction of laccase activity was observed in D. squalens pine wood cultures when compared to liquid cultures. The induction of laccase was probably due to the presence of phenols, extractable from wood with organic solvents. Two laccase isoforms, Lc1 and Lc2, were isolated from the culture liquid using FPLC. The enzymes revealed identical molecular masses of 68 kDa, however, they differed in isoelectric points and their dye decolorization capacity. The decolorization of the azo dye RO16 by Lc1 in the presence of redox mediator was followed by a regressive colorization of the sample when incubated for 72 h. Conversely, no backward trend was observed during RO16 decolorization using Lc2. In contrast to D. squalens, I. lacteus immobilized on pine wood cubes produced a low level of manganese peroxidases and no laccase induction was observed. Both fungi produced MnP as a dominant enzyme in solid state wheat straw cultures. D. squalens MnP obtained from the wheat straw cultures was able to decolorize...
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