Laccases from the lignin-degrading basidiomycetes Trametes versicolor, Polyporus pinisitus and the ascomycete Myceliophthora thermophila were found to decolorize synthetic dyes to different extents. Differences were attributed to the specific catalytic properties of the individual enzymes and to the structure of the dyes. Due to their higher oxidative capacities, the laccases from the two basidiomycetes decolorized dyes more efficiently than that of the ascomycete. The azo dye Direct Red 28, the indigoid Acid Blue 74 and anthraquinonic dyes were directly enzymatically decolorized within 16 h. The addition of 2 mM of the redox-mediator 1-hydroxybenzotriazole further improved and facilitated the decolorization of all nine dyes investigated. Laccases decolorized dyes both individually and in complex mixtures in the presence of bentonite or immobilized in alginate beads. Our data suggest that laccase/mediator systems are effective biocatalysts for the treatment of effluents from textile, dye or printing industries.
Aims: To demonstrate the occurrence of cellulolytic bacteria in the termite Zootermopsis angusticollis. Methods and Results: Applying aerobic cultivation conditions we isolated 119 cellulolytic strains from the gut of Z. angusticollis, which were assigned to 23 groups of aerobic, facultatively anaerobic or microaerophilic cellulolytic bacteria. 16S rDNA restriction fragment pattern and partial 16S rDNA sequence analysis, as well as numerical taxonomy, were used for the assignment of the isolates. The Gram-positive bacteria of the actinomycetes branch could be assigned to the order Actinomycetales including the genera Cellulomonas/Oerskovia, Microbacterium and Kocuria. The Gram-positive bacteria from the order Bacillales belonged to the genera Bacillus, Brevibacillus and Paenibacillus. Isolates related to the genera A®pia, Agrobacterium/Rhizobium, Brucella/Ochrobactrum, Pseudomonas and Sphingomonas/Zymomonas from the a-proteobacteria and Spirosoma-like from the``Flexibacteriaceae'' represented the Gram-negative bacteria. Conclusions: A cell titre of up to 10 7 cellulolytic bacteria per ml, determined for some isolates, indicated that they may play a role in cellulose digestion in the termite gut in addition to the cellulolytic¯agellates and termite's own cellulases. Signi®cance and Impact of the Study: The impact of bacteria on cellulose degradation in the termite gut has always been a matter of debate. In the present survey we investigated the aerobic and facultatively anaerobic cellulolytic bacteria in the termite gut.
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