Study On The Degradation Of Dyes With Different Structures By White Rot Fungus And Its Laccase

Dyes are widely used in textile, paper, food and other industries. But most of dyes areconsidered to be toxic and recalcitrant. The environmental pollution caused by dyes isserious nowadays. White rot fungi are extremely valuable microbial resources，they haveoutstanding abilities to degrade natural and synthetic chemicals with different structures.They have broad application prospects of bioremediation and degrading lignin andenvironmental pollutants. This research focuses on the application of white rot fungusGanoderma sp. En3and its laccase in degrading four kinds of dyes with differentstructures (azo, triphenylmethane, anthraquinone and indigo dyes) and their simulated dyeeffluents.The following results are obtained by the biodegradation of azo dyes and theirsimulated dye effluents: Ganoderma sp. En3and its laccase have strong ability ofdecolorizing seven different azo dyes, and the decoloration rate is related to the chemicalstructure of dyes. The degradation efficiency of Reactive orange16(RO16) which is mostdifficult to be degradated can be enhanced effectively by means of optimizing cultureconditions. The decolorization efficiency for1000mg/L RO16is higher than90%within24hours in the presence of glycerol and peptone which is the optimized source of carbonand nitrogen. The strong tolerance of Ganoderma sp. En3to azo dyes is one reason forhigh degradation efficiency. Under the condition of in vitro degradation, crude laccaseproduced by Ganoderma sp. En3has strong ability to decolorize these seven azo dyes.The laccase mediator syringaldehyde plays a significant role in promoting decolorizationefficiency. The concentration and type of metal ions have no influence on the degradationof azo dyes by crude laccase. The possible pathway of degradation of RO16is alsospeculated in this work.White rot fungus Ganoderma sp. En3and its laccase also have strong ability todecolorize triphenylmethane, anthraquinone and indigo dyes with high concentrations.The biodegradation efficiency is associated with culture conditions and initialconcentration of dyes. Under the condition of in vitro degradation, the decolorizationefficiency is related to the initial concentration of dyes and the type of mediator(Syringaldehyde> ABTS> Acetosyringone> Acetovanillone). Ganoderma sp. En3alsohas strong ability to decolorize the real textile dye effluent containing indigo dyes.In summary, this study successfully establishes two systems for effectively degrading four kinds of synthetic dyes (azo, triphenylmethane, anthraquinone and indigo dyes),simulated dye effluents and the real textile dye effluent: by fungal whole cultures and bycrude laccase produced by Ganoderma sp. En3. Ganoderma sp. En3has strongadaptability and tolerance to different kinds of dyes. Laccase plays an important role in theefficient decolorization of different dyes by this fungus.Our results suggest that the whiterot fungus Ganoderma sp. En3has great potential for practical and useful application indecolorizing and degrading industrial dyes and dye bath effluents. This research will lay asolid foundation for better exploitation and utilization of white rot fungi in the area ofbioremediation and environmental biotechnology.