Decolorization Of Dyes By A Mixed Culture Of Trametes Sp. SQ01 And Chaetominum Sp. R01

At present there are many alternatives to eliminate the colored effluents in wastewater. Due to friend-environment, low cost and higher decolorization rate, microbial biodegradation have attracted more interest. Up to now, white rot fungi have been reported to be the most used microorganism. It has been accepted that some extracellular lignin enzymes produced by white rot fungi, such as lignin peroxidase (LiP), laccase (Lac) and Manganese peroxidase (MnP) are responsible for decolorizing the dyes. However, there was low decolorization efficiency for some dyes by monoculture of white rot fungi, such as triphenylmethane dyes and azo dyes. Recently, it is confirmed that mixed microbial populations performed better than single microorganism did.A new fungus isolated from the contaminated culture of SQ01, which produced higher level of MnP activities compared with pure culture of SQ01, was designated R01. Phylogenetic analysis and rDNA sequence comparison indicated that strain R01 was a member of the genus Chaetomium, named by Chaetomium sp. R01. The effects of inocululation amount and timing of C. sp. ROl on MnP production by mixed culture of strain SQ01 and strain ROl was studied. The results showed that a plug of strain SQ01 and addition to the medium after one day of cultivation of strain SQ01 are an optimum for MnP production, at this time, MnP activity was 5.5 times higher that of the monocultures of T. sp. SQ01.Four dyes including Congo Red, Acid Red, Orange G and Bromphenol Blue were decolorized by a mixed fungal culture of Trametes sp. SQ01 and Chaetomium sp. R01, which were newly developed in our laboratory. MnP production was inhibited by about 40%-75% by the four dyes in mixed culture of SQ01 and ROl. The decolorization rates of mixed culture of strain SQ01 and ROl were increased by 20%-50% compared to the monoculture of SQ01. After 3 days,75%-94% of four dyes were decolorized by mixed culture of SQ01 and ROl, while the decolorization rate was only about 41%-75% by strain SQOl alone. The time-point of dye addition remarkably influenced the efficiency of decolorization by the mixed culture. The decolorization rates of dyes added to the medium after 4 days of mixed cultivation were significantly higher that that at the start of mixed cultivation. In addition to biodegradation, biosorption also played an important role in the decolorization process. The biosorption of Orange G, Bromphenol Blue and Acid Red accounted for 2%,5% and 15% of the total color removal, respectively. However, the biosorption rate of Congo Red reached up to 60%.The fungi consortium, consisting of T. sp. SQ01 and C. sp. R01, was used for decolorizing four kinds of triphenylmethane dyes, which were decolorized by individual fungi with a low efficiency. The fungi consortrum was capable of decolorizing Malachite Green, Crystal Violet, Coomassie Brilliant Blue G250 (CBB G250) and Cresol Red with the decolorization rate of 63%-96%, was much higher than that of monoculture of strain SQ01 (38%-72%). MnP activity of consortim was inhibited about 50%-88%, lower than the inhibition rate (53%-92%) in the monoculture of SQ01 by triphenylmethane dyes. For consortium, an efficiency of decolorization of Malachite Green, Crystal Violet and CBB G250 was obtained when added after 4 days of mixed cultivation rather than at the beginning of mixed culture, with the exception of Cresol Red. This is the first report that the filamentous fungi consortium has a great potential for decolorizing of synthetic dyes.In addition to Congo Red, laccase played a leading role in the decolorization of Orange G, Malachite Green, Cresol Red and Crystal Violet by mixed enzymes of laccase and manganese peroxidase. Orange G was decolorized better by laccase rather than mixed enzymes, while the decolorization rates of other four dyes in mixed enzymes were higher than that of anyone of enzymes. For Malachite Green, especially, the decolorization rate reached up to 95%. Cresol Red was not a good substrate for mixed enzymes, and the decolorization rate was less than 40%.