Decolorization Of Dyes By Schizophyllum Sp. F17 And Catabolite Analysis Of Congo Red

The total annual world textile dye production is estimated at about 800,000 tons, among which azo dyes account for 80%. During processing, up to 10～15% of the used dyestuff are released into the process water, and generating serious pollution. White rot fungus are directly involved in the degradation of various xenobiotic compounds including dyes. The study on the treatment of dye effluents by White rot fungus already obtained the widespread value.The white-rot fungal strain--Schizophyllum sp. F17, which was isolated and stocked by our Lab., is effective to decolorize a wide range of structurally diverse synthetic dyes. This paper studied the growth and decolorization ability of Schizophyllum sp. F17, and the effect of culture temperature, original pH, the time of dye addition, original dye concentration, inducer, crudes, metal ions, inhibitor on the dye decolorization percentage. At the same time, a novel decolorization and degradation system was designed, and the test of dye decolorization by schizophyllum sp. F17 under non-sterile conditions was studied too. Moreover, a degradation product of Congo Red was separated and identified, and the degradation approach was speculated. The results showed:1. The growth rate of Schizophyllum sp. F17 in potato integration solid culture mediun was quicker than that in nutrient nitrogen limited and wort solid culture medium, and the optimum growth temperature was 28℃the range of growth pH was 4.5～8.0. The optimum growth temperature of Phanerochaete chrysosporium and Trametes versicolor were 37℃and 28℃respectively, the ranges of growth pH were all 4.5～6.0.2. Schizophyllum sp.F17, Phanerochaete chrysosporium and Trametes versicolor all had the ability to decolorize Congo Red. The decolorization percentage of Congo Red reached 66.9%, 82.1% and 81.9% respectively after 72h in nutrient nitrogen limited liquid culture medium, while temperature 28℃, original dye concentration 100mg·L^-1.3. The optimum conditions of Congo Red decolorization by Schizophyllum sp. F17 were as follows: temperature 28℃, initial pH 4.5, dyes added to the medium after 3 days of incubation in shaken flasks, and original dye concentration was 100mg·L^-1. The addition of veratryl alcohol, tween 80, potato extract and deal rag all had a great promotion on decolorization percentage, the maximum decolorization percentage of Congo Red reached 97.4% after 72h, but the addition of NaN₃ and KCN all had maked inhibition action on decolorization.4. The optimum conditions of enzyme production by Schizophyllum sp. F17 were as follows: temperature 28℃, initial pH 4.5, dyes added to the medium after 3 days of incubation in shaken flasks, and original dye concentration was 100mg·L^-1. The maximum activity of MnP, the main degradation enzyme, reached 103.4 U·L^-1, LiP activity was very low, and no laccase was detected. Moreover, there was a good linear relationship between percentage decolorization of Congo Red and cimulative MnP activity, and correlation coefficient was 0.973.5. A novel decolorization and degradation system was established: 0.1 mol·L^-1 lactic acid-sodium lactate buffer solution(pH=4.0) 100 mL·L^-1, dyes 100 mg·L^-1, deal rag 3.0 g·L^-1, wet mycelial pellets about 70.0 g·L^-1. Schizophyllum sp. F17 was effective to decolorize and degrade the tested dyes in the system, and the decolorization percentage of Congo Red and Alizarin Red all reached 90% upwards after 120h, the degradation percentage all reached 80% upwards. Schizophyllum sp. F17 was also effective to decolorize Congo Red in the system under non-sterile conditions, and the decolorization and degradation percentage reached 89.7 % and 78.6 % respectively after 120h.6. In the novel decolorization and degradation system, Schizophyllum sp. F17 was effective to decolorize and degrade Congo Red, and the decolorization and adsorption percentage reached 95.1% and 6.7% respectively after 192h. Therefore, it could be known that the decolorization of Congo Red by Schizophyllum sp. F17 in the system was achieved mainly by degradation. Furthermore, the UV-Vis spectrum of Congo Red reveals that the absorption peak at 495 nm vanished and some new absorption peaks appeared at ultraviolet region at both 96h and 192h of decolorization. A degradation product of Congo Red, molecular weight of 184.2 Da, was separated by HPLC. The MS and FTIR analyses demonstrate that the functional groups were-C₆H₄-and arylamine, suggesting that the degradation product was benzidine, which was confirmed by NMR, thereafter benzidine was degraded gradually with operational time.