| In this paper ,three different media(A: for yeast cultivation; B for Laccase producing and D for white rot fungi cultivation) were compared for enriching and screening of decolorizing fungi culture from 4 different natural environment using Reactive Black 5 and Reactive Red M-3BE as selecting factors. The results showed that the microbe consortium obtained from the yeast cultivation medium could decolorize various dyestuffs, have the highest microbial diversity, and have the ability of producing at least 2 kinds of enzymes belonging to lignin peroxidase system. Due to the above properties and relatively simple composition, yeast medium was used for decolorizing study and reactor establishment. 2 groups of mixed cultures were obtained which could decolorize Reactive Red M-3BE, Acid Red A, Reactive Blue KNR with the rate of 99.73%, 97.42% and 64.59% respectively. From them, 16 strains of fungi were isolated and primarily identified as Saprolegniaceae, Eurotiaceae(Monascuswent), Erysiphaceae and Physodermatacea according to their morphological characterization. Among them, 8 strains exhibited obvious decolorizing effects to Reactive Red M-3BE, and only 2 strains (AaR1 and AeR1) reached the decolorizing efficiency of the microbial consortium. The two strains were identified as Fusarium oxysporum (99%) and Geosmithia viridis (98%) based on their 26S rRNA gene sequences.A biofilm reactor was constructed using the selected mixed microbial consortium. The influence of the nutrition concentrations on the decolorization and mineralization rates of Reactive Black BES were studied under the condition of air 40L/min, temperature 28℃～30℃and HRT 13h. The results showed that glucose concentrations had remarkable influence on the decolorization and mineralization rates, effluent pH and SS when simulated dyeing wastewater was fed in the reactor. When the yeast cultivation medium was used as the nutrient feed without any dilution, complete color removal for 30 mg/L reactive black BES was obtained, but with a low pH effluent and high concentration of SS (1300 mg/L), which suggested an anaerobic condition in the system in this case. The influent medium was diluted by 5 and 10 times to reduce the effect of glucose on decolorization. The mineralization rate was increased to 67.6% while no residual glucose was detected and the pH of the effluent was near the neutral value under the condition of 10 times dilution medium as nutrient feed although the color removal rate had a bit drop in the range of 69%~79% in this case. Further decolorization test of Reactive Red BES and Acid Red B by this reactor at the same nutrient feed conditions indicated a wide decolorization range to various dyestuffs with 62.3%～68.7% and89.9%～92.9% color removal rate and 25.4%～51% and 86.5%～90% mineralization rate, respectively. Besides, the bioreactor exhibited high color removal efficiencies to the real textile wastewater with both 90% removal rate of COD and chroma under the condition of 0.2g/L glucose fed even when the influent COD and chroma were changed within 750～1175mg/L and 200~320 respectively. Biofilm samples were collected to monitor the microbial community in the system at every steady stage of different operation conditions. The cultivation results of fungi to bacteria 6.8:1～51.8:1 suggested an absolute dominant position of fungi in the system along the whole 3 months running under open conditions. Further analysis of microbial community was conducted by constructing 16S rRNA and 26S rRNA clone libraries. The results showed that all bacterial clones were clustered in 4 groups: Alphaproteobacteria,Betaproteobacteria,Gammaproteobacteria,Actinobacteria with the majority of Alphaproteobacteria (71.4%) in the system and all the fungal clones were clustered in genera of Candida and Trichoderma with 70% of Candida.spp and 26.7% of Trichoderma viride. It was obvious that yeasts were the predominant fungi in the system.
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