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Background: The major concern to meet environmental regulations is related with the decolorization and detoxification of industrial dyes contaminated wastewater. So, this study was undertaken to examine the use of bacteria isolated from wastewater of textile factories in the removal of the synthetic textile dyes (Sudan Black, Methyl Red, Malachite Green, Rhodamine B and Brilliant Cresyl Blue). Methods: Dye contaminated wastewater was collected from some synthetic textile factories in Gorgan and Gonbad, Iran, and evaluated for the screening and isolation of bacteria capable of decolorizing textile dyes. The effect of function of operational parameters includes temperature (25, 37 and 50 °C), pH (4, 6 and 8) and initial dye concentration (100, 200 and 300 mg/mL) on the efficiency and rate of discoloration was assessed. Results: Totally, out of the 19 bacterial isolates from textile wastewater: Five bacterial isolates showed dye discoloration ability and the most efficient bacterial isolates were Enterococcus faecium and Pantoea spp. that decolorized Methyl Red, Sudan Black and Malachite Green dyes at 25-37°C, concentration of 200-300 mg/mL and slightly acidic to neutral pH. Enterococcus bacterium was able to decolorize Sudan Black to the 19.79% in the concentration of 100 mg/ml and pH=8 and temperature of 50°C. The highest amount of decolorizing was observed by Pantoea on Malachite Green to the amount of 73%. Enterococcus had the highest decolorizing on Methyl Red to the 65.7%. The amount of decolorizing on Sudan Black by Enterococcus (49.9%) was also higher than Pantoea (39.7%). Conclusion: Isolated bacteria had a significant reduction in toxicity and cationic malachite green dye and azo dye- methyl red. Thus, bacteria can be used in full-scale industrial wastewater treatment with the bio-synergy and its application in discoloration. [ABSTRACT FROM AUTHOR]