A number of aerobic species capable of decolorizing some of the dyes in a textile mill effluent were isolated. One of the isolates was able to decolorize Terasil black dye under aerobic conditions in the presence of an exogenous carbon source after 5 days. Glucose or starch (%1 ea) are essential for decolorization but the process proceeds faster in the presence of 0.5% yeast extract. Results of the BOD5 show that the untreated effluent samples have a low BOD value, whereas treated samples show an initial increase in BOD up to 15 days followed by a decrease after 20 days. FT-IR and GC-MS data also reveal that the initial components in the untreated effluent disappear after 20 days of treatment, confirming biodegradation of the dye. Phytotoxicity tests on the untreated effluent samples using the seeds of Lens orientalis, Triticum aestivum, and Triticum boeoticum indicate that the first one is the most sensitive while the last one is the most resistant. On the other hand the treated effluent allows 90% germination in Triticum boeoticum seeds and 100% germination in the other two. (c) 2006 Wiley Periodicals, Inc.