A strain of Rhodocyclus gelatinosus (XL-1) from textile wastewater could decolorized Reactive Brilliant Blue (KN-R) under anaerobic conditions. XL-1 could not decolorize KN-R when it was the sole carbon source. In the presence of peptone, it could decolorize KN-R over 93% by co-metabolism at pH 7.0 and temperature 30 degreesC. Decolorization efficiency rose greatly at a fixed concentration of KN-R (50 mg/l) along with an increase in peptone concentration. Dye concentration had an influence on the decolorization rate, with an increase in the KN-R concentration, the decolorization rate increased. After 24 h, the KN-R concentrations in wastewater, which started with different initial values, had a tendency to a uniform value. Metal compounds, especially, AgNO3, HgCl2, ZnSO4, CuSO4, had a severe inhibitory effect on decolorization of KN-R: 1 mmol/l led to about 98% drop in decolorization efficiency, but MgSO4 and MnSO4 could appreciably increase decolorization of KN-R. The ultraviolet-visible absorbance spectra of the products were determined and the maximum absorption peak in visible spectrum shifted from 595 to 453 run. (C) 2002 Elsevier Science Ltd. All rights reserved.