Decolorization of 1-amino-4-bromoanthraquinone-2-sulfonic acid by a newly isolated strain of Sphingomonas herbicidovorans

A novel isolate of Sphingomonas herbicidovorans could decolorize 1-amino-4-bromoanthraquinone-2-sulfonic acid (bromoamine acid, BAA), an intermediate of anthraquinone dyes, and grow with it as the sole source of carbon. The strain was identified by 16S rRNA gene sequencing and physiological-biochemical test. The optimal condition for both decolorization and cell growth was found at temperature of 30 °C and pH 7.0, respectively. Furthermore, the decolorization efficiency could be enhanced with higher shaking speed. The percentage of BAA decolorization could be over 98% within 24 h even for the initial concentration greater than 1000 mg l−1. The decolorization kinetics could be reasonably described by the Monod equation. Additional carbon sources such as glucose could enhance the decolorization rate. During the decolorization process, the molecular of BAA cleaved, releasing phthalic acid and an end product which might be benzene derivative substituted by amino, bromo, hydroxyl and sulfonate groups according to the infrared spectral analysis.