Decolorization mechanism of 1-amino-4-bromoanthraquinone-2-sulfonic acid using Sphingomonas herbicidovorans FL

Sphingomonas herbicidovorans FL decolorized 1-amino-4-bromoanthraquinone-2-sulfonic acid and grew with it as the sole carbon source. The maximum rate of decolorization was achieved during the exponential growth phase of the bacterial strain. Of the total organic carbon ∼52% could be removed, coupled with the partial release of ammonia, bromine and sulfate. Analysis of metabolites using gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry showed that phthalic acid was the metabolic intermediate and which may serve as the growth substrate for the bacteria. The end product was either 2-amino-3-hydroxy-5-bromobenzenesulfonic acid or 2-amino-4-hydroxy-5-bromobenzenesulfonic acid. A possible metabolic pathway is proposed.