Transformation of Reactive Blue 19 by a recombinant peroxidase DyP.

Wastewater containing recalcitrant dyes causes environmental problems. A new superfamily of heme-containing peroxidases, dye-decolorizing peroxidases (DyPs), has been found to decolorize different kinds of dyes, especial anthraquinone dyes efficiently. However, the mechanism of dyes degradation by DyPs has not been fully understood and the toxicity of dye degradation intermediates by DyPs catalysis to microbes is unclear. In this study, a purified recombinant Thermobifida fusca DyP (TfuDyP) in E. coli BL21(DE3) was used to treat Reactive Blue 19 (RB19), an anthraquinone dye. The reaction intermediates analyzed by ultra performance liquid chromatography/mass spectroscopy (UPLC-MS) indicated the initial site of TfuDyP attack on RB19. In addition, it was found that both RB19 and its incomplete degradation products inhibited the growth of Bacillus subtilis. These findings provided a novel understanding of DyPs catalysis to anthraquinone dyes.