Transformation of Indigo carmine by Phanerochaete chrysosporium ligninolytic enzymes

The reaction between P. chrysosporium extracellular ligninolytic peroxidases and the dye Indigo carmine was studied. This dye can be successfully decolorized by both manganese (MnP) and lignin (LiP) peroxidases. By using a proper culture medium composition, a growth medium exhibiting high MnP or high LiP activity was obtained. Additionally, some peroxidase isoenzymes were isolated. Although the dye was successfully decolorised by both groups of extracellular peroxidases, the reaction by MnP was faster. Besides a yellow final product, the decolorization of Indigo carmine by MnP resulted in a red product formation that was not observed at the decolorization by LiP. The final concentration of the red product can be influenced by the pH value of the reaction mixture as well as by the initial dye concentration. The maximum formation of the red product was achieved at pH 5 with 60 mg/liter of the Indigo carmine in the reaction mixture. The red product was isolated and partially characterized using UV-VIS and 1H NMR spectroscopy, and TLC.