Method to determine the decolorization potential of persistent dyes by white rot fungi by colorimetric assays

Decolorization assays allow to assess the ability of white rot fungi to degrade persistent organic molecules such as textile dyes and can contribute to discover microorganisms that can be used for bioremediation. The decolorization can be overlayed by the absorption from metabolites that are produced by fungi during screening, which interfere with the results. To compensate for this interference a method was developed by using different controls to subtract interfering signals. The method was designed for simple screening in multiwell plates that can be operated with a plate reader. It was applied to four different textile dyes (Reactive Black 5, Reactive Blue 4, Reactive Green 19, and Reactive Orange 16) that were degraded by the white rot fungus Phanerochaete velutina. The four textile dyes showed different results with a different degree of interference. The controls allow to compensate for interfering signals and to calculate kinetic parameters for the decolorization reaction and the enzymatic degradation. • Determine the non-enzymatic degradation of the dyes in experiments without fungi. • Determine the absorbance of metabolites and subtract it from the decolorization data to obtain the degradation of the dye. • Determine kinetic parameters of the degradation to compare the efficiency of the enzymes towards dyes.