Inhibitory effects of cadmium and hydrophilic cadmium telluride quantum dots on the white rot fungus Phanerochaete velutina

The white rot fungus <i>P. velutina</i> was investigated for its ability to decolorize the reactive textile dye Reactive Black 5 (RB5) that was co-exposed to CdCl₂ and quantum dots (QDs) consisting of a CdTe core capped with two different hydrophilic organic ligands (NAC and MPA). Without co-exposure, <i>P. velutina</i> completely decolorizes RB5 within 9 days. The highest inhibitory effect was found for soluble CdCl₂ with an EC₅₀ of 583 μg l^-1, followed by MPA-QDs (10,628 μg l^-1) and NAC-QDs (17,575 μg l^-1). The different EC₅₀ values indicate that the nanoparticle coatings have a strong influence on the inhibitory effects, as the organic ligands used for surface passivation prevented the leaching of acute toxic Cd ions from the metallic QD core. Compared to CdCl₂, the CdTe QDs were less inhibitory to the formation of fungal metabolites and their decolorization ability on co-exposed textile dyes. In addition, the literature comparison suggests that <i>P. velutina</i> is more resilient to cadmium than other microorganisms. The fungus could therefore be used for bioremediation applications of dye- or QD-contaminated wastewater from the textile or semiconductor industries.