Decolorization and degradation of Eriochrome Black T by mycelial pellets of Lactarius deliciosus and toxicity evaluation

Abstract:

[Objective] The mycelial pellets of Lactarius deliciosus were used to decolorize and degrade the dye Eriochrome Black T (EBT).We investigated the performance and mechanism of the decolorization by the mycelial pellets under different environmental conditions.[Methods] Single factor experiments were conducted to explore the optimal decolorization performance of the fungi.We measured the fungal enzyme activity by spectrophotometry,and performed wheat seed germination test,E. coli contact toxicity test,and Caenorhabditis elegans toxicity test to evaluate the toxicity of the EBT solutions before and after decolorization.[Results] The results manifested that the mycelial pellets of L. deliciosus were slightly affected by the shaker temperature and rotation speed.At pH 5,28℃,and 120 r/min,the decolorization rate for 400 mg/L EBT solution was 97.14%.In the decolorization process,the mycelial pellets of L. deliciosus secreted three ligninases,namely lignin peroxidase,manganese peroxidase,and laccase,which had the maximum activities of (134.15±9.93),(64.1±2.98),and (12.43±0.34) U/L,respectively.We deduced that the mycelial pellets of L. deliciosus removed EBT by the synergistic effects of biosorption and degradation.The multi-level toxicity evaluation demonstrated that the dye wastewater after decolorization had significantly reduced toxicity.[Conclusion] All these results have an important reference value in exploring the process of dye wastewater treatment with biological method.