Synthetic dyes biodegradation by fungal ligninolytic enzymes: Process optimization, metabolites evaluation and toxicity assessment

• Published in: Journal of hazardous materials Vol. 400; p. 123254
• Main Authors: Sosa-Martínez, Jazel Doménica, Balagurusamy, Nagamani, Montañez, Julio, Peralta, Rosely Aparecida, Moreira, Regina de Fátima Peralta Muniz, Bracht, Adelar, Peralta, Rosane Marina, Morales-Oyervides, Lourdes
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.12.2020
• Subjects: Biodecolorization; Biodegradation, Environmental; Coloring Agents - toxicity; Congo Red; Ligninolytic enzymes; Optimization; Oxidation-Reduction; Phanerochaete; Synthetic dye; Biodecolorization; Synthetic dye; Ligninolytic enzymes; Optimization
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.123254

[Display omitted] •Peroxidases were produced with low-cost residue via solid fermentation.•Biodegradation process was improved and the byproducts structures were proposed.•Methyl green in-vitro degradation products showed lower toxicity than original dye.•Congo red in-vitro degradation products showed higher toxicity than original dye.•Successful use of crude extract could mitigate the high costs of purification steps. This work aimed to provide information that contributes to establishing environmental-friendly methods for synthetic dyes’ degradation. The potential decolorization capacity of the crude enzymatic extract produced by Phanerochaete chrysosporium CDBB 686 using corncob as a substrate was evaluated on seven different dyes. Critical variables affecting the in-vitro decolorization process were further evaluated and results were compared with an in-vivo decolorization system. Decolorization with enzymatic extracts presented advantages over the in-vivo system (higher or similar decolorization within a shorter period). Under improved in-vitro process conditions, the dyes with higher decolorization were: Congo red (41.84 %), Poly R-478 (56.86 %), Methyl green (69.79 %). Attempts were made to confirm the transformation of the dyes after the in-vitro process as well as to establish a molecular basis for interpreting changes in toxicity along with the degradation process. In-vitro degradation products of Methyl green presented a toxicity reduction compared with the original dye; however, increased toxicity was found for Congo red degradation products when compared with the original dyes. Thus, for future applications, it is crucial to evaluate the mechanisms of biodegradation of each target synthetic dye as well as the toxicity of the products obtained after enzymatic oxidation.