Removal of pharmaceuticals, steroid hormones, phytoestrogens, UV-filters, industrial chemicals and pesticides by Trametes versicolor: Role of biosorption and biodegradation
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This study reports the removal of 30 diverse trace organic contaminants (TrOC) by live (biosorption + biodegradation), intracellular enzyme-inhibited and chemically inactivated (biosorption only) whole-cell preparations and the fungal extracellular enzyme extract (predominantly laccase) from Trametes versicolor (ATCC 7731). Because phenolic substrates are amenable to degradation by laccase, all 14 phenolic TrOC were readily biodegraded. On the other hand, only eight of the 16 non-phenolic TrOC were readily biodegraded while the removal of hydrophilic TrOC (log D < 3) was negligible. With the exception of diclofenac, no non-phenolic TrOC were degraded by the extracellular enzyme extract. The whole-cell culture showed considerably higher degradation of at least seven compounds, indicating the importance of biosorption and subsequent degradation by intracellular and/or mycelium associated enzymes. Improvement (20-90%) of enzymatic degradation of four phenolic and seven non-phenolic TrOC was achieved in the presence of a redox mediator. Compared with the whole-cell culture, mediator-amended extracellular extract achieved better removal of six TrOC, but lower removal of six others. A particular concern was the increased toxicity of the treated media when the redox-mediator was used. In addition to reporting the white-rot fungal removal of two UV filters, three phytoestrogens and a few other pharmaceutically active TrOC for the first time, this study provides unique insights into their removal mechanisms.
International Biodeterioration & Biodegradation