Abstract
Thermophilic fungi are known to develop different metabolic and catabolic activities that enable them to function at elevated temperatures. Screening heat-resistant fungi, as promising resources for enzymatic activities, are still recommended. A total of eleven wood-decay thermophilic fungal strains were isolated from decaying organic materials (DOM) collected from arid areas of Khulais (Saudi Arabia). Six of these isolates are laccase-producing thermophilic strains growing at 50 degrees C. Among Laccase positive (Lac+) isolates, Chaetomium brasiliense (G3), Canariomyces notabilis (KW1), and Paecilomyces formo-sus (KW3) were exploited to treat single selected endocrine-disrupting chemicals (EDCs) that belonged to different classes (synthetic steroid hormone: 17 alpha-ethinyl estradiol (EE2), and alkylphenols:4-tert-butylphenol (4-t-BP)). Chaetomium sp. was selected due to its potentialities against target EDCs, and then, their laccases were extracted and exploited for the biocatalytic degradation of treated municipal sewage wastewaters (TMWW) mixed with 4-t-BP and EE2. The results show that within 2 h of catalyzing at 50 degrees C, laccase could degrade 60 +/- 4.8% of 4-t-BP; however, it oxidized EE2 less efficiently, reaching 35 +/- 4.1%. The influence of some redox mediators on the laccase oxidation system was investigated. The 1-hydroxybenzotria-zole (HBT) and syringaldehyde led to the highest transformation rates of EE2 (approximately 80 +/- 2.4%). Near-total removal (90 +/- 7.2%) of 4-t-BP was achieved with TEMPO in 2 h. With the metabolites identified through gas chromatography-tandem mass spectrometry (GC-MS), metabolic pathways of degradation were suggested. The results highlight the potential of Chaetomium sp. strains in the conversion of micropollutants.