Fluorene biodegradation by P. ostreatus—Part I: Biodegradation by free cells

Fluorene is one of the most common polycyclic aromatic hydrocarbons found in the environment and it is listed as a priority pollutant by EPA. In this present work, the biodegradation of fluorene (a polycyclic aromatic hydrocarbon) by Trametes versicolor (T. versicolor), Trametes trogii (T. trogii), Ganoderma carnasum (G. carnasum) and Pleurotus ostreatus (P. ostreatus) was investigated. While T. versicolor, T. trogii and G. carnasum degraded fluorene by 30%, P. ostreatus metabolized approximately 85% of a solution containing 30.0 mg L−1 of fluorene within six weeks. Additionally, this strain was able to completely degrade the fluorene in a 50.0-mg L−1 solution and was selected for further study. P. ostreatus were subject to varying fluorene concentrations and showed that cell growth toxicity increased with increasing fluorene levels in growth media. Furthermore, P. ostreatus reduced the fluorene in a 5.0-mg L−1 solution by 92.9%. Laccase and manganese peroxidase enzyme activity were also monitored to determine possible roles in fluorene degradation. Gas chromatography–mass spectrometry (GC–MS) and Fourier transform infrared spectroscopy (FTIR) analyses were also employed to identify metabolites. These results indicate that no remarkable metabolite was detected at the end of degradation process.