Biological elimination of polycyclic aromatic hydrocarbons in solvent extracts of polluted soil by the white rot fungus, bjerkandera sp. strain bos55

Polycyclic aromatic hydrocarbons (PAH) are persistent priority pollutants of soil and sediments. Miscible solvent extraction of the soil has previously been shown to effectively clean-up PAH pollution. The purpose of this study was to evaluate the use of the white rot fungus, Bjerkandera sp. strain BOS55 in initiating the degradation of PAH present in solvent extracts. The PAH in extracts of polluted soil added to 9-day-old liquid fungal cultures were removed by 80% in 7 days with 2% (v/v) ethanol in the medium. Smaller PAH compounds of only a few rings were degraded more rapidly than complexer PAH compounds having more rings. Phenanthrene, anthracene and pyrene with 3 to 4 rings were eliminated by 96.8 to 99.5%; whereas, benzo[b]fluoranthene and indeno[123cd]pyrene of 5 and 6 rings were eliminated by 52 and 20% in 7 days, respectively. When the PAH extract of polluted soil was incubated in fungal cultures together with 20% acetone or ethanol, the cells were killed by the solvent. Nonetheless, partial bioconversion of PAH occurred which was most likely due to the presence of extracellular peroxidases.