Polycyclic Aromatic Hydrocarbons (PAHs): Degradation and Fungal Biomass (Ergosterol) in Sediment with added Nitrogen

Abstract

White rot fungi, Pleurotus ostreatus, is capable of degrading a wide range of organic contaminants including PAHs. Bioremediating polycyclic aromatic hydrocarbons (PAH) contaminated river sediment with P. ostreatus maybe a viable and less invasive method to reduce risk of exposure. The first part of this research was to determine the degradation of PAHs from contaminated sediment. The second part was to determine if sterols (ergosterol) and PAHs can be extracted with a single extraction method. Ergosterol is produced by living fungi and can be used as a measurement of fungal biomass. Contaminated river sediments were treated with P. ostreatus, grown on barley, and various amendments then incubated at 25 ⁰C. Amendments included sawdust and nitrogen supplement to stimulate fungal growth. The treatment with P. ostreatus showed degradation of total PAHs after 21 days using a Lipid Extraction Method and GC/MS. These results show that P. ostreatus is able to colonize in highly contaminated Mahoning River sediment and degrade the PAHs present. To extract ergosterol and PAHs simultaneously an Ergosterol Extraction Method (EEM) was developed. Various samples were prepared with sediment, sediment and fungi grown on barley, sediment and fungi grown on potato dextrose agar (PDA) or only fungi grown on PDA or barley. The EEM was successful in extracting ergosterol from fungi grown on barley resulting in concentrations from 17.5 - 39.9 mcg/g ergosterol. Similar results were seen in the other treatments. PAHs were also found extracted in much greater amounts compared to the Lipid Extraction Method. In addition, cholesterol, usually found in animals, was detected in the fungi P. ostreatus at easily detectable levels. With better optimization of amendments, Ergosterol Extraction Method could be highly useful and effective in analyzing the level of fungal biomass as well as PAH contaminants during bioremediation efforts.