| Ectomycorrhizal (ECM) fungi, like wood and litter decaying fungi, are believed to produce extracellular oxidative enzymes. Oxidative enzymes associated with lignin degradation have been demonstrated to effectively degrade recalcitrant organic compounds, including chlorinated pesticides and polycyclic aromatic hydrocarbons (PAHs). This thesis describes a suite of experiments investigating ECM fungi lignolytic enzymes and the fate of organochlorine pesticide in Alaskan ECM fungal cultures. In this study, molecular techniques were employed to assess the potential of Alaskan ECM fungal cultures to produce the lignolytic enzymes lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (Lac). ECM mycelia were first collected and cultured from a contaminated site in Fairbanks, AK. The site contained soils contaminated with the organochlorine pesticides aldrin (approximately 1200 mg/kg) and dieldrin (approximately 600 mg/kg), as well as PCBs, DDT, and other recalcitrant organic contaminants. Cultures obtained at this site were assayed via polymerase chain reaction (PCR) for the presence of LiP, MnP, and Lac genes. The PCR products were compared with similar products from Hebeloma crustuliniforme, a well-studied ECM species, and Phanerochaete chrysosporium, a lignin-degrading white rot fungi. Presence of the enzyme-encoding genes would indicate a potential to produce lignolytic enzymes. In a follow-up experiment, the Fairbanks ECM cultures were grown in liquid media in the presence of aldrin under two different nutrient regimens. Aldrin degradation was assessed in these systems, and the results were compared with those from H. crustuliniforme and P. chrysosporium cultures grown under similar conditions. Results of these experiments are presented in the context of employing Alaskan ECM systems for remediation of persistent organic pollutants. |
