FUNGAL DIVERSITY IN EUKARYOTE-DOMINATED BIOFILMS IN ACID MINE DRAINAGE

Eukaryote-dominated biofilms coat substrates in acid mine drainage (AMD) channels at the abandoned Green Valley coal mine site, western Indiana. Three distinct benthic communities are present: Euglena mutabilis-dominated, diatom-dominated, and filamentous algae-dominated. The E. mutabilis biofilm is the most common and is present year round, periodically covering up to 100% of the substrate. Isolated patches of diatom- and filamentous algae-dominated biofilms appear from mid to late summer and only expand across the substrate when conditions are more conducive for growth (i.e., following rainfall events that dilute the effluent). In this study, we investigate the occurrence of fungi in each of the biofilm types.

Preliminary microscopic investigations of the biofilms show no evidence of fungal hyphae, but fungi were isolated from the biofilms and from acid mine drainage samples using culturing techniques. Three growth media were used, resulting in isolation of different fungal taxa. Penicillium sp., Mucor sp., and yeasts were isolated on malt extract agar and chitin agar (near-neutral pH). Yeasts and a different species of Penicillium were isolated on a modified 9K medium (pH 3.0). Identification of seasonal trends in fungal species will continue through the summer of 2004. Future studies will focus on establishing possible synergistic relationships between fungi and other biofilm microbes, as well as evaluating the role of fungi in biomineralization in AMD systems.