Morphology and Phylogenetic Characterization of Mn(II)-Oxidizing Superfund Site Fungal Assemblages.

Environmental remediation of contaminated sites requires a detailed understanding of the chemical and biological processes that occur within the remediation system. In the Farm Lot 86 Superfund site (Raleigh, NC), dissolved manganese from influent groundwater is being microbially oxidized and precipitated, resulting in manganese (Mn) oxide sludge formation in system components throughout pump-and-treat system. To better understand the geobiological processes associated with biogenic manganese oxide formation, we conducted an investigation of the microbial community within the sludge. Fungal isolates were cultured in solid and liquid acetate-yeast (AY) media and microscopy was conducted to characterize morphology and deposition patterns of mycogenic Mn oxides. Extracted DNA (ITS genes) from the isolates taken from the airstripper (Phoma sp., Coniothyrium sp.) and carbon filter units (Coprinellus sp.)  were found to be part of a phylogenetically diverse array of fungi closely related to known manganese oxidizers and lignin degraders, respectively.  The results of this study suggest that biological production of manganese oxides occurs in the system despite the presence of potentially toxic inorganic and organic contaminants. The study also suggests that isolates from the system may have utility in designed remediation systems where heavy metal precipitation by manganese oxide is desirable.