title: Watershed-scale fungal community characterization along a pH gradient in a subsurface environment cocontaminated with uranium and nitrate.
abstract: The objective of this study was to characterize fungal communities in a subsurface environment cocontaminated with uranium and nitrate at the watershed scale and to determine the potential contribution of fungi to contaminant transformation (nitrate attenuation). The abundance, distribution, and diversity of fungi in subsurface groundwater samples were determined using quantitative and semiquantitative molecular techniques, including quantitative PCR of eukaryotic small-subunit rRNA genes and pyrosequencing of fungal internal transcribed spacer (ITS) regions. Potential bacterial and fungal denitrification was assessed in sediment-groundwater slurries amended with antimicrobial compounds and in fungal pure cultures isolated from the subsurface. Our results demonstrate that subsurface fungal communities are dominated by members of the phylum Ascomycota, and a pronounced shift in fungal community composition occurs across the groundwater pH gradient at the field site, with lower diversity observed under acidic (pH <4.5) conditions. Fungal isolates recovered from subsurface sediments, including cultures of the genus Coniochaeta, which were detected in abundance in pyrosequence libraries of site groundwater samples, were shown to reduce nitrate to nitrous oxide. Denitrifying fungal isolates recovered from the site were classified and found to be distributed broadly within the phylum Ascomycota and within a single genus of the Basidiomycota. Potential denitrification rate assays with sediment-groundwater slurries showed the potential for subsurface fungi to reduce nitrate to nitrous oxide under in situ acidic pH conditions.
authors.affiliation: Department of Earth, Ocean & Atmospheric Sciences, Florida State University, Tallahassee, Florida, USA.
authors.forename: Puja
authors.initials: P
authors.lastname: Jasrotia
authors.forename: Stefan J
authors.initials: SJ
authors.lastname: Green
authors.forename: Andy
authors.initials: A
authors.lastname: Canion
authors.forename: Will A
authors.initials: WA
authors.lastname: Overholt
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.forename: Denis
authors.initials: D
authors.lastname: Wafula
authors.forename: Daniela
authors.initials: D
authors.lastname: Hubbard
authors.forename: David B
authors.initials: DB
authors.lastname: Watson
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Schadt
authors.forename: Scott C
authors.initials: SC
authors.lastname: Brooks
authors.forename: Joel E
authors.initials: JE
authors.lastname: Kostka
mesh_terms: D044822:Biodiversity; D016000:Cluster Analysis; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005658:Fungi / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism*; D010802:Phylogeny; D018892:Proton-Motive Force; D012331:RNA, Fungal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014501:Uranium / Q000378:metabolism*; D014871:Water Microbiology; D014873:Water Pollutants / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D009566:Nitrates; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S; D014873:Water Pollutants; D014501:Uranium