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Nutrient Exposure Alters Microbial Composition, Structure, and Mercury Methylating Activity in Periphyton in a Contaminated Watershed.
Carrell, Alyssa A; Schwartz, Grace E; Cregger, Melissa A; Gionfriddo, Caitlin M; Elias, Dwayne A; Wilpiszeski, Regina L; Klingeman, Dawn M; Wymore, Ann M; Muller, Katherine A; Brooks, Scott C.
Affiliation
  • Carrell AA; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
  • Schwartz GE; Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States.
  • Cregger MA; Department of Chemistry, Wofford College, Spartanburg, SC, United States.
  • Gionfriddo CM; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
  • Elias DA; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
  • Wilpiszeski RL; Smithsonian Environmental Research Center, Edgewater, MD, United States.
  • Klingeman DM; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
  • Wymore AM; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
  • Muller KA; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
  • Brooks SC; Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.
Front Microbiol ; 12: 647861, 2021.
Article in En | MEDLINE | ID: mdl-33815336
ABSTRACT
The conversion of mercury (Hg) to monomethylmercury (MMHg) is a critical area of concern in global Hg cycling. Periphyton biofilms may harbor significant amounts of MMHg but little is known about the Hg-methylating potential of the periphyton microbiome. Therefore, we used high-throughput amplicon sequencing of the 16S rRNA gene, ITS2 region, and Hg methylation gene pair (hgcAB) to characterize the archaea/bacteria, fungi, and Hg-methylating microorganisms in periphyton communities grown in a contaminated watershed in East Tennessee (United States). Furthermore, we examined how nutrient amendments (nitrate and/or phosphate) altered periphyton community structure and function. We found that bacterial/archaeal richness in experimental conditions decreased in summer and increased in autumn relative to control treatments, while fungal diversity generally increased in summer and decreased in autumn relative to control treatments. Interestingly, the Hg-methylating communities were dominated by Proteobacteria followed by Candidatus Atribacteria across both seasons. Surprisingly, Hg methylation potential correlated with numerous bacterial families that do not contain hgcAB, suggesting that the overall microbiome structure of periphyton communities influences rates of Hg transformation within these microbial mats. To further explore these complex community interactions, we performed a microbial network analysis and found that the nitrate-amended treatment resulted in the highest number of hub taxa that also corresponded with enhanced Hg methylation potential. This work provides insight into community interactions within the periphyton microbiome that may contribute to Hg cycling and will inform future research that will focus on establishing mixed microbial consortia to uncover mechanisms driving shifts in Hg cycling within periphyton habitats.
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Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: Front Microbiol Year: 2021 Document type: Article Affiliation country: Estados Unidos

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: Front Microbiol Year: 2021 Document type: Article Affiliation country: Estados Unidos