title: Frequencies of heavy metal resistance are associated with land cover type in the Upper Mississippi River.
abstract: Taxonomic compositions of freshwater bacterial communities have been well-characterized via metagenomic and amplicon-based approaches, especially next-generation sequencing. However, functional diversity of these communities remains less well-studied. Various anthropogenic sources are known to impact the bacterial community composition in freshwater riverine systems and potentially alter functional diversity. In this study, high-throughput functional screening of large (~10,000 clones) fosmid libraries representing communities in the Upper Mississippi River revealed low frequencies of resistance to heavy metals in the following order: Mn2+>Cr3+>Zn2+>Cd2+>Hg2+. No resistance to Cu2+ was detected. Significant, but weak, correlations were observed between resistance frequencies of Cd and Cr with developed land cover (r2=0.08, P=0.016 and r=0.07, P=0.037, respectively). While discriminant function analyses further supported these associations, redundancy analysis further indicated associations with forested land cover and greater resistance to Hg and Zn. Nutrient and metal ion concentrations and abundances of bacterial orders were poorly correlated with heavy metal resistance, except for an association of Pseudomonadales abundance and resistance to Hg and Zn. Taken together, results of this study suggest that allochthonous bacteria contributed from specific land cover types influence the patterns of metal resistance throughout this river.
authors.affiliation: BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Staley
authors.affiliation: Biology Program, University of Minnesota, St. Paul, MN, United States.
authors.forename: Dylan
authors.initials: D
authors.lastname: Johnson
authors.affiliation: BioTechnology Institute, University of Minnesota, St. Paul, MN, United States; Biology Program, University of Minnesota, St. Paul, MN, United States.
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Gould
authors.affiliation: BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Biology Program, University of Minnesota, St. Paul, MN, United States.
authors.forename: Jane
authors.initials: J
authors.lastname: Phillips
authors.affiliation: Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, United States.
authors.forename: James B
authors.initials: JB
authors.lastname: Cotner
authors.affiliation: BioTechnology Institute, University of Minnesota, St. Paul, MN, United States; Department of Soil, Water and Climate, University of Minnesota, St. Paul, MN, United States. Electronic address: sadowsky@umn.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sadowsky
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D019216:Metals, Heavy / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical
keywords: Amplicon sequencing; Bacterial community structure; Fosmid library; Functional analyses; Heavy metal resistance; Mississippi River