| Title | The Arsenite Oxidation Potential of Native Microbial Communities from Arsenic-Rich Freshwaters |
| Abstract | Microorganisms play an important role in speciation and mobility of arsenic in the environment, by mediating redox transformations of both inorganic and organic species. Since arsenite [As(III)] is more toxic than arsenate [As(V)] to the biota, the microbial driven processes of As(V) reduction and As(III) oxidation may play a prominent role in mediating the environmental impact of arsenic contamination. However, little is known about the ecology and dynamics of As(III)-oxidizing populations within native microbial communities exposed to natural high levels of As. In this study, two techniques for single cell quantification (i.e., flow cytometry, CARD-FISH) were used to analyze the structure of aquatic microbial communities across a gradient of arsenic (As) contamination in different freshwater environments (i.e., groundwaters, surface and thermal waters). Moreover, we followed the structural evolution of these communities and their capacity to oxidize arsenite, when experimentally exposed to high As(III) concentrations in experimental microcosms. Betaproteobacteria and Deltaproteobacteria were the main groups retrieved in groundwaters and surface waters, while Beta and Gammaproteobacteria dominated the bacteria community in thermal waters. At the end of microcosm incubations, the communities were able to oxidize up to 95 % of arsenite, with an increase of Alphaproteobacteria in most of the experimental conditions. Finally, heterotrophic As(III)-oxidizing strains (one Alphaproteobacteria and two Gammaproteobacteria) were isolated from As rich waters. Our findings underlined that native microbial communities from different arsenic-contaminated freshwaters can efficiently perform arsenite oxidation, thus contributing to reduce the overall As toxicity to the aquatic biota. |
| Source | Microbial ecology 72 (1), pp. 25–35 |
| Keywords | ArsenicBacteriaGroundwatersGeothermal watersFreshwater ecology |
| Journal | Microbial ecology |
| Editor | Springer-Verlag,, New York,, Stati Uniti d'America |
| Year | 2016 |
| Type | Articolo in rivista |
| DOI | 10.1007/s00248-016-0768-y |
| Authors | Fazi, Stefano; Crognale, Simona; Casentini, Barbara; Amalfitano, Stefano; Lotti, Francesca; Rossetti, Simona |
| Text | 364003 2016 10.1007/s00248 016 0768 y ISI Web of Science WOS 000377998800005 Arsenic Bacteria Groundwaters Geothermal waters Freshwater ecology The Arsenite Oxidation Potential of Native Microbial Communities from Arsenic Rich Freshwaters Fazi, Stefano; Crognale, Simona; Casentini, Barbara; Amalfitano, Stefano; Lotti, Francesca; Rossetti, Simona Natl Res Council Italy IRSA CNR; Univ Tuscia Microorganisms play an important role in speciation and mobility of arsenic in the environment, by mediating redox transformations of both inorganic and organic species. Since arsenite As III is more toxic than arsenate As V to the biota, the microbial driven processes of As V reduction and As III oxidation may play a prominent role in mediating the environmental impact of arsenic contamination. However, little is known about the ecology and dynamics of As III oxidizing populations within native microbial communities exposed to natural high levels of As. In this study, two techniques for single cell quantification i.e., flow cytometry, CARD FISH were used to analyze the structure of aquatic microbial communities across a gradient of arsenic As contamination in different freshwater environments i.e., groundwaters, surface and thermal waters . Moreover, we followed the structural evolution of these communities and their capacity to oxidize arsenite, when experimentally exposed to high As III concentrations in experimental microcosms. Betaproteobacteria and Deltaproteobacteria were the main groups retrieved in groundwaters and surface waters, while Beta and Gammaproteobacteria dominated the bacteria community in thermal waters. At the end of microcosm incubations, the communities were able to oxidize up to 95 % of arsenite, with an increase of Alphaproteobacteria in most of the experimental conditions. Finally, heterotrophic As III oxidizing strains one Alphaproteobacteria and two Gammaproteobacteria were isolated from As rich waters. Our findings underlined that native microbial communities from different arsenic contaminated freshwaters can efficiently perform arsenite oxidation, thus contributing to reduce the overall As toxicity to the aquatic biota. 72 Published version Articolo in rivista Springer Verlag, 0095 3628 Microbial ecology Microbial ecology Microb Ecol Microbial ecology. simona.rossetti ROSSETTI SIMONA stefano.fazi FAZI STEFANO stefano.amalfitano AMALFITANO STEFANO barbara.casentini CASENTINI BARBARA simona.crognale CROGNALE SIMONA |
