Papers by Evgenya Shelobolina
In areas of northeastern Wisconsin, arsenic-bearing sulfides and iron oxides are distributed thro... more In areas of northeastern Wisconsin, arsenic-bearing sulfides and iron oxides are distributed throughout a sandstone aquifer used for domestic water supplies. Aqueous arsenic concentrations exceed 10 mug/L in approximately 20% of wells in this region. These wells are often subjected to in situ chlorine disinfection to control nuisance or pathogenic bacteria. Field-based experiments investigating the effects of pumping and well
Because of its rare occurrence in modern sediments, as well as the difficulty in synthesizing it ... more Because of its rare occurrence in modern sediments, as well as the difficulty in synthesizing it under low-temperature conditions in the laboratory, the origin of sedimentary dolomite has remained a long-standing enigma, often referred to as the "dolomite problem". Recently, anaerobic microorganisms, such as sulfate-reducing bacteria and methanogens, have been recognized for mediating dolomite precipitation. However, the exact role of microorganisms in dolomite crystallization is still under debate and the possible involvement of anaerobic fermenting bacteria has not been studied. In this study, we characterized the effect of purified non-metabolizing biomass and bound extracellular polymeric substances (EPS) of a natural consortium of anaerobic microorganisms dominated by fermenting bacteria and sulfatereducing bacteria on Ca-Mg carbonate precipitation. This natural consortium was enriched from sediments of Deep Springs Lake, California, where dolomite is still precipitating. Our data show that disordered dolomite, a precursor of some sedimentary stoichiometric ordered dolomite, can be precipitated in calcite-seeded Ca-Mg carbonate solutions containing purified nonmetabolizing consortium biomass. Bound EPS extracted from the consortium culture were shown to be the active component that triggered the crystallization of disordered dolomite. Further experiments show that purified non-metabolizing biomass from pure cultures of both anaerobic fermenting and sulfate-reducing bacteria closely related to those organisms present in the consortium could also catalyze the precipitation of disordered dolomite. This study contributes to the understanding of the "dolomite problem" by revealing (1) the catalytic effect of bound EPS on Ca-Mg carbonate crystallization and (2) the possible involvement of anaerobic fermenting bacteria in sedimentary dolomite formation, which has not been reported previously. This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) Cite as Authors (Year) Title. American Mineralogist, in press. (DOI will not work until issue is live.
American Mineralogist, 2020
A correlation between methanogenesis and dolomite formation has been reported; however, the mecha... more A correlation between methanogenesis and dolomite formation has been reported; however, the mechanism underlying this association is not fully understood. In this study, we conducted forced carbonate precipitation experiments at room temperature in calcite-seeded Ca/Mg carbonate solutions containing either purified non-living biomass or bound extracellular polymeric substances (EPS) of the methanogen Methanosarcina barkeri. Purified non-living biomass and bound EPS was used so as to avoid the possible influence of the complex components of the growing microbial culture on carbonate crystallization. Our results demonstrated that non-living biomass of M. Barkeri can enhance the Mg incorporation into calcitic structure and induce the crystallization of disordered dolomite. In the presence of ~113 mg L–1 of non-living biomass, disordered dolomite with ~41 and 45 mol% of MgCO3 was precipitated in solutions with initial Mg:Ca ratios of 5:1 and 8:1, respectively. A systematic increase in t...
Glass and Ceramics, 1999
ABSTRACT
American Mineralogist, 2015
under low-temperature conditions in the laboratory, the origin of sedimentary dolomite has remain... more under low-temperature conditions in the laboratory, the origin of sedimentary dolomite has remained a long-standing enigma, often referred to as the "dolomite problem." Recently, anaerobic microorunder debate and the possible involvement of anaerobic fermenting bacteria has not been studied. lular polymeric substances (EPS) of a natural consortium of anaerobic microorganisms dominated by fermenting bacteria and sulfate-reducing bacteria on Ca-Mg carbonate precipitation. This natural consortium was enriched from sediments of Deep Springs Lake, California, where dolomite is still precipitating. Our data show that disordered dolomite, a precursor of some sedimentary stoichiometric and sulfate-reducing bacteria closely related to those organisms present in the consortium could also "dolomite problem" by revealing (1) the catalytic effect of bound EPS on Ca-Mg carbonate crystalformation, which has not been reported previously.
The potential for microbial involvement in the oxidation of Fe(II)-bearing phyllosilicates is an ... more The potential for microbial involvement in the oxidation of Fe(II)-bearing phyllosilicates is an understudied aspect of soil/sediment Fe biogeochemistry. An important property of structural Fe in Fe-bearing smectites is their ability to undergo multiple redox cycles without being mobilized. An obvious choice of mineral substrate for enumeration/isolation of Fe(II)-oxidizing microorganisms would be reduced smectite. But reduced smectite is readily oxidized by air. That is why biotite was chosen as a substrate for this study. In contrast to smectite, biotite is more stable in the presence of air, but incapable of redox cycling. Once Fe(II) is oxidized, biotite is weathered to expendable 2:1 phyllosilicates or kaolinite. First, we evaluated the ability of a neutral-pH lithoautotrophic nitrate-reducing enrichment culture (MPI culture), recovered by Straub et al (Appl. Environ. Microbiol., 1996, 62:1458-1460) from a freshwater ditch, to oxidize two different specimens of biotite. The cul...
Laboratory experiments have demonstrated that dissimilatory microbial iron oxide reduction (DIR) ... more Laboratory experiments have demonstrated that dissimilatory microbial iron oxide reduction (DIR) can produce Fe(II) phases that have low 56Fe/54Fe ratios similar to those found in Neoarchean and Paleoproterozoic banded iron formations (BIFs) and shales. Direct application of these experiments to BIF formation has been hindered by the lack of Fe isotope data from modern environments that are analogous to BIFs. Here we report Fe inventories and isotopic compositions for chemically precipitated sediments in the Spring Creek Arm of Keswick Reservoir (SCAKR) downstream of the Iron Mountain acid mine drainage site in northern California, USA. The high concentration of reactive Fe(III) (ca. 50-100 mmol of amorphous Fe(III) oxyhydroxides per liter of bulk sediment) allows dissimilatory iron-reducing bacteria (DIRB) to predominate over dissimilatory sulfate-reducing bacteria in sediment carbon metabolism, making the SCAKR a better analog for BIFs compared to modern marine environments. DIR h...
Soil and Sediment Contamination: An International Journal, 2003
... Uranium-Contaminated Groundwater Evgenya S. Shelobolina, Kathleen O'Neill, Kevin... more ... Uranium-Contaminated Groundwater Evgenya S. Shelobolina, Kathleen O'Neill, Kevin T. Finneran, Lory A. Hayes, and Derek R. Lovley Department of Microbiology, University of Massachusetts, Morrill Science Center IVN, Amherst, Massachusetts, USA ...
Journal of Bacteriology, 2005
The mechanism of fumarate reduction in Geobacter sulfurreducens was investigated. The genome cont... more The mechanism of fumarate reduction in Geobacter sulfurreducens was investigated. The genome contained genes encoding a heterotrimeric fumarate reductase, FrdCAB, with homology to the fumarate reductase of Wolinella succinogenes and the succinate dehydrogenase of Bacillus subtilis . Mutation of the putative catalytic subunit of the enzyme resulted in a strain that lacked fumarate reductase activity and was unable to grow with fumarate as the terminal electron acceptor. The mutant strain also lacked succinate dehydrogenase activity and did not grow with acetate as the electron donor and Fe(III) as the electron acceptor. The mutant strain could grow with acetate as the electron donor and Fe(III) as the electron acceptor if fumarate was provided to alleviate the need for succinate dehydrogenase activity in the tricarboxylic acid cycle. The growth rate of the mutant strain under these conditions was faster and the cell yields were higher than for wild type grown under conditions requiri...
International Journal of Systematic and Evolutionary Microbiology, 2007
The goal of this project was to isolate representative Fe(III)-reducing bacteria from kaolin clay... more The goal of this project was to isolate representative Fe(III)-reducing bacteria from kaolin clays that may influence iron mineralogy in kaolin. Two novel dissimilatory Fe(III)-reducing bacteria, strains G12T and G13T, were isolated from sedimentary kaolin strata in Georgia (USA). Cells of strains G12T and G13T were motile, non-spore-forming regular rods, 1–2 μm long and 0.6 μm in diameter. Cells had one lateral flagellum. Phylogenetic analyses using the 16S rRNA gene sequence of the novel strains demonstrated their affiliation to the genus Geobacter. Strain G12T was most closely related to Geobacter pelophilus (94.7 %) and Geobacter chapellei (94.1 %). Strain G13T was most closely related to Geobacter grbiciae (95.3 %) and Geobacter metallireducens (95.1 %). Based on phylogenetic analyses and phenotypic differences between the novel isolates and other closely related species of the genus Geobacter, the isolates are proposed as representing two novel species, Geobacter argillaceus s...
INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2008
A Gram-negative, rod-shaped, motile bacterium, strain Rf4 T , which conserves energy from dissimi... more A Gram-negative, rod-shaped, motile bacterium, strain Rf4 T , which conserves energy from dissimilatory Fe(III) reduction concomitant with acetate oxidation, was isolated from subsurface sediment undergoing uranium bioremediation. The 16S rRNA gene sequence of strain Rf4 T matched sequences recovered in 16S rRNA gene clone libraries constructed from DNA extracted from groundwater sampled at the same time as the source sediment. Cells of strain Rf4 T were regular, motile rods, 1.2-2.0 mm long and 0.5-0.6 mm in diameter, with rounded ends. Cells had one lateral flagellum. Growth was optimal at pH 6.5-7.0 and 32 6C. With acetate as the electron donor, strain Rf4 T used Fe(III), Mn(IV), anthraquinone-2,6-disulfonate, malate and fumarate as electron acceptors and reduced U(VI) in cell suspensions. With poorly crystalline Fe(III) oxide as the electron acceptor, strain Rf4 T oxidized the following electron donors: acetate, lactate, pyruvate and ethanol. Phylogenetic analysis of the 16S rRNA gene sequence of strain Rf4 T placed it in the genus Geobacter. Strain Rf4 T was most closely related to 'Geobacter humireducens' JW3 (95.9 % sequence similarity), Geobacter bremensis Dfr1 T (95.4 %) and Geobacter bemidjiensis Bem T (95.1 %). Based on phylogenetic analysis and phenotypic differences between strain Rf4 T and closely related Geobacter species, this strain is described as a representative of a novel species, Geobacter uraniireducens sp. nov. The type strain is Rf4 T (5ATCC BAA-1134 T 5JCM 13001 T).
Geomicrobiology Journal, 2003
... In: Lovley DR, editor. Environmental microbe-mineral interactions. Washington, DC: ASM press,... more ... In: Lovley DR, editor. Environmental microbe-mineral interactions. Washington, DC: ASM press, p 31–52. Ernstsen V, Gates WP, Stucki JW. 1998. ... Arch Microbiol 159:336–344. Lovely DR, Fraga JL, Blunt-Harris EL, Hayes LA, Philips EJP, Coates JD. 1998. ...
Geobiology, 2010
The inventories and Fe isotope composition of aqueous Fe(II) and solid-phase Fe compounds were qu... more The inventories and Fe isotope composition of aqueous Fe(II) and solid-phase Fe compounds were quantified in neutral-pH, chemically precipitated sediments downstream of the Iron Mountain acid mine drainage site in northern California, USA. The sediments contain high concentrations of amorphous Fe(III) oxyhydroxides [Fe(III) am ] that allow dissimilatory iron reduction (DIR) to predominate over Fe-S interactions in Fe redox transformation, as indicated by the very low abundance of Cr(II)-extractable reduced inorganic sulfur compared with dilute HCl-extractable Fe. d 56 Fe values for bulk HCl-and HF-extractable Fe were 0. These near-zero bulk d 56 Fe values, together with the very low abundance of dissolved Fe in the overlying water column, suggest that the pyrite Fe source had near-zero d 56 Fe values, and that complete oxidation of Fe(II) took place prior to deposition of the Fe(III) oxide-rich sediment. Sediment core analyses and incubation experiments demonstrated the production of millimolar quantities of isotopically light (d 56 Fe)1.5 to)0.5&) aqueous Fe(II) coupled to partial reduction of Fe(III) am by DIR. Trends in the Fe isotope composition of solid-associated Fe(II) and residual Fe(III) am are consistent with experiments with synthetic Fe(III) oxides, and collectively suggest an equilibrium Fe isotope fractionation between aqueous Fe(II) and Fe(III) am of approximately)2&. These Fe(III) oxide-rich sediments provide a model for early diagenetic processes that are likely to have taken place in Archean and Paleoproterozoic marine sediments that served as precursors for banded iron formations. Our results suggest pathways whereby DIR could have led to the formation of large quantities of low-d 56 Fe minerals during BIF genesis.
Environmental Science & Technology, 2012
Fe(III)-bearing phyllosilicates can be important sources of Fe(III) for dissimilatory microbial i... more Fe(III)-bearing phyllosilicates can be important sources of Fe(III) for dissimilatory microbial iron reduction in clay-rich anoxic soils and sediments. The goal of this research was to isolate Fe(III) phyllosilicate phases, and if possible, Fe(III) oxide phases, from a weathered shale saprolite sediment in order to permit experimentation with each phase in isolation. Physical partitioning by density gradient centrifugation did not separate phyllosilicate and Fe(III) oxide phases (primarily nanoparticulate goethite). Hence we examined the ability of chemical extraction methods to remove Fe(III) oxides without significantly altering the properties of the phyllosilicates. XRD analysis showed that extraction with acid ammonium oxalate (AAO) or AAO in the presence of added Fe(II) altered the structure of Fe-bearing phyllosilicates in the saprolite. In contrast, citrate-dithionite-bicarbonate (CDB) extraction at room temperature or 80°C led to minimal alteration of phyllosilicate structures. Reoxidation of CDB-extracted sediment with H 2 O 2 restored phyllosilicate mineral d-spacing and Fe redox speciation to conditions similar to that in the pristine sediment. The extent of microbial (Geobacter sulfurreducens) reduction of Fe(III) phyllosilicates isolated by CDB extraction and H 2 O 2 reoxidation (16 ± 3% reduction) was comparable to what took place in pristine sediments as determined by Mossbauer spectroscopy (20 ± 11% reduction). These results suggest that materials isolated by CDB extraction and H 2 O 2 reoxidation are appropriate targets for detailed studies of natural soil/sediment Fe(III) phyllosilicate reduction.
clays and clay minerals, 2005
Chemical Geology, 2012
In situ technetium-99 (99Tc) immobilization by Fe(II) associated with clay minerals is a potentia... more In situ technetium-99 (99Tc) immobilization by Fe(II) associated with clay minerals is a potential cost-effective method for Tc remediation at contaminated sites. The oxidation state of Fe is constantly cycled in sedimentary environments, however the effect of this cycle on Tc reduction and immobilization has not yet been investigated. The objective of this project was therefore to study how multiple
BMC Microbiology, 2007
Background In order to study the mechanism of U(VI) reduction, the effect of deleting c-type cyto... more Background In order to study the mechanism of U(VI) reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI) with acetate serving as the electron donor was investigated. Results The ability of several c-type cytochrome deficient mutants to reduce U(VI) was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60%) the ability of G. sulfurreducens to reduce U(VI). Involvement in U(VI) reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI) reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI) reduction. A subpopulation of both wild type and U(VI) reduct...
Biofouling, 2009
Dense phase carbon dioxide (DPCD) is one of the most promising techniques available to control mi... more Dense phase carbon dioxide (DPCD) is one of the most promising techniques available to control microorganisms as a non-thermal disinfection method. However, no study on the efficiency of biofilm disinfection using DPCD has been reported. The efficiency of DPCD in inactivating Pseudomonas aeruginosa biofilm, which is known to have high antimicrobial resistance, was thus investigated. P. aeruginosa biofilm, which was not immersed in water but was completely wet, was found to be more effectively inactivated by DPCD treatment, achieving a 6-log reduction within 7 min. The inactivation efficiency increased modestly with increasing pressure and temperature. This study also reports that the water-unimmersed condition is one of the most important operating parameters in achieving efficient biofilm control by DPCD treatment. In addition, observations by confocal laser scanning microscopy revealed that DPCD treatment not only inactivated biofilm cells on the glass coupons but also caused detachment of the biofilm following weakening of its structure as a result of the DPCD treatment; this is an added benefit of DPCD treatment.
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Papers by Evgenya Shelobolina