Ronald Oremland (Former Employee)
Science and Products
Filter Total Items: 119
Bioreactors for removing methyl bromide following contained fumigations
Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (>110 μmol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell d
Authors
Laurence G. Miller, Shaun Baesman, Ronald S. Oremland
The respiratory arsenate reductase from Bacillus selenitireducens strain MLS10
The respiratory arsenate reductase from the Gram-positive, haloalkaliphile, Bacillus selenitireducens strain MLS10 was purified and characterized. It is a membrane bound heterodimer (150 kDa) composed of two subunits ArrA (110 kDa) and ArrB (34 kDa), with an apparent Km for arsenate of 34 µM and Vmax of 2.5 µmol min−1 mg−1. Optimal activity occurred at pH 9.5 and 150 g l−1 of NaCl. Metal analysis
Authors
E. Afkar, J. Lisak, C. Saltikov, P. Basu, Ronald S. Oremland, J.F. Stolz
The ecology of arsenic
Arsenic is a metalloid whose name conjures up images of murder. Nonetheless, certain prokaryotes use arsenic oxyanions for energy generation, either by oxidizing arsenite or by respiring arsenate. These microbes are phylogenetically diverse and occur in a wide range of habitats. Arsenic cycling may take place in the absence of oxygen and can contribute to organic matter oxidation. In aquifers, the
Authors
Ronald S. Oremland, John F. Stolz
Anaerobic oxidation of arsenite in Mono Lake water and by a facultative, arsenite-oxidizing chemoautotroph, strain MLHE-1
Arsenite [As(III)]-enriched anoxic bottom water from Mono Lake, California, produced arsenate [As(V)] during incubation with either nitrate or nitrite. No such oxidation occurred in killed controls or in live samples incubated without added nitrate or nitrite. A small amount of biological As(III) oxidation was observed in samples amended with Fe(III) chelated with nitrolotriacetic acid, although s
Authors
Ronald S. Oremland, S.E. Hoeft, J.M. Santini, N. Bano, R.A. Hollibaugh, J.T. Hollibaugh
Leisingera methylohalidivorans gen. nov., sp. nov., a marine methylotroph that grows on methyl bromide
A marine methylotroph, designated strain MB2T, was isolated for its ability to grow on methyl bromide as a sole carbon and energy source. Methyl chloride and methyl iodide also supported growth, as did methionine and glycine betaine. A limited amount of growth was observed with dimethyl sulfide. Growth was also noted with unidentified components of the complex media marine broth 2216, yeast extrac
Authors
J.K. Schaefer, K.D. Goodwin, I.R. McDonald, J.C. Murrell, Ronald S. Oremland
Distribution, production, and ecophysiology of Picocystis strain ML in Mono Lake, California
A recently described unicellular chlorophytic alga isolated from meromictic Mono Lake, California, occupies a niche that spans two environments: the upper oxic mixolimnion and the deeper anoxic and highly reducing monimolimnion. This organism, Picocystis sp. strain ML, accounts for nearly 25% of the primary production during the winter bloom and more than 50% at other times of the year. In incubat
Authors
Collin S. Roesler, Charles W. Culbertson, Stacey M. Etheridge, Ralf Goericke, Ronald P. Kiene, Laurence G. Miller, Ronald S. Oremland
Bacterial respiration of arsenate and its significance in the environment
No abstract available.
Authors
Ronald S. Oremland, Diane Newman, B.W. Kail, J.F. Stolz
Consumption of tropospheric levels of methyl bromide by C1 compound-utilizing bacteria and comparison to saturation kinetics
Pure cultures of methylotrophs and methanotrophs are known to oxidize methyl bromide (MeBr); however, their ability to oxidize tropospheric concentrations (parts per trillion by volume [pptv]) has not been tested. Methylotrophs and methanotrophs were able to consume MeBr provided at levels that mimicked the tropospheric mixing ratio of MeBr (12 pptv) at equilibrium with surface waters (≈2 pM). Kin
Authors
K.D. Goodwin, R.K. Varner, P.M. Crill, Ronald S. Oremland
Diversity of anaerobic halophilic microorganisms
Life in the presence of high salt concentrations is compatible with life in the absence of oxygen. Halophilic and halotolerant anaerobic prokaryotes are found both in the archaeal and in the bacterial domain, and they display a great metabolic diversity. Many of the representatives of the Halobacteriales (Archaea), which are generally considered aerobes, have the potential of anaerobic growth. Som
Authors
Aharon Oren, Ronald S. Oremland
Methyl-mercury degradation pathways: A comparison among three mercury impacted ecosystems
We examined microbial methylmercury (MeHg) degradation in sediment of the Florida Everglades, Carson River (NV), and San Carlos Creek (CA), three freshwater environments that differ in the extent and type of mercury contamination and sediment biogeochemistry. Degradation rate constant (kdeg) values increased with total mercury (Hgt) contamination both among and within ecosystems. The highest kdeg'
Authors
M. Marvin-DiPasquale, J. Agee, C. Mcgowan, R.S. Oremland, M. Thomas, D. Krabbenhoft, C.C. Gilmour
Mobilization of arsenite by dissimilatory reduction of adsorbed arsenate
Sulfurospirillum barnesii is capable of anaerobic growth using ferric iron or arsenate as electron acceptors. Cell suspensions of S. barnesii were able to reduce arsenate to arsenite when the former oxyanion was dissolved in solution, or when it was adsorbed onto the surface of ferrihydrite, a common soil mineral, by a variety of mechanisms (e.g., coprecipitation, presorption). Reduction of Fe(III
Authors
J. Zobrist, P.R. Dowdle, J.A. Davis, Ronald S. Oremland
Science and Products
Filter Total Items: 119
Bioreactors for removing methyl bromide following contained fumigations
Use of methyl bromide (MeBr) as a quarantine, commodity, or structural fumigant is under scrutiny because its release to the atmosphere contributes to the depletion of stratospheric ozone. A closed-system bioreactor consisting of 0.5 L of a growing culture of a previously described bacterium, strain IMB-1, removed MeBr (>110 μmol L-1) from recirculating air. Strain IMB-1 grew slowly to high cell d
Authors
Laurence G. Miller, Shaun Baesman, Ronald S. Oremland
The respiratory arsenate reductase from Bacillus selenitireducens strain MLS10
The respiratory arsenate reductase from the Gram-positive, haloalkaliphile, Bacillus selenitireducens strain MLS10 was purified and characterized. It is a membrane bound heterodimer (150 kDa) composed of two subunits ArrA (110 kDa) and ArrB (34 kDa), with an apparent Km for arsenate of 34 µM and Vmax of 2.5 µmol min−1 mg−1. Optimal activity occurred at pH 9.5 and 150 g l−1 of NaCl. Metal analysis
Authors
E. Afkar, J. Lisak, C. Saltikov, P. Basu, Ronald S. Oremland, J.F. Stolz
The ecology of arsenic
Arsenic is a metalloid whose name conjures up images of murder. Nonetheless, certain prokaryotes use arsenic oxyanions for energy generation, either by oxidizing arsenite or by respiring arsenate. These microbes are phylogenetically diverse and occur in a wide range of habitats. Arsenic cycling may take place in the absence of oxygen and can contribute to organic matter oxidation. In aquifers, the
Authors
Ronald S. Oremland, John F. Stolz
Anaerobic oxidation of arsenite in Mono Lake water and by a facultative, arsenite-oxidizing chemoautotroph, strain MLHE-1
Arsenite [As(III)]-enriched anoxic bottom water from Mono Lake, California, produced arsenate [As(V)] during incubation with either nitrate or nitrite. No such oxidation occurred in killed controls or in live samples incubated without added nitrate or nitrite. A small amount of biological As(III) oxidation was observed in samples amended with Fe(III) chelated with nitrolotriacetic acid, although s
Authors
Ronald S. Oremland, S.E. Hoeft, J.M. Santini, N. Bano, R.A. Hollibaugh, J.T. Hollibaugh
Leisingera methylohalidivorans gen. nov., sp. nov., a marine methylotroph that grows on methyl bromide
A marine methylotroph, designated strain MB2T, was isolated for its ability to grow on methyl bromide as a sole carbon and energy source. Methyl chloride and methyl iodide also supported growth, as did methionine and glycine betaine. A limited amount of growth was observed with dimethyl sulfide. Growth was also noted with unidentified components of the complex media marine broth 2216, yeast extrac
Authors
J.K. Schaefer, K.D. Goodwin, I.R. McDonald, J.C. Murrell, Ronald S. Oremland
Distribution, production, and ecophysiology of Picocystis strain ML in Mono Lake, California
A recently described unicellular chlorophytic alga isolated from meromictic Mono Lake, California, occupies a niche that spans two environments: the upper oxic mixolimnion and the deeper anoxic and highly reducing monimolimnion. This organism, Picocystis sp. strain ML, accounts for nearly 25% of the primary production during the winter bloom and more than 50% at other times of the year. In incubat
Authors
Collin S. Roesler, Charles W. Culbertson, Stacey M. Etheridge, Ralf Goericke, Ronald P. Kiene, Laurence G. Miller, Ronald S. Oremland
Bacterial respiration of arsenate and its significance in the environment
No abstract available.
Authors
Ronald S. Oremland, Diane Newman, B.W. Kail, J.F. Stolz
Consumption of tropospheric levels of methyl bromide by C1 compound-utilizing bacteria and comparison to saturation kinetics
Pure cultures of methylotrophs and methanotrophs are known to oxidize methyl bromide (MeBr); however, their ability to oxidize tropospheric concentrations (parts per trillion by volume [pptv]) has not been tested. Methylotrophs and methanotrophs were able to consume MeBr provided at levels that mimicked the tropospheric mixing ratio of MeBr (12 pptv) at equilibrium with surface waters (≈2 pM). Kin
Authors
K.D. Goodwin, R.K. Varner, P.M. Crill, Ronald S. Oremland
Diversity of anaerobic halophilic microorganisms
Life in the presence of high salt concentrations is compatible with life in the absence of oxygen. Halophilic and halotolerant anaerobic prokaryotes are found both in the archaeal and in the bacterial domain, and they display a great metabolic diversity. Many of the representatives of the Halobacteriales (Archaea), which are generally considered aerobes, have the potential of anaerobic growth. Som
Authors
Aharon Oren, Ronald S. Oremland
Methyl-mercury degradation pathways: A comparison among three mercury impacted ecosystems
We examined microbial methylmercury (MeHg) degradation in sediment of the Florida Everglades, Carson River (NV), and San Carlos Creek (CA), three freshwater environments that differ in the extent and type of mercury contamination and sediment biogeochemistry. Degradation rate constant (kdeg) values increased with total mercury (Hgt) contamination both among and within ecosystems. The highest kdeg'
Authors
M. Marvin-DiPasquale, J. Agee, C. Mcgowan, R.S. Oremland, M. Thomas, D. Krabbenhoft, C.C. Gilmour
Mobilization of arsenite by dissimilatory reduction of adsorbed arsenate
Sulfurospirillum barnesii is capable of anaerobic growth using ferric iron or arsenate as electron acceptors. Cell suspensions of S. barnesii were able to reduce arsenate to arsenite when the former oxyanion was dissolved in solution, or when it was adsorbed onto the surface of ferrihydrite, a common soil mineral, by a variety of mechanisms (e.g., coprecipitation, presorption). Reduction of Fe(III
Authors
J. Zobrist, P.R. Dowdle, J.A. Davis, Ronald S. Oremland