scholarly journals Microbial Communities in Contaminated Sediments, Associated with Bioremediation of Uranium to Submicromolar Levels

2008 ◽  
Vol 74 (12) ◽  
pp. 3718-3729 ◽  
Author(s):  
Erick Cardenas ◽  
Wei-Min Wu ◽  
Mary Beth Leigh ◽  
Jack Carley ◽  
Sue Carroll ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Contaminated Site ◽  
Most Probable Number ◽  
Biological Reduction ◽  
Probable Number ◽  
Oak Ridge ◽  
Sulfate Reducing ◽  
Treatment Zone ◽  
The U.S

ABSTRACT Microbial enumeration, 16S rRNA gene clone libraries, and chemical analysis were used to evaluate the in situ biological reduction and immobilization of uranium(VI) in a long-term experiment (more than 2 years) conducted at a highly uranium-contaminated site (up to 60 mg/liter and 800 mg/kg solids) of the U.S. Department of Energy in Oak Ridge, TN. Bioreduction was achieved by conditioning groundwater above ground and then stimulating growth of denitrifying, Fe(III)-reducing, and sulfate-reducing bacteria in situ through weekly injection of ethanol into the subsurface. After nearly 2 years of intermittent injection of ethanol, aqueous U levels fell below the U.S. Environmental Protection Agency maximum contaminant level for drinking water and groundwater (<30 μg/liter or 0.126 μM). Sediment microbial communities from the treatment zone were compared with those from a control well without biostimulation. Most-probable-number estimations indicated that microorganisms implicated in bioremediation accumulated in the sediments of the treatment zone but were either absent or in very low numbers in an untreated control area. Organisms belonging to genera known to include U(VI) reducers were detected, including Desulfovibrio, Geobacter, Anaeromyxobacter, Desulfosporosinus, and Acidovorax spp. The predominant sulfate-reducing bacterial species were Desulfovibrio spp., while the iron reducers were represented by Ferribacterium spp. and Geothrix spp. Diversity-based clustering revealed differences between treated and untreated zones and also within samples of the treated area. Spatial differences in community structure within the treatment zone were likely related to the hydraulic pathway and to electron donor metabolism during biostimulation.

In‐situ apparent conductivity measurements and microbial population distribution at a hydrocarbon‐contaminated site

Geophysics ◽  
2004 ◽  
Vol 69 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Estella A. Atekwana ◽  
D. Dale Werkema ◽  
Joseph W. Duris ◽  
Silvia Rossbach ◽  
Eliot A. Atekwana ◽  
...  
Keyword(s):  
Microbial Degradation ◽  
Microbial Population ◽  
Population Distribution ◽  
Microbial Populations ◽  
Contaminated Site ◽  
Most Probable Number ◽  
Bulk Conductivity ◽  
Probable Number ◽  
A Site

We investigated the bulk electrical conductivity and microbial population distribution in sediments at a site contaminated with light nonaqueous‐phase liquid (LNAPL). The bulk conductivity was measured using in‐situ vertical resistivity probes; the most probable number method was used to characterize the spatial distribution of aerobic heterotrophic and oil‐degrading microbial populations. The purpose of this study was to assess if high conductivity observed at aged LNAPL‐impacted sites may be related to microbial degradation of LNAPL. The results show higher bulk conductivity coincident with LNAPL‐impacted zones, in contrast to geoelectrical models that predict lower conductivity in such zones. The highest bulk conductivity was observed to be associated with zones impacted by residual and free LNAPL. Data from bacteria enumeration from sediments close to the resistivity probes show that oil‐degrading microbes make up a larger percentage (5–55%) of the heterotrophic microbial community at depths coincident with the higher conductivity compared to ∼5% at the uncontaminated location. The coincidence of a higher percentage of oil‐degrading microbial populations in zones of higher bulk conductivity suggests that the higher conductivity in these zones may result from increased fluid conductivity related to microbial degradation of LNAPL, consistent with geochemical studies that suggest that intrinsic biodegradation is occurring at the site. The findings from this study point to the fact that biogeochemical processes accompanying biodegradation of contaminants can potentially alter geoelectrical properties of the subsurface impacted media.

scholarly journals Effects of Monoculture, Crop Rotation, and Soil Moisture Content on Selected Soil Physicochemical and Microbial Parameters in Wheat Fields

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
A. Marais ◽  
M. Hardy ◽  
M. Booyse ◽  
A. Botha
Keyword(s):  
Soil Moisture ◽  
Microbial Communities ◽  
Crop Rotation ◽  
Management Practices ◽  
Agricultural Soils ◽  
Soil Microbial Communities ◽  
Soil Microbial Activity ◽  
Most Probable Number ◽  
Probable Number ◽  
Soil Microbial

Different plants are known to have different soil microbial communities associated with them. Agricultural management practices such as fertiliser and pesticide addition, crop rotation, and grazing animals can lead to different microbial communities in the associated agricultural soils. Soil dilution plates, most-probable-number (MPN), community level physiological profiling (CLPP), and buried slide technique as well as some measured soil physicochemical parameters were used to determine changes during the growing season in the ecosystem profile in wheat fields subjected to wheat monoculture or wheat in annual rotation with medic/clover pasture. Statistical analyses showed that soil moisture had an over-riding effect on seasonal fluctuations in soil physicochemical and microbial populations. While within season soil microbial activity could be differentiated between wheat fields under rotational and monoculture management, these differences were not significant.

Influence of the origin of the inoculum on the anaerobic biodegradability test

2004 ◽  
Vol 49 (1) ◽  
pp. 53-59 ◽  
Author(s):  
I. Moreno-Andrade ◽  
G. Buitrón
Keyword(s):  
Most Probable Number ◽  
Microbial Composition ◽  
Probable Number ◽  
Methanogenic Activity ◽  
Sulfate Reducing ◽  
Anaerobic Biodegradability ◽  
Specific Methanogenic Activity ◽  
Solids Content ◽  
Different Sources ◽  
Selection Of

Five different sources of inocula were studied to determine its influence on biodegradability tests. Inocula were characterized determining granulometry, specific methanogenic activity, solids content, and volumetric sludge index. Also, the fermentative, aceticlastic, hydrogenophilic, OPHA, and sulfate-reducing groups were determined by the most probable number technique. Anaerobic biodegradability tests were conducted with two different substrates, one easy to degrade (glucose) and a toxic one (phenol). The best performance, in terms of percent of biodegradation and lag time, for both substrates, was obtained with the inoculum from a brewery industry UASB. The results can be explained in terms of the initial activity of the inoculum. The influence of the significant variations found in the specific methanogenic activity of the five inocula studied is discussed, in terms of the microbial composition of the samples. The results emphasized the importance of the selection of an appropriate source of inoculum in order to obtain reliable results.

scholarly journals Repeated Anaerobic Microbial Redox Cycling of Iron

2011 ◽  
Vol 77 (17) ◽  
pp. 6036-6042 ◽  
Author(s):  
Aaron J. Coby ◽  
Flynn Picardal ◽  
Evgenya Shelobolina ◽  
Huifang Xu ◽  
Eric E. Roden
Keyword(s):  
Microbial Communities ◽  
Microscopic Analysis ◽  
Redox Cycling ◽  
Most Probable Number ◽  
Rrna Gene ◽  
Electron Microscopic ◽  
16S Rrna Gene Analysis ◽  
Probable Number ◽  
Content Type ◽  
Floodplain Sediments

ABSTRACTSome nitrate- and Fe(III)-reducing microorganisms are capable of oxidizing Fe(II) with nitrate as the electron acceptor. This enzymatic pathway may facilitate the development of anaerobic microbial communities that take advantage of the energy available during Fe-N redox oscillations. We examined this phenomenon in synthetic Fe(III) oxide (nanocrystalline goethite) suspensions inoculated with microflora from freshwater river floodplain sediments. Nitrate and acetate were added at alternate intervals in order to induce repeated cycles of microbial Fe(III) reduction and nitrate-dependent Fe(II) oxidation. Addition of nitrate to reduced, acetate-depleted suspensions resulted in rapid Fe(II) oxidation and accumulation of ammonium. High-resolution transmission electron microscopic analysis of material from Fe redox cycling reactors showed amorphous coatings on the goethite nanocrystals that were not observed in reactors operated under strictly nitrate- or Fe(III)-reducing conditions. Microbial communities associated with N and Fe redox metabolism were assessed using a combination of most-probable-number enumerations and 16S rRNA gene analysis. The nitrate-reducing and Fe(III)-reducing cultures were dominated by denitrifyingBetaproteobacteria(e.g.,Dechloromonas) and Fe(III)-reducingDeltaproteobacteria(Geobacter), respectively; these same taxa were dominant in the Fe cycling cultures. The combined chemical and microbiological data suggest that bothGeobacterand variousBetaproteobacteriaparticipated in nitrate-dependent Fe(II) oxidation in the cycling cultures. Microbially driven Fe-N redox cycling may have important consequences for both the fate of N and the abundance and reactivity of Fe(III) oxides in sediments.

scholarly journals Methods for the Recovery of Salmonella spp. from Carboxymethylcellulose Gum, Gum Ghatti, and Gelatin

1998 ◽  
Vol 81 (4) ◽  
pp. 721-726 ◽  
Author(s):  
René Miguel Amaguaña ◽  
Thomas S Hammack ◽  
Wallace H Andrews
Keyword(s):  
Final Concentration ◽  
Inorganic Salts ◽  
Most Probable Number ◽  
Salmonella Spp ◽  
Test Portion ◽  
Probable Number ◽  
Ph Adjustment ◽  
Gum Ghatti ◽  
Thickening Agents ◽  
The U.S

Abstract Foods analyzed for Salmonella spp. by the procedure in the U.S. Food and Drug Administration's Bacteriological Analytical Manual are preenriched at a 1:9 test portion/broth ratio. Various thickening agents preenriched at this ratio become viscous and nonpipettable after 24 h incubation at 35 C. The effects of 3 factors (presence of inorganic salts, adjustment of pH, and presence of enzymes) on the viscosity of the test portion/preenrichment mixtures of various thickening agents during incubation were determined. Reduction of the viscosities of these thickening agents was accomplished as follows: carboxymethylcellulose gum, addition of cellulase to a final concentration of 0.10℅ in lactose broth preenrichment and incubation with no pH adjustment; gum ghatti, addition of NaCI to a final concentration of 0.10℅ in lactose broth preerichment and adjustment of the pH to 6.5; and gelatin, addition of papain to a final concentration of 0.10℅ in lactose broth preenrichment and adjustment of the pH to 6.8. With these modified preenrichments, one Salmonella spp. cell/25 g (representing an approximate most probable number value of 0.04 cell/g) was generally recovered from the thickening agents.

scholarly journals Composition and Function of Sulfate-Reducing Prokaryotes in Eutrophic and Pristine Areas of the Florida Everglades

2002 ◽  
Vol 68 (12) ◽  
pp. 6129-6137 ◽  
Author(s):  
Hector Castro ◽  
K. R. Reddy ◽  
Andrew Ogram
Keyword(s):  
Carbon Sources ◽  
Original System ◽  
Agricultural Runoff ◽  
Florida Everglades ◽  
Most Probable Number ◽  
Probable Number ◽  
Sulfate Reducing ◽  
Limited Degree ◽  
Sulfate Reduction Rates ◽  
And Function

ABSTRACT As a result of agricultural activities in regions adjacent to the northern boundary of the Florida Everglades, a nutrient gradient developed that resulted in physicochemical and ecological changes from the original system. Sulfate input from agricultural runoff and groundwater is present in soils of the Northern Everglades, and sulfate-reducing prokaryotes (SRP) may play an important role in biogeochemical processes such as carbon cycling. The goal of this project was to utilize culture-based and non-culture-based approaches to study differences between the composition of assemblages of SRP in eutrophic and pristine areas of the Everglades. Sulfate reduction rates and most-probable-number enumerations revealed SRP populations and activities to be greater in eutrophic zones than in more pristine soils. In eutrophic regions, methanogenesis rates were higher, the addition of acetate stimulated methanogenesis, and SRP able to utilize acetate competed to a limited degree with acetoclastic methanogens. A surprising amount of diversity within clone libraries of PCR-amplified dissimilatory sulfite reductase (DSR) genes was observed, and the majority of DSR sequences were associated with gram-positive spore-forming Desulfotomaculum and uncultured microorganisms. Sequences associated with Desulfotomaculum fall into two categories: in the eutrophic regions, 94.7% of the sequences related to Desulfotomaculum were associated with those able to completely oxidize substrates, and in samples from pristine regions, all Desulfotomaculum-like sequences were related to incomplete oxidizers. This metabolic selection may be linked to the types of substrates that Desulfotomaculum spp. utilize; it may be that complete oxidizers are more versatile and likelier to proliferate in nutrient-rich zones of the Everglades. Desulfotomaculum incomplete oxidizers may outcompete complete oxidizers for substrates such as hydrogen in pristine zones where diverse carbon sources are less available.

Precision Parameters for the FDA Shellfish Laboratory Quality Assurance Program for 1973–1989

1995 ◽  
Vol 58 (6) ◽  
pp. 648-650
Author(s):  
JAMES T. PEELER ◽  
THOMAS E. GRAHAM ◽  
LARRY J. MATURIN
Keyword(s):  
Staphylococcus Aureus ◽  
Quality Assurance ◽  
Fecal Coliform ◽  
Quality Assurance Program ◽  
Plate Count ◽  
Most Probable Number ◽  
Probable Number ◽  
Standard Plate Count ◽  
Standard Plate ◽  
The U.S

Precision parameters from four microbiological analytical methods (coliform most probable number [MPN], fecal coliform MPN, Staphylococcus aureus plate count and standard plate count) were computed for the Shellfish Quality Assurance Program of the U.S. Food and Drug Administration (FDA). The pooled reproducibility variance (SR2) for the four methods from 1973 to 1989 were 0.0778, 0.1181, 0.0137, and 0.0087, respectively.

scholarly journals Approaches for Eliminating Bacteria Introduced during In Situ Bioleaching of Fractured Sulfidic Ores in Deep Subsurface

2017 ◽  
Vol 262 ◽  
pp. 70-74 ◽  
Author(s):  
Hendrik Ballerstedt ◽  
Eva Pakostova ◽  
D. Barrie Johnson ◽  
Axel Schippers
Keyword(s):  
Ferric Iron ◽  
Iron Oxidation ◽  
Most Probable Number ◽  
Reduced Sulfur Compounds ◽  
Oxidation Activity ◽  
Probable Number ◽  
Horizon 2020 ◽  
Cell Counts ◽  
Microbial Iron Oxidation

The major objective of the EU Horizon 2020 project “BioMOre” is the technical realization of indirect in situ leaching of Kupferschiefer sandstone and black shale ore by a ferric iron lixiviant generated by a mixed culture of autotrophic, acidophilic, iron-oxidizing bacteria and archaea in a ferric iron-generating bioreactor (FIGB). These organisms could colonize the deeply buried geological formations even under anaerobic conditions as most are able to grow by coupling the reduction of ferric iron to the oxidation of reduced sulfur compounds in the absence of oxygen. Development of an inhibition protocol to eliminate these allochthonous microbial bioreactor populations subsequent to the completion of in situ bioleaching was therefore investigated. Column bioleaching experiments using a laboratory-scale FIGB confirmed not only that metals were solubilised from both the sandstone and shale ores, but also that significant numbers of bacteria were released from the FIGB. The efficacy of 13 different chemical compounds in inhibiting microbial iron oxidation has been tested at different concentrations in shake flask and FIGB-coupled columns. Iron-oxidation activity, microcalorimetrically-determined activity and ATP measurements, in combination with microscopic cell counts and biomolecular analysis (T-RFLP, qPCR), plate counts and most-probable-number (MPN), were used to monitor the inhibiting effects on the acidophiles. Complete inhibition of metabolic activity of iron-oxidizing acidophiles was achieved in the presence of 0.4 mM formate, 300 mM chloride, 100 mM nitrate, 10 mM of primary C6 to C8 alcohols, 100 mM 1-butanol, 100 mM 1-pentanol, 0.1 mM SDS or 0.35 mM benzoic acid. No inhibition was found for 0.6 mM acetic acid and 200 mM methanol. Based on these results a recipe for the chemical composition of the “decommissioning solution” is proposed.

The Diversity of Benthic Microorganisms in Acidic Mine Lake Sediments

2007 ◽  
Vol 20-21 ◽  
pp. 489-492
Author(s):  
Huynh A. Pham ◽  
Carolyn E. Oldham ◽  
Jason J. Plumb
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Microbial Communities ◽  
Lake Sediments ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Most Probable Number ◽  
Rrna Gene ◽  
Probable Number ◽  
Benthic Bacteria ◽  
Different Depths

The sediment microbial communities of a disused coal mine lake, Lake Kepwari (pH~4.5-5) were studied to understand how the natural microbial processes in an oligotrophic acidic mine lake system influence the iron and sulphur cycles. Most probable number (MPN) viable counts were used to enumerate the benthic bacteria at different depths. MPN results revealed an abundance of bacteria that were capable of growing in sulphate reducing medium with numbers in the range of 1 × 107 – 1 × 108 cells.g-1 of wet sediment. In contrast, MPN results showed much lower numbers of bacteria that were capable of growing in ferric reducing medium with 1 × 102 – 2 × 103 cells.g-1 of wet sediment detected. Serial decimal dilution cultures were used to isolate pure strains of benthic bacteria. Strains HP1, HP2 and HP3 were isolated from benthic lake sediments at 18 m, 0 m and 10 m water depths respectively. 16S rRNA gene sequence analysis of strain HP1 showed that the strain belonged to the genus Enterobacter, strain HP2 belonged to the Order Rhizobiales and strain HP3 belonged to the sub-order Micrococcineae. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene fragments was used to profile the diversity of the benthic microbial communities at different depths. DGGE profiling of benthic sediments revealed that sediments contained mostly members of the Proteobacteria, Actinobacteria and Firmicutes phyla.

Enumeration of selected bacterial populations in a high mountain watershed

1974 ◽  
Vol 20 (11) ◽  
pp. 1487-1492 ◽  
Author(s):  
Q. D. Skinner ◽  
J. C. Adams ◽  
P. A. Rechard ◽  
A. A. Beetle
Keyword(s):  
Sampling Site ◽  
Sulfate Reducing Bacteria ◽  
Most Probable Number ◽  
High Mountain ◽  
Probable Number ◽  
Sulfate Reducing ◽  
Mountain Watershed ◽  
Reducing Bacteria ◽  
Nitrate Reducing Bacteria ◽  
Stream Systems

Nitrate-reducing bacteria, sulfate-reducing bacteria, fluorescent bacteria, and the total viable count were enumerated in three stream systems within a high mountain watershed over a period of two winters and two summers from 1970 to 1972. Spread plate and most probable number procedures showed that the number of fluorescent bacteria, sulfate-reducing bacteria, nitrate-reducing bacteria, and the total count were generally constant throughout the year at the lowest sampling site on the stream systems. However, in some cases and for short periods of time, the numbers of these bacteria appeared to be influenced by recreational use of the land and stream flow. For example, denitrifying bacteria increased in number during the winter recreational period and gave the lowest counts in July.

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