scholarly journals Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition

2002 ◽  
Vol 68 (6) ◽  
pp. 3085-3093 ◽  
Author(s):  
David Emerson ◽  
Craig L. Moyer
Keyword(s):  
Hydrothermal Vents ◽  
Microbial Mats ◽  
Direct Result ◽  
Amorphous Oxides ◽  
Fe Oxides ◽  
Cell Counts ◽  
Fe Oxidation ◽  
Oxide Deposition ◽  
High Concentrations ◽  
Dilution Tube

ABSTRACT A number of hydrothermal vent sites exist on the summit of the Loihi Seamount, a shield volcano that is part of the Hawaiian archipelago. The vents are 1,100 to 1,325 m below the surface and range in temperature from slightly above ambient (10°C) to high temperature (167°C). The vent fluid is characterized by high concentrations of CO2 (up to 17 mM) and Fe(II) (up to 268 μM), but there is a general paucity of H2S. Most of the vents are surrounded by microbial mats that have a gelatinous texture and are heavily encrusted with rust-colored Fe oxides. Visually, the Fe oxides appeared homogeneous. However, light microscopy revealed that the oxides had different morphologies, which fell into three classes: (i) sheaths, (ii) twisted or irregular filaments, and (iii) amorphous oxides. A morphological analysis of eight different samples indicated that the amorphous oxides were overall the most abundant; however, five sites had >50% sheaths and filamentous oxides. These latter morphologies are most likely the direct result of microbial deposition. Direct cell counts revealed that all of the oxides had abundant microbial populations associated with them, from 6.9 × 107 to 5.3 × 108 cells per ml of mat material. At most sites, end point dilution series for lithotrophic Fe oxidizers were successful out to dilutions of 10−6 and 10−7. A pure culture was obtained from a 10−7 dilution tube; this strain, JV-1, was an obligate, microaerophilic Fe oxidizer that grew at 25 to 30°C. A non-cultivation-based molecular approach with terminal-restriction fragment length polymorphism also indicated the common presence of Fe-oxidizing bacteria at Loihi. Together, these results indicate that Fe-oxidizing bacteria are common at the Loihi Seamount and probably play a major role in Fe oxidation. A review of the literature suggests that microbially mediated Fe oxidation at hydrothermal vents may be important globally.

scholarly journals The natural barrier to retention of the high concentration of gases: methane and carbon dioxide, methane and hydrogen under hydrothermal vents

2019 ◽  
pp. 11
Author(s):  
T.A. Smaglichenko
Keyword(s):  
Hydrothermal Vents ◽  
Geochemical Data ◽  
3D Seismic ◽  
Seismic Model ◽  
High Concentration ◽  
Geological Structures ◽  
Diffusion Parameters ◽  
High Concentrations ◽  
Tomography Method ◽  
Natural Barrier

The assumed seismic model of the area around fields having high concentrations of CH4 and CO2, CH4 and H2 dissolved in hydrothermal vents is first introduced. The model of so-called natural barrier to retention of gases accumulation has been revealed using outcomes of 3D seismic tomography method, which has been developed by the author and utilizing geochemical data that were earlier obtained by other researchers in scientific cruises and university laboratories. The built model is in agreement with a distribution of seismicity (M 2.5–4.5) that occurred during last 5 years. A comparison of diffusion parameters of methane for thermal reservoirs and rocks, and corresponding comparison of geological structures permits to suppose that the presented model can be used to find appropriated area for underground storage of gases mentioned above.

scholarly journals Anaerobic oxidation of methane alters sediment records of sulfur, iron and phosphorus in the Black Sea

2016 ◽  
Author(s):  
Matthias Egger ◽  
Peter Kraal ◽  
Tom Jilbert ◽  
Fatimah Sulu-Gambari ◽  
Célia J. Sapart ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Pore Water ◽  
Black Sea ◽  
The Black Sea ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Fe Oxide ◽  
Fe Oxides ◽  
Oxidation Of Methane ◽  
High Concentrations

Abstract. The surface sediments in the Black Sea are underlain by extensive deposits of iron (Fe) oxide-rich lake sediments that were deposited prior to the inflow of marine Mediterranean Sea waters ca. 9000 years ago. The subsequent downward diffusion of marine sulfate into the methane-bearing lake sediments has led to a multitude of diagenetic reactions in the sulfate-methane transition zone (SMTZ), including anaerobic oxidation of methane (AOM) with sulfate. While the sedimentary cycles of sulfur (S), methane and Fe in the SMTZ have been extensively studied, relatively little is known about the diagenetic alterations of the sediment record occurring below the SMTZ. Here we combine detailed geochemical analyses of the sediment and pore water with multicomponent diagenetic modeling to study the diagenetic alterations below the SMTZ at two sites in the western Black Sea. We focus on the dynamics of Fe, S and phosphorus (P) and demonstrate that diagenesis has strongly overprinted the sedimentary burial records of these elements. Our results show that sulfate-mediated AOM substantially enhances the downward diffusive flux of sulfide into the deep limnic deposits. During this downward sulfidization, Fe oxides, Fe carbonates and Fe phosphates (e.g. vivianite) are converted to sulfide phases, leading to an enrichment in solid phase S and the release of phosphate to the pore water. Below the sulfidization front, high concentrations of dissolved ferrous Fe (Fe2+) lead to sequestration of downward diffusing phosphate as authigenic vivianite, resulting in a transient accumulation of total P directly below the sulfidization front. Our model results further demonstrate that downward migrating sulfide becomes partly re-oxidized to sulfate due to reactions with oxidized Fe minerals, fueling a cryptic S cycle and thus stimulating slow rates of sulfate-driven AOM (~ 1–100 pmol cm−3 d−1) in the sulfate-depleted limnic deposits. However, this process is unlikely to explain the observed release of dissolved Fe2+ below the SMTZ. Instead, we suggest that besides organoclastic Fe oxide reduction, AOM coupled to the reduction of Fe oxides may also provide a possible mechanism for the high concentrations of Fe2+ in the pore water at depth. Our results reveal that methane plays a key role in the diagenetic alterations of Fe, S and P records in Black Sea sediments. The downward sulfidization into the limnic deposits is enhanced through sulfate-driven AOM with sulfate and AOM with Fe oxides may provide a deep source of dissolved Fe2+ that drives the sequestration of P in vivianite below the sulfidization front.

Summer flow event induces a cyanobacterial bloom in a seasonal Western Australian estuary

2003 ◽  
Vol 54 (2) ◽  
pp. 139 ◽  
Author(s):  
Barbara J. Robson ◽  
David P. Hamilton
Keyword(s):  
Inorganic Nitrogen ◽  
Cyanobacterial Bloom ◽  
River Estuary ◽  
Summer Rainfall ◽  
High Water ◽  
Surface Mixed Layer ◽  
Cell Counts ◽  
High Concentrations ◽  
Reactive Phosphorus ◽  
Australian Estuary

In January 2000, record rainfall led to the first recorded bloom of Microcystis aeruginosa in the Swan River estuary. A simple model is used to examine the bloom dynamics and the unusual conditions that produced it. Laboratory trials were conducted to determine the response to salinity of M. aeruginosa, while other parameters for the model were obtained from the literature. Growth was found to be optimal at salinities up to 4, and declined to zero at 25. The unseasonable summer rainfall flushed brackish and marine water from the estuary and produced a surface mixed layer with low salinity. The model simulations show that the hydrological conditions, in combination with high concentrations of inorganic nutrients (dissolved inorganic nitrogen >1.2 mg L–1, filterable reactive phosphorus >0.02 mg L–1) in river inflows, high water temperature and high daily insolation, promoted rapid phytoplankton growth, favouring dominance by M. aeruginosa. Doubling rates during the bloom were around 0.35 day–1 and cell counts exceeded 105 cells mL–1 within three weeks of the inflow event. Although this doubling rate ultimately determined the total bloom biomass, local concentrations were strongly influenced by physical processes that concentrated M. aeruginosa cells both vertically and horizontally, and advected a seed population from the upper estuary into the lower basin.

Microbiological bioassay using Bacillus pumilus to detect tetracycline in milk

2015 ◽  
Vol 82 (2) ◽  
pp. 248-255 ◽  
Author(s):  
Melisa Tumini ◽  
Orlando Guillermo Nagel ◽  
Rafael Lisandro Althaus
Keyword(s):  
Bacillus Pumilus ◽  
Screening Methods ◽  
Microtiter Plates ◽  
Cell Counts ◽  
Time Period ◽  
Mueller Hinton ◽  
Maximum Residue Limits ◽  
High Concentrations ◽  
User Friendly ◽  
Short Time

The tetracyclines (TCs) are widely used in the treatment of several diseases of cattle and their residues may be present in milk. To control these residues it is necessary to have available inexpensive screening methods, user-friendly and capable of analysing a high number of samples. The purpose of this study was to design a bioassay of microbiological inhibition in microtiter plates with spores of Bacillus pumilus to detect TCs at concentrations corresponding to the Maximum Residue Limits (MRLs). Several complementary experiments were performed to design the bioassay. In the first study, we determined the concentration of spores that produce a change in the bioassay's relative absorbance in a short time period. Subsequently, we assessed the concentration of chloramphenicol required to decrease the detection limit (DL) of TCs at MRLs levels. Thereafter, specificity, DL and cross-specificity of the bioassay were estimated. The most appropriate microbiological inhibition assay had a B. pumilus concentration of 1·6 × 109 spores/ml, fortified with 2500 μg chloramphenicol/l (CAP) in Mueller Hinton culture medium using brilliant black and toluidine blue as redox indicator. This bioassay detected 117 μg chlortetracycline/l, 142 μg oxytetracycline/l and 105 μg tetracycline/l by means of a change in the indicator's colour in a period of 5 h. The method showed good specificity (97·9%) which decreased slightly (93·3%) in milk samples with high somatic cell counts (>250 000 cells/ml). Furthermore, other antimicrobials studied (except neomycin) must be present in milk at high concentrations (from >5 to >100 MRLs) to produce positive results in this assay, indicating a low cross specificity.

scholarly journals Marine Fe-oxidizingZetaproteobacteria: Historical, ecological, and genomic perspectives

2018 ◽  
Author(s):  
Sean M. McAllister ◽  
Ryan M. Moore ◽  
Amy Gartman ◽  
George W. Luther ◽  
David Emerson ◽  
...  
Keyword(s):  
Hydrothermal Vents ◽  
Steel Corrosion ◽  
Coastal Sediments ◽  
Model Organisms ◽  
Rrna Gene ◽  
Transition Zones ◽  
Operational Taxonomic Units ◽  
Fe Oxidation ◽  
Subsurface Environments ◽  
Attachment Structures

AbstractTheZetaproteobacteriaare a class of bacteria typically associated with marine Fe oxidizing environments. First discovered in the hydrothermal vents at Loihi Seamount, Hawaii, they have become model organisms for marine microbial Fe oxidation. In addition to deep sea and shallow hydrothermal vents,Zetaproteobacteriaare found in coastal sediments, other marine subsurface environments, steel corrosion biofilms, as well as saline terrestrial aquifers and springs. Isolates from a range of environments all grow by Fe oxidation. Their success lies partly in their microaerophily, which enables them to compete with abiotic Fe oxidation at the low O2concentrations common to Fe(II)-rich oxic/anoxic transition zones. Also,Zetaproteobacteriamake a variety of biomineral morphologies as a repository for Fe(III) waste, and as attachment structures. To determine the known diversity of theZetaproteobacteria, we have used 16S rRNA gene sequences to define 59 operational taxonomic units (OTUs), at 97% similarity. While someZetaproteobacteriataxa appear to be cosmopolitan, various habitats enrich for different sets ofZetaproteobacteria. OTU networks show that certainZetaproteobacteriaco-exist, sharing compatible niches. These niches may correspond with adaptations to O2, H2, and nitrate availability, based on genomic analyses. Also, a putative Fe oxidation gene has been found in diverseZetaproteobacteriataxa, suggesting that theZetaproteobacteriaevolved as specialists in Fe oxidation. In all, culture, genomic, and environmental studies suggest thatZetaproteobacteriaare widespread, and therefore have a broad influence on marine and saline terrestrial Fe cycling.

scholarly journals Mining the Deep: A global assessment of biodiversity and research effort at deep-sea hydrothermal vents in relation to mining of seafloor massive sulphides

2019 ◽  
Author(s):  
Andrew Thaler ◽  
Diva Amon
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vent ◽  
Hydrothermal Vents ◽  
Research Effort ◽  
Scientific Discovery ◽  
Precious Metals ◽  
Biogeographic Provinces ◽  
High Concentrations ◽  
Seafloor Massive Sulphides ◽  
Massive Sulphides

When the RV Knorr set sail for the Galapagos Rift in 1977, the scientists aboard expected to find deep-sea hydrothermal vents. What they did not expect to find was life—abundant and unlike anything ever seen before. Submersible dives revealed not only deep-sea hydrothermal vents but entire ecosystem surrounding them, including the towering bright red tubeworms that would become icons of the deep sea. This discovery was so unexpected that the ship carried no biological preservatives. These first specimens were fixed in vodka from the scientists’ private reserves.Since that first discovery, deep-sea hydrothermal vents have been found throughout the oceans. As more regions are explored, newly discovered vent fields present the potential for entirely species and ecosystems. Increasingly, however, it is not scientific discovery, but the financial value of vent fields, and the ores they contain, that is driving exploration in the deep sea. Over the last five decades, a new industry has emerged to explore the potential of mining Seafloor Massive Sulphides (deep-sea hydrothermal vents that contain high concentrations of rare and precious metals). Multiple enterprises are developing mining prospects that include both active and inactive deep-sea hydrothermal vent fields. In order to understand the impacts of exploitation at deep-sea hydrothermal vents, scientists and miners must establish environmental baselines. Biodiversity is frequently used as a proxy for resilience and as a metric for assessing biological baselines but, since research effort is not distributed equally across the oceans, biodiversity estimates in the deep sea are rarely comprehensive. Studies have predominantly focused on a few key biogeographic provinces, while other regions have only been sampled sparingly. Managers, regulators, and mining companies are working from incomplete data, with inferences about the consequences, as well as mitigation and remediation practices, often drawn from studies of few vent ecosystems that are often different from those in which the impacts are expected to occur. To better assess our current understanding of deep-sea hydrothermal vent biodiversity, we undertook a quantitative survey of the last 40 years of vent research. A stark north/south divide was detected, demonstrating that while research was disproportionately focused in the Northern Hemisphere, mining prospects were overwhelmingly positioned in the Southern Hemisphere. In addition, we provided a ranked assessment of biodiversity in eight major biogeographic provinces, identified knowledge gaps in the available deep-sea hydrothermal vent exploration literature, and assessed sampling completeness to provide further guidance to regulators, managers, and contractors as they develop comprehensive environmental baseline assessments.

scholarly journals Exogenous Protein as an Environmental Stimuli of Biofilm Formation in Select Bacterial Strains

2019 ◽  
Author(s):  
Donna Ye ◽  
Lekha Bapu ◽  
Mariane Mota Cavalcante ◽  
Jesse Kato ◽  
Maggie Lauria Sneideman ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Milk Protein ◽  
Flavobacterium Columnare ◽  
Bacterial Strains ◽  
Fish Pathogens ◽  
Cell Counts ◽  
Exogenous Protein ◽  
High Concentrations ◽  
Species Specific

ABSTRACTA screening of environmental conditions that would elicit robust biofilm in a collection ofSerratia marcescensisolated from soil revealed that exogenous milk protein increased biofilm productivity up to ten-fold. A select screening of fish pathogens, freshwater and human isolates identified several other species that responded similarly to exogenous protein. The optimal protein concentration was species specific;S. marcescensat 5% milk protein,Aeromonassp. at 2-3%,Flavobacterium columnareat 1% andPseudomonas aeruginosaat 0.1-0.4%. Media supplemented with milk protein also increased the cell counts in biofilm as well as the protein incorporated into the biofilm matrix. These data suggest that relatively high concentrations of exogenous protein may serve as an environmental trigger for biofilm formation, particularly for pathogenic bacteria exposed to relatively high concentrations of protein in bodily fluids and mucosal surfaces.

Limnological properties of permafrost thaw ponds in northeastern Canada

2009 ◽  
Vol 66 (10) ◽  
pp. 1635-1648 ◽  
Author(s):  
Julie Breton ◽  
Catherine Vallières ◽  
Isabelle Laurion
Keyword(s):  
Optical Properties ◽  
Significant Contribution ◽  
Microbial Mats ◽  
Gas Production ◽  
Organic Soils ◽  
Large Variability ◽  
Bottom Waters ◽  
High Concentrations ◽  
Subarctic Ponds

Arctic warming has recently accelerated, triggering the formation of thaw ponds and the mobilization of a carbon pool that has accumulated over thousands of years. A survey of 46 thaw ponds in the Canadian arctic and subarctic regions showed that these ecosystems have high concentrations of dissolved organic matter (DOM) and nutrients and are relatively productive. This activity was reflected in the optical properties of DOM that indicated a dominance of allochthonous sources but a significant contribution of low molecular weight compounds. Several subarctic ponds were stratified in summer, resulting in a hypoxic hypolimnion. Most ponds were supersaturated in CO2 and CH4, with higher gas concentrations in bottom waters. However, arctic thaw ponds colonized by benthic microbial mats showed lower CO2 concentrations, likely caused by active photosynthesis. CO2 was correlated with both the quantity and the optical properties of DOM, suggesting the significant role of dissolved compounds from melting organic soils and catchment vegetation on the balance between heterotrophy and autotrophy. The large variability observed in limnological properties of this series of ponds precludes generalisations about their role in greenhouse gas production. However, the fact that all thaw ponds were supersaturated in CH4 underscores the importance of estimating their global significance.

Sign in / Sign up

Export Citation Format

Share Document