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Summers on the Colorado Plateau (USA) are typified by harsh conditions such as high temperatures, brief soil hydration periods, and high UV and visible radiation. We investigated whether community composition, physiological status, and pigmentation might vary in biological soil crusts as a result of such conditions. Representative surface cores were sampled at the ENE, WSW, and top microaspects of 20 individual soil crust pedicels at a single site in Canyonlands National Park, Utah, in spring and fall of 1999. Frequency of cyanobacterial taxa, pigment concentrations, and dark adapted quantum yield [F(v)/F(m)] were measured for each core. The frequency of major cyanobacterial taxa was lower in the fall compared to...
We characterized, at millimeter resolution, bacterial biomass, diversity, and vertical stratification of biological soil crusts in arid lands from the Colorado Plateau. Microscopic counts, extractable DNA, and plate counts of viable aerobic copiotrophs (VAC) revealed that the top centimeter of crusted soils contained atypically large bacterial populations, tenfold larger than those in uncrusted, deeper soils. The plate counts were not always consistent with more direct estimates of microbial biomass. Bacterial populations peaked at the immediate subsurface (1-2 mm) in light-appearing, young crusts, and at the surface (0-1 mm) in well-developed, dark crusts, which corresponds to the location of cyanobacterial populations....
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Bravo Dome is a commercial natural CO2 field that supplies the gas to depleted oil fields for enhanced oil recovery. In order to understand the distribution of CO2 across the greater Bravo Dome region, including southeastern Colorado and northwestern New Mexico, and to assess the impacts of high CO2 concentrations on microbes in the subsurface, 7 samples were collected from sites associated with high natural CO2 concentrations. Four water samples were collected, two from wells producing within Bravo Dome, one from an oil and gas field north of Bravo Dome associated with high CO2 concentrations, the Oakdale field, and one sample from a shallow groundwater well on the Rafter K ranch that effervesces CO2. Three samples...
We studied the bacterial communities in biological soil crusts (BSCs) from the Colorado Plateau by enrichment and cultivation, and by statistically analyzed denaturing gradient gel electrophoresis (DGGE) fingerprinting of environmental 16S rRNA genes, and phylogenetic analyses. Three 500-m-long transects, tens of km apart, consisting of 10 equally spaced samples each, were analyzed. BSC communities consistently displayed less richness (10-32 detectable DGGE bands per sample) and Shannon diversity (2.1-3.3) than typical soil communities, with apparent dominance by few members. In spite of some degree of small-scale patchiness, significant differences in diversity and community structure among transects was detectable,...
Soil drying and rewetting represents a common physiological stress for the microbial communities residing in surface soils. A drying-rewetting cycle may induce lysis in a significant proportion of the microbial biomass and, for a number of reasons, may directly or indirectly influence microbial community composition. Few studies have explicitly examined the role of drying-rewetting frequency in shaping soil microbial community structure. In this experiment, we manipulated soil water stress in the laboratory by exposing two different soil types to 0, 1, 2, 4, 6, 9, or 15 drying-rewetting cycles over a 2-month period. The two soils used for the experiment were both collected from the Sedgwick Ranch Natural Reserve...
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Low biomass waters provide a unique challenge in the field of microbial ecology. It is difficult to determine, when biomass concentrations are extremely low, whether or not the sequencing data received are of good quality and representative of the waters sampled. Fifty-nine samples including 8 blanks were collected from a low biomass hydraulically fractured well producing from the Niobrara Shale in Colorado. At least 4 samples were collected by filtering the exact volume for each listed here: 1000 mL, 900 mL, 800 mL, 700 mL, 600 mL, 500 mL, 400 mL, 300 mL, 200 mL, 100 mL, 0 mL (blanks).
The community adaptation hypothesis [7] predicts that lichens, simple communities of microorganisms, can adapt to a wide range of thermal regimes by regulating the ratio of primary producers (algae) and consumers (fungi): R(p/c). To test this hypothesis, we determined R(p/c) values by image analysis of cross sections of herbarium specimens of the lichen Cladina rangiferina, which is widely distributed between the Arctic and the tropics. We found that R(p/c) for C. rangiferina increases with summer temperature by more than one order of magnitude, consistent with the hypothesis. To assess the ecological significance of community adaptation (R(p/c) regulation), other adaptive mechanisms (e.g., photobiont substitution,...
We studied the migration of cyanobacteria in desert crusts from Las Bárdenas Reales (Spain). The crusts were almost exclusively colonized by the filamentous cyanobacterium Oscillatoria, which formed a dense layer approximately 600 microm thick located between 1.5 and 2.1 mm deep. Laboratory and field experiments showed that saturation of the crust with liquid water induced a migration of the cyanobacteria leading to a significant greening of the surface within a few minutes. Under light and rapid evaporation, the green color rapidly disappeared and the crust surface was completely devoid of filaments within 60 min. In contrast, 260 min was required to recover the original white color of the crust when slow evaporation...
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The Colorado Plateau is associated with several different commercial sources of natural CO2 and other non-hydrocarbon gases, such as noble gases. Twenty-five different hot springs, warm springs, cold springs, and/or rivers across the Utah region of the Colorado Plateau were sampled for microbial biomass. These different locations were associated with some concentration of dissolved or effervescing natural CO2 or other naturally-occurring non-hydrocarbon gases. Due to the possibility of different sources of the non-hydrocarbon gases across the region, multiple springs and rivers were sampled across a wide area of the state of Utah. Water samples were collected from non-stagnant regions of the sampled spring or river,...
Nitrogen (N) enrichment of the biosphere is an expanding problem to which arid ecosystems may be particularly sensitive. In semiarid grasslands, scarce precipitation uncouples plant and microbial activities, and creates within the soil a spatial mosaic of rhizosphere and cyanobacterial crust communities. We investigated the impact of elevated N deposition on these soil microbial communities at a grama-dominated study site located incentral New Mexico (USA). The study plots were established in 1995 and receive 10 kg ha(-1) year(-1) of supplemental N in the form of NH(4)NO(3). Soil samples were collected in July 2004, following 2 years of severe drought, and again in March 2005 following a winter of record high precipitation....
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In order to determine the innate microbial community of shale gas reservoirs and how they are impacted by hydraulic fracturing, this study analyzed biomass collected from produced water and rock from hydraulically fractured wells in the Utica Shale. The samples include rock chips from a drill core from one Utica well, produced water from that same Utica well, and produced water from 12 different Utica wells that had been in production between 1-5 years, spanning the oil and gas windows of SE Ohio. The samples were filtered for biomass, extracted, amplified, and 16S rRNA gene sequencing was performed on the Illumina MiSeq platform.
    map background search result map search result map Temporal variation in community composition, pigmentation, and F(v)/F(m) of desert cyanobacterial soil crusts. Microbial Communities Associated with Hot Springs and other CO2-rich Waters, Rocky Mountain Plateau Microbiology of the greater Bravo Dome region Microbiology of the Utica Shale Low biomass microbiology samples collected from a hydraulically fractured well producing from the Niobrara Shale in Colorado Temporal variation in community composition, pigmentation, and F(v)/F(m) of desert cyanobacterial soil crusts. Microbiology of the Utica Shale Low biomass microbiology samples collected from a hydraulically fractured well producing from the Niobrara Shale in Colorado Microbiology of the greater Bravo Dome region Microbial Communities Associated with Hot Springs and other CO2-rich Waters, Rocky Mountain Plateau