scholarly journals Erratum for Lloyd et al., “Evidence for a Growth Zone for Deep-Subsurface Microbial Clades in Near-Surface Anoxic Sediments”

2020 ◽  
Vol 86 (21) ◽  
Author(s):  
Karen G. Lloyd ◽  
Jordan T. Bird ◽  
Joy Buongiorno ◽  
Emily Deas ◽  
Richard Kevorkian ◽  
...  
Keyword(s):  
Growth Zone ◽  
Deep Subsurface ◽  
Anoxic Sediments ◽  
Near Surface

scholarly journals Evidence for a growth zone for deep subsurface microbial clades in near-surface anoxic sediments

2020 ◽  
Author(s):  
Karen G. Lloyd ◽  
Jordan T. Bird ◽  
Joy Buongiorno ◽  
Emily Deas ◽  
Richard Kevorkian ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Growth Zone ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
White Oak ◽  
Deep Subsurface ◽  
Near Surface ◽  
Cell Counts ◽  
Order Of Magnitude ◽  
Population Sizes

AbstractGlobal marine sediments harbor a large and highly diverse microbial biosphere, but the mechanism by which this biosphere is established during sediment burial is largely unknown. During burial in marine sediments, concentrations of easily-metabolized organic compounds and total microbial cell abundance decrease steadily. However, it is unknown whether some microbial clades increase with depth, despite the overall trend of abundance decrease. We show total population increases in 38 microbial families over 3 cm of sediment depth in the upper 7.5 cm of White Oak River (WOR) estuary sediments. Clades that increased with depth were more often anaerobic, uncultured, or common in deep marine sediments relative to those that decreased. Minimum turnover times (which are minimum in situ doubling times of growth rates) were estimated to be 2-25 years by combining sedimentation rate with either quantitative PCR (qPCR) or the product of the Fraction Read Abundance of 16S rRNA genes and total Cell counts (FRAxC). Turnover times were within an order of magnitude of each other in two adjacent cores, as well as in two laboratory enrichments of Cape Lookout Bight (CLB), NC, sediments (average difference of 28 ± 19%). qPCR and FRAxC in WOR cores and FRAxC in CLB incubations produced similar turnover times for key deep subsurface uncultured clades Bathyarchaeota (8.7 ± 1.9 years) and Thermoprofundales/MBG-D (4.1 ± 0.7 years). We conclude that common deep subsurface microbial clades experience a narrow zone of growth in shallow sediments, offering an opportunity for natural selection of traits for long-term subsistence after resuspension events.Significance statementThe current dogma is that the deeply-branching uncultured microbes that dominate global marine sediments do not actually increase in population size as they are buried in marine sediments – rather they exist in a sort of prolonged torpor for thousands of years. This is because no evidence has ever been found that these clades actually increase population sizes, or grow, as they are gradually buried. We discovered that they actually do increase population sizes during burial, but only in the upper few centimeters. This changes our dogma about marine sediments as a vast repository of non-growing microbes, to a vast repository of non-growing microbes with a thin and relatively rapid area of growth in the upper 10 centimeters.

scholarly journals Evidence for a Growth Zone for Deep-Subsurface Microbial Clades in Near-Surface Anoxic Sediments

2020 ◽  
Vol 86 (19) ◽  
Author(s):  
Karen G. Lloyd ◽  
Jordan T. Bird ◽  
Joy Buongiorno ◽  
Emily Deas ◽  
Richard Kevorkian ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Sediment Cores ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
White Oak ◽  
Deep Subsurface ◽  
Near Surface ◽  
Cell Abundance ◽  
Cell Counts ◽  
Doubling Times

ABSTRACT Global marine sediments harbor a large and highly diverse microbial biosphere, but the mechanism by which this biosphere is established during sediment burial is largely unknown. During burial in marine sediments, concentrations of easily metabolized organic compounds and total microbial cell abundance decrease. However, it is unknown whether some microbial clades increase with depth. We show total population increases in 38 microbial families over 3 cm of sediment depth in the upper 7.5 cm of White Oak River (WOR) estuary sediments. Clades that increased with depth were more often associated with one or more of the following: anaerobes, uncultured, or common in deep marine sediments relative to those that decreased. Maximum doubling times (in situ steady-state growth rates could be faster to balance cell decay) were estimated as 2 to 25 years by combining sedimentation rate with either quantitative PCR (qPCR) or the product of the fraction read abundance of 16S rRNA genes and total cell counts (FRAxC). Doubling times were within an order of magnitude of each other in two adjacent cores, as well as in two laboratory enrichments of Cape Lookout Bight (CLB), NC, sediments (average difference of 28% ± 19%). qPCR and FRAxC in sediment cores and laboratory enrichments produced similar doubling times for key deep subsurface uncultured clades Bathyarchaeota (8.7 ± 1.9 years) and Thermoprofundales/MBG-D (4.1 ± 0.7 years). We conclude that common deep subsurface microbial clades experience a narrow zone of growth in shallow sediments, offering an opportunity for selection of long-term subsistence traits after resuspension events. IMPORTANCE Many studies show that the uncultured microbes that dominate global marine sediments do not actually increase in population size as they are buried in marine sediments; rather, they exist in a sort of prolonged torpor for thousands of years. This is because, although studies have shown biomass turnover in these clades, no evidence has ever been found that deeper sediments have larger populations for specific clades than shallower layers. We discovered that they actually do increase population sizes during burial, but only in the upper few centimeters. This suggests that marine sediments may be a vast repository of mostly nongrowing microbes with a thin and relatively rapid area of cell abundance increase in the upper 10 cm, offering a chance for subsurface organisms to undergo natural selection.

scholarly journals Geological degassing enhances microbial metabolism in the continental subsurface

2020 ◽  
Author(s):  
Till L.V. Bornemann ◽  
Panagiotis S. Adam ◽  
Victoria Turzynski ◽  
Ulrich Schreiber ◽  
Perla Abigail Figueroa-Gonzalez ◽  
...  
Keyword(s):  
Cold Water ◽  
Thermal Conditions ◽  
Microbial Metabolism ◽  
Significant Negative Correlation ◽  
Deep Subsurface ◽  
Near Surface ◽  
Microbial Life ◽  
Biogeographic Pattern ◽  
Bacterial Replication ◽  
Species Specific

AbstractMantle degassing provides a substantial amount of reduced and oxidized gases shaping microbial metabolism at volcanic sites across the globe, yet little is known about its impact on microbial life under non-thermal conditions. Here, we characterized deep subsurface fluids from a cold-water geyser driven by mantle degassing using genome-resolved metagenomics to investigate how the gases impact the metabolism and activity of indigenous microbes compared to non-impacted sites. While species-specific analyses of Altiarchaeota suggest site-specific adaptations and a particular biogeographic pattern, chemolithoautotrophic core features of the communities appeared to be conserved across 17 groundwater ecosystems between 5 and 3200 m depth. We identified a significant negative correlation between ecosystem depth and bacterial replication, except for samples impacted by high amounts of subsurface gases, which exhibited near-surface activity. Our results suggest that geological degassing leads to higher nutrient flows and microbial activity in the deep subsurface than previously estimated.

scholarly journals Genetic diversity in terrestrial subsurface ecosystems impacted by geological degassing

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Till L. V. Bornemann ◽  
Panagiotis S. Adam ◽  
Victoria Turzynski ◽  
Ulrich Schreiber ◽  
Perla Abigail Figueroa-Gonzalez ◽  
...  
Keyword(s):  
Cold Water ◽  
Thermal Conditions ◽  
Surface Characteristics ◽  
Deep Biosphere ◽  
Deep Subsurface ◽  
Near Surface ◽  
Microbial Life ◽  
Comparative Metagenomics ◽  
Biogeographic Pattern ◽  
Bacterial Replication

AbstractEarth’s mantle releases 38.7 ± 2.9 Tg/yr CO2 along with other reduced and oxidized gases to the atmosphere shaping microbial metabolism at volcanic sites across the globe, yet little is known about its impact on microbial life under non-thermal conditions. Here, we perform comparative metagenomics coupled to geochemical measurements of deep subsurface fluids from a cold-water geyser driven by mantle degassing. Key organisms belonging to uncultivated Candidatus Altiarchaeum show a global biogeographic pattern and site-specific adaptations shaped by gene loss and inter-kingdom horizontal gene transfer. Comparison of the geyser community to 16 other publicly available deep subsurface sites demonstrate a conservation of chemolithoautotrophic metabolism across sites. In silico replication measures suggest a linear relationship of bacterial replication with ecosystems depth with the exception of impacted sites, which show near surface characteristics. Our results suggest that subsurface ecosystems affected by geological degassing are hotspots for microbial life in the deep biosphere.

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

Analysis of 2D and 3D defects associated with precipitation of Cu in silicon

1991 ◽  
Vol 49 ◽  
pp. 870-871
Author(s):  
P.M. Rice ◽  
MJ. Kim ◽  
R.W. Carpenter
Keyword(s):  
Colony Growth ◽  
Dark Field ◽  
Dark Side ◽  
Silicide Phase ◽  
Strain Fields ◽  
Near Surface ◽  
Unknown Composition ◽  
Secondary Precipitates ◽  
20 Nm ◽  
2D And 3D

Extrinsic gettering of Cu on near-surface dislocations in Si has been the topic of recent investigation. It was shown that the Cu precipitated hetergeneously on dislocations as Cu silicide along with voids, and also with a secondary planar precipitate of unknown composition. Here we report the results of investigations of the sense of the strain fields about the large (~100 nm) silicide precipitates, and further analysis of the small (~10-20 nm) planar precipitates.Numerous dark field images were analyzed in accordance with Ashby and Brown's criteria for determining the sense of the strain fields about precipitates. While the situation is complicated by the presence of dislocations and secondary precipitates, micrographs like those shown in Fig. 1(a) and 1(b) tend to show anomalously wide strain fields with the dark side on the side of negative g, indicating the strain fields about the silicide precipitates are vacancy in nature. This is in conflict with information reported on the η'' phase (the Cu silicide phase presumed to precipitate within the bulk) whose interstitial strain field is considered responsible for the interstitial Si atoms which cause the bounding dislocation to expand during star colony growth.

Shock consolidation of Ni-Ti alloy powder

1986 ◽  
Vol 44 ◽  
pp. 430-431
Author(s):  
Naresh N. Thadhani ◽  
Thad Vreeland ◽  
Thomas J. Ahrens
Keyword(s):  
Alloy Powder ◽  
Amorphous Material ◽  
Ti Alloy ◽  
Two Phase ◽  
Near Surface ◽  
Optical Micrograph ◽  
Shock Compaction ◽  
Powder Particles ◽  
Ti Powder ◽  
Rapidly Solidified

A spherically-shaped, microcrystalline Ni-Ti alloy powder having fairly nonhomogeneous particle size distribution and chemical composition was consolidated with shock input energy of 316 kJ/kg. In the process of consolidation, shock energy is preferentially input at particle surfaces, resulting in melting of near-surface material and interparticle welding. The Ni-Ti powder particles were 2-60 μm in diameter (Fig. 1). About 30-40% of the powder particles were Ni-65wt% and balance were Ni-45wt%Ti (estimated by EMPA).Upon shock compaction, the two phase Ni-Ti powder particles were bonded together by the interparticle melt which rapidly solidified, usually to amorphous material. Fig. 2 is an optical micrograph (in plane of shock) of the consolidated Ni-Ti alloy powder, showing the particles with different etching contrast.

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