A flow cytometric method to measure prokaryotic records in ice cores: an example from the West Antarctic Ice Sheet Divide drilling site

Santibáñez, Pamela A.; McConnell, Joseph R.; Priscu, John C.

doi:10.1017/jog.2016.50

Cited by 16 publications

(17 citation statements)

References 126 publications

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“…A series of duplicated cultures was established for each isolated bacterial strain using four culturing temperatures (4°C, 8°C, 12°C, and 25°C) and four NaCl concentrations in the culturing media (0.2, 0.5, 0.7, and 0.9 M). Cell concentrations were monitored over time using a PhytoCyt flow cytometer (Turner Designs) with SYBR Green I (Molecular Probes) staining following the protocol described in Santibáñez et al ().…”

Section: Methodsmentioning

confidence: 99%

Methane production in the oxygenated water column of a perennially ice‐covered Antarctic lake

Dore

Steigmeyer

et al. 2019

Limnology & Oceanography

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Aerobic methane production in aquatic ecosystems impacts the global atmospheric budget of methane, but the extent, mechanism, and taxa responsible for producing this greenhouse gas are not fully understood. Lake Bonney (LB), a perennially ice‐covered Antarctic lake, has cold hypersaline waters underlying an oxygenated freshwater layer. We present temporal methane concentration profiles in LB indicating methane production in the oxygenated (> 200% air saturation) water. Experiments amended with methylphosphonate (MPn) yielded methane generation, suggesting in situ methanogenesis via the carbon‐phosphorus (C‐P) lyase pathway. Enrichment cultures from the lake were used to isolate five bacterial strains capable of generating methane when supplied with MPn as the sole P source. Based on 16S rRNA gene sequencing, the isolates belong to the Proteobacteria (closely related to Marinomonas, Hoeflea, and Marinobacter genera) and Bacteroidetes (Algoriphagus genus). 16S rRNA metagenomic sequencing confirms the presence of these taxa in LB. None of the isolated species were reported to be capable to produce methane. In addition, orthologs of the phosphoenolpyruvate mutase gene (PepM) and methylphosphonate synthase (MPnS), enzymes involved in phosphonate and MPn biosynthesis, were widely spread in the LB shotgun metagenomic libraries; genes related to C‐P lyase pathways (phn gene clusters) were also abundant. 16S rRNA and mcrA genes of anaerobic methanogens were absent in both 16S rRNA and metagenomics libraries. These data reveal that in situ aerobic biological methane production is likely a significant source of methane in LB.

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Section: Methodsmentioning

confidence: 99%

Methane production in the oxygenated water column of a perennially ice‐covered Antarctic lake

Dore

Steigmeyer

et al. 2019

Limnology & Oceanography

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“…To assess reproducibility and identify potential carryover by the melter system, we melted and analyzed parallel replicate sections of the ice core that corresponded to 4% of our target ice‐core section (1,764–2,709 m). The replicate sections were melted days or months later than the original sections for analysis and did not show significant differences from the adjacent samples (Santibáñez et al., ).…”

Section: Methodsmentioning

confidence: 99%

“…We used flow cytometry in concert with a continuous melting system (Santibáñez, McConnell, & Priscu, ) to produce the first temporal record of prokaryotic (nonphotosynthetic members of the domains Bacteria and Archaea ) cell concentration from a deep West Antarctic ice core (Buizert et al., ) spanning from 27,000 to 9,600 year before present (27 to 9.6 ka BP). Together with other high‐resolution measurements made on the same ice core, we described the temporal trends and patterns of the prokaryotic record with respect to past climatic events and evaluated the potential atmospheric sources (e.g., plants, soils, water, and rocks (Edmonds, ; Jones & Harrison, ; Kuhlman, Venkat, La Duc, Kuhlman, & McKay, ) for the prokaryotic cells comprising the record.…”

Section: Introductionmentioning

confidence: 99%

Prokaryotes in the WAIS Divide ice core reflect source and transport changes between Last Glacial Maximum and the early Holocene

Santibáñez

Maselli

Greenwood

et al. 2018

Global Change Biology

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We present the first long-term, highly resolved prokaryotic cell concentration record obtained from a polar ice core. This record, obtained from the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core, spanned from the Last Glacial Maximum (LGM) to the early Holocene (EH) and showed distinct fluctuations in prokaryotic cell concentration coincident with major climatic states. The time series also revealed a ~1,500-year periodicity with greater amplitude during the Last Deglaciation (LDG). Higher prokaryotic cell concentration and lower variability occurred during the LGM and EH than during the LDG. A sevenfold decrease in prokaryotic cell concentration coincided with the LGM/LDG transition and the global 19 ka meltwater pulse. Statistical models revealed significant relationships between the prokaryotic cell record and tracers of both marine (sea-salt sodium [ssNa]) and burning emissions (black carbon [BC]). Collectively, these models, together with visual observations and methanosulfidic acid (MSA) measurements, indicated that the temporal variability in concentration of airborne prokaryotic cells reflected changes in marine/sea-ice regional environments of the WAIS. Our data revealed that variations in source and transport were the most likely processes producing the significant temporal variations in WD prokaryotic cell concentrations. This record provided strong evidence that airborne prokaryotic cell deposition differed during the LGM, LDG, and EH, and that these changes in cell densities could be explained by different environmental conditions during each of these climatic periods. Our observations provide the first ice-core time series evidence for a prokaryotic response to long-term climatic and environmental processes.

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“…O nce considered inhospitable to life, in recent decades icy environments on Earth have been found that preserve organic material and even harbor active microbial communities (Priscu et al, 1998(Priscu et al, , 1999Siegert et al, 2001;Priscu, 2005;Santibáñez et al, 2005Santibáñez et al, , 2018Krembs et al, 2011;Uhlig et al, 2015). Glacial ice on Earth is known to contain organic material (Barnes et al, 2003;Barletta et al, 2012), including bacteria, algae, viruses, plant fragments, pollen grains, and black carbon.…”

Section: Introductionmentioning

confidence: 99%

WATSON:In SituOrganic Detection in Subsurface Ice Using Deep-UV Fluorescence Spectroscopy

et al. 2019

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Terrestrial icy environments have been found to preserve organic material and contain habitable niches for microbial life. The cryosphere of other planetary bodies may therefore also serve as an accessible location to search for signs of life. The Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets (WATSON) is a compact deep-UV fluorescence spectrometer for nondestructive ice borehole analysis and spatial mapping of organics and microbes, intended to address the heterogeneity and low bulk densities of organics and microbial cells in ice. WATSON can be either operated standalone or integrated into a wireline drilling system. We present an overview of the WATSON instrument and results from laboratory experiments intended to determine (i) the sensitivity of WATSON to organic material in a water ice matrix and (ii) the ability to detect organic material under various thicknesses of ice. The results of these experiments show that in bubbled ice the instrument has a depth of penetration of 10 mm and a detection limit of fewer than 300 cells. WATSON incorporates a scanning system that can map the distribution of organics and microbes over a 75 by 25 mm area. WATSON demonstrates a sensitive fluorescence mapping technique for organic and microbial detection in icy environments including terrestrial glaciers and ice sheets, and planetary surfaces including Europa, Enceladus, or the martian polar caps.ADC ¼ analog to digital converter DUV ¼ deep-UV LOD ¼ limit of detection LOQ ¼ limit of quantitation LPS ¼ laser power supply PBS ¼ phosphate-buffered saline WATSON ¼ Wireline Analysis Tool for the Subsurface Observation of Northern ice sheets 784 ESHELMAN ET AL.

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A flow cytometric method to measure prokaryotic records in ice cores: an example from the West Antarctic Ice Sheet Divide drilling site

Cited by 16 publications

References 126 publications

Methane production in the oxygenated water column of a perennially ice‐covered Antarctic lake

Methane production in the oxygenated water column of a perennially ice‐covered Antarctic lake

Prokaryotes in the WAIS Divide ice core reflect source and transport changes between Last Glacial Maximum and the early Holocene

WATSON:In SituOrganic Detection in Subsurface Ice Using Deep-UV Fluorescence Spectroscopy

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