Bacterial and Virus‐Like Particle Abundances in Purged and Unpurged Groundwater Depth Profiles

Roudnew, Ben; Seymour, Justin R.; Jeffries, Thomas C.; Lavery, Trish J.; Smith, Renee J.; Mitchell, James G.

doi:10.1111/j.1745-6592.2011.01393.x

Cited by 30 publications

(26 citation statements)

References 41 publications

(46 reference statements)

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“…Although such a significant proportion of life on Earth survives in these subsurface environments, we know very little about the interactions between indigenous microorganisms, specifically between bacteria and viruses. Recent observations of viruses in shallow and deep subsurface environments have reported viral abundance ranging from 10 5 to 10 7 ml À 1 , often exceeding cell abundance, with virus-to-cell ratios (VCRs) ranging from 0.4 to 18 (Kyle et al, 2008;Eydal et al, 2009;Roudnew et al, 2012). These results are consistent with VCRs found in surface environments (Srinivasiah et al, 2008).…”

Section: Introductionsupporting

confidence: 80%

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

et al. 2014

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A variety of microbially mediated metabolic pathways impact biogeochemical cycling in terrestrial subsurface environments. However, the role that viruses have in influencing microbial mortality and microbial community structure is poorly understood. Here we investigated the production of viruses and change in microbial community structure within shallow alluvial aquifer sediment slurries amended with 13 C-labeled acetate and nitrate. Biostimulation resulted in production of viruses concurrent with acetate oxidation, 13 CO 2 production and nitrate reduction. Interestingly, change in viral abundance was positively correlated to acetate consumption (r 2 ¼ 0.6252, Po0.05) and 13 CO 2 production (r 2 ¼ 0.6572, Po0.05); whereas change in cell abundance was not correlated to acetate consumption or 13 CO 2 production. Viral-mediated cell lysis has implications for microbial community structure. Betaproteobacteria predominated microbial community composition (62% of paired-end reads) upon inoculation but decreased in relative abundance and was negatively correlated to changes in viral abundance (r 2 ¼ 0.5036, Po0.05). As members of the Betaproteobacteria decreased, Gammaproteobacteria, specifically Pseudomonas spp., increased in relative abundance (82% of paired-end reads) and was positively correlated with the change in viral abundance (r 2 ¼ 0.5368, Po0.05). A nitrate-reducing bacterium, Pseudomonas sp. strain Alda10, was isolated from these sediments and produced viral-like particles with a filamentous morphology that did not result in cell lysis. Together, these results indicate that viruses are linked to carbon biogeochemistry and community structure in terrestrial subsurface sediments. The subsequent cell lysis has the potential to alter available carbon pools in subsurface environments, additionally controlling microbial community structure from the bottom-up.

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Section: Introductionsupporting

confidence: 80%

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

et al. 2014

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“…Purging three well volumes or until chemical parameters have stabilised, e.g. Roudnew et al [52], may be insufficient. In our study it is uncertain whether the 5 m 3 sample was also influenced by the presence of the borehole.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, the chemistry of the water is likely to remain suitable with relatively high dissolved oxygen throughout the unconfined aquifer [56], although DOC [10] and nutrients may become increasingly depleted. It is uncertain how bacterial populations might change with depth, but reduced carbon and nutrients are likely to limit microbial activity to a greater extent and elsewhere authors have suggested bacterial abundance generally decreases with depth [52], [57]. Therefore the potential food supply for invertebrates may also decrease with depth.…”

Section: Discussionmentioning

confidence: 99%

Using Boreholes as Windows into Groundwater Ecosystems

et al. 2013

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Groundwater ecosystems remain poorly understood yet may provide ecosystem services, make a unique contribution to biodiversity and contain useful bio-indicators of water quality. Little is known about ecosystem variability, the distribution of invertebrates within aquifers, or how representative boreholes are of aquifers. We addressed these issues using borehole imaging and single borehole dilution tests to identify three potential aquifer habitats (fractures, fissures or conduits) intercepted by two Chalk boreholes at different depths beneath the surface (34 to 98 m). These habitats were characterised by sampling the invertebrates, microbiology and hydrochemistry using a packer system to isolate them. Samples were taken with progressively increasing pumped volume to assess differences between borehole and aquifer communities. The study provides a new conceptual framework to infer the origin of water, invertebrates and microbes sampled from boreholes. It demonstrates that pumping 5 m3 at 0.4–1.8 l/sec was sufficient to entrain invertebrates from five to tens of metres into the aquifer during these packer tests. Invertebrates and bacteria were more abundant in the boreholes than in the aquifer, with associated water chemistry variations indicating that boreholes act as sites of enhanced biogeochemical cycling. There was some variability in invertebrate abundance and bacterial community structure between habitats, indicating ecological heterogeneity within the aquifer. However, invertebrates were captured in all aquifer samples, and bacterial abundance, major ion chemistry and dissolved oxygen remained similar. Therefore the study demonstrates that in the Chalk, ecosystems comprising bacteria and invertebrates extend from around the water table to 70 m below it. Hydrogeological techniques provide excellent scope for tackling outstanding questions in groundwater ecology, provided an appropriate conceptual hydrogeological understanding is applied.

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“…As such, wells often contain higher stygofaunal abundances than aquifers252730. Previous studies have also shown differences in microbial assemblages between well and aquifer samples using community fingerprinting techniques (e.g.…”

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confidence: 99%

Wells provide a distorted view of life in the aquifer: implications for sampling, monitoring and assessment of groundwater ecosystems

Korbel

Chariton

Stephenson

et al. 2017

Sci Rep

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When compared to surface ecosystems, groundwater sampling has unique constraints, including limited access to ecosystems through wells. In order to monitor groundwater, a detailed understanding of groundwater biota and what biological sampling of wells truly reflects, is paramount. This study aims to address this uncertainty, comparing the composition of biota in groundwater wells prior to and after purging, with samples collected prior to purging reflecting a potentially artificial environment and samples collected after purging representing the surrounding aquifer. This study uses DNA community profiling (metabarcoding) of 16S rDNA and 18S rDNA, combined with traditional stygofauna sampling methods, to characterise groundwater biota from four catchments within eastern Australia. Aquifer waters were dominated by Archaea and bacteria (e.g. Nitrosopumilales) that are often associated with nitrification processes, and contained a greater proportion of bacteria (e.g. Anaerolineales) associated with fermenting processes compared to well waters. In contrast, unpurged wells contained greater proportions of pathogenic bacteria and bacteria often associated with denitrification processes. In terms of eukaryotes, the abundances of copepods, syncarids and oligochaetes and total abundances of stygofauna were greater in wells than aquifers. These findings highlight the need to consider sampling requirements when completing groundwater ecology surveys.

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Bacterial and Virus‐Like Particle Abundances in Purged and Unpurged Groundwater Depth Profiles

Cited by 30 publications

References 41 publications

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

Correlation between viral production and carbon mineralization under nitrate-reducing conditions in aquifer sediment

Using Boreholes as Windows into Groundwater Ecosystems

Wells provide a distorted view of life in the aquifer: implications for sampling, monitoring and assessment of groundwater ecosystems

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