Influence of Protozoa and Nutrient Availability on Nitrification Rates in Subsurface Sediments

Strauss, Eric A.; Dodds, Walter K.

doi:10.1007/s002489900045

Cited by 43 publications

(32 citation statements)

References 46 publications

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“…We note that thiram and neutral red were the only inhibitors we found to be 100% effective and specific to protozoa, although we cannot rule out possible effects on phototrophic protists or other species of invertebrates that we did not test. Interestingly, fumagillin is described in the literature as a specific protozoacide (Colinas et al 1994;Strauss and Dodds 1997), which we disproved.…”

Section: Discussionmentioning

confidence: 85%

Testing assumptions of the eukaryotic inhibitor method for investigating interactions between aquatic protozoa and bacteria, applied to marine sediment

Shimeta

Cook

2011

Limnology & Ocean Methods

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Eukaryote-metabolic inhibitors have been applied in published incubation experiments to inhibit protozoans and infer their impacts on bacteria. This method has been used with water-column, sedimentary, biofilm, biofilter, soil, groundwater, wastewater, and sludge samples. The approach rests on assumptions that rarely have been tested: 1) the inhibitor is completely effective against all protozoans; 2) the inhibitor has no effects on other eukaryotes in the system (e.g., microalgae, metazoans) that could influence bacterial activity; and 3) the inhibitor has no effect on bacterial activity. We tested these assumptions for 10 inhibitors used in published studies (amphotericin B, anisomycin, colchicine, cycloheximide, cytochalasin B, fumagillin, griseofulvin, neutral red, nystatin, and thiram) and one combination of inhibitors (colchicine + cycloheximide) using marine sedimentary organisms. Only thiram was completely effective against the natural assemblages of ciliates and flagellates. With some inhibitors, partial inhibition of ciliates was followed by regrowth within 6-24 h or a bloom of a resistant species. Most inhibitors also killed infaunal invertebrates. Five inhibitors were further tested for direct effects on bacteria at concentrations that inhibited ciliates. Each inhibitor altered either esterase activity, denitrification, or both. All inhibitors thus violated one or more assumptions of the method. Conclusions in published work that did not demonstrate the validity of all assumptions underlying this method should not be accepted. Any future attempt to use a eukaryotic inhibitor against protozoans must confirm all assumptions of this method for the particular habitat, species, and processes to which the inhibitor will be applied.

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Section: Discussionmentioning

confidence: 85%

Testing assumptions of the eukaryotic inhibitor method for investigating interactions between aquatic protozoa and bacteria, applied to marine sediment

Shimeta

Cook

2011

Limnology & Ocean Methods

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“…Studies at the Rifle site have shown that protozoa become abundant in the groundwater when dissimilatory metal reduction is stimulated by the addition of acetate (64). The increase in protozoan abundance is significant because protozoa can exploit substantial quantities of bacterial biomass production (52), and grazing can significantly stimulate microbial metabolic activity and growth (53,54).…”

Section: Resultsmentioning

confidence: 99%

Molecular Analysis of theIn SituGrowth Rates of Subsurface Geobacter Species

Holmes

Giloteaux

Barlett

et al. 2013

Appl Environ Microbiol

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dMolecular tools that can provide an estimate of the in situ growth rate of Geobacter species could improve understanding of dissimilatory metal reduction in a diversity of environments. Whole-genome microarray analyses of a subsurface isolate of Geobacter uraniireducens, grown under a variety of conditions, identified a number of genes that are differentially expressed at different specific growth rates. Expression of two genes encoding ribosomal proteins, rpsC and rplL, was further evaluated with quantitative reverse transcription-PCR (qRT-PCR) in cells with doubling times ranging from 6.56 h to 89.28 h. Transcript abundance of rpsC correlated best (r 2 ‫؍‬ 0.90) with specific growth rates. Therefore, expression patterns of rpsC were used to estimate specific growth rates of Geobacter species during an in situ uranium bioremediation field experiment in which acetate was added to the groundwater to promote dissimilatory metal reduction. Initially, increased availability of acetate in the groundwater resulted in higher expression of Geobacter rpsC, and the increase in the number of Geobacter cells estimated with fluorescent in situ hybridization compared well with specific growth rates estimated from levels of in situ rpsC expression. However, in later phases, cell number increases were substantially lower than predicted from rpsC transcript abundance. This change coincided with a bloom of protozoa and increased attachment of Geobacter species to solid phases. These results suggest that monitoring rpsC expression may better reflect the actual rate that Geobacter species are metabolizing and growing during in situ uranium bioremediation than changes in cell abundance.

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“…For example, in laboratory studies, inhibition of the growth of protozoa has been shown to have a positive effect on degradation of trichloroethane (Cunningham et al 2009), but to have a negative effect on BTEX removal (Kota et al 1999). Protozoa also have the ability to decrease clogging in wells in some circumstances (DeLeo & Baveye 1997;Mattison et al 2002), and affect nitrogen cycling (Strauss & Dodds 1997) and carbon cycling In situ growth on emplaced materials, T-RFLP, DNA sequencing Boyd et al (2007) Glacial sands and gravels Mohamet aquifer, IL, USA Planktonic and attached bacterial communities were distinct (only 15% of species were common to both communities). There was no significant difference in the total number of species detected in each community.…”

Section: Global Studies Of Uncontaminated Aquifer Microbiologymentioning

confidence: 99%

Microbial communities in UK aquifers: current understanding and future research needs

Gregory

Maurice

West

et al. 2014

QJEGH

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The presence and activity of microorganisms in aquifers can affect, amongst other things, nutrient cycling, contaminant degradation and water flow. The introduction of a pollutant or other changes in water chemistry can alter the microbial community composition and affect aquifer functioning. To understand the microbial response to anthropogenically induced changes, a better knowledge of baseline microbial communities in uncontaminated aquifers is needed. Here, we review the information on microorganisms in UK aquifers together with examples of research from other countries on this topic, and discuss how these communities might respond to disturbance. Research into microbial communities in UK aquifers has mostly been limited to bacteria and often reveals a community dominated by Proteobacteria. The community composition is influenced by factors such as mineralogy and water chemistry, and the natural baseline community may be altered by aquifer contamination. A UK-wide survey of aquifer microbes, similar to one recently carried out in New Zealand, would provide valuable information about the current state of UK aquifer microbiology. This would lead to a greatly improved understanding of the ecosystem services provided by the microbial communities present in aquifers, allow future monitoring and assessment of the effects of pollution, and assist in groundwater resource management.

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Influence of Protozoa and Nutrient Availability on Nitrification Rates in Subsurface Sediments

Cited by 43 publications

References 46 publications

Testing assumptions of the eukaryotic inhibitor method for investigating interactions between aquatic protozoa and bacteria, applied to marine sediment

Testing assumptions of the eukaryotic inhibitor method for investigating interactions between aquatic protozoa and bacteria, applied to marine sediment

Molecular Analysis of theIn SituGrowth Rates of Subsurface Geobacter Species

Microbial communities in UK aquifers: current understanding and future research needs

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