Validation of microbial community structure and ecological functional parameters in an aquatic microcosm designed for testing genetically engineered microorganisms

Leser, Thomas D.

doi:10.1007/bf00167164

Cited by 5 publications

(6 citation statements)

References 44 publications

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“…An important, but often overlooked, prerequisite when performing microcosm experiments is to determine whether the structural and functional properties of the source ecosystem are well represented in the microcosm, and the extent to which the experimental results are biased by the microcosm design and conditions (Leser, ). In this study, our main goals were to develop and evaluate an innovative experimental life support system (ELSS) designed to (i) study the interactive effects of multiple stressors on coastal and estuarine benthic communities, that is, environmental stressors resulting from climate change and contamination, and (ii) enable researchers to carry out complex but well‐replicated experiments.…”

Section: Introductionmentioning

confidence: 99%

Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communities

Coelho

Rocha

Pires

et al. 2013

Global Change Biology

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An experimental life support system (ELSS) was constructed to study the interactive effects of multiple stressors on coastal and estuarine benthic communities, specifically perturbations driven by global climate change and anthropogenic environmental contamination. The ELSS allows researchers to control salinity, pH, temperature, ultraviolet radiation (UVR), tidal rhythms and exposure to selected contaminants. Unlike most microcosms previously described, our system enables true independent replication (including randomization). In addition to this, it can be assembled using commercially available materials and equipment, thereby facilitating the replication of identical experimental setups in different geographical locations. Here, we validate the reproducibility and environmental quality of the system by comparing chemical and biological parameters recorded in our ELSS with those prevalent in the natural environment. Water, sediment microbial community and ragworm (the polychaete Hediste diversicolor) samples were obtained from four microcosms after 57 days of operation. In general, average concentrations of dissolved inorganic nutrients (NO3−; NH4+ and PO4−3) in the water column of the ELSS experimental control units were within the range of concentrations recorded in the natural environment. While some shifts in bacterial community composition were observed between in situ and ELSS sediment samples, the relative abundance of most metabolically active bacterial taxa appeared to be stable. In addition, ELSS operation did not significantly affect survival, oxidative stress and neurological biomarkers of the model organism Hediste diversicolor. The validation data indicate that this system can be used to assess independent or interactive effects of climate change and environmental contamination on benthic communities. Researchers will be able to simulate the effects of these stressors on processes driven by microbial communities, sediment and seawater chemistry and to evaluate potential consequences to sediment toxicity using model organisms such as Hediste diversicolor.

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Section: Introductionmentioning

confidence: 99%

Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communities

Coelho

Rocha

Pires

et al. 2013

Global Change Biology

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“…Nevertheless, the importance of this mode of DNA propagation in the environment remains a point of discussion, since most often experimental data were obtained from transfer experiments done in batch type conditions, whereas microorganisms in natural media are generally subjected to fluxes. In addition, aquatic microcosms used to study the propagation of rDNA are not systematically analyzed at the level of the biofilms present [30].…”

Section: Discussionmentioning

confidence: 99%

Recombinant plasmid DNA mobilization by activated sludge strains grown in fixed-bed or sequenced-batch reactors

Frank¹,

Simao-Beaunoir²,

Dollard³

et al. 1996

FEMS Microbiology Ecology

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The possibilities of mobilizing recombinant DNA (rDNA) by strains from activated sludge have been studied. A mixture of ten bacterial strains isolated from activated sludge was grown on a support in a continuously fed fixed‐bed reactor or in suspension in a sequenced‐batch reactor with biomass recycling. After reaching steady state, the bacteria in both types of reactors were used as the recipient population for evaluating the dissemination of the non‐conjugative and non‐mobilizable recombinant plasmid pCE328. The dissemination of this plasmid, derived from pBR328 (tra−, mob−, oriT−), was studied in comparison with that of pCE325 (pBR325 derivative tra−, mob−, oriT+), and that of the natural broad host range conjugative plasmid R388 (IncW). Initially the mobilization properties of pBR type recombinant plasmids between two strains of Escherichia coli were determined in the fixed‐bed reactor. Only the mobilization of the recombinant plasmid bearing a transfer origin (pCE325) was observed. The survival of E. coli strains bearing either the non‐transferable plasmid pCE328 or the conjugative plasmid R388 and added to the activated sludge reactors was measured in the effluent of both types of reactors. In the fixed‐bed reactor effluent, the donor populations remained stable after three days of operation and reached 103 to 105 colony forming units (cfu) ml−1, whereas they decreased in the sequenced‐batch reactors: donors bearing the pCE328 plasmid decreased by 2 log units in 20 days, whereas those bearing the R388 plasmid decreased by less than 1 log unit. Mobilization of the pCE328 plasmid could not be detected in any case. Transfer of the conjugative plasmid R388, used as a positive propagation control, was detected in strains arising from activated sludge in both types of reactors. Nevertheless, establishment of transconjugants was observed only in the fixed biomass at the rate of 10−7 transconjugants per recipient.

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“…Microcosm experiment. The three microcosms used were a modified version of the microcosm described by Leser (32). Each microcosm consisted of a pelagic part and a sediment part.…”

Section: Methodsmentioning

confidence: 99%

“…The microcosms were filled with freshly collected water from the pier at Risø, Denmark in Roskilde Fjord as previously described (32). Water was collected at approximately 1 m below the surface.…”

Section: Methodsmentioning

confidence: 99%

“…The effect of a single environmental parameter on the fate of the released microorganisms can be studied in simple experimental systems. However, the combined effects of all parameters can be assessed only in complex ecological model systems, or microcosms (13,15,32). A further requisite for determining microbial fate in the environment is use of sensitive methods for quantitating population dynamics.…”

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confidence: 99%

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Survival and activity of Pseudomonas sp. strain B13(FR1) in a marine microcosm determined by quantitative PCR and an rRNA-targeting probe and its effect on the indigenous bacterioplankton

Leser¹,

Boye²,

Hendriksen³

1995

Appl Environ Microbiol

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Genetically engineered Pseudomonas sp. strain B13(FR1) was released into laboratory-scale marine ecosystem models (microcosms). Survival of the introduced population in the water column and the sediment was determined by plating on a selective medium and by quantitative competitive PCR. The activity of the released bacteria was determined by in situ hybridization of single cells with a specific rRNA-targeting oligonucleotide probe. Two microcosms were inoculated with 10 6 cells ml ؊1 , while an uninoculated microcosm served as a control. The number of Pseudomonas sp. strain B13(FR1) cells decreased rapidly to ca. 10 2 cells ml ؊1 within 2 days after the release, which is indicative of grazing by protozoa. Three days after the introduction into seawater, cells were unculturable, but PCR continued to detect cells in low numbers. Immediately after the release, the ribosomal content of Pseudomonas sp. strain B13(FR1) corresponded to a generation time of 2 h. The growth rate decreased to less than 0.04 h ؊1 in 5 days and remained low, probably because of carbon limitation of the cells. Specific amendment of the microcosms with 10 mM 4-chlorobenzoate resulted in a rapid increase of the growth rate and an exponentially increasing number of cells detected by PCR, but not in resuscitation of the cells to a culturable state. The release of Pseudomonas sp. strain B13(FR1) into the microcosms seemed to affect only the indigenous bacterioplankton community transiently. Effects on the community were also apparent from the handling of water during filling of the microcosms and the amendment with 4-chlorobenzoate.

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Validation of microbial community structure and ecological functional parameters in an aquatic microcosm designed for testing genetically engineered microorganisms

Cited by 5 publications

References 44 publications

Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communities

Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communities

Recombinant plasmid DNA mobilization by activated sludge strains grown in fixed-bed or sequenced-batch reactors

Survival and activity of Pseudomonas sp. strain B13(FR1) in a marine microcosm determined by quantitative PCR and an rRNA-targeting probe and its effect on the indigenous bacterioplankton

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