Using microcosms to study gene transfer in aquatic habitats

Ashelford, Kevin E.; Fry, John C.; Day, Martin J.; Hill, Katja E.; Learner, M. A.; Marchesi, Julian; Perkins, Caroline D.; Weightman, Andrew J.

doi:10.1111/j.1574-6941.1997.tb00393.x

Cited by 23 publications

(2 citation statements)

References 44 publications

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“…Examples of such natural hot spots are the scum layers on standing bodies of water and the surface microlayers (SML) in lakes and oceans (17,28). Our postulate is corroborated by various studies that observed plasmid transfer or detected plasmids in such natural ecosystems (4,19,20,32,38,44). There are multiple possible explanations for the observed increased plasmid transfer at the air-liquid interface compared to that in submerged biofilms, and they likely involve a combination of the physical properties of the environment as well as the physiological state of the cells.…”

Section: Discussionsupporting

confidence: 72%

Increased Transfer of a Multidrug Resistance Plasmid in Escherichia coli Biofilms at the Air-Liquid Interface

Król

Nguyen

Rogers

et al. 2011

Appl Environ Microbiol

102

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Although biofilms represent a common bacterial lifestyle in clinically and environmentally important habitats, there is scant information on the extent of gene transfer in these spatially structured populations. The objective of this study was to gain insight into factors that affect transfer of the promiscuous multidrug resistance plasmid pB10 in Escherichia coli biofilms. Biofilms were grown in different experimental settings, and plasmid transfer was monitored using laser scanning confocal microscopy and plate counting. In closed flow cells, plasmid transfer in surface-attached submerged biofilms was negligible. In contrast, a high plasmid transfer efficiency was observed in a biofilm floating at the air-liquid interface in an open flow cell with low flow rates. A vertical flow cell and a batch culture biofilm reactor were then used to detect plasmid transfer at different depths away from the air-liquid interface. Extensive plasmid transfer occurred only in a narrow zone near that interface. The much lower transfer frequencies in the lower zones coincided with rapidly decreasing oxygen concentrations. However, when an E. coli csrA mutant was used as the recipient, a thick biofilm was obtained at all depths, and plasmid transfer occurred at similar frequencies throughout. These results and data from separate aerobic and anaerobic matings suggest that oxygen can affect IncP-1 plasmid transfer efficiency, not only directly but also indirectly, through influencing population densities and therefore colocalization of donors and recipients. In conclusion, the air-liquid interface can be a hot spot for plasmid-mediated gene transfer due to high densities of juxtaposed donor and recipient cells.

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Section: Discussionsupporting

confidence: 72%

Increased Transfer of a Multidrug Resistance Plasmid in Escherichia coli Biofilms at the Air-Liquid Interface

Król

Nguyen

Rogers

et al. 2011

Appl Environ Microbiol

102

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“…In general, microcosm studies have essentially focused on aquatic invertebrate communities [44], but some microcosm studies have dealt with aquatic microbial communities [2,39,41]. In field conditions, among the different microbial groups, only testate amoebae have received substantial attention including experimental studies simulating environmental perturbation.…”

Section: Potential Trophic Effectsmentioning

confidence: 99%

Effects of Experimental Lead Pollution on the Microbial Communities Associated with Sphagnum fallax (Bryophyta)

et al. 2007

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Ecotoxicological studies usually focus on single microbial species under controlled conditions. As a result, little is known about the responses of different microbial functional groups or individual species to stresses. In an aim to assess the response of complex microbial communities to pollution in their natural habitat, we studied the effect of a simulated lead pollution on the microbial community (bacteria, cyanobacteria, protists, fungi, and micrometazoa) living on Sphagnum fallax. Mosses were grown in the laboratory with 0 (control), 625, and 2,500 mg L _ 1 of Pb 2+ diluted in a standard nutrient solution and were sampled after 0, 6, 12, and 20 weeks. The biomasses of bacteria, microalgae, testate amoebae, and ciliates were dramatically and significantly decreased in both Pb addition treatments after 6, 12, and 20 weeks in comparison with the control. The biomass of cyanobacteria declined after 6 and 12 weeks in the highest Pb treatment. The biomasses of fungi, rotifers, and nematodes decreased along the duration of the experiment but were not significantly affected by lead addition. Consequently, the total microbial biomass was lower for both Pb addition treatments after 12 and 20 weeks than in the controls. The community structure was strongly modified due to changes in the densities of testate amoebae and ciliates, whereas the relative contribution of bacteria to the microbial biomass was stable. Differences in responses among the microbial groups suggest changes in the trophic links among them. The correlation between the biomass of bacteria and that of ciliates or testate amoebae increased with increasing Pb loading. We interpret this result as an effect on the grazing pathways of these predators and by the Pb effect on other potential prey (i.e., smaller protists). The community approach used here complements classical ecotoxicological studies by providing clues to the complex effect of pollutant-affecting organisms both directly and indirectly through trophic effects and could potentially find applications for pollution monitoring.

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Conjugative plasmid transfer betweenPseudomonas strains within alginate bead microcosms: Effect of the internal gel structure

Mater

Saucedo

Truffaut

et al. 1999

Biotechnol. Bioeng.

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Using microcosms to study gene transfer in aquatic habitats

Cited by 23 publications

References 44 publications

Increased Transfer of a Multidrug Resistance Plasmid in Escherichia coli Biofilms at the Air-Liquid Interface

Increased Transfer of a Multidrug Resistance Plasmid in Escherichia coli Biofilms at the Air-Liquid Interface

Effects of Experimental Lead Pollution on the Microbial Communities Associated with Sphagnum fallax (Bryophyta)

Conjugative plasmid transfer betweenPseudomonas strains within alginate bead microcosms: Effect of the internal gel structure

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