Off the hook – how bacteria survive protozoan grazing

Matz, Carsten; Kjelleberg, Staffan

doi:10.1016/j.tim.2005.05.009

Cited by 569 publications

(479 citation statements)

References 42 publications

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“…In more realistic low-resource conditions with multi-trophic interactions, such evolution appears to be detrimental. Given the abundance of predators in natural environments [20], it is possible that conjugation is necessary for the survival of the plasmid even within an isogenic population where every individual harbours a copy. This observation can help us understand how HGT persists in bacterial systems in the absence of positive selection by antibiotics or other threats against which conjugative elements often provide resistance.…”

Section: Discussionmentioning

confidence: 99%

Conjugation is necessary for a bacterial plasmid to survive under protozoan predation

et al. 2016

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Horizontal gene transfer by conjugative plasmids plays a critical role in the evolution of antibiotic resistance. Interactions between bacteria and other organisms can affect the persistence and spread of conjugative plasmids. Here we show that protozoan predation increased the persistence and spread of the antibiotic resistance plasmid RP4 in populations of the opportunist bacterial pathogen Serratia marcescens. A conjugation-defective mutant plasmid was unable to survive under predation, suggesting that conjugative transfer is required for plasmid persistence under the realistic condition of predation. These results indicate that multi-trophic interactions can affect the maintenance of conjugative plasmids with implications for bacterial evolution and the spread of antibiotic resistance genes.

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Section: Discussionmentioning

confidence: 99%

Conjugation is necessary for a bacterial plasmid to survive under protozoan predation

et al. 2016

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“…Protozoa and bacteria form one of the oldest predator-prey systems on earth, but apart from reports on phenotypic changes (Jü rgens and Matz, 2002;Pernthaler, 2005) surprisingly little is known on the factors driving grazing resistance (Matz and Kjelleberg, 2005) and on the identity of bacterial groups that are consumed and those that survive protozoan grazing in the rhizosphere and soils (Griffiths et al, 1999;Rønn et al, 2002;Kreuzer et al, 2006;Murase et al, 2006). Roughly estimated, 1 g of grassland soil may contain up to 10 9 bacteria and 100 000 protozoa (Finlay et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Soil amoebae rapidly change bacterial community composition in the rhizosphere of Arabidopsis thaliana

Rosenberg¹,

Bertaux²,

Krome³

et al. 2009

The ISME Journal

218

183

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We constructed an experimental model system to study the effects of grazing by a common soil amoeba, Acanthamoeba castellanii, on the composition of bacterial communities in the rhizosphere of Arabidopsis thaliana. Amoebae showed distinct grazing preferences for specific bacterial taxa, which were rapidly replaced by grazing tolerant taxa in a highly reproducible way. The relative proportion of active bacteria increased although bacterial abundance was strongly decreased by amoebae. Specific bacterial taxa had disappeared already two days after inoculation of amoebae. The decrease in numbers was most pronounced in Betaproteobacteria and Firmicutes. In contrast, Actinobacteria, Nitrospira, Verrucomicrobia and Planctomycetes increased. Although other groups, such as betaproteobacterial ammonia oxidizers and Gammaproteobacteria did not change in abundance, denaturing gradient gel electrophoresis with specific primers for pseudomonads (Gammaproteobacteria) revealed both specific changes in community composition as well as shifts in functional genes (gacA) involved in bacterial defence responses. The resulting positive feedback on plant growth in the amoeba treatment confirms that bacterial grazers play a dominant role in structuring bacteria-plant interactions. This is the first detailed study documenting how rapidly protozoan grazers induce shifts in rhizosphere bacterial community composition.

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“…However, the distribution in the sediment food web after initial predation is a complex question, and our knowledge of the sediment microbial food web is far from complete. Top-down control (predation pressure) on bacteria from higher trophic levels can also function as a strong evolutionary driver on the bacterial communities, causing, for example, larger cell sizes, filamentous growth forms, aggregation and attachment to particles (Jurgens and Sala, 2000;Matz and Kjelleberg, 2005;Pernthaler, 2005), further highlighting the importance of trophic interactions for bacterial activity and ecosystem functioning. Previous studies found clear links between meiofauna and organic matter mineralization (see for example, Findlay and Tenore, 1982;Alkemade et al, 1993;Coull, 1999), which similar to degradation of pollutants is a crucial ecosystem function and service largely driven by microbial activities.…”

Section: Discussionmentioning

confidence: 99%

Meiofauna reduces bacterial mineralization of naphthalene in marine sediment

2010

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The role of sediment-living meiofauna, benthic invertebrates smaller than 1000 lm such as nematodes and ostracods, on the mineralization of naphthalene, a common polycyclic aromatic hydrocarbon (PAH) in marine sediments, was studied in microcosms using radiorespirometry. A method to extract live meiofauna was developed and used in order to experimentally manipulate meiofauna abundance and group diversity. Higher abundances of meiofauna were found to significantly decrease naphthalene mineralization. Furthermore, a change in the bacterial community composition (studied using terminal restriction fragment length polymorphism) was also observed in presence of higher meiofauna abundance, as well as a lower number of cultivable naphthalene-degrading bacteria. The reduced mineralization of naphthalene and the altered bacterial community composition in the presence of increased meiofauna abundance is likely the result of top-down control by meiofauna. This study shows that higher abundances of meiofauna can significantly decrease the microbial mineralization of PAHs such as naphthalene and also significantly modify the bacterial community composition in natural marine sediments.

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Off the hook – how bacteria survive protozoan grazing

Cited by 569 publications

References 42 publications

Conjugation is necessary for a bacterial plasmid to survive under protozoan predation

Conjugation is necessary for a bacterial plasmid to survive under protozoan predation

Soil amoebae rapidly change bacterial community composition in the rhizosphere of Arabidopsis thaliana

Meiofauna reduces bacterial mineralization of naphthalene in marine sediment

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