Protists and collembolans alter microbial community composition, C dynamics and soil aggregation in simplified consumer–prey systems

Erktan, Amandine; Rillig, Matthias C.; Carminati, Andrea; Jousset, Alexandre; Scheu, Stefan

doi:10.5194/bg-17-4961-2020

Cited by 23 publications

(23 citation statements)

References 98 publications

(123 reference statements)

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“…Soil type is already known to affect the composition and ratio of smaller and larger predators [ 75 , 76 ]. Moreover, it has been suggested that different pore sizes in soils are main drivers of compartmentalization of different prey and predator organisms [ 77 ]. Thus, microorganisms inhabiting non-continuous capillary pores could be protected from predation by protists and Nematoda , but not from the similarly-sized myxobacteria.…”

Section: Resultsmentioning

confidence: 99%

The soil microbial food web revisited: Predatory myxobacteria as keystone taxa?

et al. 2021

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Trophic interactions are crucial for carbon cycling in food webs. Traditionally, eukaryotic micropredators are considered the major micropredators of bacteria in soils, although bacteria like myxobacteria and Bdellovibrio are also known bacterivores. Until recently, it was impossible to assess the abundance of prokaryotes and eukaryotes in soil food webs simultaneously. Using metatranscriptomic three-domain community profiling we identified pro- and eukaryotic micropredators in 11 European mineral and organic soils from different climes. Myxobacteria comprised 1.5–9.7% of all obtained SSU rRNA transcripts and more than 60% of all identified potential bacterivores in most soils. The name-giving and well-characterized predatory bacteria affiliated with the Myxococcaceae were barely present, while Haliangiaceae and Polyangiaceae dominated. In predation assays, representatives of the latter showed prey spectra as broad as the Myxococcaceae. 18S rRNA transcripts from eukaryotic micropredators, like amoeba and nematodes, were generally less abundant than myxobacterial 16S rRNA transcripts, especially in mineral soils. Although SSU rRNA does not directly reflect organismic abundance, our findings indicate that myxobacteria could be keystone taxa in the soil microbial food web, with potential impact on prokaryotic community composition. Further, they suggest an overlooked, yet ecologically relevant food web module, independent of eukaryotic micropredators and subject to separate environmental and evolutionary pressures.

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Section: Resultsmentioning

confidence: 99%

The soil microbial food web revisited: Predatory myxobacteria as keystone taxa?

et al. 2021

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“…Further analysis also revealed that these effects on bacterial community structure were likely due to individual bacterial taxa differentially responding to protist density and size ( Figure 4B ), thus suggesting that strong size-dependencies may be at play. Previous studies have shown that protist predation can select for bacterial size ( Hahn and Höfle, 2001 ; Pernthaler, 2005 ; Erktan et al, 2020 ), and both negative and positive associations with different protists have also been shown ( Oliverio et al, 2020 ). In addition to the direct predator effects on responding bacterial taxa, we cannot rule out indirect effects of the predator presence—due to higher order interactions—to explain the abundance shifts of certain responding bacteria ( Karakoç et al, 2018 ; Mickalide and Kuehn, 2019 ).…”

Section: Discussionmentioning

confidence: 99%

“…These global maps represent a step forward in clarifying the role of feeding interactions in the temperature responses of microbial communities. However, with a global biomass 200 times larger than that of nematodes ( Bar-On et al, 2018 ), unicellular eukaryotes—collectively known as “protists”—likely play a major role in regulating microbial communities at global scales ( Oliverio et al, 2020 ) through bacterivory ( Gao et al, 2019 ; Erktan et al, 2020 ). Ciliate protists, in particular, are well-known bacterivores ( Foissner and Berger, 1996 ), their population dynamics and feeding interactions are strongly temperature-dependent ( DeLong and Lyon, 2020 ), and they are present in all major ecosystems ( Foissner and Berger, 1996 ; Oliverio et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Protist Predation Influences the Temperature Response of Bacterial Communities

et al. 2022

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Temperature strongly influences microbial community structure and function, in turn contributing to global carbon cycling that can fuel further warming. Recent studies suggest that biotic interactions among microbes may play an important role in determining the temperature responses of these communities. However, how predation regulates these microbiomes under future climates is still poorly understood. Here, we assess whether predation by a key global bacterial consumer—protists—influences the temperature response of the community structure and function of a freshwater microbiome. To do so, we exposed microbial communities to two cosmopolitan protist species—Tetrahymena thermophila and Colpidium sp.—at two different temperatures, in a month-long microcosm experiment. While microbial biomass and respiration increased with temperature due to community shifts, these responses changed over time and in the presence of protists. Protists influenced microbial biomass and respiration rate through direct and indirect effects on bacterial community structure, and predator presence actually reduced microbial respiration at elevated temperature. Indicator species analyses showed that these predator effects were mostly determined by phylum-specific bacterial responses to protist density and cell size. Our study supports previous findings that temperature is an important driver of microbial communities but also demonstrates that the presence of a large predator can mediate these responses to warming.

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“…Previous studies have shown that protist predation can select for bacterial size (Erktan et al, 2020;Hahn & Höfle, 2001;Pernthaler, 2005), and both negative and positive associations with different protists have also been shown (Oliverio et al, 2020). In addition to the direct predator effects on responding microbial taxa, we cannot rule out indirect effects of the predator presence, due to higher order interactions to explain the abundance shifts of certain responding microbes (Karakoç et al, 2018;Mickalide & Kuehn, 2019).…”

Section: Discussionmentioning

confidence: 88%

“…These global maps represent a step forward in clarifying the role of feeding interactions in the temperature responses of microbial communities. However, with a global biomass 200 times larger than that of nematodes (Bar-On et al, 2018), unicellular eukaryotes -collectively known as 'protists' -likely play a major role in regulating microbial communities at global scales (Oliverio et al, 2020) through bacterivory (Erktan et al, 2020;Gao et al, 2019). Ciliate protists, in particular, are wellknown bacterivores (Foissner & Berger, 1996), their population dynamics and feeding interactions are strongly temperature-dependent (DeLong & Lyon, 2020), and they are present in all major ecosystems (Foissner & Berger, 1996;Oliverio et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Predation by protists influences the temperature response of microbial communities

Rocca

Yammine

Simonin

et al. 2021

Preprint

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Temperature strongly influences microbial community structure and function, which in turn contributes to the global carbon cycle that can fuel further warming. Recent studies suggest that biotic interactions amongst microbes may play an important role in determining the temperature responses of these communities. However, how microbial predation regulates these communities under future climates is still poorly understood. Here we assess whether predation by one of the most important bacterial consumers globally, protists, influences the temperature response of a freshwater microbial community structure and function. To do so, we exposed these microbial communities to two cosmopolitan species of protists at two different temperatures, in a month-long microcosm experiment. While microbial biomass and respiration increased with temperature due to shifts in microbial community structure, these responses changed over time and in the presence of protist predators. Protists influenced microbial biomass and function through effects on community structure, and predation actually reduced microbial respiration rate at elevated temperature. Indicator species and threshold indicator taxa analyses showed that these predation effects were mostly determined by phylum-specific bacterial responses to protist density and cell size. Our study supports previous findings that temperature is an important driver of microbial communities, but also demonstrates that predation can mediate these responses to warming, with important consequences for the global carbon cycle and future warming.

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Protists and collembolans alter microbial community composition, C dynamics and soil aggregation in simplified consumer–prey systems

Cited by 23 publications

References 98 publications

The soil microbial food web revisited: Predatory myxobacteria as keystone taxa?

The soil microbial food web revisited: Predatory myxobacteria as keystone taxa?

Protist Predation Influences the Temperature Response of Bacterial Communities

Predation by protists influences the temperature response of microbial communities

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