title: Pack hunting by a common soil amoeba on nematodes.
abstract: Soils host the most complex communities on Earth, including the most diverse and abundant eukaryotes, i.e. heterotrophic protists. Protists are generally considered as bacterivores, but evidence for negative interactions with nematodes both from laboratory and field studies exist. However, direct impacts of protists on nematodes remain unknown. We isolated the soil-borne testate amoeba Cryptodifflugia operculata and found a highly specialized and effective pack-hunting strategy to prey on bacterivorous nematodes. Enhanced reproduction in presence of prey nematodes suggests a beneficial predatory life history of these omnivorous soil amoebae. Cryptodifflugia operculata appears to selectively impact the nematode community composition as reductions of nematode numbers were species specific. Furthermore, we investigated 12 soil metatranscriptomes from five distinct locations throughout Europe for 18S ribosomal RNA transcripts of C. operculata. The presence of C. operculata transcripts in all samples, representing up to 4% of the active protist community, indicates a potential ecological importance of nematophagy performed by C. operculata in soil food webs. The unique pack-hunting strategy on nematodes that was previously unknown from protists, together with molecular evidence that these pack hunters are likely to be abundant and widespread in soils, imply a considerable importance of the hitherto neglected trophic link 'nematophagous protists' in soil food webs.
authors.affiliation: Department of Terrestrial Ecology, Institute of Zoology, University of Cologne, Cologne, Germany.|Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.
authors.forename: Stefan
authors.initials: S
authors.lastname: Geisen
authors.affiliation: Department of Terrestrial Ecology, Institute of Zoology, University of Cologne, Cologne, Germany.
authors.forename: Jamila
authors.initials: J
authors.lastname: Rosengarten
authors.affiliation: Department of Terrestrial Ecology, Institute of Zoology, University of Cologne, Cologne, Germany.|Forschungszentrum Jülich, IBG-2: Plant Sciences, Jülich, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Koller
authors.affiliation: National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Christian
authors.initials: C
authors.lastname: Mulder
authors.affiliation: Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria.|Bacterial Physiology, Institute for Microbiology, Ernst Moritz Arndt University, Greifswald, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Urich
authors.affiliation: Department of Terrestrial Ecology, Institute of Zoology, University of Cologne, Cologne, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bonkowski
mesh_terms: D000656:Amoeba / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D000818:Animals; D005060:Europe; D020387:Food Chain; D006790:Host-Parasite Interactions / Q000502:physiology*; D009348:Nematoda / Q000469:parasitology*; D011235:Predatory Behavior / Q000502:physiology*; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012987:Soil / Q000469:parasitology*; D013045:Species Specificity; D059467:Transcriptome / Q000235:genetics
chemical_list: D012337:RNA, Ribosomal, 18S; D012987:Soil