Ecological Traits of the Algae‐BearingTetrahymena utriculariae(Ciliophora) from Traps of the Aquatic Carnivorous PlantUtricularia reflexa

Abstract

Trap fluid of aquatic carnivorous plants of the genus Utricularia hosts specific microbiomes consisting of commensal pro- and eukaryotes of largely unknown ecology. We examined the characteristics and dynamics of bacteria and the three dominant eukaryotes, i.e. the algae-bearing ciliate Tetrahymena utriculariae (Ciliophora), a green flagellate Euglena agilis (Euglenophyta), and the alga Scenedesmus alternans (Chlorophyta), associated with the traps of Utricularia reflexa. Our study focused on ecological traits and life strategies of the highly abundant ciliate whose biomass by far exceeds that of other eukaryotes and bacteria independent of the trap age. The ciliate was the only bacterivore in the traps, driving rapid turnover of bacterial standing stock. However, given the large size of the ciliate and the cell-specific uptake rates of bacteria we estimated that bacterivory alone would likely be insufficient to support its apparent rapid growth in traps. We suggest that mixotrophy based on algal symbionts contributes significantly to the diet and survival strategy of the ciliate in the extreme (anaerobic, low pH) trap-fluid environment. We propose a revised concept of major microbial interactions in the trap fluid where ciliate bacterivory plays a central role in regeneration of nutrients bound in rapidly growing bacterial biomass.

The Green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with Its Endosymbiotic Algae (Micractinium sp.), Living in Traps of a Carnivorous Aquatic Plant

“…utriculariae , however, at present we have to state that this ciliate species could be only found in U. reflexa (for further details see Šimek et al. ).…”

“…Due to the high numbers of ciliates inside trap fluids, their total grazing rates lead to a fast bacterial turnover (Šimek et al. ).…”

“…Based on the high genetic distance, the ecological/physiological characteristics, and the habitat specificity (Šimek et al. ) we describe the strain from Třeboň (Czech Republic) as a new species, T . utriculariae n. sp.…”

“…We checked numerous feeding traps of seven other Utricularia species, but detected T. utriculariae only in two U. reflexa populations form Botswana and Zambia (see also Šimek et al. ). It is important to note that U. reflexa is endemic to Africa.…”

“…For a detailed description of the plant itself and its cultivation conditions we refer to Adamec (, ) and Šimek et al. ().…”