Free living ciliated protists from the chemoautotrophic cave ecosystem of Frasassi (Italy)

Abstract

This study provides the first report on a community of free-living ciliated protists from the chemoautotrophic cave ecosystem of Frasassi, Italy. This subterranean groundwater ecosystem represents a hotspot of biodiversity that still needs to be fully explored with particular reference to microbial eukaryotes such as protist ciliates. A total of 33 taxa of ciliates were identified along with one species each of flagellate, heliozoans and naked amoebae, from four main sampling sites, namely, Grotta Solfurea (GSO), Lago Verde (LVE), Ramo Solfureo (RSO), and Pozzo dei Cristalli (PDC). The last consists of small microhabitats/ponds presenting different chemical–physical and biological parameters, such as sulfur and nutrient contents and the presence of bacterial biofilms. Furthermore, an analysis of the cryptic ciliate species biosphere as a ‘seedbank’ of diversity against cave ecosystem disturbance was also performed. This study also highlights some peculiar adaptations of cave-dwelling ciliates not described in their noncave-dwelling conspecifics, such as the extreme photosensitivity of Urocentrum turbo, the cannibalism of Coleps hirtus, the variable number of thorns in Aspidisca species as a defensive response to predation, and the frequent reorganization of ciliary structures in Euplotes aediculatus. The 18S rDNA sequences were generated for five species and were compared with those of the noncave-dwelling conspecifics. Finally, our results shed light on the still largely unknown ciliate diversity in the chemosynthesis-based sulfidic groundwater ecosystem of Frasassi.

16S and 18S rDNA Amplicon Sequencing Analysis of Aesthetically Problematic Microbial Mats on the Walls of the Petralona Cave: The Use of Essential Oils as a Cleaning Method

“…Rhabditophanesschneideri, a species of nematode belonging to Rhabditida, was discovered to be phoretic on a cave-dwelling pseudoscorpion species as a means of survival [98]. Members of Colpodida can be found in various environments, including soil [99] and also in caves as in the case of the Frasassi Cave in Italy [100]. Colpodida thrives in environments with high levels of bacteria, as some of them are bacterivorous [101].…”

Cytotoxicity and Antioxidant Defences in Euplotes aediculatus Exposed to Single and Binary Mixtures of Heavy Metals and Nanoparticles

“…Despite the unknown concentrations of most HMs and NPs in the environment, exposure modelling suggests that freshwater and soil could act as significant sinks for these pollutants, accumulating at higher levels than in the air [19][20][21]. Ciliated protists, an important group of primary consumers, are unicellular eukaryotic microorganisms well adapted to life in freshwater, soil, and many other ecosystems, from the subterranean groundwater ecosystem (i.e., caves) to the Antarctic coastal seawater [22][23][24]. Due to their widespread presence in different ecosystems, these microorganisms are a good model for monitoring the effects of various physical and chemical factors on biological communities [25][26][27].…”