Characterization of ciliate diversity in bromeliad tank waters from the Brazilian Atlantic Forest.

Bromeliads are a diverse group of plants that includes many species whose individuals are capable of retaining water, forming habitats called phytotelmata. These habitats harbor a diversity of organisms including prokaryotes, unicellular eukaryotes, metazoans, and fungi. Among single-celled eukaryotic organisms, ciliates are generally the most abundant. In the present study, we used Illumina DNA sequencing to survey the eukaryotic communities, especially ciliates, inhabiting the tanks of the bromeliads Aechmea gamosepala and Vriesea platynema in the Atlantic Forest of southern Brazil. Filtered sequences were clustered into distinct OTUs using a 99% identity threshold, and then assigned to phylum and genus using a BLAST-based approach (implemented in QIIME) and the SILVA reference database. Both bromeliad species harbored very diverse eukaryotic communities, with Arthropoda and Ciliophora showing the highest abundance (as estimated by the number of sequence reads). The ciliate genus Tetrahymena was the most abundant among single-celled organisms, followed by apicomplexan gregarines and the ciliate genus Glaucoma. Another interesting finding was the presence and high abundance of Trypanosoma in these bromeliad tanks, demonstrating their occurrence in this type of environment. The results presented here demonstrate a hidden diversity of eukaryotes in bromeliad tank waters, opening up new avenues for their in-depth characterization.