Diversidade e posicionamento filogenético de ciliados (Ciliophora) do solo da Serra da Mantiqueira, Santa Bárbara do Monte Verde, Minas Gerais, Brasil

Abstract

The phylum Ciliophora plays essential roles in nutrient cycling within terrestrial ecosystems, but the diversity of these microorganisms in Neotropical soils remains poorly understood. This study aimed to molecularly characterize the community of soil-dwelling ciliate protists from the Reserva Particular do Patrimônio Natural (RPPN) Chapadão da Serra Negra using long-read sequencing on the PacBio platform. Sampling consisted of collecting leaf litter and surface soil following in situ preservation protocols. Total genomic DNA was extracted using the PowerSoil DNA Isolation Kit, followed by evaluation of DNA quality and concentration. Libraries were prepared for sequencing on the PacBio Sequel II platform to obtain full-length 18S rDNA sequences. The resulting data were processed using the QIIME2 pipeline with the PR2 reference database, and, following taxonomic assignment, the ASVs belonging to the phylum Ciliophora were selected for phylogenetic analyses. Subsequently, a phylogenetic tree was reconstructed using the Maximum Likelihood method, including reference sequences available in GenBank and the exact amplicon sequence variants (ASVs) obtained. The results revealed a high diversity of eukaryotes in the analyzed samples. Of the 722 ASVs obtained, 17 belonging to the phylum Ciliophora were distributed among the classes Colpodea, Oligohymenophorea, Spirotrichea, Litostomatea, and Phyllopharyngea. The class Colpodea showed the highest ASV abundance. Long-read sequencing provided high taxonomic resolution, revealing hidden soil biodiversity and reinforcing the importance of the reserve as a refuge for biodiversity.