Accepted_test

Basal Holomycota (Rozellida, Microsporidia and Aphelida) being obligate intracellular parasites might be an important regulator of microeukaryotes population in various ecosystems. Since metabarcoding appears one of the most promising approach for unculturable biodiversity description, we choose it for the current study of basal Holomycota in 9 freshwater bottom sediments samples taken from 2 closely located sampling sites (Turovskoye Lake and the stream between Turovskoye and Zaklinskoe lakes, Leningrad region, Russia). We compared 3 different PCR protocols in order to amplify variable regions of 18S rRNA gene of target groups and used Mothur software for Illumina MiSeq data proceeding. The discovered sequences contributed to molecular clades within the entire basal Holomycota tree, including both described species (Rozella, Paraphelidium, Aphelidium, Paramicrosporidium, Mitosporidium, Morellospora and numerous microsporidian species) and consistently reproduced in previous phylogenetic studies environmental clades (NAMAKO37, LKM46, NAMAKO35, hww6, LKM15, AZeuk2, LKM11, WIM27, dpeuk6, LKM46). A potentially new group of early microsporidia basal to Core Microsporidia + Metchnikovellida + RL107-1 was identified. All analyzed samples showed rather similar diversity profiles, except the one taken from an especially silted area of Turovskoye Lake. Basal Holomycota tended to share distribution pattern of their potential hosts, so different trends were found for parasites of protists and multicellular organisms.