g., [42]) and especially for the unicellular eukaryotes [4, 6, 43].The occurrence of diverse Chlorophyta phylotypes in both samplings (Figures (Figures33 and and4),4), most of which were affiliated with well-characterized species, is related to the hypertrophic conditions prevailing in L. Karla. Chlorophyta are indicative of ecosystems receiving high selleckchem FTY720 nutrient loadings [1]. They have been found to dominate the clone library of a hypertrophic, polluted and heavily modified lake in Greece [3]. Some of these phylotypes, for example, Scenedesmus species, may constitute an important fraction of the freshwater total phytoplankton biomass, particularly in nutrient-rich ecosystems [44]. Scenedesmus species have capabilities of successful air dispersal and colonization of new aquatic habitats [45].

The hypertrophic conditions of the newly reconstructed L. Karla render its future rather erratic, since the prediction of community and ecosystem dynamics is decreased in eutrophic systems [46].Apart from the Chlorophyta, other microorganisms in this study are associated with eutrophic/hypertrophic conditions. The found Euglenophyta-related phylotypes (Figure 3(c)) were affiliated with the genera Colacium, Euglena and Strombomonas. Members of the Euglenophyta are known to be abundant in highly eutrophic environments and on sediments polluted with organic matter [47]. Euglenophyta are considered biological indicators of organic pollution in seawater [48]. Cryptophyta (Figure 3(a)) are also a group forming blooms in eutrophic environments, yet their abundance are low due to high grazing rates of their protozoan predators [49].

Katablepharidophyta (Figure 3(a)) which were formerly classified as a subgroup of Cryptophyta, are now considered to be a sister group of Cryptophyta [50] and could have similar environmental preferences. Choanoflagellata (Figure 3(a)) are epiphytic microorganisms depending on the quality of available organic matter, and many members of this group are adapted to using dissolved organic matter and colloidal organic particles [51].The Cercozoa-related phylotypes (Figure 3(c)) were related to uncultivated environmental clones. Some well-characterized species such as Ebria tripartita, Cercomonas plasmodialis, and species of the genus Protaspis were affiliated with our retrieved sequences and fell in the Cercozoa taxonomic group.

These taxa were also identified microscopically. Phylotypes KRL01E17 and KRL01E4 formed a novel clade in the Cercozoa, highly supported by the bootstrap test. Cercozoa phylotypes have been recovered from many different Drug_discovery environments [52] but most of them are defined by molecular data and display huge morphological and ecological diversity [53]. They are mainly heterotrophs, including bacterivorous and predaceous species that phagocytize the cytoplasm of diatoms in marine ecosystems [54].