XVI International Botanical Congess

Colorless heterotrophic chrysophytes are the most common nanoflagellate in lake plankton. Spumella-like flagellates have been described from marine habitats, soil, activated sludge and organically contaminated aquifers. Although Spumella-like flagellates seem to ubiquitous only, little is, however, known about their species composition and the taxonomic position of these flagellates is still uncertain. The goal of this study was the first assessment of the diversity within the Spumella-like flagellates. We took samples from different habitats, size fractioned the sample (10 |m) to remove potential grazers. Clonal cultures were then established. To gain an overview of the genetic diversity within these flagellates a denaturing gradient gel electrophoresis (DGGE) system was established as a screening method. This DGGE system was based on the V4 region of the 18S rDNA. The sequence diversity of this region was sufficient to differentiate between the isolates and additionally permitted to assign new isolates to already characterized isolates. The phylogenetic position of our isolates were then analyzed using the complete sequence information of the 18S rDNA gene.