High resolution analysis of local and global protistan soil community structures using morphological and modern molecular techniques

• Main Author: Domonell, Anne Kathrin
• Format: Doctoral or Postdoctoral Thesis
• Language: German; English
• Published: 2013
• Subjects: ddc:570; Arctic; Antarctic; Greenland; Antarc*
• Online Access: https://kups.ub.uni-koeln.de/5360/; https://kups.ub.uni-koeln.de/5360/1/Dissertation_Anne_Domonell.pdf

The unicellular protists inhabit all types of aquatic and terrestrial environments. This thesis is focused on terrestrial protistan communities where they contribute significantly to mineralization processes and key ecosystem functions, as they are major consumers of bacterial production. The protistan soil communities of grassland and forest sites with a different land use were morphologically and molecularly investigated in this study. The morphological investigations revealed high protozoan abundances influenced by the intensity of land use. First insights to the community composition, dominated by flagellates and amoebae could be made, giving the basis for further molecular investigations. Cercomonads were the most abundant and diverse flagellates and were analyzed in more detail, resulting in new description of species. Next generation sequencing (NGS) of the V4 SSU rDNA on the same soil sites was applied. The development of an analysis pipeline for NGS data made in this study, led to a high resolution of the protistan community. This resulted in the first detailed study down to species level of total protistan community structures in soil. Several isolated and newly described species could be recovered by NGS in various samples, indicating that several very common protozoan species in soil have been overlooked. A combination of morphological and molecular studies of soil protistan flagellate communities is unique. Members of the SAR group dominated the protistan communities and land use effects by changes of testate amoebae and ciliates could be registered. Further investigations of Arctic, Antarctic and USA samples, confirmed protistan communities to be dependent on the habitat, but independent on the geographic region. The idea of unrestricted global distribution by air was supported by several genotypes reported from a variety of globally distant sites. The assumed pathways by air were supported by air, ice, snow and soil samples of a low anthropogenic influenced site in Greenland.