| Summary: | Cyanobacteria (more commonly known as blue-green algae) are photosynthetic bacteria with a worldwide distribution. They are most common in the freshwater environment but are also present in many marine waters. As they are pioneer-organisms and they can often be found in extreme environments. They also constitute the dominant primary producers in the terrestrial Polar Regions and therefore have a pivotal role in polar ecosystems. In freshwater streams, ponds, and lakes that are formed during the polar summer, they occur as benthic or floating mats several millimetres to centimetres thick, sometimes covering several square meters. These mats are the nutritional basis and the micro-habitat for several other types of organisms (primarily proto- and metazoa). This study describes the species diversity of cyanobacterial mat communities from the Arctic and Antarctic that were collected prior to and during the thesis using molecular phylogenetic techniques. The characterization was accomplished by morphological identification as well as the sequencing of the ribosomal RNA genes and the more variable ITS-region (intergenic spacer region). Conventional molecular biological methods (clone-library, automated ribosomal intergenic spacer analysis (ARISA)) were applied as well as „Next-Generation-Sequencing“ based on the 454® technology. The latter allows thousands of sequences to be obtained from a single sample. Using these methods a comprehensive picture of the phylogenetic diversity could be obtained and mats from the Arctic and the Antarctic region compared with and within each other. Cyanobacteria synthesize multiple secondary metabolites, some of which are toxic to most higher organisms including humans. Health hazards or even life threatening incidents regularly occur in the temperate and tropical regions during bloom events (mass-occurrences of cyanobacteria). This study demonstrated that cyanobacterial toxins are present in cyanobacterial mats of the Arctic and the Antarctic. In the Arctic two cyanobacterial toxins ...
|
|---|