Research focus of the microbiology part:
Harmful algal blooms (HABs) are caused by a number of phytoplankton species. In freshwater systems blooms of potentially toxin-producing cyanobacteria are frequently found, particularly of the genera Microcystis, Anabaena and Planktothrix. The most common cyanobacterial toxin present during HABs is the hepatotoxic cyclic peptide microcystin. The genes required for microcystin synthesis are known in several species of microcystin-producing cyanobacteria. However, toxin-producing and non-toxic strains generally co-occur in an aquatic system. Environmental factors that trigger a shift in the population structure and an exponential growth of toxin-producers have been studied intensively over the years. It is generally acknowledged that high temperatures and high nutrient concentrations as well as a change in pH contribute to HAB formation. Biotic factors such as protozoan grazing and viral lysis by cyanophages are influencing the formation of such blooms as well, but their role is far less understood. Of particular interest is the question whether protozoa and cyanophages lead to an increase of toxin concentration by inducing a defence mechanism of the cyanobacteria and releasing toxins by lysing cyanobacterial cells, or whether they could contribute to the collapse of the HAB by decimating the population of toxic cyanobacteria.
Identification and quantification of cyanobacterial species was until recently exclusively based on morphological microscopic analysis. However, morphological differentiation between toxin-producing and non-toxic cyanobacteria strains of the same species is not possible. In this project a molecular approach employing polymerase chain reaction (PCR) and quantitative polymerase chain reaction (qPCR) techniques will be used to target the toxin genes in order to distinguish the strains on the basis of the presence or absence of those genes. Furthermore, qPCR analysis will determine the level of gene transcription and how it is influenced by biotic and abiotic factors. Laboratory experiments will lead to a better understanding of these interactions and field studies in selected lakes will characterize the cyanobacterial population and its toxicity during algal blooms.