Preliminary thesis title: Time in Microevolution of Microcystin Synthesis

Aquatic cyanobacteria synthesize a variety of bioactive peptides, e.g. the toxic heptapeptide microcystin. Within algal blooms however, genotypes producing microcystin often occur together with inactive (mutant) genotypes that lost the ability to assemble this toxin. It is the aim of my study to investigate factors that lead to a fixation of mutations inactivating the microcystin-synthetase genes within populations of Planktothrix sp. Furthermore the occurrence and the wax and wane of those inactive genotypes will be investigated by real-time PCR analyses of DNA isolated from preserved water samples dated back to the 1940s. The prediction of toxicity within future algal blooms and the question whether non-toxic genotypes can ever be dominant in a population are of central interest.