Novel microalgae toxins

Novel microalgae toxins: Microalgae are microscopically small algae which float in water either as single cells or short cell-chains. As part of the plankton they play an important role in marine biological ecosystems and form the base of nutrients for many animals. To date, more than 5000 species of marine microalgae are described. Besides all the positive aspects, some microalgae can lead to toxic algal blooms. Concerning toxin formation two categories can be distinguished; the toxins which accumulate in the food chain and are poisonous to humans, and those which are toxic to fish. The last group is capable of killing whole fish populations within a few days. Especially, with regard to the increased usage of aquaculture to cope with the worldwide demand for fish for human nutrition those potentially fish toxic substances might be even more economically relevant. Within the project Novel microalgae toxins we will deal with the relatively poorly studied group of microalgae producing potentially fishtoxic compounds. The project will be conducted at the Department for Systems Biology of the Danish Technical University (DTU) in cooperation with the University of Copenhagen location Helsingor, as well as at the Center for Analytical Chemistry of the Department of Agrobiotechnology of the University for Natural Resources and Life Sciences, Vienna (BOKU). The main aim of this project will be to discover, isolate and characterise chemical substances which have the potential of being fish-toxic. For this purpose, we will grow the algae under controlled temperature and light conditions and characterise the produced metabolites. For the determination we will use a specific analytical-chemical measurement method - ultra high performance liquid chromatography for the separation of the compounds and high resolution mass spectrometry for their detection. To differentiate between novel and already known compounds large databases are available for comparison and additionally, a statistical approach comparing the metabolites of fish-toxic and non-fish-toxic algal species will be applied. After the identification of possible fish-toxic compounds we want to isolate and purify relevant metabolites. Those substances will be used as analytical standards for the development and application of quantitative detection methods for these novel compounds in relevant matrices (water, algae and fish) and will we test their toxicity against fish. To assess the relevance of these novel compounds in Austria a pilot study involving Austrian and imported fish as well as surface water will be conducted. While the applied methodology is already established in other areas, its application to the field of fish-toxic microalgae toxins is novel. Concluding, within the scope of the project possible threats for fish cultures caused by microalgae shall be identified.

Microalgae are microscopically small algae which float in water either as single cells or short cell-chains. As part of the plankton they play an important role in marine biological ecosystems and form the base of nutrients for many animals. To date, more than 5000 species of marine microalgae are described. Besides all the positive aspects, some microalgae can lead to toxic algal blooms. Concerning toxin formation two categories can be distinguished; the toxins which accumulate in the food chain and are poisonous to humans, and those which are toxic to fish. The last group is capable of killing whole fish populations within a few days. Especially, with regard to the increased usage of aquaculture those potentially fish toxic substances might be even more economically relevant. Within the project "Novel microalgae toxins" we dealt with the relatively poorly studied group of microalgae producing potentially fishtoxic compounds. In particular we investigated the microalgae Prymnesium parvum and Karlodinium armiger. The project was conducted at the Department for Biotechnology and Biomedicine of the Danish Technical University (DTU) in cooperation with the University of Copenhagen - location Helsingør. The return period took place at the Department of Food Chemistry and Toxicology, Faculty of Chemistry of the University of Vienna (UNIVIE). The main aim of this project was to discover, isolate and characterise chemical substances which have the potential of being fish-toxic. For this purpose, we grew the algae under controlled temperature and light conditions and characterise the produced metabolites. For the determination we used a specific analytical-chemical measurement method - ultra high performance liquid chromatography for the separation of the compounds and high resolution mass spectrometry for their detection. We could show that the diversity of the potentially fish-toxic compounds produced by P. parvum (called prymnesins) is larger than previously thought. To day we know more than 50 compounds which are attributed to the group of prymnesins. All so far investigated P. parvum isolates were capable of producing prymnesins and produce either A-, B- or C-type prymnesins. We could show a connection between the produced types and the genetic background of the microalgae. Furthermore, we were able to develop an analytical method for the determination of the concentrations of prymnesins in water and biomass samples. This method is now used to investigate under which conditions prymnesins are produced. During the return phase we could show that prymnesins are also toxic to certain human cells and therefore it is not recommended to swim in areas with ongoing algal blooms.