Different methods for toxin analysis in the cyanobacterium Nodularia spumigena (Cyanophyceae).

The brackish water cyanobacterium Nodularia spumigena produce the hepatotoxic cyclic pentapeptide nodularin. Intoxications for both human as well as animal may arise when water reservoirs are contaminated with potentially toxic Nodularia species. Here, results of three independent methods for the determination of nodularin in different strains of N. spumigena are presented. The results obtained with a protein phosphatase assay and a HPLC/UV/MS method are compared with the results obtained with a bioluminescence assay, which is successfully introduced here for nodularin determination. Statistical evaluation of the three applied methods revealed a good comparability towards the detected toxin content. The methods were evaluated taking into consideration the parameters: handling, efficiency, sensitivity and selectivity. The detection limit in the protein phosphatase assay is highest (0.05ng nodularin) and lowest (250ng nodularin) in the bioluminescence assay- it was determined with 5ng (MS) and 25ng (UV) for the HPLC/UV/MS methods. The different selectivities and sensitivities are critically discussed and an analytical pathway for the determination of the biotoxin nodularin from Nodularia samples is proposed.

Interrelationships between microbiological and chemical parameters of sandy beach sediments, a summer aspect.

At 12 stations located in sandy beach sediments of the brackish water Kiel Fjord and Kiel Bight (Baltic Sea, FRG), variations and interrelationships of microbiological, chemical, and physicochemical parameters were monitored. Depending upon location, wide variations of a number of parameters reflecting dissolved organic and inorganic nutrients, chlorophyll a, microbial number, and uptake activity of glucose were measured. Whereas most of the parameters generally showed the tendency to decrease from the inner to the outer Kiel Fjord, individual parameters (oxygen, particulate nitrogen, ribose, chlorophyll a, glucose/fructose ratio) increased with increasing distance from the inner Kiel Fjord. Similarities in the local variation pattern demonstrated various relationships between individual parameters. Among those, dissolved organic nutrients on the one hand and inorganic nutrients on the other hand were closely linked together. Variations of organic and inorganic nutrients corresponded to variations of microbial activity and physicochemical parameters. By comparing standing stock carbon with carbon production, a microbial biomass turnover time of about 100 h was calculated. Approximately 50% of the microphytobenthos primary production was fixed by microorganisms. Daily microbial carbon production (43 mg of C per m) was in the range of meiofauna carbon (35 mg of C per m).