Beschreibung:
<jats:title>Abstract</jats:title><jats:p>In 2012, Tetrodotoxin (TTX) was identified in mussels and linked to the presence of <jats:italic>Prorocentrum minimum (P. minimum</jats:italic>) in Greece. The connexion between TTX and <jats:italic>P. minimum</jats:italic> was further studied in this paper. First, the presence of TTX-producer bacteria, <jats:italic>Vibrio</jats:italic> and <jats:italic>Pseudomonas</jats:italic> spp, was confirmed in Greek mussels. In addition these samples showed high activity as inhibitors of sodium currents (I<jats:sub>Na</jats:sub>). <jats:italic>P. minimum</jats:italic> was before associated with neurotoxic symptoms, however, the nature and structure of toxins produced by this dinoflagellate remains unknown. Three <jats:italic>P. minimum</jats:italic> strains, ccmp1529, ccmp2811 and ccmp2956, growing in different conditions of temperature, salinity and light were used to study the production of toxic compounds. Electrophysiological assays showed no effect of ccmp2811 strain on I<jats:sub>Na</jats:sub>, while ccmp1529 and ccmp2956 strains were able to significantly reduce I<jats:sub>Na</jats:sub> in the same way as TTX. In these samples two new compounds, <jats:italic>m/z</jats:italic> 265 and <jats:italic>m/z</jats:italic> 308, were identified and characterized by liquid chromatography tandem high-resolution mass spectrometry. Besides, two TTX-related bacteria, <jats:italic>Roseobacter</jats:italic> and <jats:italic>Vibrio</jats:italic> sp, were observed. These results show for the first time that <jats:italic>P. minimum</jats:italic> produce TTX-like compounds with a similar ion pattern and C9-base to TTX analogues and with the same effect on I<jats:sub>Na</jats:sub>.</jats:p>