Vibrio harveyi is the main pathogen of the European abalone
Haliotis tuberculata, and recently caused important mortalities at the
production sites of this marine gastropod in France. In the present work, the monthly
antibacterial activity of two red seaweed species from the French Atlantic coast, the
native Palmaria palmata and the introduced Grateloupia
turuturu, were investigated against the abalone pathogen Vibrio harveyi
strain ORM4. Water-soluble extracts were screened using the microplate method.
Grateloupia turuturu showed an antibacterial activity with a maximal
growth inhibition in spring of around 16%. In contrast, Palmaria palmata
was inactive, as further growth of the bacteria was observed. Preliminary
one-dimensional proton nuclear magnetic-resonance (1H NMR) profiles identified the
differences between the two water-soluble extracts.