Marine invertebrate mucus--agglutinating and antibacterial activity, with emphasis on Metridium senile.

The agglutinating and antibacterial activities of mucus from marine invertebrates are described. Mucus from eleven species was tested for the presence of haemagglutinins using a range of vertebrate erythrocytes. Mucus from Metridium senile, Ophiocomina nigra and Branchiostoma lanceolatum yielded positive results and was investigated further. The haemagglutinin of M. senile was purified, characterized and shown to be mannose-specific. Mucus from this animal was subsequently assayed for antibacterial activity using seawater isolates and verified marine and terrestrial cultures. Only two test organisms were inhibited, while the majority showed significantly enhanced growth. Possible functions of the mucus barrier in marine invertebrates are discussed.