Relationships between bacteria and marine animals

A few observations establish the influence of bacterial components on animals, mainly protozoans. The ingestion of bacteria by protozoans may be controlled by secretions or constituent compounds of their preys. Unicellular organisms may even be able to choose the bacteria they feed on, avoiding such species as Chromobacterium or Serratia, which contain toxic or repulsive products (see Paoletti, 1964). Cyclic AMP (cyclic adenosine monophosphate), a well-known intra-cellular mediator, may play a role outside the cell, monitoring certain chemical communication systems. Chassy et al. (1969) observed that the slime mould Dictyostelum discoideum was attracted, in oligotrophic conditions, by C—AMP released by the bacteria on which it feeds. 

On the other hand, several observations have dealt with the antibacterial activity of marine animals alcyonarians (Burkholder and Burkholder, 1958 Ciereszko, 1962), molluscs (Prescott et al., 1962 Li et al., 1965) and sponges (Nigrelli et al., 1959). Their antibiotics eire not selective and inhibit 

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