BACTERIAL COMMUNITY MODULATE BEHAVIORS OF EUKARYOTIC ORGANISMS: NEW PERSPECTIVES IN RESTORATION OF THREATENED CORAL REEFS

Marine organisms have a complex life cycle that involves larval metamorphosis above surfaces, crucial to establish ecosystems as coral reefs. Nowadays corals face many threats and deterioration rates are alarming. Many projects try to find models that allow the recovery of coral reefs, focused in the interaction between bacteria and cnidarian larvae. Bacteria establish biofilms on surfaces producing, among others, Quorum Sensing (QS) molecules as N-acyl-L-homoserine lactones (AHLs). Here we evaluated the effect of AHLs on migration and metamorphosis of Hydractinia symbiolongicarpus, a hydrozoan that grows on shells of the crab Pagurus longicarpus. We first performed a characterization of the cultivable community of shells. Afterwards, signaling molecules extracts obtained from the community were analyzed by thin layer chromatography. We found that three bacterial species from shells synthetize four different AHLs or similar molecules. These extracts were tested in bioassays with H. symbiolongicarpus larvae, finding that QS molecules strongly induce the migration of larvae, a “pre-settlement” behavior in marine larvae. Induction of metamorphosis was more moderate; suggesting that other molecules might act synergistically with QS molecules to induce the whole metamorphosis process on surfaces. These molecules could be used in strategies directed to restore affected coral reefs.