Mono- and multispecies biofilms from a crustose coralline alga induce settlement in the scleractinian coral Leptastrea purpurea

Abstract Microorganisms have been reported to induce settlement in various marine invertebrate larvae but their specificity of inductive capacities for the coral remains poorly understood. In this study, we isolated 56 microbial strains from crustose coralline alga (CCA) Hydrolithon reinboldii using five different media either with or without additional antibiotics and/or spiked CCA extract. We tested isolates potential behavior brooding scleractinian Leptastrea purpurea . From these CCA-associated strains, identified six bacterial classes and 18 families. The culturable community associated H. was dominated by Gammaproteobacteria, Actinobacteria, Alphaproteobacteria while Illumina MiSeq analysis showed that culture-independent Alphaproteobacteria, Flavobacteria. Furthermore, found no correlation between phylogenetic relationships. Instead, L. induced specific species. Strains #1792 ( Pseudovibrio denitrificans ), #1678 Acinetobacter pittii #1633 Pseudoalteromonas phenolica #1772 (Marine bacterium LMG1), #1721 Microbulbifer variabilis #1783 rubra ) at mostly high significant levels (? 40%) remaining strongly varied activity. Multispecies biofilms consisting four (#1792, #1678, #1633, #1721) were observed synergistically increase (> 90%); however, addition multispecies negatively affected resulted a total loss inducing findings provide new insights into role bacteria process corals may help identify true nature bacteria-derived morphogenic cues.