New phylogenetic lineages of the Spirochaetes phylum associated with Clathrina species (Porifera).

Though spirochetes have been repeatedly found in marine sponges and other invertebrates, little attention has been paid to the specificity of this association. This study demonstrates that different geno-and morphotypes of spirochetes can reside within the same sponge individual and develop in considerable numbers. Specimens of the calcareous sponge Clathrina clathrus collected from the Adriatic Sea off Rovinj (Croatia) were found to harbor spirochete-like bacteria, which were characterized by scanning electron microscopy (SEM), 16S rRNA gene analysis, and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH).