Prokaryotes associated with Ectopleura crocea
Biodiversity of prokaryotic communities associated with the ectoderm of Ectopleura crocea (Cnidaria, Hydrozoa)
The surface of many marine organisms is colonized by complex communities of microbes, yet our understanding of the diversity and role of host-associated microbes is still limited. We investigated the association between Ectopleura crocea (a colonial hydroid distributed worldwide in temperate waters) and prokaryotic assemblages colonizing the hydranth surface. We used electron and epifluorescence microscopy and, for the first time so far for a marine hydroid, the 16S rDNA tag pyrosequencing to describe prokaryotic diversity. The scanning and transmission electron microscopy revealed dense populations of prokaryotes associated with the hydrant surface. Two dominant microbial morphotypes were observed. This is among the first detailed reports of bacteria living on the hydrozoan epidermis, and indeed the first study reporting bacteria associated with the epithelium of E. crocea. The results provide a starting point for future studies aiming at clarifying the role of this peculiar hydrozoan-bacterial association.