Endobacteria in the tentacles of selected cnidarian species and in the cerata of their nudibranch predators

This is the first genetic analysis comparing cultured endobacteria discovered in the tentacles of cnidarian species (Tubularia indivisa, Tubularia larynx, Corymorpha nutans, Sagartia elegans) with those found in the cerata tips of selected nudibranch species (Berghia caerulescens, Coryphella lineata, Coryphella gracilis, Janolus cristatus, Polycera faeroensis, Polycera quadrilineata, Doto coronata, Dendronotus frondosus). Shared pathogenic activities were found among other microorganisms in the Pseudoalteromonas tetraodonis group (TTX), and the Vibrio splendidus group (haemolytic, septicaemic, necrotic activity). Specific autochthonous endobacteria of extremely low similarity to their next neighbours were detected in nudibranch cerata. These organisms are regarded as new and unknown endobacteria; among them were Pseudoalteromonas luteoviolacea (95%), Orientia tsutsugamushi (84%), Gracilimonas tropica (96%), Balneola alkaliphia (95%), Loktanella rosea (97%). SEM micrographs provide insight into endobacterial aggregates in cnidarian tentacles and nudibranch cerata. Since certain nudibranch predators prey on cnidarian species, it is assumed that cnidarian tentacle bacteria are directly transferred to nudibranch cerata. The pathogenic endobacteria may contribute to the chemical defence of both the nudibranch and cnidarian species investigated

Endobiotic bacteria and their pathogenic potential in cnidarian tentacles

International audienceEndobiotic bacteria colonize the tentacles of cnidaria. This paper provides first insight into the bacterial spectrum and its potential of pathogenic activities inside four cnidarian species. Sample material originating from Scottish waters comprises the jellyfish species hydrozoa and sea anemone Mixed cultures of endobiotic bacteria, pure cultures selected on basis of haemolysis, but also lyophilized samples were prepared from tentacles and used for DGGE-profiling with subsequent phylogenetic analysis of 16S rDNA fragments. Bacteria were detected in each of the cnidarian species tested. Twenty-one bacterial species including four groups of closely related organisms were found in culture material. The species within these groups could not be differentiated from each other (one group of spp., two groups of spp., one group of spp.). Each of the hosts exhibits a specific endobacterial spectrum. Solely harboured Only in , members of the group #2 and the species and were detected. Hydrozoa provided an amazingly wide spectrum of nine bacterial species. Exclusively, in the sea anemone , the bacterial species was found. Overall eleven bacterial species detected were described recently as novel species. Four 16S rDNA fragments generated from lyophilized material displayed extremely low relationship to their next neighbours. These organisms are regarded as members of the endobiotic “terra incognita”. Since the origin of cnidarian toxins is unclear, the possible pathogenic activity of endobiotic bacteria has to be taken into account. Literature data show that their next neighbours display an interesting diversity of haemolytic, septicaemic and necrotic actions including the production of cytotoxins, tetrodotoxin and R-toxin. Findings of haemolysis tests support the literature data. The potential producers are ,

Endobacteria in the tentacles of selected cnidarian species and in the cerata of their nudibranch predators

This is a first comparative phylogenetic analysis of cultured endobacteria, discovered in tentacles of cnidarian species (Tubularia indivisa, Tubularia larynx, Corymorpha nutans, Sagartia elegans) and cerata material of selected nudibranch species (Berghia caerulescens, Coryphella lineata, Coryphella gracilis, Janolus cristatus, Polycera faeroensis, Polycera quadrilineata, Doto coronata, Dendronotus frondosus). Shared pathogenic activities were found among other microorganisms in Pseudoalteromonas tetraodonis group (TTX), and Vibrio splendidus group (haemolytic, septicaemic, necrotic activity). Specific autochthonous nudibranch endobacteria of extremely low similarity to their next neighbours (e.g. Pseudoalteromonas luteoviolacea (95%), Orientia tsutsugamushi (84%), Gracilimonas tropica (96%), Balneola alkaliphia (95%), Loktanella rosea (97%)) were detected in nudibranch cerata. SEM micrographs provide insight into endobacterial aggregates in cnidarian tentacles and nudibranch cerata. Since certain nudibranch predators prey on cnidarian species it is assumed that cnidarian tentacle bacteria were directly transferred to nudibranch cerata. The pathogenic endobacteria may serve as chemical defence to nudibranch and cnidarian species investigated