Ricerc@Sapienza

Herein, we investigated for the first time the microbiota from the hepatopancreas of the talitrid amphipod Orchestia montagui and
the oniscidean isopod Tylos ponticus, two crustacean species associated with beached leaves of the seagrass Posidonia oceanica
(Posidonia banquette). We carried out a metabarcoding analysis based on several hypervariable regions of the bacterial 16S
rRNA gene. At the same time, three representative habitats of the supralittoral zone, namely leaf surface of Posidonia banquette,
sandy shore and surface seawater were examined by means of bacterial metabarcoding analysis. Our data analyses indicated that
the bacterial microbiota from the hepatopancreas and that from the marine habitats form distinct groups in terms of the taxonomic
composition. Comparative analyses revealed that some bacteria were associated with the hepatopancreas of the syntopic
O. montagui and T. ponticus but were not detected in the supralittoral habitats. This suggests that distinct components of the
microbial community may be uniquely adapted within the hepatopancreas. The microbiota from the hepatopancreas of
O. montagui was more complex than that of T. ponticus. However, the putative presence of polysaccharide-degrading bacteria
in both species indicated symbiotic microbiomes that might be involved in the functionality of the hepatopancreas. A deeper
understanding of halophilic hepatopancreatic symbionts in the supralittoral zone also has broad relevance to applied research,
particularly to the biotechnological sector related to marine biomass conversion.