Exploring the microbiome of sandy coastal ecosystems. A new source for biotechnologically-relevant strains and biomarkers

Sandy beaches are world-wide diffused and are constantly subjected to biotic and abiotic disturbances. Supalittoral zone of sandy beaches may also contain human pathogens, due to human impact by recreational use of beaches, or urbanization. In spite of their importance as ecological transition zone between land and sea, only very recently the microbial ecology of sandy sediments, has stirred attention. Here, we describe the composition and the dynamics, in relation to environmental variables, of bacteria communities present in sandy beaches ecosystems at Marine Protected Areas of Sardinia, Italy (MPA of Penisola del Sinis e Isola di Mal di Ventre and MPA of Capo Carbonara). In particular, we have analyzed the microbiome of i) amphipod species inhabiting the dump band of sandy beaches and, ii) the sandy supralittoral sediments. Molecular techniques (T-RFLP, Real-Time PCR, NGS barcode sequencing) were applied on DNA extracted from sandy sediments and from tissue of key amphipod species (Talitrus saltator, Sardorchestia pelecaniformis, Orchestia montagui, Deshayesorchestia deshayesi) of supralittoral habitats. Obtained results indicated the presence of a very large taxonomic diversity in both the sandy sediments and in animals, with the presence of taxa known to posses pathways for biodegradation of cellulose and antibiotic production as well as ammonia oxidation. Moreover, a large number of Actinomycetes and Alphaprotobacteria was found in the gut tissues of amphipods, which could be related to cellulose degradation and probiotic acetobacteria, similarly to recent findings obtained in Insects, as Anopheles spp. Finally, seasonal shifts of bacterial communities were detected, as well relationships between community composition and environmental variables, viz. geographical location and distance from the dump band. However, additional work is required to better understand the influence of anthropic pollution on the overall bacterial community.