Exploring the Microbial Reservoir of Geodia cydonium (Linnaeus, 1767): Insights into Site-Specific Diversity and Biotechnological Potential

Marine sponges are recognized as reservoirs of diverse microorganisms that produce bioactive natural compounds. In this study, we conducted a metataxonomic analysis of <i>Geodia cydonium</i> specimens collected from four sites in Italy: Secca delle Fumose (Gulf of Naples, Tyrrhenian Sea), Mar Piccolo of Taranto and an Integrated Multi-Trophic Aquaculture (IMTA) system in Mar Grande of Taranto (both located in the Ionian Sea), and Polignano a Mare (Adriatic Sea). Our results revealed a highly diverse microbial community within the sponges, encompassing 24 bacterial phyla. Among these, Chloroflexota was the most abundant phylum, accounting for an average of 30.2% of the total community across all samples. In addition, the majority of the microbiota was composed of Actinomycetota, Proteobacteria, Acidobacteriota, Poribacteriota, Gemmatimonadota, and Dadabacteria. The sponge sample from Polignano a Mare exhibited the richest and most diverse bacterial community. This observation was supported by phylogenetic analysis, which identified seven bacterial genera, <i>Albidovulum</i>, <i>Filomicrobium</i>, <i>Microtrix</i>, <i>Gaiellales</i>, <i>D90</i> (Gammaproteobacteria class), and <i>Blastopirellula</i>, exclusive to this site. Several of these taxa are known for their potential biotechnological applications, underlining the significance of site-specific microbial diversity in <i>G. cydonium</i>.