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 Geodia cydonium 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, Albidovulum, Filomicrobium, Microtrix, Gaiellales, D90 (Gammaproteobacteria class), and Blastopirellula, exclusive to this site. Several of these taxa are known for their potential biotechnological applications, underlining the significance of site-specific microbial diversity in G. cydonium.