Exploring the Environmental, Biotechnological, and Biomedical Potential of Panarea Island's Unique Microbial Communities

Submarine hydrothermal vents are fluids discharging fractures on the seafloor, always associated to volcanic regions. They are recognized as biodiversity hotspots due to their unique and extreme environmental conditions. The water from these vents is enriched with minerals and can be very hot. Furthermore, hydrothermal water modifies the chemical and physical properties of the surrounding environment, in term of temperature, acidity, and electrical conductivity [1,2]. Studies on bacteria isolated from hydrothermal vents have reported the production of novel bioactive natural compounds with biotechnological interest, such as antimicrobials, antifungal, and antitumoral properties [3]; in addition, recent reports have led to the identification of novel enzymes [4,5]. This study focuses specifically on the isolation of both Gram-positive and Gram-negative bacteria from the Black Point (BP) hot vent, which belongs to the hydrothermal systems of Panarea, one of the seven islands of the Aeolian archipelago in the southern part of the Tyrrhenian Sea. The aim was to isolate bacteria with biotechnological potential capable of producing unique secondary metabolites and enzymes of industrial relevance, such as amylase, cellulase, and urease. We successfully isolated 45 bacterial strains, with Gram-positive bacteria predominating at 55.55%, representing eleven genera: Micrococcus, Exiguobacterium, Bacillus, Virgibacillus, Paenibacillus, Microbacterium, Oceanobacillus, Rhodococcus, Fictibacillus, Peribacillus, and Dietzia. Gram-negative bacteria accounted for 40% of the isolates, spanning seven genera: Nitratireductor, Pseudomonas, Halomonas, Brevundimonas, Alcanivorax, and Paracoccus. Finally, 4.45% of the bacteria remain unidentified. In total, 34 strains demonstrated notable enzymatic activity. Specifically, 14 exhibited extracellular cellulase activity, 13 displayed intracellular cellulase activity, 8 showed urease activity, and all 34 strains demonstrated amylase activity. Additionally, we evaluated the antibiotic production of secondary metabolites among the isolates. Only one isolate belonging to the Nitratireductor genus showed antimicrobial properties against two multi-drug resistant bacteria (Staphylococcus aureus and Staphylococcus warneri). These findings suggest that bacteria isolated from BP could be a promising source of enzymes and secondary metabolites with industrial applications.