Benthic bacterial communities composition at submarine natural CO2 vents were investigated to assess the effect of CO2 leakage and consequent seawater acidification on benthic marine microbial assemblages. Sandy sediment samples were collected off Basiluzzo Islet (Panarea Island, Italy) both at CO2 venting areas and at CO2 not impacted area, and DNA was extracted from two different sediment layers (0-2 cm and 4-6 cm). Bacterial communities was described using 454-Massively Parallel Tag Sequencing (454-MPTS).